This tank bottom is vee-shaped thus any debris or crud winds up in the vee. The tank bed was very well designed and the vee is suspended in air on all sides so no moisture was in contact with the tank.
When we cut the tank open I sifted thought the dead organisms and found a chunk of dissimilar metal right over the hole. It seemed to possibly be a piece of stainless steel that had somehow fallen into the tank somewhere along the way, possibly during a sending unit change out?
I suspect that this piece of errant metal was the cause of the pin hole. There were no other signs of corrosion despite this being a 31 year old aluminum tank. Canadian Sailcraft did a very good job designing & engineering the fuel tank & beds.
11-MAR-2009
Removing The Engine
Like anything in life nothing lasts forever, including impossible to access fuel tanks. This tank was on a CS-36T and ran port to starboard under the cockpit sole behind the engine.
At first I was clearly delusional and thought it may come out through the port lazarette, but I was sorely mistaken.
This photo shows the first step in this project, removing the engine. for removal I enlisted my main sheet, an old boom vang and a 4X4 across the companionway. Once everything was disconnected the engine came out quite easily. I had a buddy there just in case but this can be done solo on this boat.
11-MAR-2009
Placing Engine In Galley
To bring the engine into the galley I had first removed the cabin sole to prevent damaging it. I then collected some boat yard blocks and gently set the engine down on them and she sat ther while the new tank was fabricated.
In this photo the fuel tank has already been removed.
11-MAR-2009
Tank Layout
Using MS Paint I have illustrated, rather crudely, where the vee in the tank was. As you can see it was not in contact with anything and it's highly unlikely that the pin hole started from the outside, as usually happens.
11-MAR-2009
Fuel Polishing Pump
The first step in replacing any fuel tank is to remove all the old fuel. Seeing as I was planning on adding a dedicated fuel polishing system I used my new fuel polishing system pump. I made a home made stand out of some plywood and mounted the pump to it. I then connected some fuel hose a shut off valve, a 12v pigtail and a switch. I simply transferred the fuel in 5 gallon cans, through the Racor filter and I burned it in my homes oil boiler.
11-MAR-2009
Cutting Open The 31 Year Old Tank
This tank had been running biocides since new and Soltron / Startron for the last 15+ years. Because of this I wanted to see how well it kept my tank clean but at 31 years old I was doubtful. Not one to believe in snake oils I chose to cut the tank open.
11-MAR-2009
Tank Wall Sludge
With a hole cut we simply took a clean rag and blindly wiped an inner wall of the tank. NOT clean!!
11-MAR-2009
Interior View
This view is looking down into the hole cut in the tank you can see the piece of metal that fell into the tank and a baffle and also a LOT of tank grunge and grime. Remember, this boat used Soltron well before it was marketed in the US as Startron, and it had been in use religiously for the last 15+ years, yet this is what the interior looked like. It should also be noted that this was after TWO treatments Startron Enzyme Formula Diesel Fuel Tank Cleaner. Fuel tank "cleaner"? Really? Not in my experience... Oh and this tank had also been "professionally" polished by a dock side fuel polishing outfit. Polished? Really?
11-MAR-2009
More Sludge
Here's a view off towards the sending unit. No wonder the gauge was not very accurate. Doh'
11-MAR-2009
Last Few Ounces
Having never been a huge believer in the tank condensation theories that are bantered around, I wanted to see for myself how much water was actually in the absolute bottom of my tank. The answer was nada, zilch & nothing. Those gray flakes are from the plasma cutter and the fuel looked bad but still no water separated out at all. I found it rather interesting that after 31 years I found absolutely no water in this fuel tank. Perhaps the fuel treatments really do work for something..? The previous owner never even topped it off in the winter, and I drain it, but still the original pick up tube was 1.4" off the dead bottom of the tank so you never get it all. I will continue to change the deck fill o-rings, multiple times per year, as it does seem to work well..
11-MAR-2009
Aluminum Tank Fittings
As an ABYC member I tried to build my tank to the letter of the law/standard. This meant no mixing of copper alloys and the aluminum tank as many manufacturers did and still do.
So, where the heck do I find aluminum tank fittings? I asked a friend at Morris Yachts where they got their fittings and he sent me to Luther's Welding in Bristol, RI 401-253-5550. Sure enough they had aluminum tank fittings, and shipped out exactly what I ordered. The prices were also very reasonable. Great folks to deal with.
11-MAR-2009
Tank Tapping Layout
I designed this tank with multiple tappings and two baffles. There is a supply/return for the engine, supply/return for a diesel fired cabin heater and a supply/return for a dedicated fuel polishing system. I did not install tank clean out ports because access to the top of the tank is extremely limited. I will eventually remove it and install clean out ports but that is likely 10-15 years out, if at all, with this polishing system. I have a friend with a very high quality scope camera that we can inspect the tank cleanliness with in the mean time to assess any need for physical cleaning.
When designing for a fuel polishing system I definitely wanted to get my polishing pick up directly over the deepest part of the tank in order scrub/polish every last little bit of the fuel. This pick up tube is 1/8" off the dead bottom of the tank and directly over the V where any crud/bugs/algae or other junk would naturally wind up.
In order to avoid foaming with a high flow polishing system the return for the polishing system is also returned via a dip tube. Returning the fuel below the level of the fuel prevents and or greatly minimizes the potential for fuel foaming. If you click the photo and make it larger you can see a drawing of the pickup or dip tubes and the supply/return tapping locations.
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11-MAR-2009
Thread Sealant
When installing tank fittings it is critically important that you don't get any teflon tape or pipe dope residue into the tank. If you look close you'll see that I have wiped on the thread sealant and then cleaned the first two threads. Doing this prevents getting pipe dope into the fuel tank.
Teflon tape is verboten in fuel systems. I suspect this advisory from Racor and others is more for the common denominator factor than anything else. I suspect it could very well be used, if applied, correctly, but I still don't use it in fuel systems, just dope.
11-MAR-2009
Thread Sealant & Fittings
My preferred thread sealant for diesel or #2 oil is Hercules Megaloc. It is diesel rated and works very, very well and also cleans up easily. It also never fully hardens which makes slight fitting adjustments in the future doable without losing the thread sealing properties. Hercules Megaloc is available at most any good plumbing supply house but there are many diesel/#2 rated thread sealants on the market. The key is to use them correctly and not be sloppy.
11-MAR-2009
Tap To Clean Threads
With luck any aluminum tank you buy will have been properly pressure tested at the manufacture before delivery. Aluminum is soft and thus the plugs used for pressure testing tend to be harder than the aluminum and can bugger up the threads slightly.
For safety's sake I always chase aluminum threads before installing fittings into an aluminum tank. You will need an NPT tap to match the tank tapping threads for this task. Don't go crazy all you want to do is make sure they are smooth and free oil, debris or shavings. These tappings were all 3/8 X 18 NPT. After you chase and clean the tappings you'll then want to vacuum out the inside of the tank.
11-MAR-2009
Fittings Installed
In this picture all the tank fittings have been installed and any pipe dope residue wiped clean.
11-MAR-2009
Fittings Labeled
For future reference, or a future owner, I labeled the tappings on both the face of the tank and the top with a label maker. I also had wrote with a fine point Sharpie marker under the labels just in case.
11-MAR-2009
Installing The New Tank
On the CS-36T the tank runs port to starboard behind the engine and under the cockpit. Because of this the engine must be removed to replace the tank. Removing the gear box and using a block and tackle, AKA main sheet, in the companionway made this an easy task. I simply set the engine in the galley on boat yard blocs while waiting for the new tank.
This photo shows the new tank ready to go get buttered up and slid into place. Even with the engine out this was still a tight fit.
11-MAR-2009
Wedging It In
View from inside the engine compartment during the install process.
11-MAR-2009
Just Barely Fits between Engine Bed
The tank just barely fit between the engine bed stringers, which is exactly what needed to be done, in order to get it in & out.
11-MAR-2009
Almost In
Once the tank was in the engine compartment it then needed to be rotated in a port/starboard orientation. I also took the liberty of replacing the hot water heater when the tank was out. I did this under the old "while your in there" justification...
11-MAR-2009
Finally In Place
Once fitted into place I began to re-install the tank supports, hoses and associated hardware.
11-MAR-2009
Polishing System Layout
In order to facilitate my polishing system design I made a board to fit across the fore edge of the tank that was bolted to the aluminum tank support brackets. This board holds the polishing pump, Racor 900 polishing filter and the primary engine fuel filter, a Racor 500.
11-MAR-2009
Fuel Polishing System
Here is a good basic view of the entire polishing and primary engine filtration system with the engine re-installed.. The only thing missing from this photo is the vacuum gauge for the polishing filter.
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11-MAR-2009
Polishing Filter & Pump
I chose the Racor 900MA filter for my polishing filter housing. I also installed a drag needle vacuum gauge to monitor filter performance. The system is designed to run whenever the engine is running and turns the entire contents of the tank twice each hour. I also installed a switch so it can run independently of the engine or not run when the engine is on.
The recirculation pump I initially chose was a Carter rotary vane pump. This pump failed in less than two years. It appears the technician I spoke with mislead me on what defines their pump as able to run "continuously".
There are plenty of less expensive industrial filter housings and spun filters you can use that will work equally as well. Don't feel you need to spend big bucks on a Racor. For me I prefer the Racor, as I know them in-side and out, and I know Hamilton Marine has a massive stock of any part I would ever need for it.
04-JUN-2016
The Replacement Walbro Pump
As I mentioned previously, I firsts tried a Carter rotary vane fuel pump. It failed in less than two years because it could not sustain the duty cycle I desired from it. The new pump is a Walbro and is actually designed to run continuously. The new Walbro has not given me an ounce of trouble.
11-MAR-2009
Vacuum Guage With Drag Needle
The red needle is moved or dragged by the black vacuum needle. Once moved due to vacuum it simply stays where the highest vacuum was generated until you manually re-set it. Because this fuel pump is only running a polishing loop from the tank, through the filter then back into the tank, I can see very easily see when the filter begins to plug. A nice feature of a drag needle gauge is that I do not need the system running to view how plugged the filter is becoming.
18-SEPT-2012
After Three Years
The first season we ran the fuel polishing system for roughly 190 hours and the engine for 111 hours. The second season the polishing system ran for 300 hours and the engine for 122 hours (we have engine driven refrigeration so the engine runs more than most). This season we ran the polishing for 277 hours and the engine for 127 hours. These are the 2 mic polishing filter and secondary filter for the Westerbeke after 360 total hours of engine running time over a three year period. I inspected them each season then re-installed them just to see how long it would take for them to get "dirty". The primary Racor looks as new as the secondary Westerbeke filter.
The filter on top is the Westerbeke secondary on-engine filter. Both were installed at the same time. The on-engine filter is like new and at this rate could probably go five or more seasons before changing but I don't like to let the filter paper sit in fuel for that long so I'll change it bi-yearly after I am done my little "experiment" to see how long it takes them to get dirty.
I originally designed the polishing system for a 10 micron filter but the 900MA came with a 2 micron element. This element still looks almost brand new and had no additional vacuum after 767 hours of polishing. It has done an amazing job of keeping my primary Racor clean and my secondary on-engine filter clean as well. I see no reason to not continue using a 2 micron element in my polishing system.
It has become pretty clear to me that if you install a well designed polishing system, from the beginning, with a pick up tube at the dead bottom of the tank, that the tank can remain very, very clean for a long time to come.
In the previous years with this motor, before the polishing system, I had never once seen the Racor elements come out of my primary filter looking anywhere near as clean as they did at the end of the last three seasons. This is a real testament to the efficacy of a polishing system.
In summary I am running a 2 micron element in the Racor 900 polishing filter and a 10 micron element in my primary Racor 500 for the engine. All is purring along like a kitten and clean.
MAY-2006
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