Carbon fibre foam core dinghy.

[Topcat47]

Bear in mind, "exotic" materials are not ideal for home construction. GRP has the advantage of being reasonably cheap and simple to use safely. When I was in charge of a research lab workshop, fabricating in carbon and kevlar, the hoops through which we had to jump were off the scale compared with GRP construction. Even the gloves we used were "different". In contrast, we fabricated a wood and epoxy sphere from 0.5mm veneer over a plug in the car park. We used 6 layers and vac bagged after the last layer using a shop vac.

 

[burgundyben]

Bear in mind, "exotic" materials are not ideal for home construction. GRP has the advantage of being reasonably cheap and simple to use safely. When I was in charge of a research lab workshop, fabricating in carbon and kevlar, the hoops through which we had to jump were off the scale compared with GRP construction. Even the gloves we used were "different". In contrast, we fabricated a wood and epoxy sphere from 0.5mm veneer over a plug in the car park. We used 6 layers and vac bagged after the last layer using a shop vac.

Yes, I have worked on two projects with carbon and it can be nasty.

 

[lw395]

You can buy Kevlar canoes.
18ft banjo-player type of thing weighing about 50lb?
So ISTM, a Kevlar Duckling ought to be feasible.

Also, if you've got space to store the mould, if you build an ultralight, even if it's in glass/polyester/foam, if it gets damaged you can always mould in a new section.
So long as it gets you home of course!
Go for it!

 

[burgundyben]

I've put a bit more thought into this, read the entire internet and watched some youtube clips.

Here's what I think.

Turn the duckling over and heatshrink wrap it to give a nice smooth surface, use it as a buck to make a boat, no mould making.

Inner layer of 300gram biax. 5mm core, outer layer of 500gram biax. Infued with epoxy.

Inwhale and gunwhale made of foam wrapped in biax tape.

3 thwarts made of biax and foam.

Transom with a plywood pad in it so I can clamp on a very light outboard.

I reckon is 16kgs.

I reckon build it, then see if its stiff enough and work from there if it need further materail.

 

[lw395]

My limited experience of trying to make something light with epoxy is that even crude vacuum bagging makes a vast difference.
With your project, maybe I'd start by making a simple flat panel like a thwart?

 

[burgundyben]

My limited experience of trying to make something light with epoxy is that even crude vacuum bagging makes a vast difference.
With your project, maybe I'd start by making a simple flat panel like a thwart?

That's a good idea!

 

[DownWest]

That's an interesting thought - wonder what a cold-moulded 10' tender would weigh using modern resins, etc. Another option if you want to stay authentic, aviation and of that era is a Grumman aloominum dinghy. Dunno how much they weigh but it can't be a lot, not exactly British but then it doesn't pretend to be in any way. https://www.shoppok.com/poconos/a,2...-Sailing-Dinghy----500--East-Stroudsburg-.htm

We have a 13ft ally skiff by Crysler Marine. I can pick it up with one hand. Over the pond the family have a shorter one that is very light and quite stiff. Might be 8ft?