Hydraulic drive for Catamaran?

[Cadence]

Originally Posted by Sailor Doug

That's a lot of potential leaking fittings.


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Hydraulics do not need to leak. A properly made up fitting will last a long time. Now hoses exposed to UV and Flex won't last forever but still are long term items.

[Stumble]

If you are going with a single large propulsion motor driving distributed propulsion motors (so electric or hydrolic) there is one other major advantage of electric. The onboard house load generator can also be tapped to provide propulsion for the electric system. It is effectively a get home motor.

As I mentioned before the major issue to me with a hydrolic system on small boats to run sub systems (winches, thrusters, etc) is that it requires some motor to be operating at all times to power them. So just to use your powered winches you have to crank up the big propulsion motor. Which is grossly inefficient. Better to use electric and draw power from the batteries, which can be recharged the next time you need propulsive power.

[Cadence]

Originally Posted by Stumble

If you are going with a single large propulsion motor driving distributed propulsion motors (so electric or hydrolic) there is one other major advantage of electric. The onboard house load generator can also be tapped to provide propulsion for the electric system. It is effectively a get home motor.

As I mentioned before the major issue to me with a hydrolic system on small boats to run sub systems (winches, thrusters, etc) is that it requires some motor to be operating at all times to power them. So just to use your powered winches you have to crank up the big propulsion motor. Which is grossly inefficient. Better to use electric and draw power from the batteries, which can be recharged the next time you need propulsive power.

I would agree if you were powering the SI ferry. Diesel electric has a long successful past However the weight of the gen set is considerably higher than the diesel and hydraulic pump. As are the engines. Granted efficiency is probably better. Everything is a trade off.

[Stumble]

Originally Posted by Cadence

I would agree if you were powering the SI ferry. Diesel electric has a long successful past However the weight of the gen set is considerably higher than the diesel and hydraulic pump. As are the engines. Granted efficiency is probably better. Everything is a trade off.

Nope.... If you need 25hp delivered by each drive motor you are going to need at least a 50hp hydrolic pump, or a 50hp electric generator. Actually the electric generator may be able to be a bit smaller because of increased efficiency, but it probably won't be noticeable.

The propulsion motors (hydrolic or electric) make up the biggest difference, and while hydrolic may be a bit smaller, we're talking the difference in a pound or two.

[a64pilot]

Originally Posted by Cadence

Everything is a trade off.

That is it in a nutshell. Nothing is simpler than direct mechanical drive, but if your willing to Trade some complexity and expense with either a hydraulic or hybrid electric, there could be some advantages.



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[Sailor Doug]

Never swept up any electrons but sure mopped up a lot of hydraulic oil.


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[Cadence]

Originally Posted by Sailor Doug

Never swept up any electrons but sure mopped up a lot of hydraulic oil.


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You just weren't quick enough to catch the electrons.

[Sailor Doug]

Something about speed of light😜


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[Cadence]

Originally Posted by Sailor Doug

Something about speed of light😜


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Yep, they are fast.

[Michael Hubman]

I would think a set up like that would be more useful in a trimaran.

[Cadence]

Originally Posted by a64pilot

That is it in a nutshell. Nothing is simpler than direct mechanical drive, but if your willing to Trade some complexity and expense with either a hydraulic or hybrid electric, there could be some advantages.



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Best I could find hydraulics may have a 30 lose. But what is lost on twin engines as far as fuel consumption? My father was a stickler on keeping records, a log. He would run one engine if doing hull speed.

[darylat8750]

Originally Posted by Cadence

I had bought an old dozer and an old tractor. Once I had new hoses made up never had to add a drop of fluid. Hydraulics need to leak is a myth.

+1 on that. I grew up with farm equipment and lots of hydraulics. When using quick disconnects to change equipment a drop or 2 wipe it up right away. I currently have a twelve year old tractor with hyd on the loader, snow thrower and grader blade. Not a drop on the floor. There are more than one kind of fittings. Make sure you stay with the same style.

[captlloyd]

Originally Posted by Michael Hubman

I would think a set up like that would be more useful in a trimaran.

Curious. What makes you say that?

[leftbrainstuff]

Originally Posted by captlloyd

Does anyone know of a Cat manufacturer who uses a hydraulic drive system utilizing a single diesel engine to drive the hydraulic motors. Other than only having one engine, I see a few advantages with this idea. Less cost for one less engine, and much cheaper drive motors. Less weight with again one less engine and hardware plus drive motors . Any opinions please?

It will be heavy. Not ideal for a weight sensitive cat.

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[captlloyd]

Originally Posted by leftbrainstuff

It will be heavy. Not ideal for a weight sensitive cat.

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Do not follow your thinking at all. One less engine, hydraulic motor-drives less than half the weight of a transmission/transmission adapters. Total weight savings would have to be in the range of 300-400 pounds.