Gas tank leak

[Matt1989Carver3807]

Hi. After haul out fall 2020 port alum tank started to leak from an unseen site. Tank was full and appears to have pinhole leak about a cupful daily. Location is Mission Bay, San Diego. Plan local trips to San Diego Bay some nearby fishing. Mexico---No. May trip to Oceanside/Catalina. Boat is 1988 Aft Cabin 3807 with twin 454s. Thought we would replace 140 gal port tank with custom made alum smaller tanks made locally to avoid pulling engine and blackwater tank. Now I am advised this is not possible due to space. Have removed about 70 gal of gas and leak is slowed or stopped so plan is to do a cleanup and see if stopped. Then plan to run engines with blower going until port tank runs "empty". We have a tank manufacturer who has visited the boat and consulted.
After all considerations my current thought would be to totally empty tank of gas and fumes first. Then have the tank people remove the tank and have a custom made half size tank (70 or so gal) that will fit the space and can be used for gas needs and ballasting needs. Ballasting will not be perfect I realize due to smaller size. Additionally, the exhaust and manifold of the port engine can be moved and replaced without interfering with the engine alignment and minimize the cost.
Would love to hear some thoughts/suggestions.

[Viper]

That's interesting. I'll take a look a closer look at mine but going strictly by memory, I don't see how you can remove that tank without removing the engine unless they're planning to chop up the tank in place. Don't think I'd reduce the size of the tank for a few reasons but I get that the wallet dictates.

[bud37]

Source of the post Then plan to run engines with blower going until port tank runs "empty". We have a tank manufacturer who has visited the boat and consulted.

Source of the post Would love to hear some thoughts/suggestions.

Considering you have a known leak, my advice is to have it pumped dry now and repaired, don't take any chances, those leaks may start out as a seep or drip and change without notice. Never the less the fumes from even a tiny leak/seep or damp spot are explosive. Be very careful here.

[km1125]

Did you talk to a fiberglass guy about cutting the side open and removing the tank through the hole? Not sure of the exact layout on the 3807, but on the 3607 that would have been a much easier solution. Some of those fiberglass guys are so good you'd never know it was done that way.

Can you plumb or switch the engines so they both just run off the starboard tank? Then just pump whatever you have in the port tank over to the starboard side and use it up. Refill the port tank with water so if/when it leaks into the bilge it's not a big deal and it also provides ballast to counter the gas weight on the other side. Continuing to use a boat with a known gas leak would be very scary in my opinion.

[boatdave]

If you start the boat with that leaking gas tank with gas in it, you are putting your life and whomever is with you in danger. Not worth the risk. We had someone up here that went out for the day, discovered a fuel leak while at another dock. Decided to temporarily stop the leak, open the hatches, head back to the dock and BOOM! Blew him out and his wife out of the boat and both spent many days in the hospital and will never be 100% normal again.

[Matt1989Carver3807]

Source of the post That's interesting. I'll take a look a closer look at mine but going strictly by memory, I don't see how you can remove that tank without removing the engine unless they're planning to chop up the tank in place. Don't think I'd reduce the size of the tank for a few reasons but I get that the wallet dictates.

I do think removing the tank by by chopping it up is a part of the plan. I understand a pneumatic tool is used to prevent sparking.

[Matt1989Carver3807]

Source of the post

Source of the post Then plan to run engines with blower going until port tank runs "empty". We have a tank manufacturer who has visited the boat and consulted.

Source of the post Would love to hear some thoughts/suggestions.

Considering you have a known leak, my advice is to have it pumped dry now and repaired, don't take any chances, those leaks may start out as a seep or drip and change without notice. Never the less the fumes from even a tiny leak/seep or damp spot are explosive. Be very careful here.

Agree with your concern and advice. In the overall considerations I do not trust the thought that our 32 year old tank can be repaired satisfactorily due to the fact that the leak has not been located. Would prefer I think to have a new custom made tank in place.
If your concern is about running the boat engines with the leak being unrepaired, I share that concern. All gas odor would have to be gone.

[bud37]

Source of the post If your concern is about running the boat engines with the leak being unrepaired, I share that concern. All gas odor would have to be gone.

It is exactly that, by repair I meant in your case with an old tank......replace. Even with the odour gone and our noses can detect extremely small amounts, that doesn't change the fact that it could open up at any time with temp changes, vibration etc. Unfortunately this is one of those things that comes along with an older boat ( and some newer ones) that must be dealt with safely......good luck and be safe.

[Matt1989Carver3807]

Yep, Safety First. Still researching and do not plan to start anything electrical or start engines until odor is gone.

[km1125]

It would really be nice to know where the leak is and what possibly caused it, to see if the starboard tank might have the same vulnerabilities.