Fuel polishing - how often?

[Kenomac]

Originally Posted by weavis

But Ken. You just admitted to checking your tanks. That was all that was said to do.

Mr. D wants me to clean them out. But there's nothing to clean.

[weavis]

Originally Posted by Kenomac

Mr. D wants me to clean them out. But there's nothing to clean.

My sister is like that. A floor could be immaculate and she will still wash it again.

[GB32]

In my experience diesel driven shoreside equipment has fuel blockages as soon as they are used on the ships that I work on and it's common for us to drain, clean and re-fill tanks as the filters cannot cope once the tanks are stirred up. I would expect similar in boats that spend a long time stationary.
ESI, providers of polishing equipment for many motor boats including mine, detail that their pumps should draw from the bottom of the tank and agitate any debris.

They also recommend starting with 30micron, then 10 and to consider the tanks clean when the pump is sucking less than 12"Hg through a 2 micron filter.
I will be finishing polishing when at sea with a 2 micron filter and would expect my common rail Cummins, also fitted with 2 micron filters, to give long service with no urgent dash below.
As far as bugs and water - If the seperator looks clean and the filter looks clean - it probably is. Until then I'll be running my polishing system alongside and then at sea and sleeping well.

[valhalla360]

Originally Posted by Muckle Flugga

Well thats a nice idea. Also take away any air will help too… except that is not possible, unless you vent your tanks to a dynamic inert gas system… so no. Your tanks have vents… to the outside air. Air contains significant quantities of water. Condensation may be a lesser issue than filling your tanks directly wtih water, but it is absolutely still an issue. And by the way I do use a water filter for every drop going into the tanks. I have very little water in my tanks at any point, imperceptible in fact, but sludge is still an issue from time to time, as my perception and that of bacteria differ. Also, of course, there is simply the issue of dirty fuel, as in fuels that have been transported or kept in containers with other compounds and contaminants. This is very common in the 3rd world. The prefilters for filling purposes and water separation are very large mesh (or else it would take a crazy amount of time to fill your tanks). They let almost everything but (most of) the water through, and almost everything else of significance...

There is no substitute for secondary pre filtration. And a polisher helps for sure.

I've run the numbers and over the course of 6month in the winter, the best I could come up with in a worst case scenario was 2-3grams of water (think 2-3 drops the size of raisins) from condensation. Condensation is a myth in my opinion.

I am a firm believer, it's leaky filler caps and the like or water brought in with the fuel that creates most water based fuel issues.

So yes, don't let the water in and most of the issue goes away.

[Dockhead]

Originally Posted by Kenomac

Mr. D wants me to clean them out. But there's nothing to clean.

I said if you're really sure there's nothing to clean, you might skip it.

Regular inspections are the key thing, and it sounds like you have that covered

You have transparent plastic inspection ports in your tanks? Where are your tanks -- can you get at them? That sounds like really good design.

My single, large (680 liters) tank is located behind the companionway, separated from the engine room by a bulkhead, and not accessible except through the hole in which my built-in microwave is mounted. There are a few benefits to this design -- tank is well out of the bilge, in a nice dry, clean space, and it's rather vertical, which means less baffling is needed and which makes it much easier to clean out. On the downside it's hard to get at, and there's no drain or dip tube.

[Dockhead]

Originally Posted by GB32

In my experience diesel driven shoreside equipment has fuel blockages as soon as they are used on the ships that I work on and it's common for us to drain, clean and re-fill tanks as the filters cannot cope once the tanks are stirred up. I would expect similar in boats that spend a long time stationary.
ESI, providers of polishing equipment for many motor boats including mine, detail that their pumps should draw from the bottom of the tank and agitate any debris.

They also recommend starting with 30micron, then 10 and to consider the tanks clean when the pump is sucking less than 12"Hg through a 2 micron filter.
I will be finishing polishing when at sea with a 2 micron filter and would expect my common rail Cummins, also fitted with 2 micron filters, to give long service with no urgent dash below.
As far as bugs and water - If the seperator looks clean and the filter looks clean - it probably is. Until then I'll be running my polishing system alongside and then at sea and sleeping well.

Interesting post -- welcome to the Forum, GB32.

A frequently used sailboat will be good in this respect, as the tanks will get lots of agitation.

Thread drift, but a good friend of mine who is a profound diesel expert (among other things, he owned a Bosch diesel injection service company) said that common rail diesels are actually much LESS sensitive to bad fuel than normal diesels are. This was news to me. He said that the most sensitive and most expensive part of the fuel system of a diesel engine is the injection pump. If carp gets past the filters, this can be ruined in a heartbeat. Common rail diesels don't have injection pumps -- they have a normal if very high pressure fuel pump feeding the common rail, and then electronic injectors. These components are much cheaper and less sensitive than a standard injection pump. He says all diesels will be common rail pretty soon, and that there is no reason to fear this evolution, because they are simply better in every way.

For whatever it may be worth.

[Kenomac]

Originally Posted by Dockhead

You have transparent plastic inspection ports in your tanks? Where are your tanks -- can you get at them? That sounds like really good design.

Yes, clear plastic ports 10 inches in diameter. As I sit here writing this post at my saloon table, the fuel tank access port is directly under my right foot, covered up by a wooden floor panel about the same size. Lift up the panel... look inside with a flashlight (torch), it takes less than five seconds. The second access plastic port is 20 inches to the right side of my right foot under a separate floor panel... Just lift and look. The fuel dip stick is three feet away from me under a seat cushion. Just lift and check. The deck saloon is a great design with the tanks located under the saloon floor.

The water tank is the same on the opposite side of the saloon. Two clear plastic ports under two much larger floor panels... just lift and look.

Ken

[Muckle Flugga]

Originally Posted by Kenomac

Yes, clear plastic ports 10 inches in diameter. As I sit here writing this post at my saloon table, the fuel tank access port is directly under my right foot, covered up by a wooden floor panel about the same size. Lift up the panel... look inside with a flashlight (torch), it takes less than five seconds. The second access plastic port is 20 inches to the right side of my right foot under a separate floor panel... Just lift and look. The fuel dip stick is three feet away from me under a seat cushion. Just lift and check. The deck saloon is a great design with the tanks located under the saloon floor.

The water tank is the same on the opposite side of the saloon. Two clear plastic ports under two much larger floor panels... just lift and look.

Ken

This is a standard feature of all Oysters I've ever sailed on. And a typically excellent one.

[levm]

My experience before you set out for a long cruise have your fuel tank cleaned by a professional. Then keep careful lookout at your separator, if you start seeing stuff accumulating begin polishing.
To reduce the risk of getting bad fuel in countries like Greece and Turkey whenever possible I buy fuel at the nearest gas station not from the marina fuel dock, yes it takes longer to fill the tank but it assures me of fresh fuel. alternatively buy fuel from the same truck that feeds the commercial charter boats, rest assure if this truck will ever have bad fuel the local captains will slash the driver's throat. And NEVER buy fuel from a barge this is calling for problems big time ( ask me how I know).


May the good winds always be with you

[Dockhead]

Originally Posted by Kenomac

Yes, clear plastic ports 10 inches in diameter. As I sit here writing this post at my saloon table, the fuel tank access port is directly under my right foot, covered up by a wooden floor panel about the same size. Lift up the panel... look inside with a flashlight (torch), it takes less than five seconds. The second access plastic port is 20 inches to the right side of my right foot under a separate floor panel... Just lift and look. The fuel dip stick is three feet away from me under a seat cushion. Just lift and check. The deck saloon is a great design with the tanks located under the saloon floor.

The water tank is the same on the opposite side of the saloon. Two clear plastic ports under two much larger floor panels... just lift and look.

Ken

That's an excellent design feature!

Now if they would only add sumps with proper drains, it would be perfect

I agree about the raised salon sole, which does so many good things to the layout. I also have tanks under mine -- two 500 liter water tanks, gray water, black water, calorifier, plus a dedicated watermaker space and space for a 150 liter water day tank for use with the watermaker. Unfortunately fuel is in a different location, behind the companionway

[darylat8750]

Originally Posted by rhubstuff

=1 for xlantic. ...... That said, only a small amount of all the fuel that runs through the fuel pump is sent to the injectors; the rest is returned to the tank, having been polished by your regular fuel filters. So what is the point of a separate filtering system, except in places where you actually expect to get bad fuel?

I hear this a lot. Some engines yes, some engines no. Mine return less than a quart in 5 hours running. My polish pump moves 60+ gallons an hour.

[Sailorman Ed]

Kenomac - they look just like the pool filter covers we mold. Now if I could just think of how to add the matching threads to my aluminum tanks, I will be all set.

[Dockhead]

Originally Posted by darylat8750

I hear this a lot. Some engines yes, some engines no. Mine return less than a quart in 5 hours running. My polish pump moves 60+ gallons an hour.

Even if your engine returns a ton of fuel, the reason to have a separate polishing system is that it has a pickup at the bottom of the tank, versus somewhat above, like your engine's fuel system has. You don't want your engine picking up gunk from the bottom, whereas that's exactly what you want the polisher to do.

[Kenomac]

Originally Posted by Dockhead

That's an excellent design feature!

Now if they would only add sumps with proper drains, it would be perfect

The pickup for the polishing system is right at the lowest point in the stern inside corner on the tank bottom with the tube cut at an angle to facilitate parallel pick up off the bottom. The return is at the opposite corner 3cm off the bottom. This creates a washing effect across the bottom of the tank.

The primary engine pickup is several cm off the bottom at the same corner as the polisher pickup and engine return.

The lowest corner is in effect a sump.

[Charlie]

I can not stress how important it is to have inspection ports in the fuel tanks. One is needed for every baffled area. When I brought my boat down from Oregon to SF. I had to go thru the Columbia river bar. The boat was rocked quite a bit. From there We had very turbulent seas. I had scrubbed one tank with a putty knife, a scouring pad, and finally windex and paper towels. The tank was brown when I started and shiny when I was done. It didn't leave me time to clean the second tank. Well leave it to say that we had half the fuel capacity that we wanted. The seas calmed and the wind died so we ended up motoring a lot. Well the uncleaned tank clogged the filter on a regular basis. I don't know that you need to do this every year. It has been five years since I cleaned my tanks and have had no problems but I think it would be prudent of me to do it again -- like last year.