Preventing fuel spills

[skipmac]

Have asked about this before with no joy but reading about a new gadget supposed to prevent spills inspired me to ask again.

One of my biggest, lifelong annoyances in boating is spilling fuel when I fill the tanks. Why do boats spurt fuel out of the fill and vents? In my boating career I have owned three sailboats, three power boats and I can't remember how many runabouts and ski boats plus chartered four or five sail and power, crewed on half dozen or so various boats and spent time on countless friends' boats.. ALL of them spilled fuel. Every single one. Didn't matter if filled fast or slow. Didn't matter if filled at a marina or gas station. The trailerable boats spilled when filled at the same pump that just filled the towing vehicle that didn't spill a drop.

Boats, no matter how or where you fuel them, when full and usually just after the nozzle shuts off blow fuel up the fill pipe around the nozzle or out the vent or usually both.

However I cannot think of any car that ever spilled a drop. Never. No how or where it was filled.

So what is the difference? What could I do to a boat's fuel system to make it work like a car? I've tried looking at diagrams and asking mechanics about car systems but could learn nothing useful. Basically they seem about the same. Both have a large fill pipe and a small vent. I've had boats with a layout more or less identical to a car IE the fill about the same length, size and angle as a car with a similar sized tank which make no difference.

So anyone able to enlighten me?

Meanwhile I just ran into this gadget at Defender that claims to capture the overflow and drain it back into the tank. https://www.defender.com/product3.js...073&id=2914232

Anyone familiar with this or ever use one? Does it work?

[GordMay]

In the USA, motor vehicle gas dispensers are limited to a fuel flow rate of 10 GPM (37.9 liters per minute), whereas marine dispensers are not so limited.

40 CFR § 80.22 - Controls and prohibitions.
“... J. After July 1, 1996 every retailer and wholesale purchaser-consumer handling over 10,000 gallons (37,854 liters) of fuel per month shall limit each nozzle from which gasoline or methanol is introduced into motor vehicles to a maximum fuel flow rate not to exceed 10 gallons per minute (37.9 liters per minute). The flow rate may be controlled through any means in the pump/dispenser system, provided the nozzle flow rate does not exceed 10 gallons per minute (37.9 liters per minute).

After January 1, 1998 this requirement applies to every retailer and wholesale purchaser-consumer. Any dispensing pump that is dedicated exclusively to heavy-duty vehicles, boats, or airplanes is exempt from this requirement ...”

[thinwater]

Yes, I have used the Cleanway filler. It works, though I always did fine just listening. In fact, you should NOT fill the tank full but rather leave at least 5% room for expansion (cars have an engineered stop for this, boas do not--I watched boat overflow when the sun came out).



https://www.practical-sailor.com/iss...s_12102-1.html


The other spill risk, of course, is out the vent. I had a Parker Lifeguard, which worked well.

[GordMay]

Originally Posted by GordMay

In the USA, motor vehicle gas dispensers are limited to a fuel flow rate of 10 GPM (37.9 liters per minute), whereas marine dispensers are not so limited.
40 CFR § 80.22 - Controls and prohibitions...

Of course, this doesn't answer your example of the trailored boat, at an auto filling station.
Perplexing?

[John_Trusty]

Great question, and here are some thoughts.
1. Your comment "However I cannot think of any car that ever spilled a drop. - are you sure? Auto vents are hidden underneath the car and a little dripping on the ground may not be noticeable. I've seen plenty of stained concrete at filling stations. The boat spills are onto white gelcoat, and everyone is paranoid about it falling into water, so is closely observed.
2. Diesel is much more foamy than gasoline, so perhaps the difference in spilling is caused by the foaming action?
2. When I spill, it always comes out the vent, not bubbling up the fill-pipe. I don't even bother with a diaper at the fill, unless the attendant requires it, because it isn't going to spill there, but always put one under the vent. I was thinking about adding a whistle to the vent line as a warning, and was seeking feedback on this device: https://www.defender.com/product3.js...9073&id=848503

[Orion Jim]

I had an Ericsson 29 for many years and the only way to ensure the vent didn’t occasionally overflow was to pause filling the tank every couple minutes. My current boat, a Cape Dory 31, has never spilled a drop in the 12 years I’ve owned her. My fuel tank is nearly directly below the fuel fill and the hose only has a gentle bend to the tank. I always presumed that was the key as my fuel vent line runs about 10 feet to the stern. I’m just glad it’s a non-issue because it can be a real pain in the neck to ensure you are spill free.

[skipmac]

Originally Posted by GordMay

Of course, this doesn't answer your example of the trailored boat, at an auto filling station.
Perplexing?

Yes very. Same fuel (gas), same pump, filling seconds apart. Boat spews a pint or more out the filler hose more or less when the auto shutoff clicks and turns off the flow. Might be a second or so before, simultaneous but often a big gush a second or so after the fill shuts off.

Perplexing and extremely annoying. Not only is it environmentally irresponsible it gets gas (or worse, diesel) all over me and the boat.

[skipmac]

Originally Posted by John_Trusty

Great question, and here are some thoughts.
1. Your comment "However I cannot think of any car that ever spilled a drop. - are you sure? Auto vents are hidden underneath the car and a little dripping on the ground may not be noticeable. I've seen plenty of stained concrete at filling stations. The boat spills are onto white gelcoat, and everyone is paranoid about it falling into water, so is closely observed.

Well it is certainly possible that a few drops are spilled from car fill vents but if any more than a few drops I would have noticed.
On boats I have spilled as much as a quart out the fill hose and a cup from the vent.

2. Diesel is much more foamy than gasoline, so perhaps the difference in spilling is caused by the foaming action?

Happens to me with gas and diesel powered boats.

2. When I spill, it always comes out the vent, not bubbling up the fill-pipe. I don't even bother with a diaper at the fill, unless the attendant requires it, because it isn't going to spill there, but always put one under the vent. I was thinking about adding a whistle to the vent line as a warning, and was seeking feedback on this device: https://www.defender.com/product3.js...9073&id=848503

I've had some boats that mainly spilled out the vent but plenty that blew back from the fill. On those boats filling slower made a smaller blow back but still spilled.

[skipmac]

Originally Posted by thinwater

Yes, I have used the Cleanway filler. It works, though I always did fine just listening. In fact, you should NOT fill the tank full but rather leave at least 5% room for expansion (cars have an engineered stop for this, boas do not--I watched boat overflow when the sun came out).



https://www.practical-sailor.com/iss...s_12102-1.html


The other spill risk, of course, is out the vent. I had a Parker Lifeguard, which worked well.

I do try to listen but on some boats the sound isn't that noticeable and on one I can recall, as soon as I heard fuel coming up the hose it was too late. Also it's often noisy at fill docks and definitely at gas stations when I'm filling a trailer-able boat. Add that to a significant hearing loss and the audible detection method is not so useful for me.

Agree that one should leave a bit of air space but not always easy. Often I'm fueling by myself and can't see the gauge from where I fill. Also the gauge in my little motorboat reacts slowly to the fuel level and isn't really accurate anyway so that's a problem.

Thanks for the reports on the Cleanway and the Lifeguard. Think I'm going to order one of each and see how it goes.

[skipmac]

Originally Posted by Orion Jim

I had an Ericsson 29 for many years and the only way to ensure the vent didn’t occasionally overflow was to pause filling the tank every couple minutes. My current boat, a Cape Dory 31, has never spilled a drop in the 12 years I’ve owned her. My fuel tank is nearly directly below the fuel fill and the hose only has a gentle bend to the tank. I always presumed that was the key as my fuel vent line runs about 10 feet to the stern. I’m just glad it’s a non-issue because it can be a real pain in the neck to ensure you are spill free.

On my sailboat the fuel hose is almost perfectly straight and vertical from deck to tank and it will still blow fuel if I don't watch it. At least on the sailboat I have an accurate gauge on the tank and can get someone to watch that while I fill and stop early.

Will try the pause technique and see if it helps. But still, you don't have to do that with cars, why with boats?