Single skin construction using the plug - mould -hull sequence is the simplest and cheapest method to build a number of boats from the same mould. 8.1 plugs and moulds. the principles described for the construction of small plugs and moulds equally apply to large.. Jim: i have been following your boat project, it looks like its thrown every thing it can at you! did you ever find out what was the reason for the plug cracking? also did you seal the mdf with resin or anything before your first layer or dura tech? i have had problems with bondo recently when i was making a composite roof for a race car.. -build a plug out of polystyrene foam, and use ce-sense "eps coat" over it. it is a polyester based resin, which does not attack eps foam (polystyrene). either use this model as a plug for a female mould, or use it as a male mould..
The degree of perfection of the plug will be directly transferred to the mold and thence to the finished boat. since body putty is slightly porous, which can create some release problems, the plug should be sprayed with a fast-build automotive primer-surfacer.. The idea is to build up a stiff strong laminate about 3/8 to 1/2 inch thick for small molds, thicker for bigger molds. i have seen boat hull molds that are 1-1/2 inches thick. for small molds, i just use 1-1/2 oz mat. i build it up three layers at a time until there are twelve layers total on the mold.. The argus 35 tooling development designed in new zealand and manufactered in queensland, the first stage of construction requires the building of temporary plugs that are identical in shape to the finished production boat..
