Gary wrote:
" Our boat (wooden '58 Chris Craft) leaks a bit. I believe it's where
the
final "plank" meets the keel. It's not so bad that I'm scard of any
serious
problem but it is bad enough that a puddle of 10 gallons or so forms
in the
back when we're running. (It forms in the back because the bow is
up, and
the bilge pumps are in the front.)....."

Gary, a couple of things spring to mind...a 10 gallon "puddle" seems a
lot to me..how long does it take for this to happen? 24 hours or 24
minutes? Are you sure the leak is from the hull planking? Is this an
issue while moored or only underway? Could be a cooling system issue
(inboard engine?)or a though hull fitting starting to fail. Anyhow I'd
be more then a bit concerned!
How come the pumps are forward? Usually they are located in the bilge
area which is most often at the stern area under the engine. They are
only capable of handling a small amount of water, spray, the drip from
the shaft through hull packing,etc.
While 3M 5200/4200 are great products, just mushing some into and
around a seam area doesn't produce a seal. To be structually efective
the "seam" or joint needs to be opened up and a uniform bead of 3MXXXX
applied and then the joint refastened, the excess sealant removed etc
etc.
Be careful, the sea doesn't care if you live or not.
Mike