"*JimH*" wrote:
Gene, I ran across this discussion of Grady-White vs Pursuit on another
forum while searching for the lay-up schedule of SeaRay boats.

You and Tom may enjoy it. Nice forum too so don't be afraid to join.

http://www.thehulltruth.com/forums/t...rt=41&posts=41


Sorry, I don't like to try reading forums around the edge of the 'JOIN
NOW' box... who needs annoying commercialized bull****?



Gene Kearns wrote:
Thanks...

There are a lot of give-and-takes... necessary evils... in
construction. IMHO... foam core construction is a poor choice of
construction for a boat. It is often employed in aircraft construction
where weight (or lack thereof) is of paramount importance.

You're missing an important point here. It's not about weight, it's
about strength. Foam cores allow a much higher rigidity (modulus) for a
given weight; that's why they can be built lighter. A properly built
foam core panel can literally be twice as strong at half the weight of
solid fiberglass. At equal weight, it would be about 8X as strong, for
equal strength, maybe 1/4 the weight.

Foam core panels do have a number of downsides. They need to be
engineered properly, it's expensive to just build it up 10X as strong as
it needs to be, then start cutting it down until it starts flexing
alarmingly... ie standard boatbuilders engineering. They need to be
carefully laid up for max bond strength, requiring more & better labor,
higher costs. They need to be protected against water intrusion, meaning
that the owner must maintain the boat properly, and this IMHO is the
biggest cause of core problems.

Boats are like airplanes in that they pay a speed penalty for carrying
more weight. Do you like boats that use more fuel & are slower than they
should be? If so, *then* you have good cause to dislike foam core
construction.


.... Grady-White... a viable argument could be made
that marine plywood, while an excellent structural element, can
rot....

Yep, it sure can... and almost certainly will. It's only a matter of time.

... though I suspect that rotten wood and foam core have about the
same strength.. go figure...


How do you "figure" this?


Chopper guns... whether guided by computer or hand are cost effective
methods of getting glass and resin on a surface. They are poor
substitutes for providing strength and rigidity.


Chopper gun lay-up is heavy & brittle. It's a cheap way to build up
thickness & not have print-thru. IMHO a well-built boat should not have
any chopper gun in it anywhere. There's no reason to use a chopper gun
except to cut cost.

An interesting term.... "lay-up schedule"... usually involves a warp
clock and, in this discussion, implies that there is a warp.... or
stated in other terms... that there are no chopped strands involved...


No, a lay-up schedule can include random stand mat, or core-mat which
kind of like felt, as well as fabric or roving.


I like cloth for layups and that includes Pursuit and G-W.... among a
host of others..... I DON'T like chopper guns.... as that smacks of
poor strength and bean counters....


heh heh heh how do you feel about rotomolded plastic?

Again... this has more to do with opinion than anything else. I have
seen very few boats that have failed structurally... in fact... I only
have proof of one.... a Trophy that sunk off Wrightsville Beach, NC a
few years ago, while taking part in a fishing tournament. It was a
dealer boat and I got pictures of the thing when it was dumped back at
the dealership.... Yep, you guessed it.... chopper gun...


Can't say I've seen a lot of boats that have failed structurally, but
certainly more than one. Sometimes it was due to the boat being placed
in a ridiculous situation, like being trapped under one corner of the
dock in a rising tide; or left to bash against a piling for 12 hours
thru a hurricane.

It would be possible, but expensive, to build a boat that was proof
against this sort of stupidity... it would not be possible at any price
to build a boat that was strong enough to withstand any & all possible
abuse... especially if you include poor maintenance!

Fair Skies
Doug King