Polyethylene hulls?

[flybynight]

Hello! Another question from the wanna-be sailor!
Perhaps through ignorance, I was impressed by the polyethylene hulls - they say, these guys are virtually indestructible, but they lose stability over 20 ft and require reinforcements. Does anybody have any inside angle on those, and what is the best way to go looking for the used one? (Looking for appr. 25 ft sloop type). Wherever I look, it is all fiberglass. Not that I am completely married to that polyethylene idea, just entertaining options.

And what about the new (I guess) High Density Polyethylene (HDPE) hull sailboats?

Thank you!!

[Chotu]

There aren’t any. No one has adapted the technology for boats this size.

The internal framework would probably be heavy and cumbersome compared to current build methods.

The cored panel construction in use today provides the best stiffness to strength to weight ratios we can currently get.

Polyethylene is just too floppy for this purpose.

[HankOnthewater]

I agree with above, and as material it is near indestructible.
We built a RIB style boat in PE once, from 0.5 or 0.6 mt diameter pipe (that is used for slurry pumping in the mining industry), and the floor in 4 and 6 mm PE, transom reinforced with aluminum. Could not get it on a scale, but would have been around 150 kg or more, from memory about 3.4 mt long (11 ft). A 15 HP engine was not half enough.
The experiment was a success from a building and welding point of view. From a commercial point of view: not a winner, even when using free offcuts of pipes.

Of course there are PE boats around, like the majority of kayaks and sit-on paddle boards, all made in rotamould method. There are a few plastic boat manufacturers in Oz:
https://www.rotamoulding.com.au/plaka-boats/
https://www.polycraft.com.au/
Walker Bay has a range of plastic boats, but they are made in PP (polypropylene) when I last looked.
I have used many of the above boats, all heavy, needing 20 to 40% more HP compared with fibreglass or alu.

Back to original question: larger boats in PE. I don't think it is going to happen soon, except for composite construction with PE as outer layer. Or another avenue is to built a boat in PE using 3D printer technology.

Last obstacle is to make paint/antifoul stick to PE. If they invent that kind of paint I will use it on my fibreglass boat