Published: 02-04-2016
Some manufacturing ideas. Trying to find the cheapest/quickest way to build a boat.
Vertically symmetric hull mould
The idea here is to make the smallest possible mould from which a full hull can be manufactured. Making the hull in vertically split halves makes sense structurally and is often preferred to the hull deck joint technique. A hull symmetric along the midpoint can be moulded with half the surface area, but hull aren't like this by design. They generally have a sharp bow and a U-shaped aft. Can't we just make it sharp and the other end to though? And not layup all the way down the mould? That's the plan, well plan 1. Another alternative, plan 2, is to have a modular mould where the middle section remains constant but different tops and bottoms can be added. This allows the reverse image to be created. Plan 1 can be visualised like this:
Fig 1. Caption
The hull symmetrical around the z-axis rotation (plan 1) may have issues with the centre of buoyancy (COG) as it will always be aft with a very fine bow. This could be minimised by having a very slender hull with little rocker. Alternatively a bow bulb could be used to change the buoyancy. The centre of gravity (COG) is commonly slightly aft in in catamaran because of the narrow bows restricting accommodation. The slight aft COG may counter the aft COB.
Add on
The bottom part of the hull can split from the upper section using a split mould. If the bottom section is symmetrical about 45 degrees in the longitudinal direction it can be reversed and used on the other side. This allows the centre of buoyancy to be modified. It just requires a bit more work.
Flat panels and mould
The side of a hull are generally very flat and this lends itself to moulding on a flat planten table. Secondary bonding could be used to connect the fully moulded top and bottom sections of the hull to the side panels. Alternatively the flat sections of plug or female mould could be made the same way.