Once a tank is installed, it may be built-in or removable, you don’t want to have to do anything to it again other than general maintenance so it is very important to do the job right the first time.  Diesel fuel tanks can be built from stainless or mild steel, aluminium or fibreglass. Water tanks should be stainless steel, aluminium or fibreglass. Never use aluminium for holding tanks as there are chemicals in human waste that may corrode the aluminium. Both fuel and water tanks can be purchased, pre-made in rigid or flexible synthetic material.  I prefer to avoid the use of petrol or gasoline as a fuel for boat engines, or for any other use in a boat but in some situations this may be unavoidable so, be sure you seek professional advice on any such installation and what safety precautions to take. Over the years there have been some bad accidents with petrol/gasoline installations so you cannot be too careful with this fuel.

   In fibreglass boats, fuel and water tanks can be made of fibreglass, usually built in to the hull under the floor or furniture – special resins are available for this purpose and, in the case of water, are tasteless. Fibreglass tanks are not difficult to make and can save a lot of money – consult your fibreglass suppliers or boat designer for details.   Don’t forget to correctly vent all tanks.   The pipe for drawing off the liquid should enter through the top of the tank and not quite reach the bottom. In the case of fuel tanks, there should be a little reservoir around this pipe to stop the fuel sloshing around when the tank is low.   If a drain cock is fitted, it should be easily accessible and at the lowest point of the tank.   There should be access holes, large enough to allow cleaning of the tank interior, in every compartment.  The tops of these access holes should bolt in place and be fitted with a sealing grommet or compound.  Thoroughly test all tanks with up to 3 pounds of air pressure and post cure fibreglass tanks for at least 24 hours with a light bulb.  

On older long keel boats was usual to cut an aperture in the aft end of the keel to accommodate the stern bearing and propeller.   Today most long keel boats are designed with a metal or timber heel or shoe attached to the aft end of the keel so apertures are seldom cut into the keel itself.   In cases where there is not enough room for the propeller aft of the keel and ahead of the rudder, it will still be necessary to cut an aperture.

   As it may be desirable to place the engine in your hull before the installation of the deck and superstructure, it is probably a good time to consider forming the aperture or arranging the heel on your hull. If the engine is to be installed at a later date it is still possible to prepare for the installation using a cardboard or plywood mock-up of the engine and using measurements from the manufacturer’s brochure.

   The size and location of the propeller will go some way towards governing the angle of the engine (maximum angle 10 deg) and the size and location of the aperture.   Next you need to figure out the shaft line.   This can be obtained using the simple plywood mock-up of the engine.   This mock-up should show the shaft line in relation to the engine and gear box and position of the engine feet.   It is possible to buy an angled gearbox but, even though the engine remains level or near the level in the hull, the gearbox will still have to be lined up with the shaft.

   The pre-prepared profile mock-up can be arranged so that it is in the proper position relative to the engine beds.   Once the beds are installed, the profile can be used, in conjunction with a string line from the centre of the drive shaft to a hole in the aperture to obtain the correct shaft line. In fibreglass boats, once this shaft line is established, you can make a fibreglass shaft tube over a mandrel, with the cutlass bearing in place, and glass the tube in to the boat making any final adjustments through the engine mounts.

   There are three types of aperture.  One is where the aperture is cut out of the aft end of the keel.   The second is where there is a skeg and the aperture is cut out of the skeg or, better still, the propeller is just in front of it and the third, and more desirable arrangement, is where the bottom of the keel is extended in the form of a shoe (heel) which is used to take the lower rudder bearing.  The first two types are usually found on sailboats.  The third is found on both sailboats and displacement hulled power boats.   Where the aperture is cut out of the back of the keel, it should be cut out so that it will provide room to remove the propeller without having to remove the rudder and the shaft could be slightly offset so that it can also be removed without removing the rudder.   The aperture should be of sufficient depth to allow at least 2” [50mm] propeller tip clearance both top and bottom.   Once the aperture is cut then it must be reconstructed from foam or timber and shaped to allow the fitting of the shaft tube with fluting above and below the tube to facilitate a clean flow of water around the rudder and propeller. 

STERN TUBES

You may wish to fabricate your own fibreglass stern tube – if you know a bit about fibreglass, it is not difficult and a fibreglass stern tube in a fibreglass boat is the obvious way to go.   Study the illustrations shown here and this will give you a good idea of how this can be accomplished or follow details given in your plans.

SAILBOAT RUDDERS

The first step in making the rudder is to make a template of the shape using the measurements and other information shown in your plans, plus some check measurements taken directly off your boat.   The pattern should allow for the top and bottom bearings and is best made from ¼” [6mm] hardboard or plywood.   The rudder stock should be made from 316 grade stainless steel and may be solid round or heavy walled tube. Your plans should give you recommended sizes or you should consult a qualified marine engineer.   When welding the tangs to the stock, be very careful not to distort the stock by applying too much heat in any one area so make sure the welding is undertaken in a progressive manner to minimize the chance of distortion.   The rudder core may be made of plywood, timber or foam or a combination. Foam has the advantage that it is easy to shape and any water that may seep between the fibreglass and steel shaft will no effect.   When the core is in place, dress off the rudder to its desired airfoil shape.  

   Lastly, you will install a heavy laminate of fibreglass to the entire rudder.  It is important to achieve a good seal where the fibreglass meets the steel shaft.  Epoxy resin would give the best bond between the fibreglass and the stainless steel although most rudders are still made using polyester and foam as any water inside would have little effect.

By now you should have your deck and cabin top camber pattern prepared.   If you have not already done this look at your plan and transfer the measurements for the deck widths, cabin lay-in, cabin heights etc., on to the bulkheads.   Mark out each bulkhead ready to receive the decks and cabin structure.

   It is a good idea to cut several temporary camber boards to be used as intermediate supports for the cabin and deck during construction.  As it is unlikely there will be enough bulkheads to support the deck structure while you are moulding it in place or, bonding on a pre-laminated section, these camber boards should be installed until the deck and cabin are complete.   Temporarily fasten the camber boards to the deck shelf and they will then either support the hardboard form work that makes up the in-place mould, or the parts of the pre-laminated deck as mentioned above.  

BUILDING THE DECK

There are a number of methods that you can look at to build your decks.  You can use an in-place hardboard mould, a purpose built female deck mould on which the deck is laid up in one piece or sections, fibreglass sandwich panel moulded decks or straight plywood sheathed in fibreglass.

HARDBOARD IN-PLACE DECK MOULD

This method involves building a timber and hardboard mould on the hull and after the decks and cabin are completed, the hardboard mould is removed in pieces from underneath.   This method is well proven and thousands of decks have been built this way.   Using the hardboard, you will finish with a smooth interior but the outside will have to be finished. You must sand the exterior of the decks, cabin and cabin top to achieve an acceptable finish.   If you choose, it would be a simple matter to attach any suitable fabric lining material to the smooth interior.   Think of this option as a male moulded deck and superstructure.

   The camber boards or temporary deck beams are cut and installed at say 24” [610mm] centres by nailing to the deck shelf.   Next install sufficient longitudinal battens or deck stringers to support the hardboard lining.   Generally stringers should be about 9” [230mm] apart and these are checked into the temporary camber boards.   You can expect to use ¼” [6mm] hardboard or a similar material.   While we refer to hardboard in this text, you may be using a similar material such as melamine coated plywood however, to avoid confusion, we will refer to the lining as hardboard.   The whole structure of camber boards and stringers should be set ¼” [6mm] or at a thickness equal to your lining material below the upper surface of the deck shelf.   This is so that the fibreglass laminate will run smoothly from the hardboard lining material across the top of the deck shelf and go on either up the bulwark or on to the exterior of the hull to form a “Coffee can” hull to deck join.

   Nails should be kept to a minimum when fastening the hardboard to the framing for the in-place deck mould.   Any nail heads will show (unless covered with a lining material) on the finished laminate from inside.   Fasten the hardboard to the framing using contact glue.

   The upper smooth face of the hardboard will provide the surface on to which you will laminate the deck.   Study the sketches shown here and your plans which should give you sufficient guidance for the deck join and other features of fabricating your particular deck and cabin.   You will note that there are certain areas that the hardboard will not cover for a particular reason.   It will only extend out to the inboard edge of the deck shelf because as you laminate will go from the hardboard and bond on to the top of the deck shelf.

   After all of the hardboard sheeting is completely installed, remove any unevenness by placing bracing under the formwork.   Radius all edges and corners a minimum of 3/8” [10mm] – these radii will need to be fine sanded and coated, with two or three layers of polyurethane to make them non-stick for the fibreglass laminate.   This radius can usually be achieved through the careful application of resin putty (bog) using a putty knife with a rounded end. Cabin top edges will have to be formed from an easy-to-sand timber.

PREPARING FOR THE DECK LAMINATE – HARDBOARD DECK MOULD

Once you are satisfied with the finish of the form work for your deck and superstructure, you should then cover all the hardboard surfaces with four coats of non-silicone wax polish – consult your fibreglass supplier for the correct material.   Allow at least one hour drying time between each coat of wax.   Pay particular attention to the corners and joins.   The areas to be waxed are those where you will later want to remove the formwork such as the hardboard and any special shaping you have arranged for the corners.   When the final coat of wax has been applied and polished, you should then coat the entire area to be laminated with a PVA release agent.  

 Talk to your resin supplier about the supply and use of this material.

   Do not wax or cover with release agent those areas where you want the fibreglass resin to stick to the surface.   Areas such as the top of the deck shelf,  tops of bulkheads,  the toe rail, the hull sides where the laminate will be bonded to the hull,  either outside or inside the bulwark,  or any other area where you want the fibreglass of the deck to be bonded to an area of the hull or elsewhere as noted. 

PLYWOOD PADS

Now is the time to consider where you are going to place any plywood inserts to allow for later through bolting of the various fittings.   The ply inserts should be the same thickness as the core material and the fittings will include such items as chain plates, stanchion bases, windlass, bow fittings, cleats, sail track, winches and mast step or where the mast will go through the deck in the case of a keel stepped mast.    The plywood pads may be only slightly larger in area than the base of the fitting concerned.   The idea is that the plywood will not crush, as might happen with foam or balsa, when the fitting is through bolted and the bolts tightened.   Although balsa core has excellent compressive strength, it is not equal to the type of strains imposed by through bolting the fittings.   At this stage, you can make up all of the plywood inserts, mark their location, and identify each piece before they are put aside ready for installation at the same time as the core material.  

APPLYING THE DECK LAMINATE

The first job in fabricating the deck will be to install the inner laminate.   The inner laminate will consist of a varying number of layers of mat and roving.   The number of layers will depend on the type and size of your boat however the laminate should be clearly shown in your plans.  

INSTALLING THE DECK CORE

Before installing the last of the mat, check over the laminate and carefully sand off any humps or bumps.  When you are satisfied with the evenness of the laminate installed so far, simultaneously install the last one or two layers of the mat and the core material.   The core material will usually be ½” or ¾” [12mm or 20mm].   The core material, usually end grain balsa or PVC foam comes in sheets that are usually made up of small squares of material attached to a scrim cloth and in most areas you can install complete sheets however, in some areas such as the cabin sides and cockpit you will need to cut the sheets to fit.   It is a good idea to prepare one area at a time, say one third of the deck and cabin area can be pre-fitted with the core sheets.   These sheets should be numbered and laid out in an area adjacent to where they will be placed and in a manner similar to which they will be applied to the deck and cabin.   It is necessary to work quickly when installing the core so everything should be well prepared.

   When installing the last layers of the Mat before the core is to be fitted make it a resin rich layer as some resin will be absorbed by the core material.   Next, lay the core sheet on the wet mat and apply enough pressure to feel that the balsa is well bedded.   The resin should squeeze up between the joins in the blocks and where the sheets join.   It may be necessary to use a system of weights to hold the core in position.   This should only really be necessary in difficult areas, such as where there is excessive camber or where you are installing the core where it will not lay smoothly in position.   It is a good idea to use plastic sheeting under any weights, so that the weights do not get glued to the core surface.   You may want to look at using “Vacuum Bagging” to install the deck core – see later chapter.

   Once the core is installed and the resin has cured so that the core stays in place, then fill any gaps with resin putty and seal the top of the core with two coats of resin.   You can then lightly sand the surface to remove any rough edges and other irregularities before proceeding.   If necessary, you may also use a resin putty screed to smooth out the surface however do not overdo this as you may impede the bond between the core and the outer layers of the laminate – your materials supplier should be able to advise you at this stage.   The more attention you pay to achieving a smooth surface to the core the easier it will be to end with a smooth outer and final surface finish to your deck and cabin.   Some designs may suggest solid glass cabin sides, cockpit sides and coamings but stick with the core material, if possible.   On some occasions you may be required to apply the core to near vertical surfaces.   Depending upon what material you are using the answer to this problem and any others should be in the manufacturer’s brochure or available from your supplier.

    Once the core is in place and dressed off to your satisfaction, it is time to install the final outer deck and cabin laminate.   Use the same techniques here as suggested for laminating a male moulded hull.    There is no point in installing more laminate than your plans specify.   You will do more harm than good if you put in extra layers causing excessive weight in the wrong place.   This will be your last opportunity to even out your laminate and make life easy when you come to the final finishing of your decks and superstructure.    Once you have installed the outer laminates then it is time to consider finishing the surface using similar techniques to those explained in the chapter on building male moulded hulls.

When considering the deck to hull join there are three possibilities that we have available - chemical, secondary and mechanical bonding.   It is common to use at least two, chemical and mechanical or secondary and mechanical however, secondary bonding on its own is the most common and is usually sufficient.

   The chemical bond is where the deck is bonded to the fibreglass of the hull structure whilst they are both in a “green” state but this is difficult to achieve as one would have cured before a chemical bond is possible.  If too much time has elapsed between the lamination of the hull and the installation of the deck, you will not achieve a true chemical bond.  Secondary bonding is more common where the two surfaces have been sanded and cleaned in preparation for the join – if necessary, read again the earlier text on “Secondary Bonding” before you go further.   We have made test panels to simulate a secondary bonding and in destruction tests, the laminate has usually failed elsewhere before it failed at the join.

   Add to this a mechanical join, which is achieved when the toe rail is bolted through the hull and deck laminates where they meet at the sheer or where the rubbing strip is bolted through the deck laminate which has been brought over the edge of the hull.   Another join can be made when bolting the rubbing strip through the deck shelf and any inner bonding that joins the underside of the deck to hull.   So now we have the possibility of bolting both vertically and horizontally!  

LAID TEAK DECKS

It is possible to install a teak deck on top of the fibreglass deck but this means screwing into the fibreglass laminate and possible leaks, at a later date.  Keep the thickness of the teak down to say 3/8” [10mm] and install the teak planks using a marine polysulphide or epoxy.   The grooves or spaces between the planks should be filled with polysulphide.

There are specialists who do this type of work and so it may be worth while employing the expert for his experience and specialised knowledge. 

NON-SKID DECK FINISHES

All horizontal surfaces and anywhere where a person might place a foot should be finished with non-skid.   This can be achieved using either a prepared deck paint which incorporates pumice or other non-skid material, or by applying fine clean sand in the last two coats of the outer surface paint.  Washed, coarse beach sand is probably the most effective and can be sprinkled on to the deck through a stocking or a tin with holes punched in the top. The sand is applied to the penultimate coat and areas around the cabin, hatches, winches and coamings should be masked so that you have a clear area when applying the final coat.  Another method is to apply one of the synthetic or cork based non-skid materials which are sold in sheet form and are cut, fitted and glued to your decks.  

   No matter what method you use to create a non-skid surface, make sure you arrange the non-skid material in such a way as to provide small sections, strips or panels of smoothly finished deck around the edges of the sheer, around the inner surface of the decks where they meet the bottom edges of the cabin sides.   There should be a small smooth strip around all hatch coamings and areas where fittings are to be installed.  Check out other boats, you can obtain many ideas from the boats you see in the local marinas.

   Before you finish your decks, you should consider your hatches.   If you are going to fit commercially made hatches, do not cut the hatchways in your deck until you have the items on hand and can make accurate templates or take proper measurements off the hatches themselves and leave a clear strip around the hatch.

Once the decks and superstructure are complete, it is time to remove the inner timber and hardboard formwork.   First, carefully remove all the timber camber boards and supports and the longitudinal stringers – a lot of this material may be useful in framing the furniture so save what you can.  You will find some longitudinal stringers and pieces of hardboard locked into the structure by the bulkheads, so very carefully saw or cut through on either side leaving the small piece intact above the bulkhead.   You could use a very sharp knife or a saw set to a very fine depth to cut along the edge where the hardboard will be later covered with a trim strip or bonding.  Some glue can be added, if necessary, to fix this remaining piece in position or, leave it to be covered with resin putty before finally bonding the bulkheads.     

After you have removed all the form work it is time to consider the bonding of the bulkheads to the under side of the deck, cabin sides and top.  If you are not going to cover the bulkhead, you may want to mask them off parallel to the areas where the bonding is to take place, and trim the glass as it cures, otherwise the bonding will have an untidy edge.   Normally the bonding will extend three or four inches [75mm to 100mm] on to the bulkhead and to the deck or cabin side or top.   Make sure you thoroughly sand and clean the areas where a residue of wax or release agent would inhibit the bonding.

   Once the inner bonding has been completed, you have basically finished the building of your decks and superstructure.   You should now look at forming the furniture and consider what type of lining material, if any, you will use to finish the interior.   There are many attractive and serviceable types of lining for fibreglass boats.   Some builders like to use a short pile carpet that is glued to the interior, or you may choose one of the foam backed vinyl materials or, go the traditional route and install timber lining – tongue and groove timber looks good and is relatively easy to fit and, last but not least, a simple gelcoat and paint finish looks good.   Too much timber trim in a boat can make it excessively dark below.   In the areas where the bonding between the hull and the bulkheads and between the under side of the deck head has been done, you may want to install a timber trim strip to cover the join.   While you have been planning and building your boat, you should spend some time looking at other boats for ideas.   Pay particular attention to the various fitting out and finishing techniques.

SANDWICH DECKS AND CABIN

For sandwich decks, the choice of core material is either PVC foam or end grain balsa. Check with your suppliers for the best material to use. There are now some PVC foams that are suitable for decking.   The thickness of the core and the laminate requirements should be specified in your plans.   Your plans should also clearly show if any supporting beams and girders are required.   A well-engineered sandwich cored deck should not require extra beams – the strength is in the sandwich and the supporting bulkheads.   Boats over 40 feet [15 metres] may require some reinforcing in the deck especially if built to survey.

MASTER DECK MOULD

Your first job should be to cut the master camber board; sometimes your full size patterns will include this otherwise, you will need to draw out the camber from measurements.  You should make up a full width plywood or timber camber pattern.   By using a wide plank, which can be edge laminated to a suitable width, you can make both male and female patterns with the one saw cut.

   Next job is to build the master deck mould.  This mould will serve to mould for all the deck and cabin top panels and even curved cabin fronts can be laminated on this mould.   Make the mould wide enough to fit the widest section of the deck or cabin on your boat.   This may be the aft deck, poop deck or perhaps the cabin top.   On sailboats and on some power boats, the camber is often greater for the cabin tops than the deck, however for a power boat with a flying bridge, it is best if the standard deck camber is used for all purposes.  The reason for this is you do not want a heavily cambered deck in the flybridge area.

   The length of the master deck mould should be a few inches longer than the longest panel required but, as panels can be joined, 16 feet [4.9 metres] long is sufficient for most boats up to about 65 feet or [20 metres].  Build the deck mould without sheer (fore and aft camber) as when first moulded, the deck panels will be flexible enough to bend to the shape of the hull.

   Build the master deck mould using similar techniques to those used to build the hull mould.  Set up the structure on bedlogs and build the mould with the camber in reverse.   Use the female camber boards as the frames and install battens to receive the mould lining.   Waxed hardboard will serve well as the mould lining.   Attach the mould lining with contact cement and nail only where necessary.   Any nails will show up in your finished moulding so try to avoid excessive nailing although most areas will have to have non-skid applied so this is not a major problem.   Prepare the mould by waxing with non-silicon wax and, if necessary, apply release agent. Tests can be made to see how well the mould releases.

   Place temporary beams across the hull in the areas where the deck moulding may need to be supported – these mouldings should almost be self-supporting straight out of the mould.  Supporting beams should be inside the deck shelf so the pre-laminated deck part can sit flush on the shelf.   Make a pattern of the section of the deck you are going to laminate and transfer it to the mould.   To make the pattern, you can use strips of plywood stapled together to get the approximate shape and then use a spiling block to obtain the exact shape marked on to the pattern or, trim the moulding once it is in place.     Use masking tape, to outline the shape on the deck mould.  

   It is probably better not to use gelcoat as you will have to paint and apply the non-skid after moulding and joining the parts.   It is possible to apply a non-skid pattern to the mould surface however this can be tricky and should not be attempted without experience also, you will later be bonding the deck in place and would probably spoil the effect of the mould-in pattern.   Use a similar laminating technique to that used for the hull, no more than two layers per day or whatever the manufacturer recommends for the particular resin that you are using, otherwise the deck piece may distort and pre-release from the mould.   It is important to remove the deck part from the mould as soon as it can be handled.  This means that it will be “green” and can take up the sheer, if any, of the hull.   Therefore,  make sure the centre of the panel is well supported,  camber boards set right across the hull at every 3 feet [1 metre] apart should be sufficient.   Check after you install the first piece.

   Any deck beams, girders or special stiffening called for in your plans should be laminated on to the panel while it is still in the mould.   Allow for the deck shelf when installing beams as they should be shortened by the width of the shelf.   If you want to use interior gelcoat, then should be applied to the deck panel while it is still on the mould.   Keep the gelcoat away from the edges where it will later be bonded to the deck shelf.   Keep any cored material stepped back from the edge to allow the inner and outer layers of laminate to join by way of a tapered edge of the core as shown in the drawings.   Side decks can usually be laid up flat on a piece of hardboard on the ground or on a bench.

You will be surprised how quickly you can make the deck and cabin with this method.

If you can build a female mould for the cabin and cockpit you can save a lot of finishing work.   This avoids much of the sanding, which is required to obtain a satisfactory finish on male moulded decks and cabin structures.  If you are building a boat under 33 feet [10 metres], you may want to consider making a female deck mould that incorporates the deck and superstructure in one piece.   This mould would be female in form and would give you a smooth outer surface.   The inner mould surface should be covered with a lining material similar to that used for the male moulded methods.   Another choice is to build female moulds for the cabin, cockpit and other shaped parts and make the decks as flat panels.   These simple moulds are reasonably basic and easy to build using cheap pine and lining with a waxed hardboard.

Single skin decks are not usual on pleasure boats but common on workboats of over 45 feet [13 metres] where a heavyweight system of beams and girders is required to take the extreme loads of fishing gear and deck equipment.

BONDING THE DECK

All deck sections and panels should be bonded from the inside and outside.   Your plans will should show how many layers this should be and how you should taper the laminate towards the edges to allow for this, when laying up the panels.  This will help in avoiding ugly bulges where the deck has been joined.   Remember to sand off any residue of wax before attempting to bond the sections.   When joining the panels and bonding the deck to the hull it is useful to have a piece of plywood on which the fibreglass can be saturated in a down-hand horizontal position then it can be, carefully, picked up and put in place ready for rolling. This avoids trying to apply resin in a vertical or, worse, an upside down position.

CABIN SIDES

Lay up the cabin sides on a single flat hardboard table or similar mould surface.   A flat mould can produce many and varied panels for use in the superstructure and elsewhere. The cabin sides can be solid glass or cored sandwich and the procedure is the same as for the decks and cabin tops.

BULWARK STIFFENERS

If you have bulwarks on your boat and they are single skin, then you should think about some stiffeners.   These stiffeners can be very attractive and give your boat a “Little Ship” appearance.   They should be solid fibreglass and the top of the stiffeners should be at least as wide as the cap rail. They should be made so that the water can drain and disperse through the scuppers.

HULL DECK JOINS

If you are using the “coffee can” join where the deck laminate is continued over the hull sheer down a few inches on to the hull,  then you will need to mask off the hull below the line where the overlap bonding will end.   Sand the area of the hull above this line so you will have a good key for the overlapping bonding.   As the bonding proceeds make sure you trim each layer cleanly along the top of the tape on the hull side.   This will create a fair line with a clean edge that can be covered by your rubbing strip or moulding.

   When you are moulding the various sections of deck, it is a good idea to join these on the top of a bulkhead as the top of these bulkheads can be thickened with suitable timber flanges.

   Once you get used to the “Ezi-build” methods, you will find many ways to use the methods we have briefly outlined here.   Using panel construction combined with inexpensive moulds, will allow you to build just about anything, easily and quickly.   There is nothing new in the methods we have described, just the re-introduction and rearrangement of a few techniques we have been using for many years.

   These methods described in this book are best used for one off boats or where a limited number only are to be produced.   If you are intending to build more than 5 fibreglass boats of the same design,  then you should consider building timber plugs and “taking off’ fibreglass moulds which would be capable of producing any number of hulls and decks.   Nowadays, these plugs can be produced through computer modelling which is known by such names as CNC Pattern Making or CNC Milling and which is quick, accurate and painless except to the pocket!

PRODUCTION MOULDS

As mentioned, if you are planning to build a number of hulls, you may want to consider a full production mould.  The usual method is to build a plug and, from this, make a mould capable of withstanding long and frequent use.   The plug can be made of timber in a similar manner to building a one off timber and batten mould.   Cover the exterior with three or more layers of plywood and then sand and paint.   The plug must be perfect on the outside, but underneath the construction can be rough and ready as the plug only has to last until the mould is completed.

   The mould is laid up over the plug.  First, a parting agent such as wax or PVC release agent or a combination is applied to the plug.  Next, a coat of tooling gelcoat and then the laminate is gradually built up to a thickness that will make the mould strong enough to last as long as required.   The outside is fitted with foam and glass ribs to stiffen the structure.   Finally, plywood and timber, or sometimes, steel is bonded to the mould to allow it to be tilted or set on a cradle when in use.   Remove the mould from the plug and, if everything goes according to plan, the mould with some final interior finishing is ready for use.

   Deck moulds are built in a similar manner.   First, a plug is constructed from plywood, chip board or whatever will do the job, then a mould is taken off in a similar manner to the laminating of the hull mould.   Give some thought to the hull to deck join which is usually in the form of a flange or overlap.   Sometimes, the join is designed to be made under the top of the toe rail.   A coffee can join is where the deck overlaps the hull in the manner of the older types of coffee can lids.

   If your budget allows, these plugs can be produced through CNC computer modelling which, as already stated, is first class but expensive and can only be justified if you are going to make a certain number of boats.

It is quite possible to vacuum bag polyester/glass laminates, but there are a few things that you must look at to determine if it's practical for your application.

The vacuum bag process brings atmospheric pressure to bear evenly on the curing laminate but applies no load to the mould so that excess resin is squeezed out and, usually, soaked up in a disposable outer wrap. This technique requires a vacuum bag and a vacuum pump capable of pulling a significant vacuum (at least 25 inches of mercury), and various accessories and supplies. You should allow for the cost of the vacuum bagging equipment, materials (pre-release film, peel ply, breather, vacuum bags, mastic tape, vacuum pump etc.,) and extra labour as you will have to finish a complete layer, or two, before the bagging can be applied. This means that you will have to be using a slow cure, low exotherm resin. To offset this added cost, with the correct vacuum, you will gain the advantages of a near perfect resin/glass ratio and have any fumes extracted from the laminate and ejected via the vacuum pump. Until now vacuum bagging has been mostly restricted to commercial use and a few enterprising owner builders.

   Vacuum bagging epoxy laminates is more common as the cure is slower and the strength/weight ratio, usually, more critical. With polyester/glass laminates, it is more usual to use vacuum bagging on the core (dry bagging) rather than on a solid fibreglass laminate. Vacuum bagging allows cores to be bonded in place with minimal amounts of adhesive. When you compress fiberglass under vacuum, you can loose up to 30% of the thickness, which will greatly decrease the stiffness so coring the laminate may be the only way to go.

   Your materials suppliers should be able to supply most of the equipment and advice that you will need for vacuum bagging or tell you where to get it and, possibly, advise where you can see the technique in operation.

RESIN INFUSION

Resin infusion is another process that is becoming increasingly popular, particularly in the marine industry. Laminates are being made lighter and stronger while using much less resin. The cost and technical requirements rule it out for one-off boats whereas vacuum bagging is becoming a serious possibility.

WOOD – DECKS AND SUPERSTRUCTURE

If you have built your hull in timber, you will almost certainly build your deck and superstructure in the same material. To this end, your first job will be to equip yourself with a camber pattern for the decks and another for the cabin top. These master camber patterns will serve in many areas of the construction from this point onwards.  Make a careful copy of your camber patterns.   If you cut your patterns from heavy plywood or wide boards, you can have both male and female patterns produced at the same time and you will find many occasions when both will be useful.   You will be using the camber patterns to transfer the cambers on to many areas of the decks and superstructure so make them strong enough to last.

BULKHEADS

At this stage your bulkheads should be installed and standing square above the sheer.  The first thing is to mark out the width of the side decks and, to accomplish this, it helps to mark the camber right across the boat from sheer to sheer - this way you will get an even camber.   Later you will mark the amount of the cabin side lay-in and the height and camber of the cabin.  

   Now is a good time to check the headroom.   Do not be tempted to increase the headroom without checking with the designer.   An inch or two [25 to 50 mm] of extra headroom may spoil the line of the boat whereas it may be possible to lower the sole before raising the cabin. 

If you find you need more headroom it should be done in increments, partly by lowering the sole, partly by raising the freeboard of the hull and partly by increasing the height of the cabin sides so talk to the designer as it is his job to consider all aspects of changing any design especially where the changes may affect the stability of the boat.

Any camber is part of a large circle.  For decks, a camber of 3% of the boats beam is normal.  For cabin tops, 5% of the width of the cabin top is the maximum recommended.   Cambers have reduced in recent years as modern methods, materials and higher freeboard makes it unnecessary to have the larger cambers that were fashionable in the past.   For power boats fitted with a flybridge, the cabin top camber should have a maximum of 2% .

DECK BEAMS

At this time you will need to decide if you are going to use transverse or longitudinal deck beams.   In the days of wooden boats, all deck beams had to be installed transversely because the deck planking ran fore and aft.   Now that we have plywood to use for decking you may find it easier to use longitudinal deck beams or a combination of both longitudinal and transverse beams.   At the same time as you are installing the beams, you should frame up for the cockpit coamings and hatch openings.  

   If you are planning a laid timber deck on top of the plywood sub-deck, then it would be better to use transverse deck beams so that you will able to through fasten the timber deck planks unless, the deck itself was thick enough to take these fastenings.   Even if you use longitudinal beams and later decide on a laid deck, you have the option of using the diagonal or herringbone design to pick up these beams.  

Before you can fit any deck beams or decking, if not already in place, you will need to install the deck shelf around the inside of the sheer.

   After the camber is cut, you may decide to attach a transverse beam to the top of each bulkhead and at the deck line before installing beams.  This applies regardless of whether your main deck framing is transverse or longitudinal.    Even with transverse beams you will need a few short longitudinal beams such as for the cabin top in way of the mast step and one in the fore deck, known as the king plank, in way of the positioning of the mooring bitts, anchor winch or fore deck cleat.   Fore and aft king planks can be wider and shallower and can be checked into the transverse beams.

   If you are installing transverse beams, these can either be sawn or laminated.   A typical beam would be 1 ¾” wide [45mm] by, say, 2 ¾” [70mm] deep.   This beam can be made up of laminations of 1 ¾” [45mm] wide by ½” [12mm] with one thicker layer to make up the odd amount.  The layers of timber can be set up in a purpose made jig or made over a master beam assembled on the widest bulkhead.   It is a good idea to make up the beams well in advance.   These beams can be laminated, daily or weekly and set aside until needed – when made, be careful to store them out of the sun and the longer you can leave the beams on the jig, the less spring back you can expect.

   Once you have fitted all the deck framing , check it over and dress off any unfair areas.   Make use of a batten laid diagonally across the surface of the deck framing to make sure you have no lumps or hollows which will give you problems when you start to fit the plywood decking.  

PLYWOOD DECKING

When you are satisfied the framework for your deck is ready, you can you can start to install the plywood decking.   Your plans will tell you how many laminations of plywood will be needed to make up the total thickness required.   The first layer is nailed and glued to the deck framing and the second and subsequent layers are glued and stapled to the first.   At this stage, you can save a lot of time with the use of air tools to fasten the decking. 

   Be careful not over nail the first layer to the beams.   Remember the nails are only effective until the glue has cured.   In the case of the staples, these should be removed after the glue has set and between layers. 

   When finished, you will need to cover the plywood decks with fibreglass as they cannot be left unprotected and simply painting them would not offer sufficient protection.  After the fibreglass has cured the decks and cabin tops can be sanded and painted and a non-skid surface applied.

LAID DECKS

A laid deck can be structural or decorative.  For a laid deck to be considered as contributing to the structural strength of the vessel, the planking would need to be at least ¾” [20mm] thickness and the planks should be set in mastic or polysulphide and screwed to the beams or decking.  The screws heads should be at least ¼” [6mm] below the surface of the planking and protected with timber plugs.  If you install a structural laid deck, you can reduce the plywood deck to compensate for the strength of the overlay.  

   If you are intending to install a laid deck, it will need to look like a traditional installation, regardless of whether or not it is only intended as a decorative non-skid finish. There are a number of ways to accomplish this finish including buying pre-made decking, which can come in sections like plywood sheeting with the grooves cut in to one side or, pre-prepared teak deck planking from specialists that you can lay yourself or have their artisans do the job.  

   Before you decide to tackle the installation of a laid deck, be advised that it is a very labour intensive operation and either you or your hired labour will take several days to install even a modest sized deck.   The planking can be laid in several ways.  Traditionally, it would follow the curve of the sheer or it could run fore and aft parallel to the centre line or a combination of the two or, may even be installed diagonally at a 45 degree angle.  Use silicon bronze or stainless screws, depending upon the deck type, with the heads set below the surface to allow for a timber plug to hide the screw.  

The best method of protecting plywood decks and superstructure is to sheath them with fibreglass or Dynel cloth using epoxy resin.   Polyester resin can be used but, if you want the best long lasting job then, epoxy is the way to go. We have used polyesters for many years with satisfactory results but, when there is a better product that is not too much more expensive, why not use it. Generally speaking you need to use two or more layers of sheathing set in epoxy resin to get the best results. Two layers of cloth weighing 18 oz per sq yard or 500 grams per square metre would be about right. Larger boats say those over 36 ft or 11 m on deck, may benefit from additional layers of glass. 

    Before starting to sheath plywood decks and superstructure, you should fill all nail and staple holes and any other blemishes.  All holes should be filled flush with the face of the plywood and all corners must be rounded to accept the fibreglass.   Use a filler, compatible with the resin you are using, to create a radius for the fibreglass sheathing to smoothly progress from cabin sides to decks, coamings to decks and anywhere else that it is required.

   After you are satisfied the decks and superstructure are ready to accept the fibreglass sheathing, give the whole area a coat of thinned resin and allow this to cure before proceeding with the sheathing.

   Any excessive moisture content in the plywood will prevent you achieving a lasting bond between the fibreglass and the plywood decks and superstructure so be sure that the plywood is dry and the humidity level acceptable.  

   Even if you plan to install a laid fibreglass deck over the plywood, it is still advisable to install at least one layer of fibreglass between the plywood and the laid timber deck.   A fibreglass finish will form an excellent seal for the cabin sides and other areas where there is no laid decking.   If you follow our advice on the above matters, you should have a totally waterproof deck that will last indefinitely.  Once the sheathing is complete and the resin has cured it will be necessary to apply a non-skid finish to all horizontal surfaces. This can be achieved a number of ways already mentioned in the fibreglass chapter.

INTERIOR JOINERY

Once you have installed the bulkheads and the sole, the techniques used to fit out the interior of a steel, fibreglass or timber boat are all very similar.   A considerable amount of the joinery is attached to the bulkheads and the sole but where the joinery is attached to the hull, you must make special provision for this attachment depending on the hull material. Fibreglass is probably the easiest as it can be bonded almost anywhere, steel and timber need purpose grounds put in place to take the furniture.

SUGGESTED JOINERY DIMENSIONS

The dimensions of the human frame have changed considerably over the past years so we have to adjust accordingly.   When I first started to build and later design boats, a berth with an overall length of 6’2” [1.88m] was considered adequate.   Today, the same berth would be expected to measure around 6’6” [1.98m].   Here are a few measurements that I would consider relevant today.

   Single berths should be 6’6” [1.98m] or minimum of 6’4” [1.93m] long and 2’6” [7620mm] wide.   The width may be narrower at the extreme head and foot.  The main width requirement is at the shoulders.   Double berths should be 4’6” [1.37m] wide although two friends can manage with 4’3” [1.29m].   Most people will be familiar with the various measurements of Queen and King size beds and today I am often called upon to include these large size berths, especially when preparing plans for power cruisers.   Queen size berths are usually 5’0” [1.52m] wide and 6’6” [1.98m] long.   The space between upper and lower berths should be 21” [533mm], seats should be 18” [457mm] wide and between 12” and 18” [305 and 457mm] from the sole.   The higher the seat, the less foot room is required.   Seats require 3’6” [1.07m] headroom and 24” [610mm] frontage for comfort.  If seats face each other, then 30” [762mm] foot room, although this is sometimes difficult to obtain in small boats.  More time is spent sitting than standing so seating comfort requires a fair amount of consideration.

   Clothes lockers should be at least 16” [406mm] in width or depth with a height of 40” [1.016m].   Ice boxes should be as large as the space available permits and have a minimum lining of 3” [75mm] of insulation.   A well-built ice box is a creditable alternative to a freezer.   The minimum size for a sink is 10” x 10” x 6” but larger is preferable.   The sink should have at least 15” clear space above.   Deep sinks are to be preferred especially in a sailboat as the heeling can considerably reduce the working depth.   If you are going to be sailing with your female mate, please ask her advice about laying out the galley.   The standard height for tables is 28” [711mm] above the sole or 12” [305mm] above the top of the seats.   24” x 18” [610 x 457 mm] of table space is required for each person.

   Galley work benches and sinks should be at least 15” to 18” [380 to 457 mm] wide and 36” [914mm] above the sole.   Drawers should be no more than 9” [228mm] deep and the maximum dimensions should not be more than 30” x 20” x 9” [762 x 508 x 228 mm].   If the drawers are narrow, say 8” [203mm], then the depth may be increased to 15” [380mm].   Try not to make drawers too big as they can be unmanageable at sea.   Make sure you include safety catches or special slide arrangements so the drawers stay closed in rough weather.   The maximum pitch for ladders should not exceed 60 degrees and long ladders should rise 7” to 9” [178 to 228 mm] per step and each step or tread should be at least 7” to 10” [178 to 225 mm] deep.   Hatches should be a minimum of 18” x 18” for ventilation and emergency use.   All the heights given assume you have standing headroom in your cabin.

Try and think of ways you can save money on your fitting out programme.   For instance, the mould from your fibreglass hull should supply some timber that can be reused for framing up interior joinery.   If you plan ahead, you can use certain size timbers for the mould and setting up that can be either re sawn or used as they are for another purpose at a later stage.

   Tongue and groove flooring can be a very inexpensive and rewarding fitting out timber.   Second hand timber can also be very useful.  In my own early days of boatbuilding, we used to build all the fibreglass male moulds out of reclaimed house timber.   Some recycled timber is better quality than you could possibly find as new stock in your local timber yard today.

    For the construction of the saloon table, we would recommend the use of two sets of stainless steel or aluminium tubes sized so one fits inside the other.   The larger tube has a thumb screw fitted to position the height of the table as required.   Alternatively the table can be hung from a bulkhead leaving the sole space clear.   With a reasonable amount of planning, a table of this type can yield as much useful space as a fixed table and, possibly, double as a cockpit table.

UPHOLSTERY

The bunk and settee cushions can easily be made at home with the use of a modern sewing machine or, they can be purchased from your local tent or bedding supplier.   There are big savings to be made with a bit of shopping around for mattresses and cushion material and coverings and curtains.

LINING MATERIALS

If you intend to display all the interior hull surfaces, whatever building material, there will be a lot of extra work making them presentable so, interior lining is worth some thought.  There are a wide variety of lining materials used to cover a basic fibreglass or steel hull.   Quite often a wooden hull is deliberately left on display with dramatic effect.   Lining materials can include vinyl, foam backed carpet, heavy cloth or timbers such as tongue and groove or pre-surfaced plywood veneer.   I have seen ceramic tiles used to good effect in galley and stove areas, especially in traditional boats.   Depending on what finish you use, you can often run your wiring and plumbing behind the lining.  

   Around the edge of the lining, trim strips or quad or other cover strips, including plastic, can be used to hide any joints and, in fact, the cover strips can be a feature in themselves.   A vinyl, Laminex or Formica backed deck head with teak cover strips can be most attractive and relatively easy to fit.   There are materials especially designed for these jobs and these can usually be found at your marine store or marine upholsterer.

Some vinyl materials give a really professional finish and are relatively easy to apply.

These materials are made from expanded PVC and are available with an inlaid or printed pattern.  This type of material is fully flexible and has a closed cell structure, particularly suitable for lining the interiors of boats.   These specialised lining materials fit easily around corners and projections and can be bonded to almost any surface.

   It is usual to leave the lining installation until the boat is almost completed.   This allows you to install any last minute, plumbing and electrical wiring without disturbing your finishing materials.

Ready made interior joinery such as pin rails, shelves, locker doors, drawer fronts, handrails, special timber mouldings, etc., usually in teak, can be purchased ready-made from specialist timber outlets or importers and are a great time saver and make economic sense.   These items are not cheap, but will give your boat a professional finish, which may pay handsome dividends when you sell at some future dates.

   Some builders go to the trouble of making wooden patterns for casting cleats, ports and other hardware at a foundry but, unless this is for a particular reason/hobby, it is usually cheaper and quicker to buy from the vast ready made selection of castings available these days from your local chandlers.

   Unfortunately, space restrictions do not allow me to cover the fitting out with the amount of detail that the subject requires.   At a later stage, I hope to devote an entire book to the subject.  Until then, you can find several alternate publications that will be of great assistance in this area.

   Finally, avoid using your boat before the fitting out is complete.   It is almost impossible to use a boat and complete the interior simultaneously.   If, for some reason, you can’t avoid launching the boat before it is finished, then make sure you fit out one area completely before starting another.  Take your time with the fitting out process.  You will never regret it.

During the fitting out, there will be many things to consider in an orderly fashion, such as fire fighting equipment, drainage of bilge water to collection points, bilge pumping systems, ventilation, electrical installation, plumbing etc. many of these items may be covered in your plans or are subjects of complete books in their own right and are generally too complex to be covered here.  Read everything on the subject that you can get your hands on.