| There is no
point in doing anything on a boat unless you take the time to
do it right. -- Anonymous
* * * * * *
It's a fact of life
that boats leak. It's also true that as boats age, leaks
tend to increase for the simple reason that sailing yachts
are under a lot of stress. And in these times when builders
emphasize speed and lightweight, the problems with leaks
worsen since laminates are not as thick nor are hulls
as rigid as they used to be.
Leaks are not only inconvenient and aggravating,
but also cause damage to personal gear and the boat itself.
The source of leaks are usually hard to find and even
harder to stop. The typical case is where the water enters
at point A, but shows up at point B, which is six feet
away from point A. The owner spends weeks attempting to
search out the source so that he can repair it. These
are usually instances where inner liners work to distribute
the leaks to points far from the source of entry, and
are often the subject of many wry jokes.
As an aside here, I want to mention something
that I see very frequently that is just a waste of time
and makes a mess of things. That is the way some people
try to take the easy way out by just smearing some caulking
on the outside of an open seam. On boats, to make an effective
seal, the caulk has to go between the two parts that are
mated, and this is called bedding. Achieving this is not
easy, but it is the only way to effectively stop leaks.
Moreover, with the way many boats are hurriedly built
today, parts are often never bedded properly from the
beginning. If that is the case, then you have to go back
and do what the builder did not do correctly.
Of course, the granddaddy of all leaks
is the leaky hull-to-deck join, which is usually the most
difficult of all to repair. I've seen numerous boats where
the deck joint leaks so bad that either the boat is uninhabitable,
or the boat has become severely damaged as a result of
rotting internal plywood structures, wet bedding and the
like. Vee berths in both power and sail boats are often
a victim of this problem, where you end up with both rotting
mattresses and structures. Ouch! This gets expensive.
In many instances, the manner in which
the deck is joined is such that effecting an economical
repair is near impossible, or that the leakage is so pervasive
-- meaning that the deck join is leaking everywhere --
that the deck needs to be removed and reinstalled anew,
which also means that it's likely to be more economical
to get rid of the boat and buy another one, than it is
to attempt to repair it.
For these reasons, when considering the
purchase of any used boat, it is of paramount importance
to check the boat over for leaking deck joints; this is
not a problem that anyone should buy into. Leaking deck
joins are most intractable when associated with working
hull structures. Not all boats are as rigid as they should
be, and if the rigging is causing compression loading,
both fore and aft, as well as transversely, then attempting
to repair leaking deck joins may be an exercise in futility.
Checking a boat for leaks is fairly easy.
Just start opening things up and looking. The usual indicators
are, aside from the plainly obvious, are numerous rust
stains where canned goods were stored, rusty tools and
mattresses wet on the undersides. If not wet, look for
stains on the hard berth surface. Check out any place
on the interior of the hull sides where you may be able
to see water trails or heavy amounts of mildew. Water
stains on headliners, discolored cabin soles, damaged
paneling, water puddles or water lines under berths or
other places that trap water. The number of indicators
is nearly endless.
It's a mistake to think that repairing
leaks is a relatively minor problem that can be done at
low cost. Yes, repairing a leak is usually a simple matter,
but the fact is that there is often no access to the area
that needs repair, so that to make the repair requires
tearing out a part of the interior. Such is often the
case with chain plates and other deck hardware.
Chain Plates As any experienced
sailor knows, the most common source of leakage is at
the shroud chainplates where they pass through the deck.
Because of the frequent loading/unloading that occurs
at these points, it is very difficult to keep them sealed,
and on some boats it is a constant battle. However, if
the shroud chain plates are attached to plywood bulkheads,
it is critical that the leaks be stopped and the wood
protected. Due to poor design, for many boats it is impossible
to keep the chain plates sealed completely, but there
are things one can do to reduce the leakage and keep the
plywood from rotting.
One of the most common mistakes that
boat owners make is to caulk these points with the wrong
material, most often polysulphides or silicone based caulks.
These materials will not do the job because they have
poor adhesive qualities. To create a strong, long lasting
seal at a chain plate that is subject to working, one
needs a strong, resilient adhesive. Such as the dreaded
3M 5200. Boat owners frequently tell me that they hate
using the stuff because it's messy, and because once applied,
it's very difficult to remove or detach parts bedded with
it. But that is precisely why it should be used; 5200
is one of the strongest adhesives available and adheres
very well to metals and nearly all other materials other
than some vinyls and polypropylenes. Polysulphide "sealers"
are not good adhesives and silicone is not an adhesive
at all. It's primary means of adhesion is suction. That's
why you can glue glass together with it, but nothing else,
for only glass will yield a perfect suction surface. If
you ever wondered how they can glue aquariums together
with silicone, that's the reason why.
5200 is like working
with tar. It has a way of getting all over everything,
no matter how hard you try to be careful. That's one
of the reasons it's so good; it sticks to anything and
everything. When working with the stuff, you should
have plenty of rags and a quart of acetone handy. Once
you've used a rag to wipe up excess, get rid of that
rag as that rag will transfer 5200 to everything it
comes in contact with, including you. It's a real tarbaby.
Clean your hands the moment you get some on them, otherwise
your fingers will transfer it to whatever you touch.
You won't notice this at first, but weeks later dirty
finger prints will start showing up all over, and they
do not wipe off. Once it's cured, 5200 is no longer
soluable with anything.
If your bedding or caulking material
does not adhere to a part, though it may appear to cling
closely, what we end up with is a minute crevice between
caulk and the mating surface. In turn, this crevice becomes
a capillary that is capable of transporting water in amazing
quantities through a crevice so small that it may not
even be visible.
Therefore, one of the best ways of sealing
up leaky chain plates at the point where they pass through
the deck is to thoroughly clean the fiberglass surfaces,
preferably with something like a Dremmel tool with grinder
bit to get a good bonding surface. Don't waste you time
trying to caulk over a dirt laden surface, you efforts
to seal will fail. Plus you must be sure that there is
no waxy or oily residue. Thus, it's best to sand or grind
all surfaces to be bonded.
Often times the width or length of the
rectangular hole is too large to be able to fill it in
adequately. If that's the case, you can glue in appropriately
sized filler strips with 5200 so as to reduce the gap
between the chain plate and deck. Once the 5200 has cured,
then you can come back and apply the final bead of caulk,
and bed down the rectangular flange plate if there is
one. Because of the strength and durability of 5200, this
method should last for many years assuming that there
is not excessive structural movement involved.
If the chainplate is attached to a plywood
bulkhead, it's a good idea to treat the area to prevent
deterioration. A successful method I have used is to unbolt
the plate, grind down the surface to get it good and rough,
and then coat the area and bolt holes with epoxy. This
will help shed water and greatly reduce the potential
for rot if the attempts at sealing the leaks are not successful.
Stanchion Bases and Other Hardware
The next most common source of leakage are those pesky
lifeline stanchions. These stanchions are subject to an
incredible amount of stress, so that over time even the
best installations will begin to leak. However, I see
far too many boats where the basic design of the base
is poor. The foot print of the base is often so small
that it has little or no chance of providing a stable
attachment. If that's the case, the only option is to
change them out, if possible.
Properly repairing leaking stanchions
often becomes a nightmare job because the boat builder
has provided no access from the underside. If you can
reach the under side, the job is fairly easy. First, the
bases should be removed entirely. Check to see that the
bolt holes are properly sized to the bolts. If the holes
are oversized, a rigid attachment cannot be obtained.
Correct this by completely filling the holes with epoxy
and milled fibers; then redrill the holes (using a drill
guide) to their proper size. Lightly sand the outer surface
to remove dirt and mold release compound that may still
be present. If the base did not have a back up plate,
you should add one, space permitting. Aluminum or a blank
of scrap laminate will work fine. Use the stanchion base
as a pattern to drill the holes. Don't use plywood with
nuts and washers as these will crush the plywood and permit
loosening.
Again, the material to use for bedding
stanchion bases is 5200. Both the stanchion base and the
back up plate on the underside should be thoroughly bedded
as this will create a double seal. When pushing the bolts
down through the holes, and while the head is standing
proud about 1/4", make sure that there is bedding
under the head. If not, add some.
Deck Drainage I don't know what
it is about sail boat designers, but they seem to have
a superb knack of overlooking deck drainage. As I make
my rounds through marinas and boat yards, it's amazing
the number of boats I see with water standing on the decks.
When hardware is present, leaks are sure to follow, which
are also a serious hazard to cored decks. One way or another,
you have to find a way to provide adequate drainage, whether
by notching the rail or installing a scupper.
Ports, Windows and Hatches These
tend to develop leaks because the structures to which
they are attached are not completely rigid and are subject
to movement, thus breaking the bedding seals. This is
often the case with port holes in the sides of cabin trunks.
Jumping on the deck near them results in flexing that
breaks the seal. Many boat owners just smear some caulking
around the exterior seam. All this will do is create an
unsightly mess, but will not stop leaks.
The bedding seals in port holes break
loose because a non adhesive bedding compound was used
to set them, usually because the ports are plastic. The
common reasoning for this runs, "Well, these parts
are plastic and if I use 5200 they will never come off
without breaking. Therefore, I will use polysulphide or
silicone." That is true, but what you've now got
is leaks, so it's your choice between leaks and costly
interior damage, and parts that come off easily. It's
true that if you bed a plastic port with 5200, you may
end up destroying the port trying to get it off. On the
other hand, if you use 5200 and bed it properly, you shouldn't
ever have to deal with leaks again.
If the flexing is excessive, there will
be essentially no way to stop the leaks short of reinforcing
the flexing area. This is a fairly common problem with
side decks adjacent to trunk cabins, and around hatches
set in a wide expanse of deck; if the deck flexes at all,
the hatch or port won't stay sealed.
Alternative Methods Whenever
you suspect that slightly flexing structures are the primary
cause of leaks, such as hatches on deck or coach roof,
or port holes in a cabin trunk or even hull side, try
jumping on the deck or stressing the surface by some method
to see how much it flexes. If flexing is only moderate,
an alternative method of leak stoppage may be appropriate.
Instead of bedding and bolting the part down hard with
wet bedding, in which case you squeeze most of the bedding
out, leaving only a thin film of bedding that will seal
less well, try using this method of creating a gasketed
joint, which usually takes two persons to accomplish.
For this method, you can use any high quality flexible
caulk rather than 5200.
Cut a number of shims of equal thickness,
say 1/8". Apply the bedding thickly and evenly around
the mating surface using a putty knife to smooth it out
to slightly more than that thickness. Use a new putty
knife and wax it so the caulk doesn't stick to it. While
you begin to set the hatch or port frame in place, have
the other person shim it all around. The objective here
is to create a layer of bedding of uniform thickness by
using the shims and excess of caulk that will serve as
a flexible gasket. The idea is that if there is structural
movement, rather than creating a rigid joint that is going
to break loose, we create a more flexible join by this
method.
Obviously, great care has to be taken
that there are no big bubbles or voids between the hatch
frame and caulking layer. Set the hatch frame in place,
and press down until the shims stop it. A lot of caulk
should be squeezing out the sides. Next, run all the screws
or bolts in, but do not draw them tight. Leave enough
space under the heads that more caulk can be added. Now,
allow the bedding to fully cure, at which point you come
back , recaulk under the bolt heads, and then draw them
tight. What you have done is to create a gasket. If leaks
redevelop due to a flexing structure, you can come back
and retighten the fasteners.
Note: When retorquing the fasteners,
be especially careful with cast aluminum or plastic flange
plates; if torqued too much or unevenly, they are likely
to crack or break. Extruded aluminum will not break, but
you do run the risk of distorting the flange if torqued
too much or unevenly.
Windlasses These are another
common leakage problem. Because the leakage occurs within
the rope locker where leaks usually do not cause interior
water damage, the leaks often cause severe damage to the
windlass drive motor and housing. Windlasses usually develop
leaks because they are highly stressed, breaking the seal
around the deck and bolts. If you don't already have leaks,
you can usually avoid them by being careful not to place
very heavy loads on the windlass. Don't use it to force
out stuck anchors.
There is only one solution for curing
leaks around the windlass base, and that is to pull it
and rebed it. Not a pleasant task, but keep in mind that
just smearing some caulk around the base won't help. Very
often, I find that the real cause is that the builder
failed to provide an adequate foundation for it during
construction. In other cases, the builder cored the foundation
area with plywood, but the windlass installer failed to
thoroughly caulk the bolts with 5200 and water got into
the plywood and rotted it. Whatever the cause, you need
to evaluate the source of the problem and correct it.
Leaking Packing Glands It is
often a great mystery to boat owners why they suffer from
chronic packing gland leakage after repeated repackings
and tightenings. Some try converting to the "dripless"
type of glands and still that doesn't solve the problem.
Chronic packing gland leakage is usually
the result of excessively flexible engine mounts on diesel
engines. Because small diesels cause a lot more vibration
than larger diesels, sail boat builders prefer to use
softer mounts which allow for more engine movement. Engine
movement, of course, causes shaft misalignment which,
in turn, causes packing glands to leak because the shaft
is spinning eccentrically and wears the packing out more
rapidly on one side. This, in turn, usually results in
rapid cutless bearing wear which results in even more
shaft movement, at which point even freshly repacked glands
won't end the leakage.
Obviously, there is no particularly good
solution because you will have to trade off higher vibration
levels with stiffer mounts to achieve less leakage. Whatever
you do, don't switch to an expensive dripless type of
gland because the shaft misalignment caused by flexible
engine mounts will damage it and it will be a wasted effort.
If the engine mounts are very old, say ten years or more,
it's a good idea to replace them. Replace cutless bearings
at the point where you can move the shaft in the bearing.
Shaft concentricity can be easily checked
without the use of a dial indicator. If the shaft is dirty,
clean it off with sandpaper while it is rotating until
you get a nice, shiny surface. A shaft that is running
out of true as little as 0.010' is plainly visible. At
0.020" out of concentricity is unmistakable and at
800RPM you will notice the wobble. If so, you need look
no further as to why you have leakage problems. But why
is it wobbling? Is it a bent shaft, or the result of engine
movement?
A good way to find out is to directly
observe how much engine movement or vibration is occurring.
This, too, is usually plainly obvious. Check this at various
engine speeds. Usually the largest amount of movement
will occur within the lower half of the RPM range, and
tend to go away at higher speeds. If the shaft is bent,
the eccentricity will become a blur but not go away. The
strong vibration will increase. If you put your hand on
the stuffing box, or the transmission, you will feel it.
If the wobble smoothes out and the vibration tends to
lessen, then the shaft is not bent and the mounts are
the likely culprit.
If the engine mounts prove to be too
flexible, it's a good idea to change them out to a more
rigid type.
Thru-hull Fittings With today's
modern materials and cored hulls, leaking thru-hull fittings
is not a problem in and of itself. But it is a problem
that threatens water intrusion into cored structures of
all types, including decks.
To eliminate this danger, it is only
necessary to adhere to a very simple rule: Never, but
NEVER install a through hull fitting or fastener directly
into or through a cored structure. Also, never install
a through hull on a surface with a pronounced curve. Otherwise,
it will no seal properly, or, if you draw it too tight,
it will cause a dimple in the hull skin. The proper method
of ensuring that water never gets into a core is to never
breach the core. When it comes to through hull fittings,
especially if you have to add one, this is not as difficult
proposition as it may seem, though it's a bit more time
consuming than for a non-cored structure where you just
drill a hole and pop it in. The entire job takes about
4 hours over two days, not including time to obtain materials.
The first thing is to remove the core
from the immediate area where the sea cock or whatever
will be installed. This is done from the interior. Let's
say, for example, that you are going to install a sea
cock that has a 2" diameter foot print. You'll need
to remove about a 6" square of inner laminate and
core. There are a variety of means to do this, depending
on working space available. Usually a die or angle grinder
with abrasive cutting disc will work fine in tight spaces.
Cut through the inner laminate only and remove the square
of inner skin only. Next, cut out the core with a knife
in a circular shape. The reason for this is that is necessary
to relaminate and completely seal up the exposed areas
of the core. It's a lot easier laminating the rounded
corners than it is a square one.
Next, using an 80 grit grinding pad on
a very small grinder, you smooth out all surfaces in preparation
for closing up the exposed edges, keeping in mind that
the laminating surfaces must be absolutely clean, and
the bottom of the hole must be flat.
There are several ways to finish up here.
The method I prefer is to use a high quality marine epoxy
paste and 2 or 4 oz. Cloth. Don't use mat because you'll
end up with a big mess. Trowel the paste heavily onto
the edges of the core, working it into the cells and rounding
out the corners at the bottom. Use more rather than less
epoxy. It will help to round over the top corner of the
expose foam. Then I cut the cloth to the appropriate size
-- meaning about a 1" overlap each onto the inner
skin and outer skin, and then press these strips into
the wet epoxy completely around the circumference of the
cut out. Following this, you then trowel the remainder
of the epoxy paste onto the outer side of the fabric,
making sure that there are no holes or gaps, and then
smooth it out. I use latex gloves and smear the epoxy
around with my fingers. Note here that you must use fresh
two part epoxy for this job, not old stuff that has become
thick and stiff.
This method will ensure that there is
no chance that water will leak into the core, because
you have completely sealed it off. Once it's cured, come
back with the grinder and smooth out irregularities. Now
you're almost ready to drill your hole for the new sea
cock and install it in the usual manner, but there is
another important detail to attend to. That is providing
a doubler block under the sea cock so as to relieve strain
on the outer skin.
What to use for the doubler? Well, the
ideal material would be a piece of fiberglass laminate
scrounged from a boat yard or trash can. Or any other
type of reinforced plastic that is 1/4" to 1/2"
thick. The doubler should be about 1" larger than
the foot print of the sea cock and be completely flat.
It's best to bed this in place with epoxy, let it cure,
and then drill the hole through both parts at once to
get the best fit. Now you're ready to install the sea
cock and never have to worry about it leaking.
|
Dealing
With Leaks 
