higher density EPS for rails on a compsand?

Has anyone used higher density EPS for rails on a compsand?
I saw a water absorption comparison test with 2.5lb EPS and Polyester MDI at WNC (www.wncsurf.com ) and the EPS sucked less water and dried out as good as the Poly.
EPS lighter, stronger, stiffer? Any thoughts?
I was thinking it might be an easy DD blank for them to offer (1lb core with 4lb 1” rails).
I was thinking no stringers and getting a bed from the leftover.

3lb is the densest EPS you’ll find.

It’s also solid as a fricken rock…heavy too.

Ken at Segway Composites has cut me a 3/8" sheet of 3lb, a blank and a bed.

The 3lb blank is the twin to a 1.5lb blank.

My original thought was to cut rails out of the 3lb and just glue it directly to the 1.5lb and
then put the high density sheet over the top of the whole thing; Light core, hearty deck and

The problem here is that cost becomes prohibitive.

The 3lb won’t want to bend to curves as readily so you have to cut the curve in to your
3lb block which compounds the cost with lots of potential waste.

One solution that dawned on me while typing is to get multiple sheets of the 3/8" 3lb and
lay multiple layers up to get your rail density and then fair one in to the deck contour as well.
Those thin layers will wrap curves just fine.

I’m confirmed for Saturday…will be in touch.

I’ve done

1" thick Bluedow XPS

1" thick 6lb Precision Board

1/2" 6lb thick corecel

you can bend it using heat and strapping tape

or use a vac bag like we do

use stretch wrap to temporarily hold it into place

best is to have an adjustable rocker table with a pegboard-like base that you can create variable outline jigs with.

can’t be any worse that trying to bend 1/4" balsa around the outline with a heat gun and water

Thanks for the input fellas,
I guess having the machine cut outlines and rails (2 identical blanks dif density) would be a lot of waste.
I got some ½” PU sheet foam from Ken a while back that I am using for the next one, just thinking ahead for what’s next.
Do you guys use vents in your boards?
If 1” XPS rails glued on to 1lb core (no stringer) got heated up and out gassed, would a vent in the 1lb core help the rails?

Surfding can show you an XPS board that’s 4 years old and has surfed heavy,
tropical conditions and is still solid as a rock.

He (and others) don’t believe that XPS needs to be vented.

I’m building two XPS boards and will not vent either of them.

1lb…some people won’t…but I did it on my SUP…there’s just a lot of foam there
and I’m sure it’s going to see some hot days on the sand.

I don’t vent 1.5lb EPS.

I am building one right now. Taking pics along the way. Not sure I would recommend it, but I have used 3.5 pound EPS in 1/2 inch strips separated by bamboo perimeter stringers. It is EPS/bamboo/EPS/bamboo/EPS/bamboo for a total rail build of 1 1/2 inches using 1/40 inch bamboo.

I did it because I had the 3 pound EPS and no PU laying around, and because I thought it would look cool to see the bamboo showing through the rails like layers in a foiled fin. I am nervous this will end badly. Pics to follow.

I’ve done a few with the blue dow foam as perimeter stringer. I don’t like the color, so I’ve either done colored lams or carbon over it, but I really like to shape it. 1/2" thick blue foam from lowe’s bends easily, and with two layers you have a nice 1" perimeter to shape down. Plus it’s cheap and easy to get!

Nice, I like the sounds of the XPS more now. I think it comes white also?
Greg, I am looking forward to picts.

I’ll bring some scraps I have down with me so you can take a gander at it.

Could be useful for finbox inserts if you ever do that sort of thing.