Design issues from transat 6.5m

Forgot to add. All production minitransat are CE category B certified. (again rule requirement).

 

colson 650

i just bought the Colson 650
and i am doing few modification
great little boat inspired by minitransat
www.colsonyachtdesign.com.au

 

aluminium frame

there is a designer in Australia who build boat with a Aluminium frame
Computor Craft
www.ccplans.com

 

HDPE has been used in some production boats, but I don't think you'd call it a success. Most of them are already out of business. The weaknesses inherent with this material require an injected, expanding foam to back up the external skin. Lots of problems including some serious wrinkling, and water weight gain... probably not something you'd want in a sail powered vessel. It makes a pretty good cooler, though!

 

Then, there are these guys, who have shown that the HDPE build technique and materials are working just fine for them.

http://www.triumphboats.com/

 

Water weight gain ? Please explain. Are you saying it soaks up water ? Seems improbable to me.

 

No, the HDPE doesn't gain water weight, the expandable foam does. The boats I've seen have no bilge or drain plugs. Water gets in through hardawre mounts and can't get out.

 

HDPE is a great material for many things, but I don't think this is one of them.

Several points:

Triumphboats appears to be a foam core skinned in HDPE, which is a different animal than what the OP is proposing. The foam core provides the structural strength of the hull, with the HDPE acting to contain and protect the foam from damage.

HDPE is a material that expands and contracts a tremendous amount with temperature changes. If you attempt to tie and HDPE skin into a metal frame, the skin will likely either wrinkle horribly, or tear it'self apart.

HDPE has very high wear resistance, but it isn't strong in the structural sense, it's very flexible. It also creeps over time with an applied load. I would think that you would end up with a skin that dimpled in between the frames and longitudinals.

If it's protection from reefs you desire, consider a hard chined conventionally build craft, with hdpe sheet fastened to the outside on wear surfaces.

Why do you want to use HDPE? I think I detect a desire for an "unsinkable" boat by reading between the lines. If that's the case, give up now. There is no such thing.