Before working with glass and resin you will need a range of safety equipment. This will including breathing masks, to prevent you form inhaling noxious fumes and dust particles.   You will also overalls or other protective body clothing and goggles or industrial spectacles for eye protection.  In some cases, prolonged exposure to resins and other glass fibre materials can cause skin rashes or unpleasant discomforts.

Hooded suits are becoming more popular as they totally isolate you from the environment.   Some hoods have built in breathing apparatus with filters and most are designed so they do not restrict your vision or movement. 

A respirator or mask is one of the most important piece of safety equipment when working with fibreglass.   You will need protection from simple dust through to potential cancer causing fibres and vapours, especially in some paint systems.   These items of safety equipment range from the simple paper mask, through to simple air supply units, which totally isolate you from the surrounding environment.   You should discuss the various options with your fibreglass supplier who will advise you on the availability for each particular use and workplace situation

Some respirators will not work when used over a beard or for that matter (designer) stubble.   If you are not clean shaven, then consider using a suited hood.

Amongst others the 3M Corporation have available some excellent breathing appliances.

A well-run building workplace can take the pressure off the safety equipment by providing a clean environment.   Keep rubbish off the floor.  Remove fibre trimmings immediately and make sure you have adequate ventilation.   Keeping a clean workplace will go a long way to keeping you healthier.   You will reduce fire risks and keep your insurance man happy.

HAND PROTECTION

You are working with chemicals so your hands should be well protected.   Although most fiberglass boatbuilders work without protection, using gloves or barrier cream will protect sensitive skin and even non-sensitive skin.

EYE PROTECTION

Some hoods and respirators also incorporate eye protection.   For certain jobs, separate goggles are important.  You will need to choose between goggles and safety glasses, both of which should provide side protection.   When grinding fibreglass and other associated materials, it is amazing the various trajectories the ground particles can take so always wear eye protection when grinding.

EAR AND HEARING PROTECTION

If you are working in conditions where the noise level is in the 80 plus decibel range, you should consider using ear plugs or earmuffs.  One professional boatbuilder even insisted that the foam earplugs have florescent cords so the foreman could see, from a distance, that the plugs were being worn!

BODY PROTECTION

Good body protection is achieved by wearing a disposable body suit  Suits have improved in the past few years and most now feel more comfortable to wear while still providing the necessary protection.   How you feel about wearing a suit may depend on the climate.   Some hot climates call for creative arrangement such as the tissue paper suits worn by some boat builders.  Overalls are still a good option.

FOOTWEAR

Your feet are the easiest things to protect.   A lot of fibreglass workers wear sneakers/sand shoes and although these aren’t the ultimate protection they do a good job in this environment. When gun laying sneakers are very useful as they can be slipped on and off without hands which is useful when you came off the job and want to change footwear.  

PAINT SCRAPERS

You will need an assortment of paint scrapers.   Usually the cheaper ones have more flexible blades and these can be used for handling the resin putty “Bog” and fairing up various areas of filler.   Purchase a selection of widths from 1” [25mm] to 6” [150mm] of which one or two can have the corners rounded so that they can be used for creating fillets.   Paint scrapers can be cleaned in acetone after removing any residue of hardened bog.  

DISK SANDERS

It is a good idea to buy a disc sander of reasonable quality as it will do a lot of work.   The right size is about 7” [175mm].   Choose a low or duel speed disc sander that will be happy running at 4000 RPM.   As well as a rigid backing, the sander should be capable of being fitted with an 8” [200mm] circular foam pad (Ferro) to which you can attach the adhesive type sanding discs for finishing work.   You will need a selection of varying grits.  

OTHER SANDING DEVICES

You will need a selection of sanding blocks and boards.   One particularly board is a piece of plywood 4’ 6” [1.37m] x 6” [150mm] x ½” [12mm] thick which when fitted with handles and sandpaper attached makes an excellent device for obtaining a good finish on a hull or deck  The board is handled with long sweeping strokes that follow the contour of the hull and will tend to even out any unfair areas.   There is a variety of power sanders with all types of actions so check them out and find the best for your job.   Always use any new sanding tool on a test area before committing its use to large areas of your boat.

BRUSHES

All the brushes you purchase should have unpainted handles and you will need a variety of sizes

MOHAIR ROLLERS

Mohair rollers are used for applying and spreading resin as part of the hand laminating process. Again you will use different sizes but mainly 5” [125mm] and look for plastic or unpainted handles and it is a good idea to have a few replacement sleeves.   After use, always remove the sleeve from the roller and thoroughly wash in acetone.   Make sure you always use mohair rollers as other types, sold for painting, will soon fall apart when used with fibreglass resins.

PLASTIC BUCKETS AND CONTAINERS 

For mixing resin save all suitably sized plastic containers and have your friends save theirs too. You should also be able to buy ice cream container “seconds” from your fiberglass suppliers.  You may also purchase some small plastic buckets.   Half gallons [2 lit.] and one gallon [4 lit.] will be the best size for the job.   The hardened resins will crack out of these after use.   It is a good idea to use one specially calibrated and marked bucket for measuring out the specified quantities of the resin as this will save the bother of actually weighing every batch.

JIGSAW

When building any boat, there is a considerable amount of trimming required and an electric jigsaw is one of the best tools for these jobs – able to be used on a work bench or in confined spaces.   On glass fibre, you should only use high grade cutting blades including tungsten and diamond blades and the unit will handle the fibreglass laminate with ease.   Equipped with the correct wood cutting blades a jigsaw will make short work of cutting out plywood bulkheads and furniture

SURFORM

A great little tool for surfacing wood or fiberglass, it comes with flat and rounded blades and is available from most hardware stores.

ELECTRIC DRILL

A good cordless drill is not only for drilling holes but with the addition of a set of hole saws and other attachments will see plenty of action during, and after, any boatbuilding project.  

STEEL ROLLERS

Steel rollers used for rolling the mat and roving remove any air bubbles trapped in the laminate.   With a bit of practice, these steel rollers also roll the material to a smooth finish.   A range of sizes is required including some very small diameter ones for getting in the corners and wide ones for bulk work.   Check with your supplier regarding the various sizes and types.

SCALES

A set of kitchen scales that weigh up to 10 pounds (4.5 kg) will be ideal for weighing out the resins and you may be able to pick these up second hand.

SCREEDS

You will need a variety of screeds, most of which are made from flexible plastic or thin metal.   You can make your own or buy ready made from your supplier.   A handy screed can be made from an old saw blade with, or without,  the teeth ground off. 

VACUUM BAGGING EQUIPMENT

You may want to use vacuum bagging when installing any core materials used during the construction of your hull and deck.   Details of the equipment required will be covered in a special section dealing with vacuum bagging techniques.

MISCELLANEOUS ITEMS

Other important tools include some heavy duty scissors to cut the fibreglass roving. CSM should be torn unless you want a sharp edge and with woven roving, pull out a strand as you cutting line.  Also needed is a paddle mixer which can be attached to a variable speed electric drill running at slow speeds.   A table on which to lay out the mat and roving with a device to hold the roll at one end is a necessity.   Also required is a measuring glass or bottle for the catalyst and a selection of woodworking tools,  clamps, and ladders etc.

With the advent of Computer Assisted Design CAD and Computer lofting, it has become possible for the designer to supply the builder with very accurate full size patterns.   Usually included with the full size patterns, are the frames, stem, expanded transom, deck beams, cabin top beams and miscellaneous other items, which can be made directly from these patterns.   Before CAD and computer lofting, drawing the lines plans and lofting the boat full size was a long, skilled and expensive process taking around 250 man hours to complete.   Now it is possible to reduce this time to less than one tenth, so we invest more time elsewhere in the designing process.

   Having the personal knowledge of several thousand 18’ to 70’ [5.48 M to 21 M] boats being successfully built using full size patterns,  I can say with absolute confidence that  you should try to obtain a plan with full size patterns.   You will save many frustrating man hours and the boat will be shaped as the designer intended it to be.

For masochists and those who either want to build a boat from archive materials where patterns are not available, or for those who are unfortunate enough to deal with a designer who is unable or unwilling to provide full size patterns, you may be forced to undertake the job of completely lofting your chosen design full size.   There are several books available which cover the subject fully.   I will leave it to you to research lofting if you are forced into this action.

   If you do have to loft full size, make sure you do the complete lofting job.   Do not take shortcuts by lofting frames only, without drawing out all the water lines, buttock lines etc., all full size.   If you take short cuts with lofting, you will regret it when you start to assemble and fair your hull.

   If you are fortunate enough to receive full size patterns with your plans, please use the patterns.   On no account should you try to “improve” the patterns by re-lofting the lines.   There may be a slight movement in paper patterns due to atmospheric changes but this movement is usually evenly distributed throughout the patterns.   Provided you are working under reasonable conditions, these variations will not be large enough to affect the finished product.   When ready to use the patterns, you should pick a day when you believe the temperature and humidity will remain constant.   Prepare to transfer the paper patterns to a plywood floor or “take off” the frame shapes and other various items as shown on your patterns.   If you want the ultimate accuracy and are prepared to pay extra, then you can ask your designer to supply the patterns plotted on Mylar film but this is expensive and unnecessary.

Most full size patterns are plotted or traced on 24” [610mm] or 30” [760mm] or perhaps even 36” [1 metre] wide paper or Mylar film.   These sections are laid side by side wallpaper fashion to reveal the complete set of fames, stem pattern and other elements of your boat that are supplied full size.

   You will find the patterns generally show one side, or half the shape of the frame.   As most boats are symmetrical, your patterns need only show one side of the boat.   Usually frames 0,1,2,3,4 and 5 are shown on the right side and frames 6,7,8,9 and 10 are on the left side of your assembled patterns.   Some designs may also have half frames, for example 1.5, 2.5 and so forth.   You will need the radius of the expanded transom so you can later form the transom to its correct rounded shape.   Study your patterns with the lines plan.   The lines plan will contain frame spacing and other important measurements that you will need when setting up your hull framework.

When you are making up the frames, or moulds as they are sometimes called, it is best to make up the two halves of the frame at once.   This is achieved by nailing the two pieces of timber together, usually 1” by 8” [25mm x 200mm] or similar sized material and of suitable length to cover the section of the frame you are making.   The two pieces are tacked together and the pattern marked out on one side.   Clearly mark the waterline, sheer line and headstock line where they occur, on any one frame section.    After you have joined up, faired and clearly marked the line of the outer edge of the frame you are making; then carefully cut the frame section out on a band saw or other suitable saw.   Make sure you cut the frame piece square off the marked surface otherwise the two sides of the frame will not match.

   Once you have assembled the pieces of the frame to make up one half, which consists of two layers; these should be joined on one side with gussets.   Next remove the nails holding the frame halves together and lay out the frame as you would open an oyster and bingo you have the entire frame.  

   Before you attempt to assemble the complete frame, measure directly from the patterns, the width of each frame at the headstock line; sheer line and waterline and make a check mark on the opposite side of the frame patterns and include the frame number.   Now you have three reference points to make sure the other half of the frame is laid out symmetrically.   Problems can arise if you try to use the offsets when taking the measurements off the patterns as these may not have been corrected at time of lofting.

   Now you can lay out the complete frame by installing the headstock or baseline board,  and gusset the keel together;  add bracing and strengthening members to the frame as shown in the your plans.   Your frame must pass the test of both sides matching the master pattern.   You now have one completed frame ready for installation on the strong back, bedlogs or setting up rails.   After you have marked out all the frames, stem and the backbone and they have been cut out and assembled, your next job is to prepare your strong back or bedlogs. 

SETTING UP THE FRAMES

Usually, the bed-logs or strong back are made from 6” x 2” [150mm x 50mm] or similar sized timber, depending on the size of the vessel.   Your plans should give guidance on the scantlings and assembly method for the setting up base.  The size of the strong back, which is the width and length, will be decided by the shape and size of your hull. The forward end will be narrower to accommodate the shape of the frames whereas the aft end will be wider for the same reason.   As the widest part of the hull is normally around or just aft of the centre, it will be easy to arrange adequate support in this area. Sometimes it is best to build the strong back coffin shaped, to offer the best support to the hull, at all its various widths.  

   The setting up height is quite important.   The hull will be upside down and there must be room for you to have easy access under the sheer and into the interior of the hull.   Your hull must not be so low as to allow the bow, which is usually the lowest point, to touch the floor.  

Once the strong back is completed, it should be checked for level in all directions. The use of chocks and wedges can correct any misalignment.   Make sure any blocking or wedging is done so it will remain permanently in position until the hull is completed.   If you are working on an earth floor you may wish to install concrete pads.   The strong back and the whole mould structure must be capable of supporting the weight of the completed hull, until the laminating and fairing is completed and the hull turned over.  

   Once you are satisfied that the strong back or support rails are level in all planes and securely in position, install a string line down the centre line and mark out the station spacing on the rails on both sides of the strong back.   All station marks should be marked square off the centre.   Nailing 2” x 1” [50mm x 25mm] cleats across the strong back or bed-logs, at each station point, may be the best way to accurately position the frames.   Make sure you consider which side of the station mark your frame is to be positioned.   Make sure the frames are installed square off the centre line and level across the headstock line.   It will be necessary to attach each frame to the strong back.   You may attach the headstock to the upper rail or the bed-log, by through bolting, coach screws or skew nailing.   Access to the strong back or bed-logs may decide your method of attachment.   Remember you will not want the strong back to come loose and be waving about during the turning over process.  

The next step is to install the stem and backbone.   Fit these parts in the slots that have been pre-cut to receive them.   The stem will need temporary support until the battens are installed.   Take check measurements to make sure the stem is in the correct position, relative to the sheer line and the centre line of the hull.   At this stage, the biggest mistake you can make is to have the stem off the centre line of the hull.   Check everything against the centre string line and use plumb-bobs, a large square and tape or ruler to make absolutely sure everything is correctly located.

A word about the keels and skegs on sailboat hull moulds.   You should attach the keel frames to the hull frames by screwing - do this in a way that allows you to unscrew the keel section before removing the mould.  Sometimes the keel will be reluctant to part from the mould so by making provision to allow the hull mould to be removed without the keel section, you will overcome this potential problem.   Skegs can also be built separately and attached to the mould with a screwed gusset as the same problem may arise.

THE BATTENS

You should now have your mould battens prepared and these may be scarfed into full length to match the length of our hull or you may join them on the job using plywood fairing strips as described later in this chapter.   It is wise to obtain battens of the correct width and thickness otherwise they will not bend to a fair shape on your hull.   For sailboats between twenty-five feet [7.5m] and sixty-five feet [20m] the best size battens are 1 Ύ” x 5/8” [44mm x 15mm].   For power boats, with flat bottom sections, you may use larger battens in this area, say 4” x Ύ” [100mm x 20mm] which will usually lay in place without giving you any problems.

   Once the frames, stem and backbone are in place, you may install a few battens to check the fairness of the structure to this point.   If you have followed the full size patterns and cut and assembled the frames with due care, you should find the framework very fair and accurate.   The main thing is to have a fair hull so you may shim and trim frames as necessary to make sure the battens lay in a fair curve.   From now on, your eye will be your guide.   You will soon develop a skill that will allow you to spot an unfair lump or hollow in your mould.  

INSTALLING THE BATTENS

You can start the battening process at any part of the hull mould,  but make sure that the battens are progressively installed on either side.   If you batten up say twelve inches [310mm] on one side of the hull, then make sure you next install the battens in the same area, on the opposite side of the mould.   This will prevent any pulling or deforming of the structure due to having battens in one area and not having battens to balance the opposite side.   At this time you should be particularly careful, to make sure, that the stem remains straight and true, right on the centre line.   After installing a few battens over the entire area of the hull, you will find the mould will take on a more rigid form and it will be easier to maintain the correct shape. 

   During the early stages of installing the battens, you should be giving consideration to building and installing the transom.   There are several ways to build a transom and one is to form it as we have shown in the photos and sketches.   Most of the latest plans include the developed shape for the transom, this with the known radius, will offer another way to easily form the correct shape as the designer intended.   We have noticed that some designers who specialize in plans for amateur builders have taken to designing boats with flat transoms.   A flat transom is an exceedingly ugly thing and not at all necessary.   It is so simple to have at least a small amount of camber or curvature in the transom of your boat.   Flat transoms always look concave or hollow, so we suggest you don’t do it.  

   As the battening of the mould former proceeds, keep a careful check to make sure there are no low or high points in the structure.   If you find several battens wanting to go past a frame without touching it or can only be made to touch the frame by pushing inwards and deforming the batten, then let the battens lay as they may, and pack out the frame to suit.    If you find one frame is particularly high and needs some trimming to make the battens lay fair, then dress a little off that frame.

After installing the battens on the hull and the transom,  the next step is to add internal strips, as shown, which are installed to fair up the battens between the frames.   The battens that need to be joined can be joined on these fairing strips.   Installing these fairing strips is a job for two people.   One person to nail through the batten into and through the fairing strip, and another person inside the hull structure with a “dolly”,  or heavy metal weight against which the nail can be driven.   This procedure will cause the nail to bend over and clinch up tight.   Clinching is a common boat building practice and one that you would use frequently if you were building a wooden boat.   The “dolly” should be a solid piece of steel, of a size that will fit comfortably in the hand.   The ideal shape is a piece of solid round steel say 2 ½” diameter by 6” long [60mm x 150mm].   The dolly is used end on.   When the battens are joined between frames on the plywood fairing strip, they will be held firm and fair.   If there any small irregularities they can be lightly sanded at a later time.

   Use adequate plywood strips, at least one or two between each frame and no more than 1’-6” [500mm] apart, so if frames are more than 3’-0” [1 metre] apart, use two strips between each frame.   Clinch nail to every batten.   Best cut the strips into 4” [100mm] widths and use Ό” [10mm] to ½” [12mm] thickness of plywood.

CHECKING THE MOULD

A ½”  x  Ύ” x 6’-0” [12mm x 20mm x 2m] long timber fairing batten laid diagonally across the mould battens will show up the high and low spots on your mould.   If there are any localized bumps or lumps, such as where you have joined the battens, you should fair these areas using an angle sander fitted with a heavy grit disc.   Something in the region of 16 grit should be ideal for the job.   Now is the time for you to go carefully over the entire hull and fair off any irregularities with the sander.   As in all your work from now on, let your eye be the judge.   View the mould from every angle and when you are satisfied that it is as fair as you can possibly make it, it is time to take the next step in your building programme.

FINISHING THE MOULD

By this stage you should have decided whether you are going to use a cored method such as PVC foam or balsa to provide the sandwich structure or the cheaper urethane foam, which will later be removed, and add stringers to the interior of your hull.   The next step is to cover the entire mould structure with builders’ plastic.   This plastic is quite thin but strong.   Check at your local hardware store where you should get a good choice of materials.   The plastic comes in rolls and is best installed by taping it into position with plastic tape and stapling where necessary – cover staple holes with plastic tape.     Once you have the mould covered in plastic the next job will be to install the core material.

OPEN FORM VERSUS SOLID FORM MOULDS

At one time we used both end grain balsa and foam core for building fiberglass hulls. In recent times balsa core has become dis-credited due to the number of hulls that have become damaged due to water penetration of the fiberglass and into the balsa core.  In our own defence we generally recommended balsa be installed above the waterline. In the light of current experience, we do NOT recommend balsa cores except for decks construction.

   One method we have used for attaching the PVC foam core to the mould is to sew it on.   For best results use a medium size bag needle with light string or nylon yarn.   Make the stitches about 3” [75mm] long.    Outside the hull the stitches are let into grooves, which you cut as you proceed so they will lie flat with the surface and do not interfere with the installation of the laminate.   The rows of stitching should be 9” to 12” [230mm to 310mm] apart.   We have found it best to stitch vertically up the sheet, first along one edge and then progressively working across the sheet in vertical rows.  Additional stitching may be necessary where the sheets join, using a cross stitch patterns up the edges of the sheets which should ensure that both sheets lay uniformly on the mould former.

   Another possible method, depending on the suitability of the foam, is to drill holes in the battens and screw the foam from the inside, removing the screws before the hull is turned for removal. One or two missed screws will stop the mould releasing so you have to get them all out.

   Install the foam sheeting carefully to insure there are no hips or hollows in the hull surface.   It will take a considerable amount of work to fair out any large irregularities created at this stage, so utmost care will ensure a fair hull and one that will need the least amount of finishing to provide a professional looking surface when the hull is completed.

There are certain areas of the hull where it is not recommended to use core material and these include the skeg, keel and areas below the cabin sole line, effectively, anywhere below the waterline so, in cored boats, these areas of the mould should be sheeted with a cheap polyurethane foam which is later removed. The keel sides and bottom can be covered with Ό” [6mm] Hardboard/Masonite which is waxed and a release agent applied to eases the removal of the mould former from the hull. Some keel moulds have to be made detachable from the hull mould to facilitate removal of the hull.  It would be wasteful to install an  expensive core materials in areas where it will later be removed. In our own designs we always recommend that the area under the cabin sole be single skin so this means that the hull area below the waterline should always be covered with a cheaper foam which is shovelled out after the hull has been turned upright.   As with all forms of construction, there are many ways to achieve the same results.   You should follow your plans.   If you have a good idea not covered in your plans, then consult your designer before making any major changes to the recommended building methods. 

Previously plywood, as a core material in the transom, was popular. The problems of water penetration and rotting the plywood has been discovered over the past few years so if possible try and avoid any plywood except in the interior fitting out of your fiberglass boat.

   If you are building a powerboat and planning an outboard or stern drive installation, then the plywood cored transom is a possibility but make sure the plywood is of the best quality marine grade.   As your transom will have some camber or curve, you can pre-laminate several layers of thin plywood to this camber and after cutting to the approximate shape install in position, on the mould.   Now you can trim the transom to the exact shape to allow it to tie in with the side of the hull.   Make sure you fasten the transom from inside the mould so you can release it after turnover and before you remove the mould from the hull. 

After installing the core,  the next job is to apply a prime coat of the resin and then you should go over the whole hull checking the fairness and applying resin putty or fairing out any imperfections, where necessary.   It is important when building a fiberglass boat on a male mould to see that it is as perfect as possible before going on to the next stage.   Different core materials will absorb different amounts of resin prime coat.   With balsa core, after filling any gaps with resin putty, you may want to apply one or two thinned coats to seal the surface and then another coat of regular laminating the resin – check your suppliers recommendation    PVC core will needs at least one coat of resin primer. 

For a single GRP skin hull over a male mould, the building of the mould follows the same procedure as for a cored hull.   Instead of using a PVC foam core you will now use cheaper urethane foam which is removed once the hull is turned. This is a rigid foam and is purchased in sheet form similar to PVC. It is usually removed with a shovel and the interior of the hull has to be sanded in preparation for further laminating, stringers, bulkheads etc.