Alternative Hollow Board Materials

Probably in Paul J’s department but I’d like to throw this open to all interested parties.

The following piccies show the edges of a couple of materials I’d like to experiment with in making a hollow.

They are not joined together just side by side for comparison.

The dark material is compressed foam with a skin on either side and comes in 5mm and 10mm thicknesses. It’s primarily used in the printing industry as a backing for large photos/displays. The sheet size is 8’ x 4’. The sample I got was 10cm square and I could not break it with my hands.

The white material is called Gatorboard, seems to be made of PVC, bends on the X axis but not on the Y axis, 5mm thick and also comes in 8’ x 4’ sheets. Usually used for shop signs in an A frame shape outdoors. Like real estate signs eg, Home Open.

My question to you all is has anyone ever used this material in any form of construction and if so how did it turn out. I’m keen to give both a go but would like some feedback from anyone with experience with either.

Many thanks in anticipation…



Very poor structural results. Try building a scale model.

Both are designed for temporary use panel signage.

Why are you interested in using them?

This is also a sign product, offering outstanding strength-

to-weight ratios, machining and bonding abilities for building hollow surfboards. HDU foam:

Australian distributor:

Danthonia Designs

Glen Innes Rd.

Inverell, NSW, AU 2360

Toll Free Phone: 1800 552 700

Phone: 02 6723 2100

Fax: 02 6723 2204


That’s great, thanks for the info mate. What have you built with it?

My plan was to build a hollow using mainly the compressed foam maintaining the centre wooden stringer and then covering it with 2 x 4oz and epoxy. The gatorboard seems to have directional strength so it could be used as internal structure. I was told it is very weather proof but it wouldn’t be exposed to water.

The black stuff in the picture seems to be very strong and works out to be around $80AU per sheet, lighter than ply and could be shaped for the rails.

If it all goes to plan I would look at having the deck and hull printed then glassed.

I’d love to get my hands on a sample of HDU though and get a feel for it.



I’ve used HDU for all sorts of sculpted things including a few surfboards and fins. Contact your Australian SignFoam distributor- they should be able to provide you with free HDU samples. Try the 10 and 15 lb. densities.

Good on you!

Some of those folks at another site are experimenting with what appear to be some other innovative material although I have no idea if they are having much success or if the materials would be good on a hollow. Maybe worth checking out…


this has no connection with hollow surfboards (although, I, too, am interested in such techniques and materials), but I just wanted to let you know that I just love your “I look back and smile and I look forward and dream” signature. So true. Maybe because I’m very old and smile a lot while still not being very wise and dreaming a lot, too…