Fiberglass boats are made from boat molds. Many small start-up companies will purchase used boat molds then go into production making fiberglass boats. That is one way and probably the cheapest boat molds to be found. Buying used boat molds is the lowest cost because most boat companies do not want to store older models and are looking to practically give them away. Another way to start boat manufacturing is to find a used boat hull then make some modifications to it then cast a mold from the modified hull. This strategy is not too expensive and will make the new boat semi unique.
Buying a used hull, then modifying, then making a mold will add some distinction but still the original brand is usually still recognizable. The ultimate strategy and most expensive way to begin new fiberglass boat production is to make a completely new design then make new molds that are yours and unique. The advantage is obvious. If you did a good job in the design then chances are there will be some demand, and, the only source will be to order from you. This is the best scenario for making boat molds for boat production. This leads to two ways to proceed with making your molds.
If you are a hands on person with a small budget you can build the plugs and molds in stages as follows. First draw your design on paper assuming you have some hull design experience. Once you have a drawing that makes sense you put some scale to your drawing. The next step is to make a life size model from 2x4s, planks, plywood bulkheads then cover with plywood, then final finish shaping your newly designed hull with body filler. Once you have feathered out the shape it is best to hire a professional finisher like a vehicle body finisher and painter to get the look, contours, lines, surfaces and finish sufficient for mold casting.
OK, you made your plug or life size model from scratch according to your drawings on paper. Now you are ready to start the boat mold casting phase. Before you can cast your mold from the plug needs to be waxed with mold release wax, McGuires is the best and most common mold release wax used that I know of. I have used it since the Stone Age. The waxing phase takes many coats; when you think you have waxed it enough, wax it again as many times as you did the first time, then three more times after that. Now the next point some may debate. I say better to be safe than sorry. If your mold casting does not release from the plug, you are in serious trouble and could add a significant amount of cash to recover.
I suggest the next step be to spray on PBA or PVA which stands for Ploy Butyl Acetate or Poly Vinyl Acetate. A half dozen of one or six of the another. The main idea is to ensure proper and clean separation from the plug. After the PBA is applied then the gel coat can be applied. The gel coat can be applied two ways. One way is to apply by brush and roller. The other way is to apply with a spray gun. It all depends on your skill, budget and a few other factors. So now apply the gel coat and cast the mold by following the lamination schedule drawn up at the same time the design was drawn.
OK, so now you cast your mold and it is time to release. If you followed the steps and did not forget any of the 1000 minute details involved than you should now have a great set of molds. Congratulations on a job well done; but hold on the job is not finished. Now it is time to figure out how many boats that will make from the new boat molds, and what kind of finish is expected from the boats made. If the plan is to make a few hundred boat hulls then one method is followed. If only a handful of boat hulls is to be made from the molds then another method is followed. The kind of finish expected will determine the next phase of mold finishing, as well as how the boat hulls will be cast from the new boat molds needs to be decided.
Time to look at that pesky budget again. Want to make plenty of boat hulls with a nice finish and use the best method for casting hulls? Then the budget for the mold finishing phase needs to be 70% more than the cheaper way in the boat mold finishing process. If you are smart, then you have the budget to do this thing right and will opt for the better option. In this phase several more layers of material are applied then the last few layers will wrap around the turn table frame. If you donâ€™t know what a turn table frame is, then when you get to this point email me and I will tell you. Next after the frame is set up and the boat mold is fixed to the turn table, swing frame, pivot or the whatchamacallit mold turning thingy, the final finish sanding phase is performed.
At this point the person who is paying for this thing is either thanking God he did a good job on the plug phase and waxing phase and did not cut corners, or he is throwing a fit yelling at everyone because if corners were cut and shortcuts were taken these mistakes will rear their ugly head at this stage after thousands have been spent. One reason is that is at least ten times harder to correct imperfections inside the boat molds than they are to correct on the outside of the plug.
Letâ€™s assume the plug and waxing was performed correctly. Now is when the vehicle body finisher is brought back to sand and apply a mirror finish to the new boat mold. After the final mold finishing the boats are ready to be made. The level of quality and care put into the mods will be evident when the first hull is cast.
Now let us assume you are not a hands on guy. Then you need to have at least ten times the budget to make new boat molds the hands on method, with the carpenters, plywood, fiberglass laminators and vehicle body finishers method. Assuming you do have the budget then you probably are not reading this and have already met with your board members to hire a naval architect consulting firm that has located a 3D CNC router to cut your plug from a house sized block of specialized structural foam. If that is the case then you already have the millions or at least a million to start your boat building business. In the end, the product made will be comparable either way. It is the uniqueness, quality of finish, contours and surfaces that counts.