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Old 07-09-2016, 05:48 PM   #41
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The goal of fuel polishing is to clean the fuel, well duh. To do this you want to pick up the fuel from the bottom of the tank. Some diesel tanks actually have a small sump to collect the dirt, biologics and water and get it collected and pumped out to the filter. In a well-designed polishing system, the return fuel is sent down a tube to the bottom of the tank with an elbow to shoot the returned fuel across the bottom and move more dirt to the pickup tube. To really stir the fuel up you need a serious pump, 50 gph or more. A 2 gph pump cannot stir and move the detritus.
Many people polish their fuel when the boat has been sitting a long time. The trouble with this approach is that most of the debris is lying on the bottom of the tank. It may seem counter intuitive, but the best time to polish the fuel is during and after a rough day on the water. When it is rough the water swishes and swirls around the baffles and loosens lots of debris.. Running a polisher for 4 hours after a rough day, is much more effective than running it after the boat has sat still for a month.
Which brings me to my final point. For boats in regular use, buying fuel in the coastal US and Canada, a fuel polisher really is not needed. We are running a Cummins 5.9B series engine. On all the engines of this series, the fuel pump is a 50 gph pump. We only burn 2.3 gph at cruise. In a 6 hour day on the water our pump has moved 300 gallons of fuel. Our primary filter is 10 micron and our secondary is 2 micron. Our tanks are 200 each. If the tank is full the fuel has been turned 1.5 times. If the tank is half full the fuel has been turned 3 times in a dayís run. For each tank, the fuel is filtered about 30 times before it is burned. ( Anyone remember their calculus and can calculate this?) So for most boats cruising in North America, a fuel polisher may really not be necessary at all.
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Old 07-10-2016, 07:44 AM   #42
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Fletcher 500, as you can see the answer to your post is yes, no and maybe.
I polish my single 280 gallon stainless steel fuel tank which has a well built into it to draw from the bottom of the tank. I have no idea how much fuel is returned to the tank while operating our 100 HP Volvo TMD 31A engine. I do know that my Gulf Coast fuel polisher removes contaminates by inspecting the filter element in the polisher and the Racor filter elements.
Keep in mind when diesel fuel or gasoline is made at the refinery it is pure and clean BUT the transportation of it to your boat can be less than perfect with the chance for contamination always possible.
A good read by an expert is " The Spin on Centrifugal Separation " by Steve D'Antonio.
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Old 07-10-2016, 08:46 AM   #43
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Fuel polish, frequency?

We have two 325 gallon tanks and have a Reverso fuel polisher installed that has an automatic timer on it. It runs for two hours per day whether we are moving or at dock. It has a vacuum green and red light to help determine if Reverso filter needs to be changed. I manually switch tanks about once a week or daily when underway. I do try to fill up at mainly Valvtect fuel suppliers and keep tanks topped up. Over the past 4 years I've never had a fuel feed issue with my twin 453 Detroit Diesels and "knock on teak" won't have any in the future. Keep in mind that when first installed the Reverso I had to change Reverso and Racor filters rather often. It then tapered off to infrequently on Reverso and never on the Racors due to being dirty.
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Old 07-10-2016, 08:57 AM   #44
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Quote:
Originally Posted by tadhana View Post
Our tanks are 200 each. If the tank is full the fuel has been turned 1.5 times. If the tank is half full the fuel has been turned 3 times in a dayís run. For each tank, the fuel is filtered about 30 times before it is burned. ( Anyone remember their calculus and can calculate this?)
Two things. First, half who read this post are the choir and the other half add premium fuel the their regular rated vehicle. The second half are not hurting anything and are driving the economy.

Second, if where you buy boat fuel does not have an in line spin on filter near the hose outlet - buy elsewhere. Refiners and haulers are regularly checked for fuel quality, not so the dock supply tanks.
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Old 07-10-2016, 10:20 AM   #45
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Two things. First, half who read this post are the choir and the other half add premium fuel the their regular rated vehicle. The second half are not hurting anything and are driving the economy.

Second, if where you buy boat fuel does not have an in line spin on filter near the hose outlet - buy elsewhere. Refiners and haulers are regularly checked for fuel quality, not so the dock supply tanks.
I'm not sure which half of the group you are putting me in, but I will say that in 50 years of messing about in boats I have yet to pick up bad fuel. In most states, the law requires fuel sellers to test their tanks for water and keep a log of it. I have been a marine fuel reseller and have been through this. In my own experience, the location of a filter next to the pump has never been an issue one way or the other. I have been in some ratty looking fuel docks in the Carolinas and in some high end resort fuel docks in MD and VA. For me, the important factor in choosing a fuel dock is to find one that pumps a lot of fuel. Those fuel supplies seem to be clean. Those docs also seem to have pretty fair pricing too.

As to running high test fuel in gasoline engines, I was a Yamaha dealer, and know first hand that high octane fuel can damage the larger Yamaha outboards. Yamaha speaks to this in their owner's manual, and warns you not to burn high octane fuel.
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Old 07-10-2016, 12:22 PM   #46
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Is this what you are talking about when discussing lower octane fuels?

It’s been recently proven that non-ethanol fuel gets better gas mileage than Ethanol (E-10) fuel. An outboard burning 93 octane Ethanol (E-10) fuel has less combustion, and thus less horsepower than a non-ethanol 90 octane fuel. That means the non-ethanol fuel is going to give you better gas mileage, less problems and better performance between oil changes.

Yamaha Offers Help with Ethanol Fuels | Yamaha Outboards

These recommend a minimum of 89 octane

Offshore Outboard Boat Motors, V6 Offshore | Yamaha Outboards

So do these.....

4 Stroke Engine, Inline Four Engine | Yamaha Outboards

A marine engineer....asked me this.....

"Also, I would love to know how a higher octane can damage an engine?"

I too have been lucky, but as an assistance tower there are some tows where bad fuel from the marina was a problem. Usually gas but some diesel too. Lots of places outside the US can also be suspect. So having ways of dealing with it make some sense, of as usually pointed out...sampling and filtering before it enters your tank has a lot of merit.
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Old 07-11-2016, 10:35 AM   #47
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I don't polish fuel. I have a multistage system. 30 to 10 to 7 micron.
This is my 10 micron element from my weekend filter change. Has been in service for around 80 hours and 1 year.
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Old 07-11-2016, 12:22 PM   #48
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Fuel polish, frequency?

My son is in charge of the service department for engines and machines at a rental/sales outfit. He works on everything from small chain saws and weed trimmers, all the way up to bob cats and small excavators. What he says:

1) old bad gas is the number one cause of engine problems. Bob has a chain saw with 50:1 gas mix that's 5 years old, runs the saw for an hour and it eventually won't start. The gas smells bad and the carburetor will need to be taken apart and cleaned or otherwise be replace.

2) At least for small tools, higher octane fuels run too hot in these machines. He told me to use regular unleaded 50:1 that has fuel stabilizer. Don't know about outboards, but he suggested the same grade for my carbureted outboard.


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Old 09-02-2016, 07:26 PM   #49
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Fuel polish, frequency?

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Fill once a year. Fuel polish when we move fuel from tank to tank. New fuel goes into the aft tanks and is polished when it is moved to the front tanks. Fuel for the port tank is moved to the starboard tank to trim the boat. The engine draws and returns to the starboard tank.

If you polish and return to the same 100 gallon tank, the half life theory means you have only polished 50% of the tank when you have polished 100 gallons. If you repeat the process and move 100 gallons through the system again, you will have polished 75% of the fuel. So it is more efficient if you can move fuel from a full tank to an empty tank.

The PO put an expensive ESI system on the boat, as well as new fuel tanks. Personally, I think it's overkill, but I have it so I use it.

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I just finished replacing the filter on my fuel polishing system. The PO installed the system in November 2008 when he replaced the fuel tanks. He said never replaced the filter and I hadn't either until today. I've put 850 hours on the boat over 4 summers and I move fuel from tank to tank to trim the boat and also to keep the older fuel separate from the new fuel. So I use the system a fair bit, but I'm not anal with it either. The filter needed to be changed because of its age but it really wasn't all that dirty. The 2 micron filters on the main engine were much dirtier when I replaced them this past spring.

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Old 09-02-2016, 08:03 PM   #50
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Fuel polishing is merely fuel filtering. If you move fuel from one tank to the next and filter it along the way, that is one step filtering. Your primary and secondary filters are what really polish your fuel. In our case the fuel pump on our our Cummins QSB 5.9 230 HO pumps 50 gallons per hour, but our engine only consumes 2-3 gallons per hour. Each 200 gallon tank runs about 100 engine hours. So to burn 200 gallons of fuel we filter 5,000 gallons. We burn about 150 gallons per month, so our fuel never has time to sit and grow gunk. So if you use your boat, there is no need to "polish" the fuel it is being continuously polished while you are running. You are polishing your fuel any time the engine iss running. Fuel polishing is really only needed if the boat has been sitting a long time and not been run.
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Old 09-02-2016, 08:09 PM   #51
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Use your boats, use the fuel, then you won't have to polish.

I am on my third half-fill (1000 tanks) since Feb.
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Old 09-02-2016, 09:00 PM   #52
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Fuel polishing is merely fuel filtering.
What many are referring to as polishing is just fuel filtering. When you call professionals to polish or a true polishing system on a boat is much more and involves centrifuges and coalescers in addition to filters. That's the equipment difference.

Here is the difference in terms of you're trying to accomplish from diesel fuel doctor.

Filtering: the process of separating suspended particles from a fluid by flowing both through a porous material in which the fluid can pass while the suspended particles are retained.


Polishing: the removal of water, sediment, non-combustible particulate matter and microbial contamination below levels stated in ASTM D975 (Standard Specification for Diesel Fuel Oils) while resuspending combustible particulate matter to maintain ASTM standards for BTU value, lubricity, and cetane.


Most recreational boaters who don't cross oceans don't need polishing. Yachts over 120' or so will generally have polishing equipment. Some smaller boats will. Some larger boats will not.

The need for polishing is based on where you fuel and where you travel. If my plans were to cross oceans on 10-20 day trips across, then I'd definitely have polishing to lessen the probability of fuel problems.
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Old 09-02-2016, 09:21 PM   #53
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Fuel polish, frequency?

I'm only reporting my observations. Personally, I wouldn't install a fuel polishing system based on my experience. But I have one and I use it to move fuel around. I fill once a year, 500-600 gallons.

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Old 09-02-2016, 09:36 PM   #54
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Polishing: the removal of water, sediment, non-combustible particulate matter and microbial contamination below levels stated in ASTM D975 (Standard Specification for Diesel Fuel Oils) while resuspending combustible particulate matter to maintain ASTM standards for BTU value, lubricity, and cetane. [/INDENT][/I]

BandB. I agree with your points on fuel polishing. However I note that your exact text is repeated on several commercial fuel polishing sites, and one PPT presentation from another commercial interest. It's not from an independent scientific source, IMO.


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Old 09-02-2016, 09:42 PM   #55
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I'm only reporting my observations. Personally, I wouldn't install a fuel polishing system based on my experience. But I have one and I use it to move fuel around. I fill once a year, 500-600 gallons.

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ESI has been around over 15 years and claims no fuel failures in that time. They call their system a total fuel management system. They also do things like emergency fuel delivery and delivered after Katrina when fuel was a major problem. They're also big in supplying critical industry that must be fail-safe.

There's a very good discussion of their system here:

ESI Fuel-Polishing System

That article also explains the difference between their polishing system and filtering systems.

I've never used their system but a lot of ocean crossing vessels do.
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Old 09-02-2016, 10:38 PM   #56
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Quote:
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ESI has been around over 15 years and claims no fuel failures in that time. They call their system a total fuel management system. They also do things like emergency fuel delivery and delivered after Katrina when fuel was a major problem. They're also big in supplying critical industry that must be fail-safe.

There's a very good discussion of their system here:

ESI Fuel-Polishing System

That article also explains the difference between their polishing system and filtering systems.

I've never used their system but a lot of ocean crossing vessels do.
I'm sorry but I'm afraid I have to call BS on that article.

The system pictured in it is nothing more than a Racor filter, a pump (most likely a gear pump) a timer and a magnet of very dubious usefulness.

It is in no way special.

"Moreover, the unit has a high-flow continuous-duty pump that is tweaked to optimally agitate contaminates in the boat’s fuel tanks during the system’s operation, thereby facilitating total, as opposed to partial, processing."

Now that is first class marketing BS right there.

The pump is "tweaked" to "optimally agitate " the fuel in the tank !? Yeah, right!
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Old 09-02-2016, 10:57 PM   #57
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J

I'm sorry but I'm afraid I have to call BS on that article.

The system pictured in it is nothing more than a Racor filter, a pump (most likely a gear pump) a timer and a magnet of very dubious usefulness.

It is in no way special.

"Moreover, the unit has a high-flow continuous-duty pump that is tweaked to optimally agitate contaminates in the boatís fuel tanks during the systemís operation, thereby facilitating total, as opposed to partial, processing."

Now that is first class marketing BS right there.

The pump is "tweaked" to "optimally agitate " the fuel in the tank !? Yeah, right!
As I said, I haven't used ESI. We do use Alfa Laval which has a centrifuge. Not based on that article, I have talked to people who use and praise ESI. Thanks for pointing that out.
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Old 09-03-2016, 05:30 AM   #58
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"fuel tank which has a well built into it to draw from the bottom of the tank"

If this an actual deep sump, there would only be a need to drain the sump before it fills.

This can be done with a pump or with a properly designed system by hand thru the fill pipe.

"Polishing" would never be required.
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Old 09-03-2016, 07:39 AM   #59
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Some boat builders put a sump in the tank and run the pick up tube into the sump. The theory is that if there is water and debris you want to get it out of the tank and into the filters. Hatteras for one was doing this.
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Old 09-03-2016, 09:04 AM   #60
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We do use Alfa Laval which has a centrifuge.
Now you're talking "polishing"!
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