Thanks Robbi - hadn't got to that part of the Black river sleds website yet! Pity there's little indication of diameter there, but guess I can work it out from the length. Rough guess at 20 inches diameter and about 14" thick. Cheers!
I was involved in THIS group by which fell through last year. I think the mimimum order is for 3 people. I saw your post on toboggans, are you interested in going thirds on one of these?
Im wanting to build one as well.
3mm is plenty thick enough but it's better to use UHMWPE.