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so i am putting together a diesel electric system with a 10hp yanmar chinese L100 engine, and appropriate alternator to charge the batteries for my torqueedo electric outboard.

Now the thought occurs to use the diesel to alternatively run a pump that drives  a hydraulic motor which then (magic happens here) drives a prop. i was thinking to maybe cut out the engineering of a pod with prop approach by purchasing an old outboard, scrapping the engine, and hooking directly to the drive shaft.

So, obviously totally loony here. But engineering issues? anyone  have any experience with small scale *(tiki21) hydraulic props?

As an aside there was a tehini in the Med that had dual props driven by a single pump to diesel. Anyone know who designed it? thanks.

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 Hello Clif, I have a little experience with this, my catamaran is a CSK not a wharram but a classic glass over ply none the less.  our cat had two drive legs profesionally built and very nicely done, with the hydraulics designed and installed by proffesionals, while they did drive the boat very well  and gave us great directional control in tight places. They SUCKED. they leaked almost always, every time we would have the hydrualic motors redone the would leak 50-100hrs later, and oh my Buddha LOUD, loud and noisey and leaky .

 I cannot say enough against even trying this system, we went back to outboards a few years ago and have been very happy with the results.

 We did consider the torqueedos for electric drive, I would be very interested to hear how well they work if you use them.  Thanks Doc

doc

i have a torqueedo. It works great for the 25 foot umiak trimaran, and the tiki 21.  i can get 11 knots at 3/4s of my amperage draw.

just as a thought, i have never had a hydraulic system leak. Once replaced an isuzu trooper engine, and had it not leak (a real accomplishment). Such systems need not be bad. And just because someone charges money for a task, and claims professional status does not mean that they are competent. This more true in boat world than elsewhere though why i do not know.

 I appreciate the feed back on the torqueedos, I think maybe the next boat I do will go that way. I tell you the drive legs on our old system where very nice and worked very well, I guess our biggest problem was the noise and the mess, and well the noise , those hydraulic motors are very loud.

  I do have to agree  that having done alot of farm equipment( tractors etc.) with hydraulics that never seemed to have much leakage problem, I think maybe the motors being exsposed to the salt water/air wasnt a good idea.

 Just FYI knowing how the marine industry is full of "professionals" we actually had the hydrualics done outside the marine world, and had them done by an areonautics manufacturer, They work on planes right it should be good?

  Some boats just arent ment to fly.

  Have a great day.  Doc

Gud Day Clif

I am designing the same system for our boat. I mean the hydraulic drive. I have sum drawing of a system that I found online a few years ago. I will try & post them soon. I will also b using the hydraulics for the anchor. I will also b uploading sum of my ideas soon.

My diesel engine will b driving a lay shaft thats geared up to get max output, from the lay shaft there will b a hydraulic pump, a alternator for charging the batteries. Still workin on all the logistics.

Iain 

I have added sum pics of a hydraulic drive that I recently found, 52' but not Wharram. It looks quite old & rusty so must b working rite. Boat goes out quite often.

Iain 

Hi Clif,

Have a chat to Max from Seascapes who owns (amongst others) two Tiki 38's he charters out of Phuket. Those are set up with a hydraulic system as you describe.

The Heavenly Twins cats had the option of a hydraulic system. It had its pro's and con's. Don't have much info on it, but you could probably Google it.

Cheers

Carl

You can check out surpluscenter.com, they have lots of hydraulic components.

received  the 10hp diesel engine the other day. Looks skookum. Four stroke. Air cooled, but while this is a problem normally indicating noisy as a giant can full of pennies, this one is very nicely designed. A few fan additions, and some air flow control knowledge from the  local pot growers, and i think i can button this puppy up in a noise reducing box, put it out on ama, and not (mostly) even hear it. It has electric start so i can remote that to the  pilothouse. These engines are the upcoming 'new product class' from china. The yanmar design and common L100 class of parts should make them pretty ubiquitous throughout asia and SE pacific moving over to South America soon. i think maybe 20 years of hard life in one.

Im building a 51' Tehini and am thinking of a diesel hydraulic with one engine and to long shaft powered by hydraulic motors.   Iain if you have any drawing Id love to see them.   Mike at madjk@hotmail.com

Iain & Cherry Mae Cairns said:

Gud Day Clif

I am designing the same system for our boat. I mean the hydraulic drive. I have sum drawing of a system that I found online a few years ago. I will try & post them soon. I will also b using the hydraulics for the anchor. I will also b uploading sum of my ideas soon.

My diesel engine will b driving a lay shaft thats geared up to get max output, from the lay shaft there will b a hydraulic pump, a alternator for charging the batteries. Still workin on all the logistics.

Iain 

Good day Mike Smith,

I have change the plan on this. i will dig out the drawings sometime for you ASAP in the new year.

Still hydraulic, however not oil. I have been experimenting with using sea water that gets pumped thru a hydraulic motor. The motor has a prop on it. So using a high pressure pump to pump filtered water thru a motor.

My motors one in each hull , drop out of the hull {drawings to follow} and then fold back into the hull when done.

I have found this way, there is no need to cool the oil and worry about messy oil leaks. 

All the best for the new year. & good luck with the build.

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