Gas tank leak

[Matt1989Carver3807]

The leak is not visible from the interior side or end views of the tank. A top leak is not present because the leak continues. There is about a 6 inch area at the ends and interior which is not visible and of course the entire bottom and outboard areas are not visible. The space allowed for the tank fit is only about 1/4" so a flexible scope wouldn't help either.

[Matt1989Carver3807]

UPDATE 5/24/2021..............Progress to date........Have removed 71 gal of gas and now tank is "empty" as measured with a dipstick. Coincidentally this is a few gallons shy of the last amount put into the tank last fill when leak was discovered. There remains about 1/4" of fuel in tank. THE LEAKING OF GAS INTO THE SPACE SURROUNDING THE TANK HAS STOPPED.
Conversation with boat mechanic (a really knowledgeable source) is leaning toward opening the hull from the outside and pulling the tank out of the side of the boat. Will checkout available haul out sites and fiberglass installers.
Next duty is to remove all sources of gas odor which now appears decreasing with just air circulation.

[bud37]

Any fuel that has soaked into the wooden tank support platform etc will regenerate fumes when opened up so still be aware of this..... the hull thing sounds scary but may be the best solution. Only thing to be aware of is the " while were are in here statement "....
After this repair assuming you go ahead, will you be planning on keeping this boat for long haul ?

[g36]

It wouldn't want to be watching the side of my boat cut opened either, would be really scary.

[tomschauer]

Mc Daniels, which was the big Carver Dealer here for many years, would always cut open the side of the boats to replace engines, or tanks on the aft cabins, even under warranty. They said it was much faster and cheaper. When their glass guy was done, you would never know there was a hole in the side at one time.
The first time I saw them do this I was amazed and glad I didn't have and aft cabin!

[Matt1989Carver3807]

Progress 5/27/2021. Have had windows open about a foot for the past 5-7 days and a fan with about a 2 foot diameter blade running for about 6-8 hours. As a result the aromatic odor of volatile gas has disappeared. There is only a hint of some residue odor and some residual "boat smell" which has been present all along. The Carver 3807 has 3 bilge pumps. The midships sump was pumped out with an outboard type primer bulb attached to a 10' 3/8 inch clear hose. This same setup was used to empty 70 gal gas from the port tank.
Today attention was focused on the forward bilge pump area. There was a slight suggestion of possibly raw gas smell in the forward head. Removing the foot square hatch in the companionway revealed the source of the odor. Pumping out the pump area produced about 2 cups of raw gas and about 3.5 quarts of water which was probably taken on during the haul out when there was an open sea strainer source.
The midships bilge pump area also produced 2-3 quarts of water probably from the same source.
So the only area now to be checked is in the vicinity of the aft bilge pump.

[Matt1989Carver3807]

Source of the post Any fuel that has soaked into the wooden tank support platform etc will regenerate fumes when opened up so still be aware of this..... the hull thing sounds scary but may be the best solution. Only thing to be aware of is the " while were are in here statement "....
After this repair assuming you go ahead, will you be planning on keeping this boat for long haul ?

1. Keeping the boat is the plan. Hope to make a trip to Oceanside and probably Catalina after some local trips about San Diego.
2. Thanks for the advice to look for wood that is exposed releasing gas/fumes.
3. Am aware of the dangers of the "while we are in here" persuasion". Unfortunately/fortunately we have plenty to keep us busy already.

[Viper]

Certainly check the aft bilge but I've found that water flows forward on this model, at least on mine it does. There's a hatch under the mattress and one under the drawer at the foot of the bed.

If you still have the original open top shower sumps, make sure they're actually working or they'll overflow and stale water will collect on the outboard side of the starboard stringer in the aft cabin. You can barely see the area through the access under the drawer mentioned above. These open sumps are a source of some of the odor in the boat along with permeated waste hoses. I replaced both of my sumps and am really happy I did. A real pain to replace, especially the aft one, but doable.

[Matt1989Carver3807]

I typed a long reply to your comment but unfortunately it went missing. Agree location of leak but appears impossible without looking at the invisible areas of the tank which means moving the tank. Would refer you to entry made freshly 5/30/2021 for my latest thoughts.
Considering the expenses involved I am not enthusiastic about addressing the starboard tank as there is no evidence of a problem leak.

[Matt1989Carver3807]

5/30/2021 More progress: Aft bilge was dry with no water or gas. Fowd bilge was cleaned as best possible and dry. Gas smell was gone. Changed selector to run both engines from stbd tank and ran both engines for about 20 minutes with bilge blower going. Still no smell of gas. Feel this is a safe and stable condition.