T-Pain Is On A Boat: Re: [Electric Boats] Hydraulic motor drive with Hybrid Electric and Diesel Motors

Friday, May 24, 2013

Re: [Electric Boats] Hydraulic motor drive with Hybrid Electric and Diesel Motors

Thanks for the input, I agree big hoses are good. As for pressure, of course there is a high pressure relief valve in case something goes bad. But the control valve is "open center", that means when the diesel engine is started there will be very little hydraulic pressure, the pump is running but no back pressure except for pressure lose from circulating hoses and fittings. As you move the lever into forward or reverse the the center position closes and pressure builds to drive the pump. There is no load until you engage the forward/reverse lever. Typical hydraulic systems don't do that.

I'll build a system and test it, and I will also be happy to provide all the data, parts list and cost to everyone. Bottom line is that I'm trying to create a solar powered system without the "common" problems associated with battery banks, motor controllers, electrolysis corrosion, pulleys nor belts, nor the need for a backup generator system.

After a considerable amount of research, I convinced myself that a dual system using solar electrical motor and a diesel motor would provide the best combination. I saw no "practical" way to mount an Electrical motor and a diesel engine on the same drive shaft, so I turned to hydraulics. I created a system that uses solar power and a diesel motor to drive the propeller through the use of hydraulic pumps. Since "things break", I also wanted to be able to run the electric motor directly from the solar panels (should the batteries or solar controller crap out).

As for cost, I went through the efficiency calculations. Pumps/motors vary in efficiency from 93% to 85%. Sure enough I can spend more money than I budgeted and have a more efficient system, but for me, that approach is just plain foolish. We are stuck with the basic inefficiencies of the engine, transmission, and propeller in a boat drive system, so the upper efficiency limit is about 25%.

To put cost in prospective, in the last 10 years I've used about 300 gallon of fuel on my sail boat. If I spend an extra $5000 to purchase "high" efficiency components and improve efficiency by say 12% (which is doable); That 12% will give me a 3% system improvement; 3% would save me about 12 gallons of fuel or about $48 in the next ten years. I don't know about you, but I'm not going to spend $5000 for a $48 return. And I am talking standard components... the system will have standard hydraulic parts, shaft couplers, fittings, hoses and motors. $1650 is my goal, so far I've spent $768 and have an estimated cost at $1570 (some items are less expensive than I thought).

On Wed, May 22, 2013 at 5:08 PM, Kevin Pemberton <pembertonkevin@gmail.com> wrote:

You can reduce heat build up and much of the friction with very large ports and hoses, much like using over sized wire in an electrical installation. You can lower heat build up by designing the system to minimize use of the relief valve. That said we are not talking standard components, so the price went to the moon and back. For mega watt wind generators variable speed transmissions using hydraulics. Price is a small part of the package, but we are not planning to make money here.

Kevin Pemberton

On 05/18/2013 09:11 AM, James Sizemore wrote:

I have no experience with hydraulic systems at all, I have seen it discussed in the past. Vetus does make such a setup see link below. From what I could see from the previous threads the down sides seem to be cost (hydraulic cost a lot more then belts or planetary gears) and space ( you need a large fluid cooling tank to use hydraulic for traction application.) The upsides being flexibility in engine location.

http://www.nauticexpo.com/prod/vetus/hydraulic-propulsion-systems-for-boat-21508-213867.html

On May 17, 2013, at 11:44 PM, reesekc wrote:

I have a Hughes 35.5 Sloop of which I just removed the Atomic Four motor with a V-Drive. I am planning to replace the motor with a hybrid hydraulic drive system. A hydraulic motor will be used to drive the propeller shaft; and to power this motor, I'm planning on installing a 3 HP electric motor with pump; as well as an 18 HP diesel also with a hydraulic pump. The plan is to connect the motors in parallel with check valves to prevent back flow, so the motors may be used independently or together.

The electric motor will be supported with solar panels and a small battery bank. The diesel motor will drive a larger pump and of course have an alternator for general electricity and recharging the batteries.

I believe the hydraulic pump/motor system is simple and reliable, and I also like the idea of hybrid power system which greatly reduces the battery bank size. I've done a search through past posts, but I could not find much on "hydraulic motor driving a propeller". If anyone could steer me to a previous thread, or if anyone has some comments on the plan, I would appreciate input.

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