Diesel Tank

[carlager]

I am discussing the risk of sailing with a 1/4 full tank vs a full tank.

My friend claims that the risk of sucking conterminants into the motor is the same because fuel is sucked a few inches from the bottom anyway.

Is my friend right ?

[a64pilot]

I think so, cause even full there is some slosh, and hopefully you have tank baffles to cut down that anyway.
Two schools of thought, one is let everything settle to the bottom, draw the fuel from a few inches above to not suck up stuff.
Second school is draw right off of the bottom and suck it out as it is formed, and never let any build up. That is what the filters are for.

I’m of the second school, never let it build up, so I’d say go sailing with a 1/4 tank to hope it gets stirred up so your filters can remove it.

The other issue is if you think there is stuff, have your tank cleaned or do it yourself, but if there is much stuff, you know it’s going to clog a filter and shut your engine down at the worst possible time, that being big seas and bad weather

[denverd0n]

Originally Posted by a64pilot

I’m of the second school, never let it build up...

I agree. Of course, this school dictates that you must be very rigorous in monitoring and maintaining your filters!

[Kenomac]

Or better yet, buy and install a high quality fuel polishing system, and never worry about it again. That reminds me... it’s time to turn ours off.

[Chuck34]

A lot of diesels have fuel pumps that pump way more fuel than the engine needs and the extra is returned to the tank. With a good fuel filter, this in itself is a fuel polishing system as the fuel may go thru the filter a number of times before the engine actually uses it

[Kenomac]

Originally Posted by Chuck34

A lot of diesels have fuel pumps that pump way more fuel than the engine needs and the extra is returned to the tank. With a good fuel filter, this in itself is a fuel polishing system as the fuel may go thru the filter a number of times before the engine actually uses it

You can continue to believe that, but it’s not correct. A good fuel polishing system will pump 150-200 gallons per hour through a filtration system; your diesel will only pump a very small fraction of that amount. The whole idea is to run the entire tank of fuel through 3-4 times during each filtration cycle.

[Chuck34]

No question 150-200 gph is a great way to go. However, my last boat only had a 25 gallon tank, engine used less than a gallon per hour and I believe the pump pushed about 6 gallons per hour, maybe more, so yes, I got a fair amount of fuel polishing. I never topped off my tank, usually kept 1/3 to 2/3’s max in the tank

[Cheechako]

I think the washing action inside the tank from sea motion will be greater than with a full tank. Fill a jar with water 1/4 full and rock it back and forth. Fill it full and rock it and compare.
So if there is gunk in the tank you may very well have an issue clogging things up.

[a64pilot]

Originally Posted by Kenomac

You can continue to believe that, but it’s not correct. A good fuel polishing system will pump 150-200 gallons per hour through a filtration system; your diesel will only pump a very small fraction of that amount. The whole idea is to run the entire tank of fuel through 3-4 times during each filtration cycle.

No Ken, an operating Diesel engine is a fuel polisher, some return way more fuel than others.
My Common rail truck motor used the fuel to cool the electrics that operated the injectors, they were very high amp consumers and it therefore pumped large amounts of fuel.
Usually the fuel is used to cool the HP injection pump on any motor and that is why there is so much return fuel.

A fuel polisher can’t hurt of course, but unless your getting some nasty fuel, they aren’t really necessary.
The overwhelming majority of boats don’t have them and almost never suffer any issues, and those that due it’s most often because they didn’t know to treat their fuel for “bugs”
Did either of Your Oysters come with fuel polishers from Oyster?

[Kenomac]

Originally Posted by a64pilot

No Ken, an operating Diesel engine is a fuel polisher, some return way more fuel than others.
My Common rail truck motor used the fuel to cool the electrics that operated the injectors, they were very high amp consumers and it therefore pumped large amounts of fuel.
Usually the fuel is used to cool the HP injection pump on any motor and that is why there is so much return fuel.

A fuel polisher can’t hurt of course, but unless your getting some nasty fuel, they aren’t really necessary.
The overwhelming majority of boats don’t have them and almost never suffer any issues, and those that due it’s most often because they didn’t know to treat their fuel for “bugs”
Did either of Your Oysters come with fuel polishers from Oyster?

I won’t be baited into an argument with you. There’s a big difference is all I have to say... you’ll eventually figure it out for yourself.

[GordMay]

Fuel cleaning systems can polish at rates from 100 GPH to upwards of 6,0000 GPH.
The fuel pump, on a typical small diesel engine, delivers something on the order of 2 to 3 times the rate of consumption - so perhaps 2 GPH to upwards of 4 GPH.
As Ken says, there's a big difference.

Ie: The Reverso DIY Fuel Polishing Module has a flow rate of 150 GPH.
☞ Fuel Polishing Module

Kenomac: What is your polishing system's flow rate?

[a64pilot]

So what is the advantage of “polishing” the fuel quickly?
What micron level are you polishing to?
I don’t polish my fuel and change filters yearly as a scheduled maintenance item, and haven’t clogged a filter in years.
Why polish?

[Sailmonkey]

Originally Posted by a64pilot

So what is the advantage of “polishing” the fuel quickly?
What micron level are you polishing to?
I don’t polish my fuel and change filters yearly as a scheduled maintenance item, and haven’t clogged a filter in years.
Why polish?

The higher rate will allow the turbine aspect of the racor 500 type filters to function, as well as agitate the tanks.

But we’ve also never polished our fuel and have had no problems.

[a64pilot]

Originally Posted by Sailmonkey

But we’ve also never polished our fuel and have had no problems.

See that is the issue right there, do we need to spend $1,000+ to fix a problem that doesn’t exist, unless of course you buy nasty fuel.
For that I carry at least a dozen filters, that I’ve never had to use.
Actually now that I think about it, I didn’t change filters last year, so I’m on year two now, but I do have a vacuum gauge.
I have the dual Racor filter, which was probably another $1,000 I didn’t need to spend. I don’t remember what it cost to be honest, just remember it wasn’t cheap.

I just don’t like it when we tell people that they need spend big chunks of money on things, that maybe they don’t really need.

Now as I said in the beginning a polisher doesn’t hurt, I mean the fuel can’t be too clean, just I think the majority of people don’t need one.

[GordMay]

Originally Posted by a64pilot

... Now as I said in the beginning a polisher doesn’t hurt, I mean the fuel can’t be too clean, just I think the majority of people don’t need one.

Indeed, and probably so.