Running Diesel tank empty?

[Sea Angel1]

I wonder, that your Dufour 35 has a built in Mitsubshi engine. It should be a Volvo Penta, but anyway that is not the problem. From the engine there should be existing curves with diesel usage as a function of rpm. 2 liter per hour seems to me very very low. My Volvo Penta 55 HP (built 2012) at 1500 rpm is using about 3 - 3,5 l p h. That s fairly new engine with appr. 600 hrs. But as alread read before , register your fuel consumption constantly, fill up to full and refill every 10 hrs out of jerrycans to full and than you will learn the fuel consumption. Easy

[wingssail]

Originally Posted by rbk

I can add that we don't have a fuel gauge and the dip stick is a PITA to access. I record fuel ups and hours and knowing your burn rate its easy to figure out how much you have left to within 5%-10%. When we fuel up its a game, how close are our calculations (rounded to whole numbers), closet wins and all are usually within a gallon up or down.

Yes, great procedure and we do it too. We have a spreadsheet with some formulas. After a period of operation we enter the engine hour meter number and the RPM. The formula calculates the usage. When we add fuel we put that in the spreadsheet too. So we have a running total. Over time the RPM/fuel table has gotten quite accurate, to within a couple of liters on a major fill-up. So we have a good record for each tank (there are two), plus a good record of engine operation, fill ups, etc. We can run a tank down to 1+ gallon with some level of confidence that it won't run out.

[Garbonz]

Oh boy, this is entertaining. Getting clean diesel is not a trivial matter in many many places, especially in the marine world.

Having Jerry cans of fuel strapped everywhere on deck, even tho common practice is horrible idea, don’t do it, ever.

Every one should have a foolproof way to check their fuel level, check their tank content, and completely drain their tanks.

The question here and answers is the smallest part of the fuel system equation, not a good idea to run dry certainly, but Jerry cans, inspection and accurate gauging is are even bigger vulnerabilities.

Why are we talking about airplanes? Lol

[EmeraldCoastSailor]

Originally Posted by rbk

I can add that we don't have a fuel gauge and the dip stick is a PITA to access. I record fuel ups and hours and knowing your burn rate its easy to figure out how much you have left to within 5%-10%. When we fuel up its a game, how close are our calculations (rounded to whole numbers), closet wins and all are usually within a gallon up or down.

Very glad to know I am not the only one who plays the "how much will it take" guessing game at the fuel dock when I top off. I record hours at the end of each outing and calculate hours since last fill up, consider any fuel added via jerry cans (common for me and I try to do it in 5 gallon increments to make calculations easier), and consider special conditions so that I can make an educated guess how full my tank is. My fuel gauge works ok but I don't rely on it. I usually guess the amount of fuel needed to top off within a gallon.

[Danm1]

No fuel gauge and I am not organized enough to constantly record engine hours/minutes (15 minutes out of harbor for a day sail, maybe 20 back depending on where I drop sail). But I have managed to get access to shine a light on the side of my poly tank and have roughly figured one gallon is .66 inches. Yay! I get to play the guess how much it will take game too.

[model 10]

[QUOTE=Garbonz;
Why are we talking about airplanes? Lol[/QUOTE]


Because if you had bothered to read the OP, he was asking for info on running a fuel tank dry. The only info he found was for auto's.

[sailingharry]

The OP hsan't come back or posted any more thoughts, but I think a lot of folks aren't quite getting the same picture that I am.


He has a small boat (35', with a tank under 30 gallons, from what I can tell). He won't be adding additional tanks!


He is probably NOT talking about making this a normal operation. I suspect that when in port and seeing his tank at 1/8 on the gauge, he's going to refill. He specifically said "AT SEA!"


On my last boat, with a 20 gallon tank, I routinely filled with 5 gallon jugs. When I was down 1/4, I'd get another jug. It was easier to fill a jug on the way to the boat rather than spend an hour or two to get to a fuel dock. But, even though I tracked my fuel consumption rather fastidiously, I very rarely got a true full-to-the-top fill, so doing run-time estimates of tanks was iffy at best. Also, I've done a calibrated fill, which does help interpret the gauge -- but like your car, the first 25% down still shows "full" and the last 1/8 can be really hard to read. Bottom line -- the gauge is more like a guess!



I read it this way. He's out on a passage. He's used 80-90% of his fuel, but would like to continue motoring (still probably has 5 or 10 hours left in the tank). He'd like to KNOW he's got 10 hours in reserve. So, he wants to motor until he runs out, then put in the 20L and then consider himself on "emergency rations." He could put it in earlier, but then he'd miss out on those last 5 or 10 hours of motoring. And, when making landfall, if his tank is low, he can add the 20L when still 10 miles offshore. I think I like the idea.


As far as any possibility of "crud" getting to the filters. I don't like crud or water in my tanks, and I certainly don't like the idea of storing it there! I have my pickup as low as possible (current boat has a small "sump" that the tube sits in). This way any water or crud is sucked into the filters immediately -- not waiting for a big surge in a seaway to clog it all at one time.

[Pete17C]

Originally Posted by a64pilot

And in case anyone was wondering what happens in a single engine piston airplane if the tank is run dry or the fuel switched off, the answer is not much.
If your cruising along at say 120 kts and the engine runs out of fuel, and you take no action at all, the nose of the airplane will drop a little so that the airplane hold approximately 120 kts, the engine will continue to spin as the wind is windmilling the engine. If you turn the fuel back on, the engine begins to run and the airplane will level out and fly at 120 kts.

Even if you intentionally slow the airplane way down so that the engine stops, simply putting the nose down will cause the engine to turn again as the wind drives the propellor, when it gets fuel again, it will run all by itself, you don’t even have to start it.
https://vimeo.com/268448424

Any pilot has hopefully been demonstrated the vast difference in glide ratio with a stopped prop as opposed to one windmilling. like spins and spin recovery isn’t required anymore but should be. The first time you see a spin shouldn’t be when you have inadvertently gotten yourself into one and are now trying to save your life.

I got my PPL at a local flight school that just taught spin avoidance. Joined a local club and on the checkout their CFI asked me about my spin training. He then had me do two or three recoveries.

But I never had any CFI shut the motor down during a 'simulated engine out'. I asked about it, and was told it's pretty much the same reason you wait until your at a safe altitude before reducing power during climb out.

There is no reason to take the chance that something might go wrong at an inopportune moment.

Unless your engine is seized (which you can't practice), I think your prop (unfeathered) is likely to be windmilling in any attitude except climbing, which you not going to be doing for long. Feathered it may stop, but this will reduce the drag substantially as well.

[Cpt Mark]

Originally Posted by a64pilot

You apparently only flew larger aircraft, likely with paying passengers.
It’s very common to run a small piston engine dry before switching tanks, it’s one way to know for sure that the fuel you have in the other tank is all there is. People have been known to convince themselves there is fuel in the other tank, when there isn’t much, run it dry and there is no question.
It hurts nothing at all, the engine just begins to windmill, you switch tanks and it almost immediately picks back up.

Well, I have only flown small piston planes and throughout my training and association with a great many CFI's nobody teaches such a dangerous act as intentionally running out of fuel in a plane. It is not common. Find me one reference in ANY training manual.

[Alita49DS]

Originally Posted by Ecos

Because if you had bothered to read the OP, he was asking for info on running a fuel tank dry. The only info he found was for auto's.

Err, sorry. I thought this was a site about boats. Which tend to have diesel engines. Not something I am aware are fitted to planes. If I wanted to read about planes I would be looking somewhere else.

More amusingly, 4 pages about a darned silly idea. Who in their right mind would deliberately want to run their boat engine dry? Presumably the same sort of person who thinks that it is a good idea to run their car dry. I suppose I could find a car site where there are people who espouse that. There is just such a frisson about putting oneself and others in danger for no good reason.

[az_r2d1]

Originally Posted by S/V Illusion

When the fuel runs out, most diesels tend to stop running.

Captain obvious,

It's that moment where it stalls that it is not getting the lubrication but things are still moving. Not good.

[az_r2d1]

Originally Posted by S/V Illusion

The short time involved makes it a trivial concern but I admire your fastidiousness. Stuff happens and running out of fuel is among those events.

Not really. If you keep good truck of running time and add some buffer for worst case scenario, it will never run dry.

[model 10]

[QUOTE=Alita49DS;2955114]Err, sorry. I thought this was a site about boats. Which tend to have diesel engines. Not something I am aware are fitted to planes.




Why did you feel the need to comment on something you know nothing about?
There have been diesels in planes since WWII.

[Stu Jackson]

It's NOT as "guessing game" (although with crew it could be a fun lottery to see who will do the dishes after a spaghetti dinner that night!).


For me, it is to avoid overfills and leaking fuel into the water.


Even with a (crappy) fuel gauge, how do you know?


I pull up, say I need "50-55 liters" and we watch carefully, both the dockhand and me, at the amount of fuel on the pump.


Easy.

[parkstone bay]

Leaving aircraft aside, the original question was about running the tank dry. I'd suggest there are a few really practical issues: 1. If he can bleed the engine without getting "some" diesel fuel spillage/leakage, he's doing very well. (That's why most people change their filters, etc deliberately, in a nice flat marina, with plenty of mopping-up capability to hand). 2. If he can replenish his tank in a seaway from a can, without getting "some" diesel fuel spillage/leakage, he's doing very well. (Similar reasons to 1 above). 3. If he can time his run-out so that it never happens during a sailing problem, he's doing very well. (Obvious reasons). As a comment, yes, running the tank dry will (not may) suck up any crud that's in the bottom of the tank. If it is felt that draining the tank is needed, then do this as a controlled/timed operation whilst on the dock, using a separate pumping and fuel-cleaning system. There have been a number of very practical answers to the thread, most of which involve logging a measured amount versus engine hours. But how about making a dipstick? I made one by measuring the outside tank dimensions and taking 4mm off each measurement to approximate to the internal dimensions. It was remarkably accurate: clearly if you're working in imperial units you have to convert cubic inches to gallons (231 in3 = I US gallon, 277.4 in3 = I imperial gallon), and if the tank is tapered, it's a bit more complicated, but a reasonably numerate person can manage the maths.