I repost with some variations. I replied some hours ago but I don't see any
my message.

"Jim Conlin" wrote:

Perhaps I misunderstood the original question. Was it about plywood or
solid okoume?

It is solid okoumè.

I know that cedar is better: lighter and more durable .

In Italy, the North American Cedar is a very valuable wood, very difficult
to find and much more expensive than Okoumè (solid).

Therefore, red cedar I found has high weight, similar to okoumè:
450kg/cu.meter (sorry,metric, but ratio is the same).
Cedar should be1/5 less heavy to be good.
For that I'm asking about.

Alternative could be Spruce, light as cedar but less durable than
okoumè.
In any case wood will be 'encapsulated' in coatings, as Ron says.
My doubts are on strength of these different woods.

Plywood-lapstrake could be a good solution, but I need a smooth round bilge
for a modern 19' racer.

Ciao
Leo