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

Saturday, May 18, 2013

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

- While the reliability and available output speed(s) of hydraulics is seductive, as I understand it every motor or pump stage (often the same thing being fed instead of feeding) loses 20% power, so 1 x hydraulic pump = 20% loss, 1 x hydraulic pump driving 1 x hydraulic motor = 36% loss.

- So your 3HP electric motor spinning an hydraulic motor + pump combination immediately becomes 1.9HP at the prop shaft.

- Before the cutting edge brigade hits me with the new designs of variable volume, Geromotor, rolling vane or servo controlled variable expansion units, there are the "what's available today" economic and availability issues that you have to face in the real world, and that of course always brings us back to reality.

Cheers

On 18 May 2013 05:44, reesekc <kcr@kcrproducts.com> 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.