Bow Thruster

[DeepFrz]

There is more than just price. Electric thrusters can be limited in the amount of time they can be used before they overheat.

Also the cost of the cable to the bow of the boat can be very expensive, or extra batteries and a charger near the bow, so may not be that much difference in cost.

[DSDman]

I do like the reliability of the hydraulic so if I can get the price point in the ball park I will probably go that route. then at some point in the future when the windlass goes I can replace it with a hydraulic one. The location of the thruster in the floor of the sail locker tends to make me think that an electric motor down there wouldn't last very long. but I will precede with step one and see where I get.

[David M]

Another factor of whether it is hydraulic or electric depends on the size of the vessel. You get to a point where it is too big and requires so much horsepower that it is not practical to use an electric motor.

[DSDman]

I've gotten reliable information that the thruster and motor are in good condition. Does anyone here know what spec I would need in a hydraulic pump? I can only guess at the pump characteristics. based on the tunnel diameter 9 7/8. I would assume the thruster provides about 350 lbs thrust and operates at 3000 psi turning around 2000 rpm. anyone with something close to this care to share pump specs? since I don't really know can I get a bigger pump and dial it down if required?

[Sailmonkey]

vetus has their specs online for hyd thrusters

Vetus Hydraulic Bow Thruster 1215 Lb Including Hydro Motor, 33Kw (44 HP), 550HM

you could use these as a starting point.

[DSDman]

Unfortunately they just talk about the motor not the pump. They say if you buy the motor you will get an appropriately sized pump. But then says nothing about the actual pump. It's like a big secret, I guess they don't want me to do exactly what I'm doing.

[mrm]

Originally Posted by DSDman

I've gotten reliable information that the thruster and motor are in good condition. Does anyone here know what spec I would need in a hydraulic pump? I can only guess at the pump characteristics. based on the tunnel diameter 9 7/8. I would assume the thruster provides about 350 lbs thrust and operates at 3000 psi turning around 2000 rpm. anyone with something close to this care to share pump specs? since I don't really know can I get a bigger pump and dial it down if required?

I think there is one parameter still missing. Try to find out what volume of fluid needs to go through the motor for each rotation. This will give you a required flow per minute. Together with other data you know it should be enough to specify a pump. A disclaimer though, my understanding of hydraulic circuits is basic, hopefully some pro will chime in..

[Sailmonkey]

MRM has nailed it.

If you can dig some more specs off of the motor, the pump matching will be easier. Otherwise.....the possibilities are endless

s.p.h.p. hydraulic products

[DSDman]

I wish there were some dang numbers on the pump...there is not. I was hoping someone on here might have had a lamborgini pump in the past or know someone who had. Talking with a couple of guys who know something about hydraulics and they say to buy a bigger pump that is variable and I can turn the flow rate and pressure up or down to maximize the motor and prop efficiency. To fast and the prop cavitates to slow and not enough thrust.

[DSDman]

My best guess is .42 CU Inch per rotation.

[stillbuilding]

To make your calculations for pump size you need pressure required (BAR) and flow rate (LPM) then standard tables will give you motor size required or the following equations may help (allow 10 - 20% efficiency loss)

KW = (BAR x LPM)/600 = (BAR x CC/Rev)/(600 x 1000) = (NM x RPM)/9550

RPM = (KW x 9550)/NM

Pump displacement CC/REV = (KW x 600 x 1000)/(BAR x RPM)

BAR = (KW x 600)/LPM

There a standard tables for oil flow capacity of hose and tubing.Hit Google.

[stillbuilding]

Hydraulic vs electric bowthruster is an age-old discussion. If you are set up for it or can do so in a 60' boat then hydraulic will go the distance better. Smaller boats, less space, short keels then maybe electric. Sleipner reckon electric is easier and cheaper but 60' is a lot of boat to push for more than a minute. I notice a review of the Beneteau Sense 55 (short keel of course) in the latest Yachting World;

"We came into a windy marina on a Sense 55 and I had the confidence to hold the boat off and go alongside a new powerboat three times. Perfect - until it beeped and shut down! Over-use of the bow thruster swamping battery demand was the problem."

Now, I don't know about you but this would worry me (and maybe cost a me a bucket of powerboat repair as well). Does anyone really think a fishing boat would find this acceptable? Horses for courses - get hydraulic for a 60' boat.

[DSDman]

I agree I was up in the air on it until I found out that the hydraulic motor and drive unit checks out good. Since I have those installed already I'm going hydraulic. Having looked around a bit online at various hydraulic sites and checking the prices I can't figure out why marine hydraulic pumps are so much more expensive than normal pumps. Anyone know of any good marine salvage yards that might have this stuff?

[DSDman]

This is where the pump is supposed to mount, I think....

[carstenb]

Do yourself a favor. Call a local Parker distributor have him send a salesman out (no charge at this stage) Let him size the pump/valve/hoses and quote it. Then you'll know. Lamborgini is a very large italian company and i'm sure they have representation in the states. but you will also need to consider doing a motor rebuild. if the seals in the motor have dried out they will need to be changed. you'll also need a hydraulic reservoir - the parker guy can help you determine size etc.