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A Fuel System for Island Eagle
The fuel system on Island Eagle when we acquired her was a hodge-podge of different valves, pipes, tubes and filters, with no diagrams at all. After a few weeks of study, we understood it fairly well, and we determined that it would not meet our needs (big surprise!). After completing the interior renovation we turned our attention to bringing the entire fuel system up to snuff.
Step One - The Tanks
The tanks on Island Eagle are typical for boats of her age: two tanks of welded 1/4" steel, well-mounted against the hull and stringers. At roughly 1000 gallons each, replacing them is not really something that you want to contemplate. The good news is that they are both equipped with good-sized manholes, allowing them to be thoroughly cleaned. Once again we turned to our young pipefitter friend, Aaron, who spend a few very very unenjoyable days pumping the old diesel out and then thoroughly cleaning out the tanks. Thankfully, the interiors of the tanks were in fairly good condition, with only a few gallons of dirt and rust at the bottom. No signs of algae were found. Aaron did find one place where there was some fairly deep pitting, and we had the welders do a bit of surface cladding in that
area (yes, they were welding the inside of a fuel tank, in a wooden boat, in the engine room... my hair is even greyer).
The other change which Aaron recommended was to relocate the fuel pickup. It had been located at the extreme aft end of the tank, and 1 inch above the bottom. Aaron was concerned that this would lead to the engine ingesting contaminants, and he recommended that we relocate the main fuel pickup several feet forward of the aft end and about 4 inches off the floor of the tank. While the welders were in, we had them make this change, as well as adding new fittings for sight gauges and new fuel return fittings. We left the old bottom outlets in place to use for the fuel polishing system. After this Aaron pressure-tested the tanks for 24 hours before pronouncing them fit for use.
At the end of the day the tanks were clean, dry ready for another 40 years of use.
Step Two - Designing The New Fuel System
Now, you know, there are thousands and thousands of boats out there. And they all need fuel systems. And the fuel systems have to follow some pretty strict regulations from the Coast Guard and it's recommended that they adhere to even stricter recommendations from the AYBC. So designing a fuel system should not be all that hard, right? Wrong!
I started the fuel system design process with a few ideas that I thought were pretty good, including:
1) Ability to draw and return fuel to either tank.
2) Ability to transfer from tank to tank.
3) Ability to polish fuel (draw and return to same tank through filters), using a separate filter bank.
4) Filters mounted at eye-level for good visibility.
5) A fuel pump pushing fuel through the filters.
With these goals in mind I drew up a plan and ran it by a few folks whose opinion I trust. Dieter the Electrician showed them to his colleague, the engineer on a 200 foot high-speed ferry. Our friend George, the local Transport Canada inspector, offered his opinion. And Ron Sparks, a frequent contributor on www.boatdiesel.com, also had a look at the plans. The result? I was roundly criticized. They made some excellent points, though:
1) You should always return fuel to the same tank you draw from. It reduces contaminations, and prevents overflows.
2) Filters should always mounted as low as possible, so they will gravity-fill in a pinch.
3) Filters should always be mounted in the suction lines.
4) A full-time fuel pump was not required.
Finally, my initial design had a lot of flexibility, but that came at the cost of complexity. The KISS principal was quoted. Also, there were a few other excellent suggestions, including:
1) The ability to gravity transfer fuel between tanks.
2) The ability to drain fuel from the lowest point in each tank.
3) The ability to use the transfer pump to prime the fuel filters.
So, I went back to the drawing board and came up with the final design (click the image for a printable PDF version):
After checking with the experts, this was approved.
Verdict: In practice this system has worked very well. The only change that we have made is to add a tee just before valve ST4, with another valve and a hose. This is so that we can use the fuel transfer pump to fill a portable container with diesel if we ever need to.
Step Three - The Components
The next step was to decide on the actual components to use. The tanks were already there, so that was no problem. We already had a set of Racor 1000-series filters which had originally been on the engine and that we would use as the transfer/polishing filters. On eBay we acquired a set of dual Racor 75-1000 MAX filters. These have a built-in valve that allows you to change a filter while underway:
 We also picked up some Racor 500MA filters for the genset and heater:
Next came the problem of the pump. Many folks choose either impeller or vane pumps for this application, and these pumps typically will do about 12 to 15 litres per minute. But in our case, with roughly 4000 litres per tank, the pumps would burn out before the fuel was transferred or polished. We decided to go with a Groco CP-20 centrifugal pump, which has a high flow rate and is rated for continuous operation. The only downside is that it will not self-prime, and therefore you must mount the pump below the tank outlet. In our case, that was no problem, as we planned on
mounting the pump below the floorboards.
The final decision was regarding what hoses to use. The original fuel hoses on the boat were 3/8" soft copper with flare fittings. Now, I grew up making flare fittings for diesel furnaces, and I hate flare fittings! They leak, they are inflexible, the copper pipe kinks, and to top it of the copper is not fireproof. So that was out.
The other popular solution is to use marine fuel hose (e.g. Trident), barbed hose ends, and hose clamps. I hate hose clamps! They're ugly, they rust, and they catch your fingers and cloths. Plus, once a fuel hose has been clamped up for a few years, you can never get it off the barbed fitting. So that was out.
My initial idea was to use hydraulic hoses with crimp-on connections. Hydraulic hose is tough as nails, inexpensive (about $2 per foot in the size I needed), and (if you have access to a crimping machine) easy to work with. They terminate on JIC fittings, which are like flare fitting but way better; they are the standard hydraulic fittings for industrial use and withstand about 5000 PSI no problem. I visited my friendly Parker store and priced out the options, and it looked good. The hose was excellent, and he assured me that
it came off the same line as the marine hose. While I was there, the tech showed me their field-attachable fittings, and these were really cool: With just a vise and a wrench, you could put on a hydraulic fitting that was a strong as a crimp-on, without needing a crimper! Now we were cooking. I started making a list of the parts I'd need and got ready to buy.
But... just before I bought, I happened to mention my plans to my friend the big-ship engineer. Uh oh. "Sure" he said "I know lots of fishing boats that use hydraulic hose for fuel. And it works. But if you ever have a fire, your insurance will be void. And you can never have your boat Coast Guard inspected". What? Well, I looked into it and he was right. Hoses for boat fuel systems must be clearly marked as Coast Guard approved, and hydraulic hose was clearly not. The good news, though, was that Parker made just the hose I needed: Parker 221FR marine fuel hose. And it was available for... $15 per foot! And I needed about 100 feet! Clearly this was out of the question.
Back to the drawing board. I did some looking, and some more research. One option was to use inexpensive Trident-style rubber hose with Parker-style field-attachable JIC fittings. I found a few mechanics who swore up and down that they used this method all the time, but every supplier I talked to told me that if I did this, they wouldn't provide any warranty at all.
Slowly, I came to the realization that the only proper solution was to put in proper coast-guard approved top-of-the line hose, with the manufacturer's approved fittings. My choices were between the aforementioned Parker 221FR hose, and a similar product from Aeroquip, FC234. I didn't want to actually do the math, but it looked like it would be costing me at least $3000 for the hose and fittings. I decided to take a peek at eBay and see what I could find. After a few days, unbelievably, I had a hit: I guy in North Carolina had ordered 110 feet of 221FR and had been supplied shorter lengths instead of a single length, and he was selling the initial order:
The only downside was that it was 5/8" inside diameter, which was way overkill, but after some tense bidding I had 110 feet or genuine Parker 221FR-12 for $195. Astounding, considering that the retail price is about $25 per foot!
That still left fittings. I needed Parker 20620-12 field attachable hydraulic fittings, and darned if eBay didn't come through again: A helpful seller (www.etruckequipment.com) was discontinuing a certain product line, and had about 40 fittings for sale at about $1.50 a piece. Sold!
So, for about $250, plus another $150 for shipping, I had most of the hose I needed.
Verdict: The Parker 221FR has been absolutely flawless.
Step Four - Assembly
The plan was for Aaron to assemble the entire fuel system before we came out to use the boat at the end of March. But due to bunch of factors beyond hos control (mis-shipped parts, a malfunctioning heater, etc.) this was not possible. So, Aaron & Scott spent several very very late nights (actually early mornings) getting it all together. Aaron measured and cut all of the hose (more complex than it sounds, since 221FR is steel-reinforced it must be cut with an abrasive wheel). Scott then took the hose up to the shop and installed the fittings. Aaron then assembled the entire system.
Here are some pictures:
Assembling the hose fittings:
Aaron measuring the hose and running the hose through the bilge:
The new outlets on the tanks and the new sight-glass fittings (brass). Note the tabs welded to the tanks, these will hold Lexan covers to protect the sight glasses:
The completed suction and return valves. These will be mechanically linked together so that fuel will always be returned to the same tank it came from. In the background you can see the second set of Racors for the fuel polishing system:
The next challenge was getting the tanks filled. They were absolutely empty, so we couldn't even get to the fuel dock. So, we started by humping 100 gallons down in 5-gallon gerry cans (that's Scott Nattrass below with an empty). Then, we fired the main (it started!!!) and made it to the fuel dock under our own power. When we filled the tanks for the first time, we first balanced the boat and then filled them in 250 litre increments, marking the sight gauges with zip-ties:
Verdict: In use, the fuel system has proven to be simple, flexible, and bulletproof. There have only been a few problems. The major one, and still uncorrected, is that the fuel tank vents are only 1/2". This means that we need to be very, very, very careful during fueling to not exceed a fill rate of about 5 GPM. Yes, this means three hours to fill the tanks. Yes, we are going to increase the vent size. Yes, this was not built to ABYC standards. The only other change is that we've added an additional outlet to the fuel transfer pump so that we can fill gerry cans (particulaly because our tender requires diesel).
Fuel Return Lines
One of the problems that we faced was that the fuel return lines are about 8" below the top of the tank, and if I ever needed to work on the return lines with the tanks full I'll need the ability to close them off. So, I installed two ball valves right at the tank. Then I made sure that they were both open. Then I put a big label saying "These valves to be left open at all times". And then (here's the important part) I removed the handles and put on on a hook in the engine room. Voila. If I really need to turn off the return, I grab a handle, slip it over the valve stem, and turn it off. The rest of the time, the valves are open because there's no way to close them. Here's a picture showing the ball valve without a handle:
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