Rich Stern wrote:

Many manufacturers are touting "no wood/no rot" construction, and some are
using a composite grid system (fiberglass over some type of foam) to replace
traditional hull stringers and forms. Several bay boats I am interested in use
this type of construction. Of course, from a marketing perspective, it sounds
great. But I'd be interested in some real world opinions.

OK

Is such a boat less prone to flex?

Than what? It is certainly less prone ot flex than the same hull with the same
layup and no grid of any type. Is it less prone to flex than the same hull & grid
with wood as the grid core? No, because wood is stiffer than foam.

In order for the grid to be stiffer due to the foam, then either the hull or the
grid (or both) have to be of stiffer construction such as triaxial weave, vacuum
bagged, etc etc.


Does it result in a more solid boat?

Not necessarily. If the grid is not laminated properly then it may not even last
longer. Foam doesn't rot but some types can become saturated and all types can
delaminate.

Some people hate foam core construction, probably because there are so many bad
examples that have long term problems. But it can be a great type of construction
*if* the details are properly done.

Are there other problems
to be aware of? Any pre-purchase inspections that can be accomplished,
assuming it's even possible to see the below-deck structure?

There are a number of things to inspect that indicate good quality work. Without a
lot of details plus pictures, it's difficult to compress 'how to do a structural
survey' into one usenet post. I'm not the greatest expert anyway.

http://boatdesign.net/articles/foam-core-properties/

Some resources on the web, another good place to look would be in your nearest
library in books on surveying boats.

Some people will say 'foam core = crap' and they probably have some bad experiences
with poorly done foam core. Like anything else, there is good and bad. When it's
good, foam core construction can be very very good.

Fair Skies-
Doug King