Engine Room Limber Holes

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December 2005 --

The limber holes in the stern area needed rework,
as they've never worked while I've owned the boat.
The RI factory yard did something incredibly stupid.
The limber holes were constructed with flexible hose
packed in silicone. The hose was installed, then the fuel tank was installed on top, and the whole area was packed with foam which expanded and crushed the hose.
That's the short version. Thanks, Barry.
(He's the guy who ran the yard when my boat was built.)

This is the silicone that surrounded the hose that ran under the tank that lived in the boat that Barry built.

Whatever. I knew this needed to be done when I bought the boat.
I just didn't know it would take me
this long to get around to it.

After pulling everything out, I overdrilled the existing holes with
a 1-1/4" hole saw to get down to new wood and oversize the hole.
Besides water, I also want miscellaneous dirt to pass.

I like to hose down the inside
of the boat occassionally.

The sawdust was slightly damp.

That's weird. It's not rotten, thank goodness, but it's damp and smells like diesel.
Some of that crud that was sitting around the old fuel tank made it into the wood.

Bummer. I'd been hoping that the old silicone had kept moisture away from the wood.

I can't seal it up when it's damp, and
my project plan calls for doing another scrubbing and hosing down on this weekend, so now it'll get even wetter.

I'll need to dry out the entire bulkhead
(see Engine Room page)
before completely painting it,
but that won't stop the limber holes
from going in.

This was an interesting discovery.

Farther back, there's a
structural bulkhead that
supports the rudder.

My IOR stern narrows and rises into a champagne glass transom.
I wasn't comfortable using a hole saw, as it couldn't be
pointed up at a safe angle,
even with a right angle adapter
to make the drill shorter.

I don't want to miss and drill a hole in the bottom of the boat.

That would be a bummer.

Time to break out my
Handy Dremel Tool.
This 80 grit flapper wheel did the best job, slowly removing the fiberglass and plywood.

Silicone caulk is *really* hard to remove, and I've always resorted to cutting it away with a knife and scraping the knife against the underlying laminate to remove any residue before using power tools, since silicone residue can contaminate the tool and impede the replacement bond.

I had this little router bit for
my Handy Dremel Tool, and it's really sharp,
just like a knife. It cut that old silicone away in short order. Of course, I wrecked the blade on the fiberglass, but I'm feeling a bit manic today and I'm willing to sacrifice the bit.
The job got done.

As you can see from this picture,
I have a slightly overwhelming number of projects going on at the same time.

The area was coated with dust from sanding and grinding, and needed a good scrub with detergents
and degreasers prior to
the next round of epoxy and fiberglass.

So now the holes are even wetter.

I left these two 125 watt heat lamps
pointed at the holes, and went to work for more money.

This is a four inch section of
1.25 inch PVC pipe.

I used it as a guide, and eventually my Handy Dremel Tool made it to the other side
at the right spot.

The holes are lined with 1-1/4" Schedule 40 PVC pipe.

The forward holes were really easy. I just set the pipe in place and packed them in a super thick putty
of epoxy and colloidal silica.

Because the holes are a couple of inches off the centerline, they actually left a small area in between them that was lower.

I filled this with epoxy, so there won't be a constant puddle of water right under the lowest spot of the fuel tank.

This turned out to be a stupid idea, and after thinking about it
I made an adjustment.

The holes back by the rudder post were more work.

It was really hard to reach the other side, even with everything out of the boat.

I faired down the back side by feel, checking my work in a mirror after every attempt.

Finally, I quit
trying to fair the super thick epoxy down smooth,
and will sand it smooth after it cures.

Cleaning the excess epoxy out was really easy, by
using this slightly worn down flapper wheel on my
Handy Dremel Tool with the extension wand.

It was worn down from other work,
and fit perfectly in the pipe.

Zoom Zoom.

I also used it to sand the epoxy smooth around all the holes, and round off any rough edges.

I woke up and realized there's no rule saying
you can only have two limber holes.

This is the fuel tank's lowest spot, and the point where the tank is closest to the hull.
I need Air Flow in that area, and as much space as possible, so I ground out the epoxy, drilled another hole, and sunk in a third piece of pipe.

(In the foreground you can see one of the new braces for my new fuel tank. That was a job!)

It doesn't quite match the other two.

So what.

I'll clean it up with my
Handy Dremel Tool, and paint it.


After a few days, the holes were still damp. It's been raining and in the 50F range, and that seems to be keeping the aft set of holes from drying out very quickly.

The forward holes are already dry.

I set this electric heater
on 1000 watts, and let it blow
warm air through the holes
for a week.

That dried them out just fine.

One should always be careful
with electric heaters
on unattended boats.

Finally, the compartment
for the new fuel tank is ready to paint,
so the limber holes are done as well.

Here it is after the first coat. I really slapped on the Interlux Bilgekote, because the whole area is pretty rough. So the paint dripped and sagged. That's okay, once the tank is in I'll never see it again.

Note the new supports for the new tank --
but that's another story.

These are the forward limber holes,
looking forward from the rudder post.

I slapped on a second coat of paint, which covered the spots I missed the first time.
It'll have a couple of weeks to get good, dry and hard before the tank goes in.
I need to work on the cockpit sole and reinstall the rudder thrust bearing
before installing the new tank.

Besides, the top of the bulkhead
is still drying out. It's full of holes,
and heat lamps are on it
when I'm not on the boat,
so the paint job isn't finished.

Post Mortem March 2006 --

If I were to do it again, what would I do different?

I would make a little small ledge, about 1/4" high, directly below the limber holes. That sounds crazy, but here's why: Everything I drop in the transom area goes directly down, through the nice big limber holes, and under the tank. While installing the steering, I had to pull the fuel tank out four times to retrieve things.

Instead, I'm going to stuff a "chore boy" down at the bottom of the transom area, to allow water through but stop larger objects from rolling down and under the tank.