Beach launch compact fishing design

I think inflatable is an option, but you'd need extra protection against abrasion on that shingle or gravel. Aluminium is not an option to build yourself, you won't meet the weight requirement with back-yard methods.

 

There are 3 or 4 companies building aluminium boats where I live. Also one company building RIBs with alloy hulls.

If I find a shape that works on a plywood prototype I could have it built professionally in alloy. Or I could make it in glass.

I do like the look of those boat collars. It would be easy enough to make something like that out of foam and enclose it within the structure of a glass boat.

I can see the weight advantages of an inflatable and they are comfy to sit on the side but not that durable as a fishing boat - fish spines, hooks, gaff etc.

 

The only way glass will work is with a core, and high strength, high re-inforcement content laminate. Otherwise the weight will kill you. A small cathedral hull would meet a lot of your requirements, though the ride quality is fair at best. But for a couple of miles, perhaps tolerable. A rectangular plan hull gives the best solution for stability is a small, light boat, but a cat would not suit, in my opinion, as well as a tri/cathedral, for several reasons.

 

That's the option i would look at. Or get something made in alloy.

 

Don't be fooled into thinking a skinny boat with some sponsons attached, is inherently more stable than a vee hull of similar overall proportions. It might have a margin of extra initial stability, but you will pay with reduced ride comfort.

 

Why not a cat with a creatively designed platform adapted for fishing? Some have been built to collapse and light enough for one man to carry or roll. Maybe a search under Everglades challenge will turn up something with ideas you can use, whether mono or cat.

PC

 

A search suggested everglades challenge is for sailboats? I want a power boat.

There are some compact alloy cats available here but all quite heavy and power hungry e.g. a 3.7m is 2ookg and 30HP

 

Thank for all your input it is very helpful and has changed the direction of my thinking significantly

You are right but the idea is to be able to go anywhere in the bay and launch on a sheltered (from wind) shore with a short motor to a fishing spot. Once I'm fishing I don't mind how rough it is (within reason).

Sponsons are mainly for buoyancy. That being the case .... I could build a slightly narrow v-hull (panga proportions) with internal 'sponsons' on the inside in the form of full height side buoyancy tanks along both side of the boat, meeting in a triangular tank at the bow.

They could be multi-chamber for safety and provide some stiffening and wide gunwales (great for free diving). With some thought they could be quite light

I could still build in a gull-wing or reverse chine aft for a bit of stability at rest.

 

Where do you re-enter the boat after diving ?

 

Transom/side doesn't worry me.

I used to SCUBA dive out of a 12ft dinghy without any issues

 

Am I right in thinking you want a boat with a fairly narrow, self-draining "well", with wide side decks ?

 

Yes that's what I'm now thinking of.

Self draining is not essential but it's desirable. If the volume of the well is small, relative to the combined volume of the buoyancy tanks then it can't sink.

But shedding water ASAP is beneficial when crossing surf. I've capsized a few times crossing surf over the years and it always took more than one wave. Usually three waves to swamp, turn and finally roll the boat.

 

I'd say you could adapt an existing alloy boat by dropping in a "well" body as I illustrated, but it would be best made from lightweight foam/GRP or your weight would exceed your limits. Building from scratch, you would need less transom deadrise than shown in the sketch, imo, or be too tippy. It would probably be better to have a slot about 3 inches or so high, let in say 6 " along each internal side-wall, this would make it much better to walk around. Your drain flaps would be at the transom end of those slots.