First go at a composite hull

Ivan does not make shallow boats, and 15 is not wide enough. There cool prop boats but none have ever played the shallows game.

 

Get a hovercraft, get into those shallows !

 

Cold and wet up north. For a northern environment I would go with an aluminum hull. Epoxy repairs for any composite hull need minimum 60F for curing. Aluminum also handles shoreline scrapes & bumps against rocks better. If you have a heated workshop with decent climate control (70-80F with low humidity is best range) you can make repairs regardless of weather and a composite hull would be more maintainable.

 

The new design would accept a jet, but it still may not be shallow enough. I can’t remember what he said the draft of the new hull was, but it was less than the prior model.

Unless you use more expensive materials and methods aluminum hulls tend to be lighter than composite hulls. Once you drop the weight of the composite hull it will tend to be less durable in a rough and tumble industrial environment.

 

Just reading through the post with interest. I would be very wary of carbon fibre in this environment and pretty brittle stuff, on the outside anyway, maybe to reinforce areas..
Doing some very rough shoe box calculations (Assuming your boat is a 16.5ft square with a triangle on the front bring the length to 32ft) you need to reduce your weight by roughly 8000 pounds (quite a lot of Alumium to get rid of)


Looking at the picture/ video you posted I would stick with your aluminium hull but replace everything else, all the deck, housing, bulkheads are ideal parts to replace with sandwich panels. You should know which bits you bump and which bits you can make super lightweight.
If you build yourself a set of moulds for the internal parts its a far smaller project and will give you a lot of knowledge working with composites. Later down the line, you can still replace the hull.

Can you reduce engine size, it is all aluminium?
Having spent enough time struggling with vacuum infusion and dry spots.. I would wet lay and vacuum consolidate afterwards to pull out all the extra resin out.

 

You are mixing terms. You mean wet lay and vacuum. Not wet lay and vacuum infuse. A boat this size to wet lay and vac is impossible. I suppose you mean to wet bag any fixtures; like head enclosures where they used plywood. This is a good ideal for sure.

 

It's going to be a challenge for the boat hull itself but not for smaller parts. Especially if there are a few people with rollers..
If you're using something like west system 209 if you work at 12 degrees you're going to get roughly 2 hours, you would then need to warm the workshop up to 30 degrees to get a complete cure and get the resin viscosity to drop.

 

33' long panel....68F, 70 minutes to bag n seal, 2 hour epoxy, amateur hour with the vac on the part

 

Foam or hex cell cores are too fragile. Strip plank composite epoxy and glass, with, as you say, Kevlar for abrasion. Dave Gerr's Elements of Boat Strength is a great read. As others will immediately point out, there are more sophisticated scantling rules, but none you can get out of the library and read immediately.

For shallow draft and high cargo capacity, and speed when ridiculously loaded, nothing beats a Hickman Sea Sled. I'm building one now for exactly those requirements.

Surface piercing props are generally associated with soooper doooper speed, but they are the shallowest draft prop arrangement. Only jet drive is shallower, and those have terrible fuel efficiency. Read Paul Kamen's 1995 article on their history and design, then Albert Hickman's original 1911 article in The Rudder. Professional Boatbuilder Magaziner reprinted the article recently. It's brilliant.

I phoned the guys at Winninghoff Boats in Massachusetts a while back. They built a bunch of sea sleds for the savagely competitive brine shrimp fishery in great salt lake. One of those starting gun fisheries, where everyone blows up their engines racing to the grounds, they have spotter planes circling to direct them, and the fishery ends for the year the moment the quota is reached.
Marcus Lee in Sitka built a dozen sea sleds, but he's retired.
Winninghoff also built one for the Australian sea cucumber fishery. A 55' boat that could get on the plane with 50,000# of catch on board, using a pair of iirc 300hp outboards. Terrifyingly fast running light.

Anyway, I'm off to the shop. Time to hit my thumb with a hammer a few times.

John