| The diesel tank on my boat was capped
off at least 12 years ago by Bodhran's previous, owner.
A 22 gallon fuel tank was installed on the battery shelf under
the cockpit. Unfortunately it blocks access to the steering cables
and the thru hulls in the aft section of the boat. I also hated
the idea of a 70 gallons of space not being used, so I decided
to try and repair the old tank and remove the tank under the cockpit
sole. Fortunately Good Old Boat had an article instructing
me on just what to do. |
 |
| Figure 1. Masked and ready to cut. |
|
The first step in repairing the tank
was cutting access into
the top of the tank. I used a Fein Multimaster with with a piece
of masking tape 3/4" up on the blade to mark the depth of the teak
and holly plywood sole. Instead of drawing on the floor, I used
masking tape to mark off the dimensions of my new access hatch.
This way when I'm done I can use the cutout for the hatch.
|
 |
| Figure 2. Fiberglass hull liner revealed
after wood is cut out. |
|
The first cut is only through the wood sole and
not the fiberglass liner. |
 |
| Figure 3. Caption goes here. |
|
Then I cut through the hull liner leaving a 2" rim
around the opening to act as a base for the hatch. I assumed that
there
would be baffles
both fore to aft and port to starboard so I cut another access
hatch in the galley floor and removed the drawers from under the
galley counter to be able to access the port side of the tank.
It turns out that there is only one baffle running port to starboard,
so only the cutout at the base of the companionway is needed. I
glassed back in the cutout in the galley to try and return some
of the lost structure from cutting through the hull liner. |
 |
| Figure 4. Using template to align holes. |
|
I located the baffle in the tank by thumping
the top of it and installed inspection ports on either side of
the baffle. I used Seabuilt (www.seabuilt.com) 10" aluminum inspection
ports for diesel tanks. The ports were a bit pricey but were a breeze
to install. The packaging for the ports is used as a template. |
 |
| Figure 5. Completed opening. |
|
All the holes lined up on the
first try. |
 |
| Figure 6. Sludge clogging the fuel draw
line. |
|
Once inside, I found that the draw line was clogged
and there was good layer of sludge at the bottom of the tank.
The draw line on these tanks comes in at the aft end, runs down
to the vee bottom and ends at the foreword end of the tank. |
 |
| Figure 7. Inspection holes on either
side of internal baffle. |
|
I thought that it was possible that the tank was
capped just because the draw line was clogged, so I decided to
pressure test the tank. I attached a bicycle pump valve and dial
pressure gauge to the fill line. I used a bicycle pump to blow
out the fill line and then sealed off the inspection ports, the
vent, return and fill lines. |
 |
| Figure 8. Pressure testing the tank. |
|
I pumped the tank up to 3psi to determine whether
it was air tight or not. I could hear a leak somewhere from the
aft end of the tank, so I "painted" all the fittings and as much
of the tank I could get to with soapy water to see if I could find
the leak. Unfortunately all the fittings were air tight, and I
couldn't find where the tank was leaking. |
 |
| Figure 9. Cleaned up and ready to paint. |
|
Next I wire
brushed as much of the tank as I could reach using a 4.5" angle
grinder and then a hand brush for all the corners. I then wiped
down the inside of the tank with acetone. |
 |
| Figure 10. Epoxy paint seals leak. |
|
In order to seal the tank I decided to use Ameron
Amerlock 2/400 high solids content epoxy paint. It was recommended
to me by a company down in Seattle that specializes in fuel tanks.
I cleaned out the tank as well as I could by hand. I painted the
inside of the tank using a small extension handle and a foam brush.
The
Amerlock paint goes on thick, so only one coat was necessary. I
went back over all the welds and corners to ensure that they got
an extra thick coat. |
 |
| Figure 11. Finished and no more leaks. |
|
After waiting 3 days for the paint to cure, I resealed
the tank and pumped it back up to 3 psi. After holding 3 psi for
3 days I decided that the tank was indeed airtight and suitable
for use again. Even better, I now have a way to keep the tank clean. |
| |
|
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