FIRST LAMINATES

The day after you have applied the gelcoat, you should apply the first layer of light chopped-strand mat, usually ½ ounce per square foot [150 g/m 2].   This layer is very important and should be carefully rolled out to avoid any chance of air bubbles.   Air bubbles in any layer are a nuisance but in the first layer, they could lead to problems. Vacuum bagging is one solution to avoiding these voids – see chapter.

   Once the gelcoat and first layer of mat are in place you will have passed the most critical stage of your laminating process.   Providing you follow some form of temperature control, you should go on to complete the laminate without any problems.   As mentioned earlier, always finish your laminating at the same part of your hull each day.   Three willing workers can lay up a fifty foot [15 metres] hull in a few days.   Two layers of fibreglass per day, one mat and one roving, is a reasonable amount to install at one go without causing the laminate to overheat. New resins are being formulated all the time so you must have the latest technical data and support from your materials supplier.

   The number of layers of mat and roving required will be shown in your plans.   After the layers that cover the whole hull surfaces are completed, you will most likely be required to install extra layers in the areas of the keel and below the hull waterline.   Most laminate schedules call for overlapping and or interleaving the various layers in the areas such as the chine and keel, thus building up extra strength where it is required.

   Again, we remind you to trim the sheerline of your hull each day.   This will usually be done as work progresses and about an hour after the final layer for the day has been installed.   Once you have installed the basic laminate and any extra layers called for in your plan laminate schedule, you should add any stringers, sole shelf, deck shelf etc and any other reinforcing members called for in your plans.

   You should then install all the ribs, stringers, bulkheads and web floors before you remove the hull from the mould.   After you have completed the installing of the stringers and ribs etc and if you do not plan to use the mould again, you may prefer to remove only the mould above the chine or water line, leaving the bottom section to act as a cradle.

EZI-BUILD SANDWICH HULLS

If you are building an Ezi-build sandwich hull, then you will lay up the outer laminate plus any extra layers in the critical areas, before you install the core material which may be PVC foam or end grain balsa.   In either case, the best method to install the core is to use Vacuum bagging techniques that are described elsewhere in this book although the core can be installed manually.   If you intend building a sandwich hull, please read the chapters on one off building, where you may pick up a few ideas on the handling of core materials.

PANEL CONSTRUCTION

The panel method of building a one off fiberglass boat is a variation on the Ezi-build technique.   The method is ideally suited to building chine hulls including catamarans and any power boat or single or multi-chine sailboat hull.   The main advantage of using this technique is that a full mould is not required.   You will retain the advantage that a minimum of finishing is required for the outer surface of your hull.   Very little filling and sanding will be needed to achieve an excellent professional standard of finish.

   For panel construction, the system of building the female frames and setting them up on a set of bedlogs, is similar to the methods used when building an Ezi-build mould.   Only a few battens are required to hold the frames square and vertical.   The technique of setting up the basic framework to hold the fibreglass panels is similar to the first stages of building the Ezi-build mould.   The fewer battens required and the absence of a mould lining material, are the main differences between the Ezi-build and the Panel methods.

   Additional bracing is used on the outside of the frame assembly and once the frames and the few battens are installed, the mould is ready for the fibreglass panels. The success of the Panel method depends upon the builder obtaining accurate information such as computer generated full size patterns for the frames and either patterns or computer lofted offsets for the panels.   We have successfully used this method when designing power catamarans and out builders report excellent results using the technique. 

LAMINATING PANELS

Once you have the basic framework in place, you can think about laminating the panels.   Before you proceed, check over your framework to make sure it is true and level.  It is very important that the framework is sufficiently braced to insure that the shape will be maintained during the installation of the panels.

LAMINATING TABLE

First you will have to build a laminating table.   The surface of the table is very important as any blemishes in the surface of the table will be faithfully reproduced in the outer surface of your laminate, so it should as smooth as you can make it.   The top surface of the laminating table can be made from any one of several materials, however ¼” [6mm] tempered hardboard backed up with adequate framing would be my choice.   There are many others to choose from as long as they have a smooth shiny surface and are compatible with polyester resins, should serve nicely.   As the sandwich panels can be large, the table top material is best if available in one piece.   Check this out as the fewer joins the better.   In most cases, you will need to prepare the surface with a wax and release agent.   See preparing the Ezi-build mould.  

   Once the panels are laminated they are laid inside the framework and joined together.   The method of making each panel is quite simple, providing you have accurate patterns or offsets for each panel.

   Using masking tape, mark out the shape of each panel on the laminating table and lay up the required laminate to form one panel.   If you are using a core material, it should be installed while the laminate is on the table.   Consider which way the panel will need to bend, if any, when it is laid in the mould, before installing the core on your laminate.   Depending which brand you are using, cores often take a bend better in one direction than another.  Usually only outer laminate and the core are installed while the panel is on the table.

STEPPING BACK THE LAMINATE

The edges of the panels do not receive the full laminate or core.  These are stepped back from the edges so that after installation, the full laminate can be completed where two panels join.   When a panel has been laminated, it is removed from the table as soon as possible.  The panel is installed in the framework while it is still “green” as it is easier to fit into place while it still has some flexibility.   When you have all the panels in place and they have been joined, the remainder of the inner laminate is then installed.

   Some deck parts, cabin sides, cabin tops and other areas of your boat can have both sides the sandwich laminated while the panel is still on the table.   This is only recommended in areas where there is a minimum bend required to place the panel in its final location.      Installing the interior laminate, stiffeners, if required, and bulkheads etc., follow similar methods to those used in other fibreglass hulls.