Hi

nobody I prefere to ansver in the group as when you ask for the
measures for the frame around m then what a lot don't realise is, that
in denmark and many of the other "metric" we acturly still use inches
and feet --- in plumbing with timbers we still use inches but we
adabted to the english inch system as we had our own inch but this is
many years ago .

So when you ask for the measures for the perfect small raft with foam
core then it was made from two 22 mm standard plywood sheet one acting
as deck and one as bottom nailed with galvanised boats nails to a frame
that was 3 inch by luck just the hight of two 12 cm, thick foam sheets.
Now you maby wonder why I mix up these measures -- well I have a
metric tape measure with inch measures and metric measures on same tape
and in that way I don't mix uo inches and cm. Anyway I was lucky to
find that 3 inch plank and my best advise are for you to remember to
make the corner assembly , maby not as dovetail but then with strait
dovetails , it is quite easy even you have to make 4 corners , but it
is my experience that it is the heavy and strong frame that make a raft
these measures work so smooth and last so long ---- the raft need to be
both heavy but also offer enough volume ,then I build one just like
that and it served the local comunity and still do for some 20 years
and it have if just the deck are repaired with a new plywood sheet, 20
more years.