wet bagging is a **** ton of work and way slower for that 15 footer
I don't know the build specifics, but consider you cannot torture a fully skinned panel much.
So, it is possible that only half the panel is built on the table. The. The rest of the boat is hand glassed on the entire boat bottom? Or big bagged which is a **** ton of work for one guy; probably impossible with onehour epoxy.
The reason the sizes vary is a mystery to me. I have only one idea. The chemicals are made into a puck and that puck must have limitations on how large it can expand? The expanded foam is then perhaps trimmed to the highest yielding size?
No way would I build a Merten's small boat in foam. The build speed with plywood is significantly faster. To be honest, if I was to start over. All of my work would be done with infusion. Wet bagging is stressful. Wet bagging also has higher waste rates than infusion. The issue is you don't have 60 minutes to play with and minimize resin use. From the time you mix; you have about 50 minutes to get the parts in the bag before gelation. This includes wetting both sides for a two sided layup; wetting the downside core. Wetting the topside laminate which is the same size. Peelply laid nicely. Release and breather and bagging. Removal of gum tape backers on 3 sides. Laying the bag well. Pleating. All must be done before gel or you entrain air.
Agreed that its a ton of work but i'm a glutton for pain and whatever keeps me out of the house and away from the TV is awesome by my book.
the epoxy I use kicks off pretty fast in the mixing container but it takes a couple hours to gel on me when laid up on the glass. i would need to mix the resin in small batches and feed my wife a bottle of wine in order to convince her to help me laminate. but the parts ( other than the hull) are all flat panels, so as long as i'm careful i could reuse the bagging film and bagging tape a couple times. basically make a table out of plywood lay down plastic to avoid bonding anything directly to the table, baggage tape along the 4 outside edges and apply bagging material to one side of the table, prepare one side of the foam, g;*** it, peel ply, bleeder/breather, seal bag and pull vacuum. this would save time and work. also if I bagged it all, i would only do 1 side at a time.
the build is roughly planned as below, although i'm sure im missing a step or two.
1. they want you to build a base that will serve as a vacuum table and later a support for your buck. the table is 4, 4 x 8 sheets of ply wood.
2. cut out all the foam parts from the foam and bond via butt joint the parts together that are to big to fit on 1 sheet.
3. for the stringers, bulkheads and a few other parts, vacuum bag one side of your part on the table, flip over and do the other side.
4. set all those parts aside and build the buck or male (ish) mold. basically this consists of a handful of plywood frames laid out like a strongback design ( I think thats what its called) and then you run stips of wood 1/2" thich by 1 or 2" wide from bow to stern. this gives a general shape of the boat.
5. cut out the foam for the hull bottom and sides. this is bare foam and no glass. the boat has mostly a flat bottom so the foam layout should not be to complicated. use drywall screws to anchor the foam to the mold.
6. thickened epoxy at the seams and fiberglass tape on top of that. when that cures you can remove the screws and the hull should hold shape.
7. 2 layers of glass on the outside. you can do finish work or at least start it at this point but to complete the tunnel hull you have to flip the boat over and do that first, for some reason.
8. flip boat, work the tunnel, transom and false transom out of foam and fiberglass.
9. fit the stringers and bulkheads into place, fliet the seams and tab everything in.
10. bond the preglassed sole and decks with thickened epoxy and i think tab them in but I cant remember off hand. Im sure ill end up tabbing them in though either way.
11. prep, paint, add power.
