Fuel polishing during layup periods.

[JohnP]

I have a simple fuel transfer system that can draw fuel thru my racor and return it to my tanks.* I can turn over my fuel in about* 4hours.* Timed it by pumping from one tank to the other.* Anyway the boat is sitting idle now since Nov.*How often should I turn over my fuel (polish it).

Been doing it about once per month.

Is that too much or not enough?

JohnP

 

[Tom.B]

Does it clog up the filter every month? If it does, then it's working and needs it. If not, I'd say it was too much.

 

[markpierce]

Surely it isn't doing any harm.* I'd say do it as often as it makes you confident of the fuel.

 

[El Sea]

Any filtration is good, however repeatedly Polishing the fuel will only cleanse the fuel near the fuel pickup, thus leaving the condensation and microbial growth resting on the bottom.

We normally recommend that the tanks be:
1.*near full or absolutely empty for long layup periods
2. avoid mixing ethanol & non-ethanol blend (if gasoline)
3. avoid mixing bio-diesel & regular diesel
4. treat the full by the size of the tank
5. carry a six-pack (of fuel filters) when boating

When we come across saddle tanks (one port, one stb'd) we find a very different quailty in the fuels. This is due to the contaminated tank being exposed to a greater temperature change while at dockside, on a trailer, in a field (as in farm & construction equipment), parked in a driveway, etc.

 

[FF]

Constant "fuel polishing' might keep the fuel clean , but it wont help a dirty tank to GET clean.

What has stuck to the side walls needs force , a wooden scraper, to exit.

-- Edited by FF on Monday 14th of February 2011 05:50:09 AM

 

[Tom.B]

FF wrote:

What has stuck to the side walls needs force , a wooden scraper, to exit.

That's what I was afraid of.

 

[JohnP]

FF wrote:

Constant "fuel polishing' might keep the fuel clean , but it wont help a dirty tank to GET clean.
---------------------------------------------------------------------------------------------

Will polishing fuel on a regular basis keep a clean tank from getting dirty?


Does the chemical process that causes diesel to degrade happen because the fuel is sitting stagnant?* Will moving it keep it fresher?


-- Edited by FF on Monday 14th of February 2011 05:50:09 AM

*


-- Edited by JohnP on Monday 14th of February 2011 10:07:58 AM

 

[RickB]

"Does the chemical process that causes diesel to degrade happen because the fuel is sitting stagnant?* Will moving it keep it fresher?"

No, letting it splash back into the tank from the fuel return lines above the fuel level will just add oxygen and hasten the oxidation process.

 

[JohnP]

RickB wrote:

"Does the chemical process that causes diesel to degrade happen because the fuel is sitting stagnant?* Will moving it keep it fresher?"

No, letting it splash back into the tank from the fuel return lines above the fuel level will just add oxygen and hasten the oxidation process.

Interesting point.** Looks like doing nothing is better- I can do that!* JohnP

*

 

[sunchaser]

As seen on this and related threads, fuel polishing issues can make one paranoid. One very large charter company in the PNW steam cleans their "single manufacturer vessels" fuel tanks every 1000 hours. The cost and hassle of doing this they view as far less problematic and cheaper than fuel polishing setups*that may not do any good in the long run.

The mantra on boatdiesel.com is use a big spin on filter as*your primary and change it out as needed.*In this case, don't*worry about polishing, if*crud buildup does occur, filter it at the critical point - before the engines.

Even though I have been involved with the purchase and use of*tens of millions of gallons of diesel for off the road use, I never heard of fuel polishing until I started reading these types of boating forums. Am I believer of fuel polishing - not unless I were a serious blue water cruiser buying fuel off some pretty iffy docks. But, today's serious cruisers usually have enough tankage such that iffy fuel purchases can be avoided.

 

[RickB]

sunchaser wrote:unless I were a serious blue water cruiser buying fuel off some pretty iffy docks. But, today's serious cruisers usually have enough tankage such that iffy fuel purchases can be avoided.

And if it is a "serious blue water" cruising boat it would most likely have a centrifuge between the storage tanks and day tanks so fuel contamination issues are much less likely.

In addition, those boats tend to purchase large loads of fuel from reputable commercial suppliers who tend to cycle through huge quantities of fuel on a regular and rapid basis. They also sell to folks who require documentation of fuel specs and take samples for retention on board so there are few chances of fuel surprises.

*

 

[Tom.B]

Wait... What?!?!?! Am I wasting my time?

 

[jleonard]

In my 20 + years of boating with diesels I have only polished fuel once and it was a waste of time in my opinion as the filters didn't really get dirty.
I changed to multi stage filtering and never had an issue since.
Happy polishing.

 

[RickB]

GonzoF1 wrote:Wait... What?!?!?! Am I wasting my time?

Well, you need to look at it from a couple of different angles. If you are enjoying the process and learning something about your boat and its systems and how to work with stuff that is new to you and learning how and why one way might perhaps offer more than another, then no, you are not wasting your time.

If at the end of the job you feel like you have gained more "ownership" of your boat and confidence in your abilities to work on it, then the project returned far more than it cost.

If you believe you need to "polish" your fuel to have a more enjoyable or reliable boating experience, yes, you are wasting your time.

Except for a few issues related to the*health and safety of yourself and the passengers who rely on you for their own well being, all of this stuff is for recreation. It's a hobby, a sometimes very rewarding and often frustrating and expensive hobby but most folks do it for fun, not to save time or money.

*


-- Edited by RickB on Monday 14th of February 2011 01:44:52 PM

 

[Tom.B]

Great! And here I thought I was doing something awesome, when all the time I was doing something... meh.

 

[RickB]

You started out in version I by saying "I am going to reconfigure Skinny Dippin's entire filter rig to be a multi-stage filtration and add a simple fuel polishing circuit."

No one can judge your right or reasons for doing it. I don't believe anyone even questioned it, quite a few people provided a lot of support and helpful ideas.

If you had asked if it was "worth it" you might have had a variety of answers. I know what mine would have been. But you decided to start the project and seemed to be enjoying it. That made it worthwhile in my eyes, for that reason alone.

I think that at this stage the only question that is valid is "does this do anything positive for the fuel and is it worth continuing?" Even that one has two answers. *

I don't think it does anything particularly good for the fuel but it doesn't hurt it all that much either. It does provide you with a very nice filtering and transfer capability (even though I would not choose to use the fuel return lines for that purpose) and you have had a great learning experience so far. It's a bit like the credit card ad isn't it?

Edit: * Duh, well I guess there are two answers, there are two questions ...

-- Edited by RickB on Monday 14th of February 2011 03:28:12 PM

 

[sunchaser]

Gonzo - Months ago when you had a fuel filtering issue, Jay Leonard, me and others said*put your filters in a multi stage setup. You followed that advice (soon) it would seem, and then went a step further and added (soon) a polishing loop. As RickB says, that is fun and OK. I do all sorts of*fun and OK stuff on my vessel and it sure beats gardening. Keep us informed, you are to be commended on your persistence and nice dining room floor.

 

[Tom.B]

I guess you are right... I have learned a great deal about my boat including systems that are not directly related to this "upgrade". And,in a frustrating way, it's been "fun". But, the original $500 budget has now ballooned to more than twice that. I suppose that in the end, it might add a certain appeal to a potential buyer (should that day ever come). Until then... I guess I'm in it up to my neck, my boat doesn't run while the fuel rig is on the dining room floor, I already have all the parts, and I am closer to finished than started, so I must press on and finish this thing.

I just really figured that fuel polishing was a service that every boat yard provides. It made sense that it's an important thing to do. So if I can do it onboard, I'd save money in the end. I didn't realize there were two schools of thought on this. Anyway, I don't want to hijack THIS polishing thread too as I have with the others.

Tom-

 

[Jay N]

GonzoF1 wrote:

I just really figured that fuel polishing was a service that every boat yard provides. It made sense that it's an important thing to do. So if I can do it onboard, I'd save money in the end. I didn't realize there were two schools of thought on this. Anyway, I don't want to hijack THIS polishing thread too as I have with the others.

Tom-

Tom, I don't want to beat you up on this issue any more then you have been, but:*

*1)* My fuel is polished when the engine runs, and based on*vacuum gauges, filter changes occur every*4-6 years;

2)** I drain the sumps every 4 weeks or so; and

3)** There is a three filter system which*provides sufficient capacity to*generally overcome a batch of bad fuel (which I have not seen in more than 25 years, including a previous boat).

By keeping water from sitting in the tank bottoms, I have no need for additives (Although every couple of years, I*seem to end up getting some diesel from a marina that*carries the Valvtech*additive fuel oil, but I only buy it because it is the cheapest fuel at the time).

The above three items (if you can get all three) essentially preclude the need for fuel polishing services, but not tank cleaning services.

My tanks are 37 years old, I think the previous owner had the tanks cleaned around 1995, but based on what comes out of the sumps, they're not ready for cleaning again.

 

[Marin]

GonzoF1 wrote:

It made sense that it's an important thing to do.

It's not important unless your fuel needs polishing.* And it doesn't need polishing unless it's dirty or contaminated.*

If you use your boat regularly (by which I mean it doesn't just sit for half a year or more) and you buy your fuel from a reputable supplier with good tanks and plumbing to the fill nozzles, and their* fuel doesn't sit for months and months in their tanks, and they buy it from a reputable distributor, your fuel should never need polishing.* We have certainly had no need to polish our fuel in the twelve-plus years we've had our boat.

If your tanks are crudded up this can contaminate your fuel but while polishing the fuel will clean it, it will just get dirty again from the crudded up tanks it goes back into.* You'll be attacking the symptom, not the problem.

We have a polishing system of sorts on our boat installed as part of the new fuel system the previous owner had fabricated for the boat the year before we bought it.* We've had no occasion to use it.

-- Edited by Marin on Monday 14th of February 2011 07:22:17 PM

 

[JohnP]

Marin,* When you transfer fuel from your main tanks to your day tank do you*pump it thru a filter?. If so you are basically prepolishing every gallon of fuel you use.

JohnP

 

[El Sea]

When you polish the fuel and do not clean the tank....

"You are putting the baby back in the dirty diaper".

When we clean a tank, the by-product is polished fuel. There is a BIG difference in the two processes.

 

[Marin]

JohnP wrote:

Marin,* When you transfer fuel from your main tanks to your day tank do you*pump it thru a filter?. If so you are basically prepolishing every gallon of fuel you use.

No. The fuel transfers via gravity from the lowest point in each saddle tank directly into the day tank in the bilge.* From there, it is pulled out by the lift pump on each engine.* Of course the fuel goes through a Racor 500 before the pump on each engine and then*two spin-on Baldwins between each lift pump and each engine's*injection pump, so I suppose*you could say it's being "polished" between the day tank and the injection pump

* But in that regard, every boat has a "polishing" system on it.

*

 

[FF]

The fuel transfers via gravity from the lowest point in each saddle tank directly into the day tank in the bilge.

The "lowest point" is where the water collects.

 

[Marin]

FF wrote:The "lowest point" is where the water collects.

Not if that's where your draining the fuel out of.* It goes into the day tank, which also feeds the engines from the lowest point (there is no pickup tube) which means that any water that ends up in any tank is separated out by the filters.* Water only collects at the bottom of a tank if there is no way to get it out.* Far better to never let water collect at all in a tank than provide a place for it to sit.

*

 

[Per]

my boat had been sitting a while when i bought her and she had almost full tanks, my diesel mechanic recommended that i have the diesel polished.
as part of the process, the tanks were also polished and cleaned.
after removing all the fuel and while the fuel was being polished through their system, basically the tech drilled a couple large (3-4 inch) inspection holes in the top of the fuel tanks, inserted what looks like a plumbing snake. the snake banged around inside the tanks and sucked out all the gunk which might have collected in the tanks over 20+ years.
it cost around $1k and seemed well worth the effort. the tech says many boaters have their tanks cleaned once a year.

 

[Delfin]

Delfin has 2400 gallons of fuel tankage, so polishing is pretty important to us since it takes awhile to burn that fuel.* We polish routinely at 30 microns, and transfer at 10 microns into the day tank or boiler tank.* From there, the fuel passes through a 2 micron filter before hitting the CAT or Northern Lights OEM filters.

The picture below is the 30 micron filter after polishing tanks over a 12 month period. I can't tell you how many times the fuel has passed through this filter, but that is probably less important than the amount of gunk trapped.* I looked at the transfer filter, and it isn't ready to change yet.* Pretty good argument for polishing fuel, IMHO.

By the way, my fuel comes from a dealer who is 5 miles from the refinery, so when it's loaded on, it doesn't get any fresher.

 

[RickB]

Delfin wrote:I can't tell you how many times the fuel has passed through this filter, but that is probably less important than the amount of gunk trapped.

It looks like normal stable asphaltenes to me. Since the filter has been exposed to countless gallons of fuel that has gone through the engine and been heated thoroughly for who knows how many times it looks pretty good for being there a year.

What is the picture supposed to show anyway?

Even the cleanest newest fuel has asphaltenes in it. Heat it over about 130-150 degrees passing through the injector and back to the tank it will have quite a few more. Keep adding oxygen by letting it splash back into the tank and it will oxidize and darken.* It's the nature of the chemical.

But, polishing is an exercise of faith, not science, so do what you like, just don't expect to convert everyone else.

*

 

[Delfin]

The fuel has never been heated because it has never been returned from the engine.* We use a day tank, which would be the return point for circulated fuel.* This is fuel from the other 2300 gallons of tankage. * Not having a coherent understanding of what is going on has never stopped you from weighing in in the past, so I guess I shouldn't be surprised that you are, once again, uninformed, but convinced in your opinions.

I suppose the point is that diesel fuel has precipitating components that end up somewhere.* Since you don't own a boat, perhaps this isn't important to you Rick.* To others who do, it is.

So, I'm curious, since the fuel I have been polishing has not been "Heat(ed) over about 130-150 degrees passing through the injector", nor has it darkened, is it your position that removing the natural asphaltene precipitates in diesel that occur without heat has no value?

We'll put you down as one who doesn't believe in polishing fuel, and I am sure than none of the boats that are owned by the people who hire you would have such systems against your advice.




-- Edited by Delfin on Wednesday 16th of February 2011 11:04:16 PM

 

[FF]

Far better to never let water collect at all in a tank than provide a place for it to sit.



Thats a great theory , but hard to do in the real world.

The simplest tried and true system is a sump and a pump , to catch the water below the tank bottom.


It would have been an extra $10 on a new build , so don't look for it.