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Wet
beds, mildew, rust stains in the cabinets, water stained and rotting
paneling, stained headliners, rotted deck cores with soft spots
. . . these are just a few of the damages caused by deck leaks.
Whether we're talking sail or power boats, deck
leaks tend to be a pervasive problem, one which few people give
much thought to until its too late and the damage has been done.
And as the boat building industry keeps on turning out boats of
ever decreasing quality, the problem continues to worsen. Sometimes
the leaks can be repaired, other times not.
Let's begin with the fact that nearly all boat
decks are cored with materials like balsa, plywood and foam. The
coring is necessary for several reasons, including strength. But
the cores are also good heat insulators too, and there's nothing
wrong with the basic concept of coring a deck except when water
gets into it. Leaking decks usually have two basic causes:
1. Improper
design, construction and installation of hardware.
2. Installation
or removal of hardware and other equipment by the owner.
The first thing we need to understand about decks
is that the cores must be designed to be completely water proof,
followed by the rule that nothing must ever be done to the deck
to damage that water proofing. Of course, people find it necessary
to attach things to their decks, and that's where the second basic
problem arises. They drill holes in the deck and screw things down
without realizing that what they are doing is creating a point of
water entry into the core.
"Oh, but I caulked the hardware when I fastened
it down," people tell me. Unfortunately, they don't understand
several important points. First, screws are a lousy way to attach
things to fiberglass which is brittle and will not hold screws very
well. Secondly, as the screws loosen, even just a little bit, the
caulking also loosens and the leaks begin. So what they thought
was a good job of attaching something was actually doomed right
from the start.
If you own a used boat, you may find yourself the
victim of the former owner's ignorance. If you bought your boat
new, pay heed to what you should and should not do as respects adding
hardware.
Those folks who build top quality boats make it
a rule that nothing should ever be attached (1) with screws, and
(2) to a cored structure. When you look at a well designed boat,
what you will find is that at every point of attachment (a) there
is no core in at that point, and (b) the hardware is bolted through
the deck. This should be the inviolable rule for both boat builders
and boat owners. Never, ever, attach anything to a cored structure.
Illustrated below is the proper design and installation method of
hardware to cored structures. Notice that the deck has to be designed
properly in the first place.
If the builder just ran screws through a cored
deck, you've got a problem.
Pre Existing Holes I would
venture to guess that about 75% of all boats that I survey have
holes drilled in the decks, holes that are revealed by the removal
of hardware, and holes that were never even properly repaired. Whether
there are existing holes in the deck, or you plan to remove a piece
of hardware, the first thing you must be aware of is that you just
can't fill the hole with putty and forget it. Fiberglass expands
and contracts with heat and cold, so that just filling the hole
with putty won't seal it. The putty will loosen and the leaking
will begin.
If you have existing holes, or holes with open
seams around the filler, they need to be repaired immediately. But
before you can do that, you need to determine if there is water
in the core. It won't do you any good to try to fill a hole that
is wet. You might as well paint your boat while its raining for
all the good that will do. To determine if its wet, drill a 3/8"
hole on the underside: if the core shavings come out wet, you got
a problem. Now, I know some of you are going to be thinking, "Sheesh,
I gotta go through all that rigamarole just for a coupla lousy screw
holes?" Well, let me tell you what's likely to happen when
you don't. A few years down the road when its being surveyed for
the new buyer, the surveyor says, "Well, gee, look here, there
are holes in the deck and the core is all rotted and that's going
to cost $2500 to fix." And guess who's pocket that comes out
of. Right, yours!
So now that you know that dinky li'l hole in the
deck is serious business, here's what's got to be done to fix it.
What you do is to drill a total of four more holes on the under
side in a rectangular pattern, bracketing the area. You can just
take a small drill and run it straight through the deck from the
hole(s) that you're going to fill to locate the area from the underside.
Temporarily cover the holes on deck with silicone sealer, and then
wait at least two weeks for the core to dry out. Once the core is
dry, then take a drill that is just slightly larger than the old
holes and drill them out to get a nice clean surface to which your
epoxy paste can adhere to. Using a nail or something similar, work
the epoxy paste down into the hole until the hole won't hold any
more. On the surface, pile the epoxy up a little to make a slight
hump that you'll come back with a razor blade and slice off nice
and smooth after it has cured. Its not likely that you're going
to go to all the hassle of gel coating the finish, so you can just
touch up with a dab of white enamel. It won't look so good, but
at least you won't end up with a rotted deck core.
Railing Stanchions The
most common point of leakage is from stanchion bases. For some strange
reason, the boating industry has never seen fit to manufacture stanchion
bases that are wide enough to resist the tremendous amount of leverage
that is placed on the base by a 36" stainless steel pipe. When
you lean against a stanchion, you are likely to be placing at least
several hundred foot-pounds of pressure at the base. With that in
mind, its not hard to understand why they so often come loose and
start leaking. And to make matters worse, you'll often find that
on small boats, the rails are simply screwed and not bolted on.
And if that's the case, there's not a darn thing you can do about
it because its just plain built wrong.
The above illustration shows the proper method
of installing a stanchion or any kind of hardware. Notice that there
is no core in way of the point of attachment, an area of solid fiberglass
called a 'boss." This eliminates any possibility of water getting
into the core, and provides a very strong point for mounting. Obviously,
if your boat is not built this way, there's nothing that can be
done to change the original design.
Repairing Leaking Stanchions Leaking
stanchions can be repaired if you have some access from the underside.
Unfortunately, in most cases you have to tear the interior of the
boat apart to get that access, which accounts for the reason why
deck leaks are rarely ever repaired. The leaks just go on and on
until the interior is ruined and the boat gets junked, or some poor
fool comes along thinking he can restore it.
If you cannot reach the stanchion bolts from the
underside, its a waste of time to try to caulk it from the exterior.
No amount of exterior caulking is going to stop the water.
There is only one way to effectively stop the leaks, and that is
to rebolt the stanchion bases, and to add aluminum doubler plates
to the underside if it doesn't already have them. Its the lack of
doubler plates that is probably part of the problem in the first
place, and unless you resolve this, nothing short of strengthening
the mounting will help.
There should be no deck coring in way of the stanchion
bases but, if there is, what you have is a badly designed boat.
If the core is deteriorated around those bases, then what you are
looking at is a repair job of major proportions, and one that almost
no one will foot the bill for. If there is no core in way of the
bases, then all that is necessary is to remove the headliner or
whatever is covering up the fasteners on the inside and remount
everything. The thing is, if they were bolted on in the first place,
they are not likely to be loose, meaning that what you've got is
probably screwed on stanchions. The only way to remedy this is to
bolt them on. That's easy to say and very hard to do.
Hatches The second most
common offender is improperly installed hatches which, just like
improperly installed stanchions, are extremely difficult to correct.
Most often the causes are as follows:
(1) There is not enough framing in the deck so
that the deck sags somewhat, making it impossible for any caulking
under the hatch frame to seal. In this case, you can remove the
hatch frame, recaulk it, only to have it start leaking again. The
only solution for this is to drop the headliner (if possible) and
add frames around the hatch opening to strengthen it against deck
deflection.
(2) While the deck may be strong enough, the hatch
opening may be improperly designed. If all the builder did was to
cut a hole in the cored deck (as many do) and simply screw the hatch
frame in place, then that is the source of your problem. Whatever
small about of deflection there is in that deck is going to break
the screws and caulking loose. Check the screws: if they're loose
and won't tighten up, then that's the problem.
Remove the frame and check if the hatch is screwed
into the core. Chances are it is, and if that's the case then it
can be fixed fairly easily. Here's the method I used for repairing
a foredeck which had no frames whatever, and a hatch that was installed
through the core.
My deck was very weak, so what I did was to cut
two fir frames and heavily glassed them to the underside of the
deck, one forward and one immediately aft of the hatch. Since the
headliner was glued to the underside, I opted to replace it with
new white vinyl and contact cement. Took 3 hours with 2 people.
The basic idea here is to remove the core (balsa
or foam) and replace it with a wood frame as show in the above illustration.
In my case it was balsa and I cut it all out 2-1/2" around
the perimeter of the hatch, mainly by just digging it out from between
the glass laminates. Then I smoothed off the rough inside laminate
surfaces with a sanding disc. Next, cut a teak framework to fit
the perimeter of the hatch, making the frames about 1/16" less
than the distance between the void space that you have created by
digging out the core. If the deck is slightly curved, you need to
shape the teak strips accordingly by planing them to the proper
contour. This is likely to be only a few degrees of arc and won't
be difficult, but if you fail to do this, it will distort the deck!
Next, fit the pieces between the laminates, set
the hatch frame in place and drill new bolt holes to size of the
new bolts (instead of screws) that you're going to use. If the headliner
is glue to the deck underside, you should bolt right through the
liner, or be prepared to install moldings to cover up the bolts.
After all the new holes are drilled, you next load the void up with
epoxy, fit the teak frames into the void, caulk the underside of
the frame, and then bolt the whole mess together while its
still wet. Make sure that the edges around the new framework
are completely sealed off with the epoxy, as well as the surface
of the exposed teak.
Before putting it all together, perform a dry fit
to make sure that when you bolt the frame down that it does not
distort the frame when the bolts are tightened. It should merely
squeeze it altogether, not cause any distortions in the deck. If
you did the job right, I guarantee you this hatch will never leak
again. This part of the job took about 8 hours.
Deteriorated Deck Cores Sometimes
these are repairable, sometimes not depending on where the problem
is and what has to be cut out to make the repairs. If you have,
or suspect you have, water in a deck core, the way to tell is to
simply drill a couple of small holes in the underside and see if
water runs out.
The best way to repair deck cores is from the underside
when that is possible. Making repairs is easy, but putting back
together everything that has had to be torn out is where the real
work comes in. The problem with repairing from the exterior is that
it is extremely difficult to accomplish a finish repair that doesn't
look like its been repaired, and its not a job for an amateur. If
you can't make the repair from the underside, you should not try
an exterior repair yourself unless you are highly skilled in this
sort of thing. Few people are. If you can't get access from the
underside, then you have a major and costly problem on your hands.
Window Frame Leaks A pervasive
problem, window frame leaks almost invariably occur because the
structure in which the frame is mounted is weak. That usually means
either the deck below or the house top above it is distorting and
causing the caulking seal to break open. Whether or not it can be
repaired needs to be evaluated by an expert, as you don't want to
waste a lot of effort and money at resetting the frames only have
them start leaking again.
One possible method of repair is to remove the
frames and to reset them using bolts instead of screws. Problem
is, you're not likely to be able to get at the inside without ripping
things apart, so now what? Here's a possible solution that will
require several days to accomplish. Remove all the window frames,
and remove all the old caulking completely. Use
acetone to get it all off. Then sand the mounting surface with 80
grit paper to rough it up. What you will do next is to apply a very
heavy layer of caulking and then reset the frame. Only instead of
completely pulling the fasteners tight, you will put 1/16"
to 1/8" thick shims under the frame and only draw the frame
against these shims. This will leave a layer of caulking that will
form a gasket. After you've done this, you wait 2 days for the caulking
to cure. Then you pull the shims out and draw the fasteners tight.
What you will have accomplished here is to provide
a greater degree of flexibility to the joint surface that will permit
some movement of the supporting structure without breaking it completely
loose of the seal. As long as the fasteners are holding, you can
continue to draw it tight if the leaking continues. This method
will work for good quality frames and for a structure that is not
hopelessly weak. It will only work for frames that have flat, and
not concave inside surfaces.
Leaking Port Holes Ports
in hull side usually leak because the hull side is weak and panting.
This causes the caulking seal to break loose and the frames to crack
or distort, particularly if they are plastic. Kick the hull side
with your foot. If it flutters, then you know what the problem is.
You can pull it apart and recaulk, but it will probably soon start
leaking again.
Sometimes builders install the port frames with
a vinyl or fabric liner under the inside frame that causes water
to wick through. Others installed plastic frames in curved surfaces
so that, when the fasteners are drawn tight, the frame distorts
and the gasket will not make a complete seal. This can sometimes
be corrected by releasing the flange or base plate. If it springs
back to a level surface, you can recaulk with 5200, but this time
do not draw the fasteners completely tight where the gaps appear
on the curved surface. Just draw it tight enough to bring the flange
into the caulking so that there is a seal. This may allow the thicker
layer of caulking to flex without breaking the seal. Then again,
it may not.
Even on well built boats, as they age time will
break the caulking seals around ports. For hull sides that are fairly
solid, you can use the same method as for window frames described
above.
Chain Plates Most people find
that sealing chain plates that go down through decks to be impossible.
Between the flexing decks and the stress on the plates, it really
is. Silicone and other types of caulking won't work because it won't
stick to stainless steel and its impossible to get a water tight
seal. To make matters worse, if the chain plate is bolted to a plywood
bulkhead, the leaking is going to cause the plywood to rot and eventually
the rig will topple over. The answer to this problem is to design
a method that limits the amount of water that can enter.
First of all, remember that when it rains, water
is going to run down the rigging. You don't notice this, but it
does, and that's one of the reasons so much water gets in through
those tiny cracks. The other is that the stainless bar penetrates
the deck in a place where water is standing.
The above illustration shows a collar arrangement
that is effective in stopping most of the leakage. The collar is
made of acrylic plastic, cut on a band or hand saw to fit around
the chain plate. It is clamped together with a screw fore and aft
and serves two purposes. The caulking gap between plastic block
and chainplate should be close to 1/4" to allow for movement.
What this accomplishes is that, first, it creates
a cofferdam at deck level so that standing water won't leak in around
deck level. Secondly, since we can't get an adhesive bond to the
metal, we've going to use a pressure bond instead by tightening
the screws against the 5200 caulking AFTER it cures. The contact
surfaces of the plastic should be rough cut to help with adhesion.
The plastic is then glued to the deck with 5200, and caulked around
the chain plate. Rough up the gelcoat surface on the deck with sandpaper
or a Dremmel tool and bit. You should shoot for a layer of caulking
between the collar and the deck of nearly 1/4" thick to allow
for as much flexibility in the caulking as possible. Then, after
the caulking is cured, we come back and tighten the screws slightly
. . . . but no so much as to pull the plastic collar loose from
the deck.
The nice thing about this arrangement is that if
you don't get a good seal the first time, you can always pull it
up and start over, or redo it if it starts leaking again later.
Notice here that the whole idea is to allow for some flexibility
without seams opening up.
Posted July 9, 1998
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Deck
Leaks
