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.