Sport Today

If I were you, I wouldn't worry about it.  I've got the same board (89
Seatrend 9'5") and it's had small cracks around the finbox for over a
year now in about the same location as you describe .  It hasn't
gotten any worse in that time and I've sailed it pretty hard.  My
guess is it wouldn't be any more expensive to repair it when it's
*really* broken than to try and fix it now - that's why I've let mine
go.  Of course, it all depends on where you are when it finally does
break.....

Greg

If I were you, I WOULD worry about it.  I had a 1986 (?) 9'6" Seatrend, and
it went to the dumpster two years ago.  I had the same kind of symptom
around the finbox you're describing, and believe it took on enough water to
"explode" from thermal cycling.  (Big "vent" along one rail.)

A symptom I might have caught but didn't: change in shape around the
fin.  The whole section was bulged before it "blew."

I don't have a lot of expertise (in spite of the experience), but I would
definitely get a couple opinions from people familiar with that PARTICULAR
construction from SeaTrend.  They seem to have done a lot of on the job
training with their products.  :-(

Tom "don't have the coolest anymore, but I know how to fix it" von Alten

I disagree with this.  Cracks around the finbox may be an early
sign of failure of the supporting structure around the finbox.
Since this is a big board, you're probably using a pretty big fin, at
least 11", or 12" if you use a pointer.  With the amount of lift a big
fin can generate, along with the stress of landing jumps, it could
blow out at any time.

If the cracks don't get bigger when you push the tip of the fin sideways,
and you sail in a place where it's not dangerous if you break down, you
could probably risk sailing it.  I don't and I wouldn't.  

Finbox repair is probably beyond the abilities of most people.  I had
a shop fix my epoxy Seatrend last year.  They cut out the old finbox
all the way to the deck along with most the glass around it, contour a
carbon fiber finbox to mate to the deck exactly and glass it in place,
install woodies, and then glass over the entire tail several times.
It was expensive ($150), but it's never coming apart.  The board will
break in two before the finbox comes loose.

-Jonathan