Hydraulic fluid in keel tank

[charleskaluza@gmail.com]

I am finishing out a steel sailboat project which came with a hydraulic drive system. The hydraulic tank was built into the aft keel. Coast Guard does not allow integral fuel tanks but I can find no info on hydraulic tanks.

Assuming the hydraulic drive works as promised, the existing 35 gallon tank would be perfect. Any thoughts on hydraulic fluid in the keel? Keel tank has been pressure tested and has 1/2 steel bottum with 3/16 sides.

Thanks

Charlie

Live more and die less

[Alan Wheeler]

built into the aft keel

What do you mean "aft keel".
Hydraulics are very inefficent. A lot of power is wasted driving the system.
The question would be why does the CG not allow intergral fuel tanks. Which seems a little strange to me, but OK, so if it is for prevention of fuel escaping in a collision, the surely any tank with a pertoleum product in it would be the same.

[charleskaluza@gmail.com]

The keel is divided into 3 seperate compartments, with the ballast in the center compartment.

Hard to justify not using the system which is installed and paid for if it works. I will not live long enough to see the fuel savings pay for converting to a standard v-drive.

I expect you are right about all oil based products.

Charlie

Live more die less

[GordMay]

Originally Posted by charleskaluza@gmail.com

... Coast Guard does not allow integral fuel tanks but I can find no info on hydraulic tanks...

ABYC Section H-30 HYDRAULIC SYSTEMS does not prohibit integral oil reservoir tanks; and Section H-33 DIESEL FUEL SYSTEMS does not prohibit integral diesel fuel tanks.
What leads you to believe that the USCG prohibits integral tanks?

[charleskaluza@gmail.com]

Gord,

I appreciate your reply and the reference provided. The marine surveyor mentioned it to me on his survey and then I found this link:

http://www.uscgboating.org/safety/boatbuilder/fuel/183-550-a.htm

This may only apply to commercial manufactures, I hope.

I will press on with the finishing of the boat and report back on the performance of the hydraulic drive.

I spent my summers growing up on Sanford Lake to the north west of you, many fond memories.

Charlie

Live more and die less

[hellosailor]

FWIW, "fuel is fuel" is a petrochemical all the time. There are hydraulic systems that use vegetable oil and other non-petroleum based oils. One of the largerst apparently is in Las Vega, the Cirque de Soleil theatre has a huge articulated stage powered by thousands of gallons of hydraulic oil, all vegetable oil because the LAFD was concerned about fires, and wouldn't allow it.

So, maybe the USCG is just concerned about petroleum products? Or the relatively tiny size of hydraulic systems on small craft didn't show up on their radar?

(In the US, there are often loopholes and omissions in regulations, that's nothing new or unusual, or specific to the US.)

[Evan]

Your link didn't work for me, but I can guarantee that USCG does not prohibit integral fuel tanks in either commercial or pleasure craft. I'm a working naval architect.

Integral hydraulic tanks are not a great idea due to condensation. Water in fuel can be gotten rid of due to good filters, but it's not as easy on hydraulic systems. If you go this route, make sure you keep the reservoir full so condensation cannot form on the inside of the tank walls.

[jrd22]

I had a hydraulic drive in a Cascade 29, worked fine but had a high pitched whine that was annoying. I would try to incorporate a lot of quality sound proofing around the pump and motor if you can. I don't see why a keel tank would have much more condensation than a regular tank that is subject to more changes of outside temperature. Make sure you incoporate a good hyd. filter into the system. I really liked the ability to go from full speed ahead to full speed astern at the flip of a lever, no change of throttle. We could stop in about one and 1/2 boat length from cruise speed.

John

[charleskaluza@gmail.com]

Many thanks for the information. Here is a copy of the regulation I cited.

FEDERAL LAW
183.550 - Fuel tanks: Installation
(a) Each fuel tank must not be integral with any boat structure or mounted on an engine.

Each fuel tank intended to be permanently installed, must be made as a separate component and then installed in the boat. Portions of a boat’s structure, i.e. hull surfaces, bulkheads, stringers, floors, decks, frames, etc., may not form part of a fuel tank.
Fuel tanks glued, bonded or foamed-in-place are not considered integral and are therefore acceptable. However, that installation must comply with the applicable portions of this regulation.
Fuel tanks may not be mounted on an engine, except if the engine is part of a portable piece of equipment that is not permanently installed in the boat. If a fuel tank is removed from an engine to be installed in the boat, the installation must comply with the requirements of this standard. Particular attention is directed to the fuel tank vent requirements and the requirements for all openings to be in or at the topmost surface. Many tanks installed on engines have a bottom fuel supply; this fuel tank is not acceptable for installation in a boat.
TO COMPLY WITH THE LAW

• Each fuel tank is not integral with any boat structure.
• There is no fuel tank mounted to a permanently installed engine.

I made the surveyor double check the rules and sure enough the rule only applies to commercial vessels…so I should be good to go.

I will go with a much oversized filter with water trap. Keeping the tank full to prevent condensation should not be a problem.

Thanks for the report on the noise issue, I have started the research on soundproofing. The Admiral is a musician so noise must be controlled.

Advice of those with more experience is a valuable resource, so thanks again.

Charlie

Live more, die less

[Alan Wheeler]

hydraulic oil, all vegetable oil because the LAFD was concerned about fires, and wouldn't allow it.

Hmmm, Hydraulic oil is usually non-flammable. Not sure why, but it will not burn. I have a friend that heated large tunnel houses for Tomato growing with used oil burners. I gave him hundreds of litres of used Hydraulic Oil and the burners simply would not fire up.
Yet Vegetable oil burns. So????....

[hellosailor]

Dunno Wheels, but check out:

Hydraulic Fluid Flammability Test (MIL-H-5606 Versus MLO 68-5).

Apparently our US military was setting hydraulic oils on fire and comparing them to new versions that wouldn't burn as much. Or at least, weren't supposed to burn as much.

Maybe you got "new" oils down under?

[Alan Wheeler]

So we need to stay away from folks holding 50cal. weapons loaded with incendery tipped munitions :-)
I know that the oil I used (HLP-46) was highly loaded with Zinc and anti-foaming additives. I wonder if those reduce the ability to ignite the oil. Aaarh who cares, I am off on a Nerdy tangent.

[hellosailor]

Yeah, especially the ones using them under your keel integrated tanks.[g]

[NoTies]

Beg to differ about hydraulics efficiency Alan. A properly designed hydraulic propulsion system is significantly more efficient than a mechanical drive train. I can't remember all the data but explored this in depth for a mussel harvester project I was working on. The mechanical loss in a hydraulic system is way less than a pure mechanical system and the fact of being able to run the engine at rated revs regardless of power output also increases savings. BTW, the "hydraulic pump" you sold me for my steering has been performing extremely well, not bad for a cobbled toghether hybrid pilot setup. I'm managing 93 deg tacks in 20 knots without ever touching the wheel.

[BigCat]

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