[Rhodes22-list] hull deck joint reseal questions

Wed May 1 10:38:37 EDT 2013

Mike: 

The picks might work fine. This is really a trial and error process. What
works partly depends on what the sealant is like. Silicone might come out in
longer pieces but other types are more tenacious and will probably have to
be cut or scraped out as it tends to crumble. The concave shape of the hull
makes it easier to get the tool in the slot. You might try protecting the
any visible surface with tape. If you try the hacksaw blade you can get a
plastic handle for a few bucks  that will make life easier for you. I would
be reluctant to put anything in the slot that does not completely compress.
As that might simply hold the gap open. I think the trick is to get the
sealant way up inside and then compress the join before the sealant cures.
You will not get as good a seal if you wait for it to cure even though some
like Don Casey suggest a two-stage process of tightening it down moderately
until the sealant sets and then more firmly afterwards. Mind you, he is
talking about deck hardware where you have big bolts with backing plates
that allow you to apply heavy compressive forces. Others are very critical
of that approach and I happen to agree with them. I want the sealant to
spread out and fill all voids and I can't see that happening once it has
set. Neither can I see how the sealant will adhere to the surfaces once it
has set even if you could apply enough compressive force to make it spread.

When I removes the foredeck of my boat I was able to expose the hull deck
join and found that the sealant has been applied sparsely and with
significant gaps. If your boat is like mine, careful installation of the
sealant will produce much better results than the original. The hard part,
but most critical, is getting the old stuff out.

By the way, if you look at a cross section of the hill-deck join (see
attached photos) you will see that the plywood core at the edge of the deck
is exposed to anything that gets up the slot - whether water of bugs - I had
both. So the problem is not just a matter of a few splashes of water inside
the boat, it is also a matter of possible core rot and bug infestation. So a
good seal is important. Using a sealant with good adhesive qualities will
also strengthen the whole boat. The strongest is 5200 but that stuff is
impossible to remove if that ever becomes necessary. If it is done well,
removal should not be necessary so it might be the most permanent solution
but the stuff worries me. It is another one of those double-edged swords. 

As an aside, you will also see from the photos that the plywood core
literally hangs on the outer skin with some kind of caulking and the inner
liner then hangs onto the plywood core. There is no structural support that
I could find. So, all of the downward force is pulling the sandwich
construction apart. Even the adhesive between the layers of the plywood had
given way. I hope that later model boats use better plywood. With flexing
over the years it can all come apart.  When I removed the foredeck on my
boat I found that the caulking holding the plywood to the outer skin and
liner was very sparse and in places not even touching both surfaces. I could
pull the liner off and remove the plywood with my hands. Hence the spongy
deck. You can see the delamination in the close up photo. Of course this
kind of "fix" was extreme and ultimately was unnecessary once I knew what
was happening inside the core but at least it provides some photos of what
is under the skin of the deck for those who might have a spongy deck and are
wondering about the options to fix it. As you might guess, putting it all
back together was a major pain. I wish I had know then what I know now. It
would have saved me a ton of work. On the other hand I now have a foredeck
that is as solid as concrete and probably able to pierce a steel hull -
which is nice for a change.

BTW, I have a vent in the cabin top that once removed gave me a view of the
core at least in that area. It appears to me that the top is made much
better with a core that is over one inch thick. I saw no indication of
delamination, thank goodness.

Graham 

-----Original Message-----
From: rhodes22-list-bounces at rhodes22.org
[mailto:rhodes22-list-bounces at rhodes22.org] On Behalf Of Mike C
Sent: May-01-13 6:46 AM
To: rhodes22-list at rhodes22.org
Subject: Re: [Rhodes22-list] hull deck joint reseal questions

Graham - thanks for the idea of wedging the joint open a bit wider to get
the sealant further in!  Muireann definitely has screws that were behind the
rub rail mounting strip and, so far at least, no rivets that I've found. 
Starting to clean things up.  I'll try the hack saw blade, though I confess
some trepidation about damaging her paint.  Also, our friends at Harbor
Freight have a four piece hook and pick set
(http://www.harborfreight.com/4-piece-pick-and-hook-set-66836.html) on sale
this month if your get their coupon book mailing.  For $1.49 it may be worth
a try.  The depth of the gap has me tempted to try to get something else way
up in the gap before trying to force sealant in.  On Muireann it looks as if
the sealant was in general only intruded about halfway up the gap.  I could
probably push something up higher to help serve as a further water intrusion
deterrent, maybe rope caulk, if that's still around, or teflon valve stem
rope.  Heck, even 1/8" inch nylon or PP cording would slow down any water
intrusion that got by the sealant and maybe turn what would have been a
"squirt" from burying the bow into a trickle.  Oh well, plenty of time to
think about that while I clean out as much of the old sealant as I can.  

-----
Mike Cheung
s/v Muireann
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