Replacing C 310 fuel tank

SJN

.
May 30, 2021
32
Catalina C310 Seattle
My 2004, hull number 260 Catalina 310 has been providing a mystery source of diesel in the bilge over the past few years. Two years ago I thought I solved the problem, a loose fuel connection to my Wallace cabin heater.

Then, last fall, diesel in the bilge was back. Fortunately nothing went overboard .

Once again, I did my best to try to find the source of the leak. The tank sits behind the water heater, the Wallace heater, the auto helm connections and under the propane locker. Thus visual access to all parts of the fuel tank is impossible. Using small bits of diesel pad attached to a narrow stick I was able to pick up diesel along the bottom edge of where the tank is held in place by stringers.
Now the question: is it possible to get to the tank by removing parts and not cut fiberglass?

Remove the propane locker. Remove the heater. Remove the Wallace ducting. Remove the Auto-helm connections to the rudder post.

The problem for me: I am big, old and creaky. I do not fit into the places that make removal of said parts possible. Thankfully, after several turn downs by mechanics not interested in the work, I found an angel disguised as a expert with fuel systems willing to take on the project. The angel and his angel partner removed all the bits and parts without cutting fiberglass. They determined that the old tank was not repairable. The old tank had several very small pinhole leaks along lower corner welds. The boat is 20 years old thus a new water heater was ordered along with the fuel tank from Catalina Direct. Catalina Direct was extremely helpful and careful to make sure I ordered the correct replacements. New replacement fuel tanks use thicker material than original.

Yesterday, the two angels installed the tanks, adding thin rubber type strips under the fuel tank to allow air under it, hooked up new hoses as needed, and we put 8.5 gal of diesel into the new 27 gallon tank. The new fuel gauge read 1/3 full.

Hopefully few will enjoy this problem. If you do, all you need to address is patience, perseverance, and maybe finding an angel.
 
Last edited:
Jan 4, 2006
6,491
Hunter 310 West Vancouver, B.C.
I found an angel disguised as a expert with fuel systems willing to take on the project.
You may want to pass along their company name and contact info. for quality work like that in the Seattle area.
 

SJN

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May 30, 2021
32
Catalina C310 Seattle
The company that did the work, wonderful people. Seventh Wave Marine, Sequim WA, 360 808 0505
 

Tom J

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Sep 30, 2008
2,306
Catalina 310 Quincy, MA
I had the same issue with my 2003, hull #231. Shortly after I bought it in 2005, I noticed diesel fuel accumulating in the bilge and traced it to the area under the tank. I had a marine contractor remove the tank and they found a pin hole in the bottom corner weld. I took the tank to a welding shop and they repaired the leak. I called Catalina hoping they would be willing to reimburse me because the fault was a manufacturing one. They said the warranty was only good for one year, so no dice. The yard installed rubber strips under the tank like yours and the tank has been fine since.
 

john2

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Nov 26, 2022
38
Catalina 310 58 Leimuiden
on a 310 everything what leaks goes in the bilge , but also through the whole bilge....
I made a water tight ridge (3 inch high ) on the liner where the boiler and fuell tank are placed on. At the lowest/front ridge of it.
this keeps the bilge space under the aft bed and engine dry and clean.
 
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Tom J

.
Sep 30, 2008
2,306
Catalina 310 Quincy, MA
john2. This is a good idea for trapping any initial leakage from the fuel tank. Ideally, you would smell diesel fuel and fine a puddle behind the dam you made. Otherwise, you will find diesel in the main bilge the first time you go sailing after the leak has started. This is what happened on my boat. Even the small dam the factory had made just forward of the tank was enough to hold back the diesel fuel until I went sailing, and then the fuel would spill into the bilge.
 

john2

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Nov 26, 2022
38
Catalina 310 58 Leimuiden
Our boat was a mess when we bought it....
I had several leaks in the back, hwh connections water hose , the cap above the rudder post , toilet, galley pump and filter , mast base , some deck fittings, windows. (maybe i forgot something)....
So i made 2 water "dams" one at the back , and one in the middle of the bilge. This makes searching for a leak a little easyer.
A simple water detector with sound alarm at 4 lowest points gives me info if there is any leaking.
1 rudder/tank area. 2 under engine. 3 rear of bilge (gally and toilet). 4 front bilge (mast and watertank).
I used one alarm unit with 4 switches , by turning of switches you check where it leaks.
 
Jan 17, 2013
442
Catalina 310 St. Simons Island, GA
My old thread from when I went through this is above and below...