Final Verdict: "O" rings set free, as fuel vents go to the hoosegow

And the guilty party is the fuel vent.

The worn "O" rings on the filler caps have been exonerated. And while forced into retirement, they will have their past records expunged.

Since i had most of the stuff cleared out of the Engine room, I finally had the ability and the will to crawl back there behind the fuel tanks and take a look see.

Mostly, good news, very good news, in that there are spider webs and no sign that the top of the fuel tank has ever been wet, from water for fuel.
The vent hose and fitting look like new.

The boat was clearly very well maintained before it became Dauntless.

Now, the bad news, only bad in the sense that i see no easy solution at this time, but I'm sure someone will suggest something that I'll end up doing. The vent hose goes straight up and out the side at the deck level, which is only about a foot above the top of the tank.

The problem as I see it, is that I had wanted to lengthen the hose and put a large loop in it.

(By the way, I think it was Marty or maybe Jim, who first gave me the heads up that this is what I would find).

So, with the boat heeled over so much, chug a lug as we use to say in the dorms:lol:

Which would certainly explain how I got so much water (8-10 gal) in that lee tank.

Any chance you could put a two way valve on it and be able to switch it to a vent in the aft cockpit for the bad passages and back to the side when in normal use.. Might be a dumb idea but just a thought...

Remove your existing vent line at the tank and cap the hose. Add new hose at the tank and run the "new" line to where ever you want; aft deck or by the engine rooms vents. The only potential down side is when you're filling the tanks, if they over-flow, the diesel doesn't go over board which is actually a good thing.

Roger and Larry,

Two really good solutions, that did not occur to me, but yes, I would rather not vent overboard.

Thanks.

They sell vent fittings that are specifically designed to keep the water out but vent as required. Bought 2 online last year for my center console. Can't for the life of me remember the manufacturer though.

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mbevins said:

They sell vent fittings that are specifically designed to keep the water out but vent as required. Bought 2 online last year for my center console. Can't for the life of me remember the manufacturer though.

Sent from my Nexus 4 using Trawler

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I've thought of that, a duckbill. But I hesitate to reduce the vent effect, even if only very little.

Also, I like the idea of moving it inside our at least someplace that if the tank is overfilled, I won't have an automatic fuel spill.

There is a reason why fuel fills, vents, air intakes and exhaust are all well above decks on ocean going vessels.

Can you get inside that side-support for the upper deck? You could run the hose up inside that and out the top. Fancy Chrome deck fitting or just a u-loop. If you can't get inside, polished stainless pipe.

Wxx3 said:

I've thought of that, a duckbill. But I hesitate to reduce the vent effect, even if only very little.

Also, I like the idea of moving it inside our at least someplace that if the tank is overfilled, I won't have an automatic fuel spill.

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I had the duckbill kind on a sailboat and spider built a nice web inside as thick as a q tip . I like to have never figured out that fuel problem .

Wxx3 said:

I've thought of that, a duckbill. But I hesitate to reduce the vent effect, even if only very little.

Also, I like the idea of moving it inside our at least someplace that if the tank is overfilled, I won't have an automatic fuel spill.

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My understanding is that a duckbill or similar one-way valve would not be good because the fuel tank breathers have to vent both ways - out when filling, and let air in as fuel used. However, shouldn't be to hard to redirect to a place where they can do both safely and effectively without getting blocked or taking on water..?

bayview said:

There is a reason why fuel fills, vents, air intakes and exhaust are all well above decks on ocean going vessels.

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Yes, but remember I had already gone like 5,000 nm, 2/3 of that on open water, before I had an issue. Two mitigating factors that contributed:

1. I happened to be using the lee side tank,
2. the last 18 hours, only the lee side paravane pole was out, thus the boat would stay heeled to starboard (lee) longer than windward.

And those were a result of operator error, not desgn.

With the combination of of those two issues, the engine was sucking water into the tank.

Even without moving the vent, I doubt I would ever have this problem again.

It's too easy to move vent though, as I would feel pretty stupid in the middle of a typhoon, if my engine conks out because i didn't.

I take these incidents as warnings. Ignore at great risk.

The usual O ring hassle is not the Vent , but the fuel fill itself.

We resolved the problem by tossing the deck fill fitting , cutting a hole in the deck for a 6 inch bronze plate and lowering the fill hose, installing a brass nipple with cap.

Even if the 6 in deck plate were lost the fitting of the brass cap would keep water out of the tank, tho not the boat should the deck get awash .

With a hole drilled in the side of the cap, no additional tank vent would be required.

KISS

Would adding higher loops on the vent hoses also be a solution?

My tank vents exit the hull about 6 inches below deck level, but the tops of the loops are well above the decks. Seems like this would add a little extra margin if the decks are awash.

I found the vent fittings if interested.
"Attwood 16746 Stainless P-Trap Fuel Tank Vent" just Google it.

FF said:

The usual O ring hassle is not the Vent , but the fuel fill itself.

We resolved the problem by tossing the deck fill fitting , cutting a hole in the deck for a 6 inch bronze plate and lowering the fill hose, installing a brass nipple with cap.

Even if the 6 in deck plate were lost the fitting of the brass cap would keep water out of the tank, tho not the boat should the deck get awash .

With a hole drilled in the side of the cap, no additional tank vent would be required.

KISS

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I'm glad that is your version of KISS. To me, it sounds like a major overhaul

yes, Angus, I could do that, but no easy way to get it higher where it is. At that point, might as well just do Larry's suggestion which would be to move it close to the air intake.

Wxx3 said:

yes, Angus, I could do that, but no easy way to get it higher where it is. At that point, might as well just do Larry's suggestion which would be to move it close to the air intake.

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I was wrong in my earlier post. The top of the loop on my Defever just reaches deck level