hydraulic pod drive 30' displacement hull

essenmein · Jan 13, 2015

whitepointer23 said: ↑

if you go to all that trouble why not use a variable flow pump or motor. Swashplate are infinitely variable and super reliable. But a 6 hp will be about the same as 3 hp with shaft drive.
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Nah won't be that bad, however this is nothing more than mental exercise for an idle mind.

In terms of trouble though, its really not much trouble at all, id just walk into princess auto and maybe $600 later I'd have a system that would be very simple to install compared to getting engine bed, framing and shaft all lined up and built into a boat.

brian eiland · Feb 26, 2026

You fellows might have a look at this hydraulic motor I mentioned a long time ago just might find usage in your projects,..
Power Propulsion https://www.runningtideyachts.com/power/

While working on a new bow thruster design, a Hungarian gentleman has developed and built several entirely new and unique gearless, twin-rotor, angular-piston, hydraulic motors. This patented mechanism employs two rotors which are interconnected by angular pistons that are all contained and bearing mounted in a common housing. The linear displacement of the pistons in one of the rotors is directly converted into the rotational motion of the other rotor, interactively. The geometrical and mechanical relationship between the two interconnected rotors provides optimum conditions for direct conversion of linear displacement of the pistons into rotational displacement of the rotors. Barring frictional losses, the conversion is 100% efficient. None of the commercially available axial piston motors have such direct and efficient means for converting linear displacement into rotational motion.

And maybe more importantly, the design is greatly simplified by the elimination of the traditional angular swash plates, sliding shoes, and related components. There are many fewer moving parts in this motor, which should significantly increase their reliability while decreasing the maintenance and manufacturing cost of these units. Simultaneous linear and rotational motion of the pistons within the rotor bores results in even wear, increasing the life of the motors.

Industrial

Marine

Employing suitable valving, the motor can be operated at two levels of speed and torque output at the same operating pressure and flow rate of fluid. Simultaneous pressurization of the pistons in both rotors produces the "wedge effect", driving both rotors with equal power and higher torque. The interactive function of the pistons assures optimum transmission of the driving torque between the rotors by distributing the load to all pistons. This exceptionally high torque efficiency allows direct drive of the propeller without gears, and the using only medium rather than high pressure pumps.

The motors are bi-directional, and the direction of the rotation can be selected externally by valves, or internally by interchangeable valve plates. The motors have automatic hydraulic pressure and propeller thrust compensation. The replacement of the mechanical transmission by hydraulic components provides a stepless speed control from stand still to full speed, as well as instant reversal, reportedly assuring the availability of full power at any moment.

Having no mechanical connections between the engine and the propeller drive units, the marine designer has complete freedom in the positioning of single or multiple propeller drives and the engine units themselves.
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BlueBell · Feb 26, 2026

Brian, this thread is over 12 years old and most of the interested parties haven't even been on the Forum since then.
Give your head a shake man.

brian eiland · Feb 28, 2026

There are times when one is not looking for just past participants in a subject thread, BUT rather the history of whats been tried in the past.

I guess I'll just have to start a new subject thread. I'm interested in a 'steerable prop' arrangement on a single engine trawler, that might substitute for twin engine's maneuverability.

I experienced a great maneuverability when I put a single steerably outboard motor on a 37 catamaran.

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hydraulic pod drive 30' displacement hull

essenmein Junior Member

brian eiland Senior Member

BlueBell . . . _ _ _ . . . _ _ _

brian eiland Senior Member

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