Looking for Fuel Tank Design Input

[John Stone]

I’m looking for experienced input on the best choice of materials for the fuel tank that will support our inboard diesel engine. I have reviewed the ABYC standards which indicate a wide range of materials authorized from SS to aluminum to steel to plastic, etc.

Our tank will have flanges and be bolted to a bulkhead so no concerns about bilge water or corrosion from sitting on a shelf. Though the tank will be about 20 gallons we plan to have a baffle.

Can you recommend a shop or person to build this tank to ABYC standards? We are leaning towards Luther’s Welding in Bristol RI. They built our kerosene tank which I’m happy with.

What has your experience been with tank materials? Any design considerations that you recommend?

Appreciate your input.

Thanks.

[Jim Walsh]

I’m looking for experienced input on the best choice of materials for the fuel tank that will support our inboard diesel engine. I have reviewed the ABYC standards which indicate a wide range of materials authorized from SS to aluminum to steel to plastic, etc.

Our tank will have flanges and be bolted to a bulkhead so no concerns about bilge water or corrosion from sitting on a shelf. Though the tank will be about 20 gallons we plan to have a baffle.

Can you recommend a shop or person to build this tank to ABYC standards? We are leaning towards Luther’s Welding in Bristol RI. They built our kerosene tank which I’m happy with.

What has your experience been with tank materials? Any design considerations that you recommend?

Appreciate your input.

Thanks.

Luther’s made my replacement aluminum diesel tank several years ago. The specified dimensions were critical to my installation and they were precise with the finished product. I wouldn’t hesitate to use their services again and I’ve recommended them with no hesitation.

[Steve Laume]

The original aluminum tank, on Raven, lasted about 20 years, while sitting on an unfinished, plywood, shelf in the cockpit locker. It started to weep through the bottom after being treated that way for that long. The original tank was made by Florida Tanks. It had been installed before the boat was fully assembled because it would not come out in one piece unless I cut up the boat or removed the engine. I contacted FT and asked them to make a new tank 1 1/4" shorter. They agreed to do this but not until I approved their drawing. The new tank fits through the locker opening, is slightly thicker material and sits up on a rubber mat with lots of air circulation under it. It is now an 18 gallon tank. It should last my lifetime.

Aluminum seems like a good comprise for diesel tank material. I know you are all about engine less sailing or limited use. That may be true but if you have the room, I would install a larger tank. It all depends on how you use your boat but not having to search for fuel during an extended cruise would be a great relief and would simplify your experience. Extra jugs of fuel are a huge PIA no matter where you store them. If you ever decide to install some sort of diesel heater then the extra fuel would also be welcomed. If you are going to all the trouble of reinstalling an engine you might as well embrace the thing and not limit yourself with a relatively small amount of fuel, Steve.

[John Stone]

I’m looking for experienced input on the best choice of materials for the fuel tank that will support our inboard diesel engine. I have reviewed the ABYC standards which indicate a wide range of materials authorized from SS to aluminum to steel to plastic, etc.

Our tank will have flanges and be bolted to a bulkhead so no concerns about bilge water or corrosion from sitting on a shelf. Though the tank will be about 20 gallons we plan to have a baffle.

Can you recommend a shop or person to build this tank to ABYC standards? We are leaning towards Luther’s Welding in Bristol RI. They built our kerosene tank which I’m happy with.

What has your experience been with tank materials? Any design considerations that you recommend?

Appreciate your input.

Thanks.

Luther’s made my replacement aluminum diesel tank several years ago. The specified dimensions were critical to my installation and they were precise with the finished product. I wouldn’t hesitate to use their services again and I’ve recommended them with no hesitation.

Thanks Jim.

[John Stone]

The original aluminum tank, on Raven, lasted about 20 years, while sitting on an unfinished, plywood, shelf in the cockpit locker. It started to weep through the bottom after being treated that way for that long. The original tank was made by Florida Tanks. It had been installed before the boat was fully assembled because it would not come out in one piece unless I cut up the boat or removed the engine. I contacted FT and asked them to make a new tank 1 1/4" shorter. They agreed to do this but not until I approved their drawing. The new tank fits through the locker opening, is slightly thicker material and sits up on a rubber mat with lots of air circulation under it. It is now an 18 gallon tank. It should last my lifetime.

Aluminum seems like a good comprise for diesel tank material. I know you are all about engine less sailing or limited use. That may be true but if you have the room, I would install a larger tank. It all depends on how you use your boat but not having to search for fuel during an extended cruise would be a great relief and would simplify your experience. Extra jugs of fuel are a huge PIA no matter where you store them. If you ever decide to install some sort of diesel heater then the extra fuel would also be welcomed. If you are going to all the trouble of reinstalling an engine you might as well embrace the thing and not limit yourself with a relatively small amount of fuel, Steve.

Hi Steve
Sounds like aluminum is the way to go. 20 gallons is all I can manage in the space I have available. I don’t plan to carry any jerry cans as I just don’t like the clutter. So, I’ll have to manage the range issues. You’re right...I don’t plan to use it much. We shall see though. If I were to ever get the boat into the European river system then I suppose I could purchase a couple plastic jerry cans for that specific event. I will probably have to carry one 5 gallon jug for transporting fuel as I am loath to take the boat along side a fuel dock. And 18 gallons of useable fuel should give me a range of about 250 nm at 5 kts. But that’s all theoretical. I’ll have to see what happens in the real world. I think I only used 3 gallons of gas for the 9.9hp outboard in the last six month cruise but most of that was idling.

I have a heater (Refleks) plumbed to a 10 gallon tank in the starboard cockpit locker. But the heater is jetted for kerosene which is so much better than diesel for a heater. The kero also supported the kero Nav lights which I will replace with LED. But, I still need the kero for my interior cabin lights which I intend to keep using. However, I suppose if I had to I could rejet to diesel and then I’d have a second tank. But I have no plans to do that, though it’s an option.

What kind/size engine do you have in Raven? What kind of fuel consumption have you experienced at say 5 kts?

Anyway, thanks for the input. Very valuable.

[David van den Burgh]

I used Luther's as well. 5052 aluminum. I have yet to read/hear that SS or poly is a better choice, particularly if the tank is mounted in a clean, dry location. And steel? Only if cost is a concern, which I doubt it is. Resale would certainly not be as good with a steel tank. At 20 gallons, I suspect you'd have to request the baffle.

[Paul D.]

I second Steve's comments on considering the largest tank you can fit... it just makes sense, and I also recommend 5052 aluminum mounted in the latest recommended manner. Femme has her original aluminum tank that is approaching 40 years old. We're on the best fresh water lake in the world, and it is somewhat cold so that helps. And I also do my best to keep water, moisture out of the engine area and check it all regularly too.

I am sure Femme's diesel tank would never come out without being cut up. At night, I dream of cutting in and laying up a proper cockpit sole hatch like on an Amel or Pacific Seacraft. I am an amazingly patient and skillful fiberglasser in my dreams! At some point, the time will come for replacement or the big stuff down in there...I already am replacing some of the original Edson steering gear. Oh for a cockpit hatch.

Good luck with your tank project.

[tjr818]

I second Steve's comments on considering the largest tank you can fit....

And I am of the exact opposite opinion. I seldom go through more than 5 gallons a season. I feel that I must top off the tank to prevent condensation, but that means that I am carrying 15 gallons of fuel that will take me three years to use. if I top off every year, I will never really have fresh fuel odin the system. I wish I had a two tank system, maybe a one gallon day tank and a larger reserve tank to this longer trips. I would seldom need to fill the reserve tank; for a long trip I could fill the reserve tank. Stale fuel vs. range anxiety

[Steve Laume]

Hi Steve
Sounds like aluminum is the way to go. 20 gallons is all I can manage in the space I have available. I don’t plan to carry any jerry cans as I just don’t like the clutter. So, I’ll have to manage the range issues. You’re right...I don’t plan to use it much. We shall see though. If I were to ever get the boat into the European river system then I suppose I could purchase a couple plastic jerry cans for that specific event. I will probably have to carry one 5 gallon jug for transporting fuel as I am loath to take the boat along side a fuel dock. And 18 gallons of useable fuel should give me a range of about 250 nm at 5 kts. But that’s all theoretical. I’ll have to see what happens in the real world. I think I only used 3 gallons of gas for the 9.9hp outboard in the last six month cruise but most of that was idling.

What kind/size engine do you have in Raven? What kind of fuel consumption have you experienced at say 5 kts?

Anyway, thanks for the input. Very valuable.

You will most likely find yourself using an engine more often once you have an engine.

I despise the jerry cans as well but still carry two, in the cockpit, when cruising. I definitely don't want them on deck where they would impair my movement and could be washed overboard, They actually reduce the amount of water the cockpit could hold if pooped so there is some advantage to having them in my way. With only 16 or 17 gallons of usable fuel, in the main tank, it seems prudent to carry another 9 or 10 gallons in reserve. I have had to use the jugs to carry fuel to the boat on one occasion, when cruising. I regularly use them to bring fuel from home. It is easier to carry two than it is just one. If you have to walk or get a ride to a fuel station then doing it for only 5 gallons, hardly seems worth it and if that is your situation, then you certainly don't want to make more than one trip.

I have no more problem coming into a fuel dock than any other docking situation. The only difference is that there is usually someone on the fuel dock to take your lines.

Raven has a two cylinder Universal engine. I have never accurately determined fuel use but it seems to be around a third of a gallon per hour at about 80%, which moves me at about 5 knots. So my range is about 250 miles and then another 150 if you factor in the jugs. If there is no wind where I would just be rocking around with the sails slating then I will often run at reduced RPMs. This will still charge my batteries, steady the boat and move me in the direction of more wind while keeping the noise and vibration to a minimum. Where fuel use increases drastically is when you are trying to beat into a harbor, against strong winds and steep waves. This also tends to be at the end of a voyage when your tank may be low and things are sloshing around so you don't get to use the last drop. I spent two hours, to go the last two miles, at two in the morning, on my last trip to Bermuda. If I had continued sailing all the way, I could have entered in daylight. I have had similar experiences, entering narrow fjords except that it was still light outside. There are definitely times where just getting to a safe harbor is far more important than doing it under the power of sail.

When I first got Raven, I strived to use the engine as little as possible. I now view it as something that adds both safety and convenience to my sailing experience. She is still the most fuel efficient vehical I own, Steve.

[fmueller]

John,

We put a Moeller 12 gal poly in Jerezana. Got one taller / less wide/long and moved it down and inboard than the OEM aluminum mounted position. The OEM tank was corroding inside and out. These Moeller tanks are far more robust than the typical outboard portable tank for instance ,or for that matter, my existing water tank and holding tank (which look practically new). If it was a much bigger tank, I'd agree baffling would be an issue. I think some of the larger Moeller tanks do have baffles, but there is no such thing as custom sizing.

Being a bay/day type sailor, like Tim I'm ok with about a 125 mile range ... Just happy to have a clean tank. Also, I can just eyeball fuel level. Don't have or need a gauge.

Fred

pix before it got strapped in ...

[John Stone]

That’s excellent Fred. Sounds like a good fit for Jerezana. The challenge for us is to fit a very specific space so I can keep lockers and space behind engine available for more accessible storage. Though I wish it would, off the shelf tanks won’t meet our needs.

I built the tank mock up yesterday. It’s 20 gallons. Will test fit it today. If the space works out there will be very little loss of usable storage except for the actual engine footprint.

Thanks for the input.

[fmueller]

Yup. AlUminum is the only way to go for your situation. I just throw reply’s into these threads as a matter of record for folks who may be looking at what‘s possible.

Cheers.

[gonesail]

these guys in central Florida are good .. they will do exactly what you want. http://www.boydwelding.com/

[hilbert]

these guys in central Florida are good .. they will do exactly what you want. http://www.boydwelding.com/

This is a Boyd 11 gallon fuel tank purchased in 2010, constructed from 1/8" 5052 Mill Aluminum.
So that it would fit through the lazarette, Dave Boyd modified the the tank to my specifications at no extra charge.
Rather than venting it to the exterior as was done by Cape Dory, there is a roll over safety vent that allows air in but does not allow fuel out.
The tank is mounted on tabs and does not come in contact with any surface. This tank has a 3" aircraft style fill cap.

I installed easily accessable dual fuel filters, that can be changed over on the fly with three way valves:

[John Stone]

Hilbert. That looks very nice. Similar design to my 10 gallon kero tank in the port cockpit locker. I’ll be sure to get a quote from Boyd Welding. Does the roll over vent allow escape of diesel odors/fumes inside the boat?