Diesel Vent Burp

Seattle Scott · Sep 29, 2009

John, On your boat I just stand in the opened stern locker, reach over the locker lid and hold a rag loosly over the vent in the transom while filling the tank with the other hand.

Yeh, I didn't answer your question - so whats new.

sandpiper10471 · Sep 29, 2009

John: I think this is a brilliant suggestion. The bottle would have to be diesel resistant and easy to inspect. As long as there is sufficient diameter in the hoses both in and out I cannot see a downside. One could even put a petcock in the bottom to make draining easy. Don't know what the regulations would have to say about the installation.

I think I will pursue this idea myself after a recent incident. I had asked a very experienced attendant to top up my tank. He found the fuel kept backing up the fill pipe and was having difficulty getting any into the tank. He was going very slowly. Eventually he said it was gushing out the vent and the tank must be full. Now I know my engine is efficient but didn't think $14 (and that is at Cdn fuel prices!) would cover the amount of motoring I had done since the last fill. Three days later while weighing anchor, the engine died. Tank bone dry. I hadn't checked the tank guage as I don't trust them, the boat is relatively new to me and I trusted his experience.

On retrospect, what went wrong. The previous dockhand (different marina) had filled the tank until the diesel gushed out the vent. A low spot in the vent hose would leave a puddle, creating back pressure on the next filling and when the puddle got pushed out the vent it was assumed the tank was full. Your suggestion would have alleviated the problem. Now I know that when my tank guage says empty it really means it!

Dalliance · Sep 29, 2009

Another solution might be a Fuel Vent Whistle. I just bought one at WM and plan to install it this week, so I don't know how well it works yet. It is supposed to make a whistling sound as fuel goes into the tank and air is pushed out through the vent. When the whistle stops, the tank is full.

Ed Schenck · Sep 30, 2009

Fuel vent whistle!? Wow, learn something everytime I sign on. The fuel vents on our H37Cs are a real problem. Almost impossible to keep the hose from collecting fuel and/or water. Then it can take an hour to fill the tank. I have cleaned mine so many times over the years(vent hose). On the cruise from Erie to Tampa I would first remove two or three screws from the gauge mounting. Those three little holes were sufficient to allow the fuel to flow. I had worried about fumes but it was never a problem. And the q-berth was a crew quarters. On my 1979 the original gauge has always been accurate.

I like the bottle idea. Especially if it could be mounted such that it was the only low spot in the line. Then you would never have a plugged line(except at the transom outlet with spiders, etc.).

aboardduet · Oct 10, 2009

We don't fuel up too often, and as a result, the fuel vent gets clogged, allowing just a trickle of fuel to go into the tank.

My cure is a fuel-catcher on the transom and a rag wrapped around the fuel nozzle as it's stuffed into the inlet. A few good bursts of fuel blow air (and sometimes fuel) out the vent, clearing it, into the catcher. Fuel then flows full-speed into the tank.

dbecker68 · Oct 12, 2009

We carry an extra fuel can

in the lazarette, containing about 2 gallons of diesel. Every week or two, I top off the tank from the fuel can, and I can hear/see when the tank is nearing full.
We refill the can at a service station, and avoid marina prices for diesel fuel. It works well for us. Two gallons will last us for several months of normal sailing (about two hours of engine time per week).

Benny · Oct 12, 2009

That bottle will also need a vent so where do you end? It will be hard to monitor the bottle when you are busy managing the fuel hose nozzle and you are by yourself. It probably would not help either when fuel spurts up the filler due to high pressure. Remind the fuel dock hand that most of the liability for any spillage will likely spill down to them once the attorneys for your insurer get involved. I rather doubt that dock hand would know who to call and that any authorities would respond to a minor diesel spillage at a fuel dock that more than likely would have dissipated by the time they got there. Must be a California thing as have never had that problem in the East coast.
I always fill up in a responsible manner avoiding even small spills. Let he who has never spilled fuel cast the first stone

Dalliance · Oct 17, 2009

A quick follow-up on that "Fuel Vent Whistle" I mentioned - it's actually called a Fuel Whistle and is installed in the vent line about 12" from the tank. I installed it last week, along with a new fuel filler hose and re-routing of the vent hose to eliminate a trap and create a high point above the vent outlet so any water splashed in will drain back out rather than go into the tank.

This afternoon, I filled the tank and the fuel whistle performed exactly as it is suppose to. It gave off a good loud whistle until the tank was nearly full, shifted to a warble for a couple seconds and then stopped when the tank was full. Both my fuel fill and the whistle are located in the lazarette, so it is really loud. If it were more remotely located though I think it would still be effective, just not so loud. In my opinion, it is definately worth the $32 investment and the attendant at the fuel dock commented that he wished more boats had them.

By the way, your jar idea is interesting as an additional safety measure. It occurs to me that what you are describing actually sounds like a raw water strainer without the filter. An inlet and outlet both at the top, and a removeable jar below. Might need some adapters to accomodate a typical 5/8" vent hose though.

petersea · Oct 18, 2009

"Fuel Whistles" have been used by the home fuel oil delivery industry for years. The idea is as long as there is air going out the vent the tank is filling when the air stops venting the tank is full. Do not "top off" after whistle stops as then fuel will flow out the vent.

My personal choice would be the fuel whistle rather then a jar or some type of container only because you can still overfill the container or jar in the vent and still spill fuel. You will also need to empty the overflow container so now it is a maintenance item that needs regular attention. There is always the possibility of a spill when emptying container also(possibly inside the boat). I would also think as "fuel tanks" are not allow to have drains any drain or petcock on the overflow tank would technical be against code and illegal. Don't mean to be so negative about your idea because I know you are trying to do the right thing. Just my 2 cents worth ......

Kind of a rude remark on the fuel dock persons part ! I would have asked him how he would be able to determine if the vent overflow was more then 1/2 cup ?? If you have two tanks is it 1/2 cup per tank ?? or 1/2 cup "limit" each time you fuel ?? Got to love the fact that their supplied overflow bottle fell off empty,can you imagine what would have happened if it was full of fuel when it fell off ? I wonder if the fuel dock would have accepted responsibility as it was their defective overflow container that caused a spill ?? This is the kind of case some lawyers live for ! This alone makes a good case for buying fuel on shore and putting it in yourself even if only a couple of gallons at a time. (most likely not legal in Calif ? but then what is legal in Calif ?) and probably against marina rules so check first. Find another place to fuel !

sandpiper10471 · Oct 22, 2009

Pete: I didn't know it was illegal to have a drain cock at the bottom of the fuel tank. I had one on my boat in the tropics and it saved my bacon a number of times. I was able to drain off water and algae from condensation, a leaky fuel fill and poor fuel easily. I thought it was a great modification. The primary filter on my H37C, and I believe it was OE, has a drain valve at the bottom. Is that illegal too? Shouldn't be, I believe all the Racors have them too.

sandpiper10471 · Oct 22, 2009

And having just had a look at Racor filters, it appears they have already addressed this thread issue. The RAC LG 100 is designed to go in the vent between the tank and the outlet. AND it has a drain on the bottom!!! Rated for both diesel and gas, up to 85 gph! Might just be big enough for one of our Cherubinis!!!! Retails for about $85. I think I will make my own or go with the whistle.

petersea · Oct 23, 2009

http://www.parker.com/portal/site/P...L+/+AIR+SEPARATORS&Wtky=FUEL+/+AIR+SEPARATORS#

Sandpiper see the attached link from the Racor web site it does not show a drain but rather it returns the fuel to the tank. Might be a better alternative to the homemade bottle vent. I would have to check the code and regulations but it is my impression it is illegal to have a tank drain. Maybe under certain circumstance when there is a catch basin it may be allowed or if the filter and drain are installed within the foot print of the catch basin for the engine it may be legal but you will notice Racor has lots of filter with catch basin installed. the theory is not to allow fuel to be split accidentally into the bilge and then pumped overboard. I personal think the whistle is a better idea, I don't get the advantage of "TOPPING OFF" the tank with every ounce of fuel. At the point when you are overflowing the vent you have overfilled the tank.

sandpiper10471 · Oct 25, 2009

Pete - you are absolutely right. Your last link does not have a drain. Doesn't need one. However it is not a fuel filter. All the Racors that would fit our small engines have the drains so I am thinking it is just illegal to have a drain on the tank itself. Interesting. http://www.maesco.com/products/racor/r_spn_intro/r_spn_mar/r_spn_mar.html

In fact this site suggests two inches of clearance for collecting off fuel and water. Still, the whistle looks like the best of all ideas. No whistle on initiation of filling, grab a rag.

jcherubini · Oct 31, 2009

Easy solution to fuel vent overflow/spill potential.

Just mount the vent HIGHER than the fuel fill! --hello!!! I still haven't figured out why boatbuilders haven't thought of this. In my boat the fuel-tank vent is in the Dorade box, on level with the coaming and the fill is in the seat right below it... so in case of any overflow it would run back into the filler neck, but that wouldn't happen because the vent is higher than the filler.

The only reason why the vent fittings were ever located in the side of the hull in the first place is so that that gooky fuel wouldn't overflow into the cockpit (horror!) but pass overboard into the water (sigh of relief! --and no clean-up! --imagine!). Times have changed and new-boat builders need to smell the fuel spill and get with a more responsible program. And older boats need to be brought up to par.

This is the kind of issue the NMMA and others need to have legislated. Also it's a really easy upgrade any owner can do himself, so I would not be averse to having this legislated and made retroactive. If they can require us to upgrade complex sanitation systems, they can make us drill a new hole and move something that's already hooked up. Not something to cry over.

sandpiper10471 · Nov 6, 2009

John: I wish I had read this in a more timely manner. Your solution is a forehead slapper. Such an elegant solution I can't figure out why the rest of us keep getting frustrated and inventing far more complex and expensive remedies. Have we been so trained by the chandleries that we cannot conceive of solving problems without spending large amounts of money?