"Best" foam core

[dshowalt]

Best being a relative term. I have read the spec sheets for various foam core materials (Airex, CoreCell, Divinycell). And I'm still confused as to which would be "Best" for a small trailerable catamaran (LOA 21' Beam 10') strictly for inland lakes and protected waters. What I need is some comments that start out "I prefer Corecell because........" or whatever you core material of choice is.

Thanks

[fng]

corcell is stiffer in is raw state than the other foams, this can be good or bad depending on the type of hull form you want to achieve. You would most probibly be using 10mm thick foam for that size of cat. If you were thinking of strip planking the core, then corecell would be better. If you were thinking of a batten mould then any of the others would be better.

[dshowalt]

Thank you fng, I was thinking about a male one off over frames similar to this. http://www.voile.org/trimaran/

[Ad Hoc]

If your boat is being hauled around on a trailer, you need to ensure the core is capable of taking the additional localised high impact loads and able to trasnfer this load effectively.
BUT, as you said, best for what?...it has many answers for varing scenarios.

[kroberts]

There was a page I saw a while back, it was a collection of boat damage pictures from after a hurricane. I think it was Katrina. They showed the picture, then the caption said what type of construction it was.

Foams of all sorts did poorly, as I recall. Non-foam cellular sandwiches seemed to do better. Wood core sandwiches did extremely well.

The previous paragraph is subject to my often faulty and at the time not much interested memory. I'm trying to find the link, but you may do better than I do on that.

That is, of course, if catastrophic damage tolerance is part of what you think is important in a core material.

[rasorinc]

This covers some of the issues. Best, Stan http://www.yachtsurvey.com/structuralissues.htm

here is more pics and issues. http://www.yachtforums.com/forums/general-yachting-discussion/10591-catastrophic-delamination-new-bertram-63-a.html

[kroberts]

That's not exactly the site I was thinking of, but it covers even more information.

I just discovered that I know more about this problem in boats than I had thought. I have personally seen some of these problems on my hovercraft, and on others as well.

I have an interesting time ahead of me, learning about boats and best practices.

[rasorinc]

Ken, you do not have these issues if you build out of wood. Wood Lasts Generations. Stan

[ondarvr]

For wood to last for generations it needs to be built correctly with the right type. Its the same for a composite hull.

[sigurd]

Thank you fng, I was thinking about a male one off over frames similar to this. http://www.voile.org/trimaran/

that looks like a plywoode boat, otherwise why the draggy corners everywhere'?

[dshowalt]

As I understand the Scarab 22 origionally was Plywood. But this build was done in foam. http://www.voile.org/trimaran/
I just was talking about the "type" of building not the boat it's self.
I did find this article while loooking at the links rasorinc sugested at Yachtsurvey.com
http://www.yachtsurvey.com/ATC_Core-Cell.htm

[sigurd]

don't know what you mean by type of building. is it laminated flat on a table for one side, then cut up and stitched into hull shape and then laminated on the other side?


If you put the foam on stringer mold and vacum the skin onto the foam, then there is less risk for empty pockets underneath skin

than if you

make the skin first and then vacuum the foam to the skin.

Guess foam don't need holes if you put one skin on at the time.

I just would never build a foam boat with a ton of chine (unless it is a planing shape) and hard transitions to deck etc.

Vertical strip seem easier and much nicer. But I never tried either.

Seems possible to get nice rounded shapes with infusing panels on a table and stitch and glue, also. Search Kelsall and KSS and Rob Denney they have some experience with it.

Are you goin g to infuse or vac bag or neither?

[dshowalt]

By "type" I was talking about the Laminating on a table and then cutting pieces etc. Seemed like a good way to adapt a plywood design to a foam core build. To me vacuum bag on a table seems easier than infusion on a frame.

[sigurd]

agree. esp. how he did the main hull, no taping outside..