Soft decks are a very common problem with old Lasers. Over many years, the weight of the sailor in
the middle of the deck leads to delamination of the sandwich structure. Instead of a tightly bonded sandwich of
fiberglass – foam – fiberglass, the top layer loses the bond with the
foam. This leaves the sailor supported
by a 1/8” thick piece of fiberglass. The
affected area widens over time with the repeated flexing of the soft deck.
Recently I have had two lasers suffering from this
condition. Rather than attempt to cut a
hole in the cockpit sidewall, and grind out and rebuild the sandwich
construction, I elected to use the epoxy injection method described in Eric’s
This Old Hull.
Unlike Eric, I had no confidence that I could maintain air
pressure in the hull for 24 hours. I was
using a pump designed to inflate water toys like ski tubes. The nozzle fit quite well into the transom
drain hole, but I had no way to keep it there except tape. To control the pressure in the hull I taped
over an inspection port and put small holes in the tape until the air pressure
lifted the deck to flat, but no higher. I
didn’t trust this crude pressure control system for more that 2 – 3 hours, which
dictated a much faster process than Eric used.
Instead of a slow cure hardener (all West System products),
I used a fast cure hardener. This meant
I had to work a lot more rapidly. I got
a helper to double the rate at which the holes could be injected with
epoxy. I also used bigger holes, 1/8”,
to get epoxy into the space faster. I
used several batches of epoxy (4 pumps of resin and 4 pumps of hardener per
batch) and between mixing and injecting, the two of us were still racing the
clock to beat the set up time of the epoxy.
I was repairing two boats on both sides so I had four tries
to perfect my process, and I tried to learn something each time. My primary concerns were making the process
simple and straightforward and controlling things that affect the aesthetics of
the finished product. I tried hard to
hide the repairs and avoid the machine gun bullet holes look.
First, I used a 2” x 2” rectangular grid because it was much
easier to lay out and I thought it looked a little less distracting to the eye
than Eric’s 60 degree grid. On the first
deck, I started by covering the entire area with masking tape and drawing on
the tape. I then drilled the holes
through the masking tape. Each time the
depth stop on the drill bit hit the tape, it made a small tear in the
tape. I learned later that this meant
that some epoxy got on the deck, undermining the masking process. I also learned that until the tape comes off,
you don’t really know how well it worked.
TAKE IT OFF BEFORE THE EPOXY IS SO HARD IT CAN’T BE REMOVED.
Aesthetically, it is very important to keep excess epoxy off
the deck. Much easier said than
done. I spent more time on this than on
the rest of the process.
As a result of what I learned on the first try, I resolved
to drill the holes first and then apply the tape that protects the deck from epoxy
overflow. I didn’t want to draw all over
the deck, so I had to mask first, drill, remove the first tape and re-tape
it. Half way through this I realized I
could make a template for the holes and save a lot of time and trouble. This made a lot of sense with a second boat
to fix. After drilling the holes, I
taped the entire area with blue painters’ tape.
I then punched holes in the tape.
Just like Eric did, I clamped pieces of wood into place to keep the deck
from arching upward when air pressure was applied.
Lessons learned for the second side:
Hanging chads from the
tape can get stuck in the epoxy and leave little blue marks in the holes. Use standard masking tape.
When taking the tape
off for a cleanup before the epoxy is cured, you have to work around the wood
struts that hold the deck down. Plan
carefully where the wood is located in relation to tape strips and holes.
Clean-up is a painstaking
operation if you want a clean deck.
If you can catch the
epoxy at the stage where it is still rubbery, but not rigid, you can used a
razor blade scraper to remove excess. If
there is a bump where a hole was filled, the scrapper cuts it off flush. This is the perfect way to get the holes
completely filled and absolutely flat.
I learned another good lesson when I went to West Marine for
more resin and hardener:
There is an additive
for the epoxy which makes the color white.
It turns out that mixing the slightly yellow resin/hardener solution
with white additive yields an almost perfect color match for off white
decks. When done well, the filled holes
can be just about invisible.
Employing all the lessons learned so far, I advanced to side
one of boat two. In the universe’s
unrelenting desire for me to learn new things, a new problem arose. The process of putting epoxy in one hole,
forcing the air out of the next hole until epoxy came out of that hole, broke
down. With several of the holes, the air never stopped coming, and, in fact,
was a steady stream of perceptibly moving air. As I injected epoxy into
these holes, air bubbled through the epoxy until the epoxy settled and
disappeared. There was a break somewhere
between the pressurized hull and the bottom side of the sandwich. This was undermining the ability of the
pressure inside the hull to push up the bottom half of the sandwich and make a
tight seal. With no good solutions
apparent, I had no choice but to keep filling the holes trying to fill as much
of the void as possible. This used a lot
more epoxy and made the clean-up that much more tedious. The next day the deck was firm, but a few
holes still remained and had to be filled.
With some of the imperfections, I thought I would try gel
coat to pretty up the filled holes.
There are three pitfalls to this.
It can be difficult to achieve a color match. It is difficult to apply one drop of gel coat
and achieve a not concave, not convex, but flat finish. The scraper method of clean-up does not work
at all. When the gel coat is rubbery, it
all comes off in a ball, and when it is firmer, the blade can’t cut through
it. Over all, I concluded that gel coat
was more trouble than it was worth. (Gel
coat is required to prevent breakdown of the epoxy from ultraviolet light. Because I keep my boats covered when not in
use, I don’t think either I or the boat will live long enough for this to
become a problem.)
Side two of boat two went smoothly. When all was said and done, both boats have
rock solid decks (at the cost of a couple of pounds of weight gain) and
cosmetically acceptable scars, some better looking than others.
Standard masking tape, white epoxy additive, and using a
razor blade scraper at the right time are the keys to getting the best look.