Roger Long wrote:
I asked a well regarded and experienced surveyor about the through
hulls. Here is his response:

"The standard response to unused thru hulls is to cap them. The
removal
and reglassing is suspect. I think your approach is the proper
solution and
will last beyond any other approach."


I don't understand how "reglassing is suspect." As for capping
thru-hulls, one very rarely sees that and it leaves a vulnerable point.
You might consider asking the ABYC.

When it comes to holes in your hull, the "more is better" approach
doesn't sound good.

DSK

Well, the hole in this discussion is already there. The question is
how it get's plugged up. It's either going to get plugged up with
fiberglass or with the existing bronze fitting designed for this
critical service and mechanically locked into the fiberglass by the
flange and nut.

As someone who has been designing boats (including fiberglass ones)
and figuring out how to keep the water out for over a quarter century,
I'm in favor of the latter.

If cost and time were not issues, and I wanted the inside and outside
of the boat to look like nothing was ever there, I would have no
qualms about a properly done fiberglass fill in. This is a case though
where, as an engineering judgement, I think the easy way out is
actually the most reliable by a small margin.

I find it very interesting what a minority I seem to be on this
(except for the single professional second opinion I've obtained).

--

Roger Long



"DSK" wrote in message
.. .

I don't understand how "reglassing is suspect." As for capping
thru-hulls, one very rarely sees that and it leaves a vulnerable
point. You might consider asking the ABYC.

When it comes to holes in your hull, the "more is better" approach
doesn't sound good.

DSK

Roger Long wrote:
Well, the hole in this discussion is already there.

Yes, and it seems you don't want it there... or you wouldn't be talking
about plugging it up, right?

... The question is
how it get's plugged up. It's either going to get plugged up with
fiberglass or with the existing bronze fitting designed for this
critical service and mechanically locked into the fiberglass by the
flange and nut.

As someone who has been designing boats (including fiberglass ones)
and figuring out how to keep the water out for over a quarter century,
I'm in favor of the latter.

If cost and time were not issues, and I wanted the inside and outside
of the boat to look like nothing was ever there, I would have no
qualms about a properly done fiberglass fill in.

The issue here is "properly done." If you were talking about a temporary
plug, until you are planning to haul the boat later and fiberglass over
the hole, I'd say it's fine to put on a cap or a plug. But in the long
run, it's still much more vulnerable to corrosion or breakage than a
fiberglass patch.

Personally I wouldn't haul the boat *just* to do this one job. If that's
your point, I'm with you.


... This is a case though
where, as an engineering judgement, I think the easy way out is
actually the most reliable by a small margin.


Why? What is "fiberglassing over the hole" vulnerable to? You still
haven't explained that part. And it's certainly not prohibitively
expensive... I did exactly that to an unused thru-hull on our boat

http://community.webshots.com/photo/...73346002sUSTvu

and used probably ten bucks or so worth of stuff... of course I do a
fair amount of fiberglass & epoxy work and buy the materials cheaply.

Fresh Breezes- Doug King

"DSK" wrote in message
.. .
Why? What is "fiberglassing over the hole" vulnerable to? You still
haven't explained that part. And it's certainly not prohibitively
expensive...

It's not vulnerable to much unless there is impact and flexing. I
wouldn't want to just fill the hole on a solid layup (which my boat
is) as there isn't much to hold the patch in. The fiberglass should
be tapered back so there is a good, long scarf for bonding. You're
right that it wouldn't be expensive to do yourself but I'm thinking
yard time (after all, my time is worth something too and unenjoyable
jobs like grinding fiberglass don't have their own rewards). By the
time it is ground, filled, faired, and re-painted, it will cost a bit
either in other things you didn't get done or out of the checkbook.

With a cored hull, you can and should dig out as much core as you can
reach to seal if from the water. This will create a good mechanical
as well as adhesive connection since the patch will extend between the
skins.

The cap and fill will last as long and reliably (actually more so due
to the watertight fill) than the rest of the through hull plumbing.
That's good enough for me. Getting plastic through hulls, especially
the ones near the waterline that can freeze, replaced with bronze is a
much more important issue.

--

Roger Long

Roger Long wrote:
It's not vulnerable to much unless there is impact and flexing.

I'd say even then, it's not any more vulnerable than the rest of the
hull, given a proper job.

... I
wouldn't want to just fill the hole on a solid layup (which my boat
is) as there isn't much to hold the patch in. The fiberglass should
be tapered back so there is a good, long scarf for bonding.

Sure, that's part of doing it right. I assumed you were comparing the
cap/plug to a proper repair, not just slapping in some putty.

... You're
right that it wouldn't be expensive to do yourself but I'm thinking
yard time (after all, my time is worth something too and unenjoyable
jobs like grinding fiberglass don't have their own rewards). By the
time it is ground, filled, faired, and re-painted, it will cost a bit
either in other things you didn't get done or out of the checkbook.


Agreed. But... if the boat is already hauled for other work, and you
already have other fiberglass work in hand, doing a patch on a former
thru-hull hole is no big deal. I spent more time on the work pictured in
putting up & taping a drop cloth in place to keep grinding dust from
getting all over the engine room.

With a cored hull, you can and should dig out as much core as you can
reach to seal if from the water. This will create a good mechanical
as well as adhesive connection since the patch will extend between the
skins.

Agreed. In this case it would be important to make sure the core is
thoroughly dry & still bonded, and to use material compatible with the
core. Not many hulls are cored below the waterline though AFAIK.


The cap and fill will last as long and reliably (actually more so due
to the watertight fill) than the rest of the through hull plumbing.

Sure, but that's the point. A thru-hull is a vulnerable point. It's a
hole in the hull, a potentially disasterous leak. Vulnerable to
grounding or other impact, flexing, corrosion, freezing, electrolysis,
and occasional misadventures. As opposed to a hole that has been
fiberglassed over, which is vulnerable to... umm, you haven't explained
that part yet...

That's good enough for me. Getting plastic through hulls, especially
the ones near the waterline that can freeze, replaced with bronze is a
much more important issue.


If that's already on your work schedule, then removing & fiberglassing
over the old unused thru-hull during the same haul-out is a trivial
addition IMHO. But hey it's your boat

Fresh Breezes- Doug King