12 volt hydraulic pump

[mirabriani]

My yacht has a manually operated hydraulic keel, weight about 1000 lb
I have sourced an electrically powered pump, details are:-
12 volt 1.6 kw motor and solenoid
0.8cc/rev pump
suitable for 2.5 lpm @ 140 bar
3 litre reservoir
I am told 1.6 kw is quite a load and I will need heavy cable ie car starter?
Would I be wise to fit a dedicated battery as close as possible?
It would seem to be wise to keep a manual pump, could I fit a tee with taps?
Finally, should the fluid be thin ie brake fluid or thick auto tranmission fluid?
I do not want to risk £300 plus before some research.
Many thanks for any thoughts
Briani

<hr width=100% size=1>

 

[William_H]

Hello Briani many of the larger outboards have a 12 volt hydraulic pump which I would think would be ideal for your job. Try an O/B wrecker. 1.3 kw is 100 amps which does need a stout cable however it is not as much as a starter motor (about 400 amps) The current drawn by the pump motor would depend on the load and 1.3 kw would be at max load and I would guess at actual in operation current about 50 amps. This depends of course on the size of your ram at the keel. A larger diameter ram woyuld move more slowly but with more force while a smaller diameter ram will try to move the keel faster but require much more hydraulic pressure (hence more motor current). The thing works just like pulleypurchase on a tackle in the same way the ratio of area of the rams. It is not so easy to relate to the rotating pump as it is with a stroke pump. I would expect as starter that you would decide the time you want the keel to lift in from the pump supply rate and the ram stroke needed you could come up with a ram diameter.That would be starting point for experiment. Some keels are lifted by a wire rope in a pulley arrangement so that the keel moves twice as far as the ram. So twice as much force needed. This is done to accomadate vertically lifting keels inside the cabin. If yours is a swing keel then a lot less power will be needed.
Goodluck I admire someone willing to try these things. No I don't think you should have another battery and yes you could have a manual pump with shutoff valves. will

<hr width=100% size=1>

 

[Avocet]

Can you contact the yacht manufacturer and get a spec. sheet for the manual pump? It will probably tell you how many CCs per stroke of the handle. You can then count the number of strokes to fully raise the keel and that will give you a better idea of how long the electric one will take to do the job. The alternative is to get the effective area of the existing ram (which will be different depending onwhether it pulls or pushes) and multiply this by the stroke. That will give you the volume of fluid needed to raise the keel. If the electric pump shoves out 0.8cc/rev, you can then work out how many revs you'll need to fill the cylinder and thus get an idea of how fast it will do the job.

If the keel weighs half a ton and moves (say) 3 feet, then 1.6kW should (theoretically) take less than 4 seconds to move it that didtance (assuming no inefficiency in the system!!!!) in reality, I'm sure there will be various losses and inefficiencies so you could maybe double that as a very rough guess but even so, you might be able to get a less powerful unit to do the job.

<hr width=100% size=1>

 

[snowleopard]

going on from that, if you know the capacity of the ram, you can work out how long it will take the pump to move the piston the length of the stroke. then if you know how far the weight of the keel rises during the stroke you can calculate the work done. if that is less than half the power of the pump, it should be up to the job.

my electric windlass is 1000w and it trips an 80A breaker if it's overloaded. the wiring is car starter cable which is more than adequate.

<hr width=100% size=1>

 

[RMA]

I fitted an electric pump to my Southerly two years ago. The keel on that weighs about 1 ton, and it took a good 5 minutes to raise it with the manual system. I went to a local firm of hydraulics engineers, told them what I wanted and they sold me a pump. They told me it was the type fitted to Transit sized tipper trucks. It was supplied with a waterproof switch unit on a length of cable, so it can be used in the cockpit. It works fine.

You will need heavy duty cable. I bought cable from a firm of auto electricians, its not quite as big as battery cable but very nearly (you will have gained some idea of my technical expertise by now). I connected them to my existing battery bank (three 100 amp/hour heavy duties).

I felt it was important to keep the manual pump. The lines from the power pump were teed into the original lines, but I fitted valves to shut off the lines between the tees and the manual pump – I was concerned that the pressure from the power pump would simply blow the old pump up.

At first the power pump let the keel down far too quickly, to the extent that I really thought something would break, so I had to buy an adjustable pressure switch.

The whole lot cost me about £600. It was worth every penny. My boat is in Essex – you are welcome to come and have a look.


<hr width=100% size=1>

 

[mirabriani]

Thank you for the replies. Sorry for the delay, I was unable to log on yesterday.
The information is very helpful, although I am a little worried about earning admiration (I thought it would be easy)
As a result of this post some one has offered me a pump surplus to his requirements, which may be suitable.

Regards Briani

<hr width=100% size=1>