Hydraulic bow Thruster, increasing power?

[Arthurc]

I have about a 30 year old naiad hydraulic Thruster that will run for days but after installing a side power stern Thruster just seems weak. When I run her at 800rpm versus the 600 idle she has tons of power however.
What are my least expensive options? Can I replace the pump or change the system in some way to run at 800rpm like output at 600rpm or is it better to try and change the propeller unit to a newer more efficient model? It seems like just increasing the pump output for a given rpm would be easy but i might be missing something. I don’t know much about hydraulic systems so guidance would be appreciated.

Arthur

 

[LaBomba]

Arthur, most hydraulic motors use a flow control valve on the inlet to them. So long as your pump puts out adequate pressure and flow, it may be as simple as opening the flow control valve a little to boost the rpm on the motor. Don’t get crazy on the speed though.

 

[twistedtree]

What do you have for gear controls? Some can be configured to give a quick and easy high idle for just this.

 

[FF]

Some folks simply use a second hyd pump on the noisemaker.

These usually run at 1200- 1500-1800 RPM, so are plenty fast for most hyd pumps.

With everything else , tank, lines , cooler in place the added pump expense is not great, maybe $200 plus some hoses.

 

[Ski in NC]

What propulsion engine and gear do you have? Most can handle shifting at a higher rpm just fine. You could just bump the throttle to 800 when using thruster.

To make any changes in the system would require going item by item and analyzing the whole system.

 

[cafesport]

In hydraulic systems hp is a function of flow and pressure. Naiad probably designed your system to go max flow at cruise rpm. Since thrusters are most effective at zero stw and rudders gain increasing control at stw > 0 you only have a couple of options 1) put another pump on your generator for docking as ff mentioned 2) change the way you handle your boat as Peter mentioned. Since you only need a thruster when you have 0 speed on, just run your engine at fast idle while maneuvering sideways. Do not even think about increasing the system pressure without consulting a hydraulic shop.

 

[jleonard]

If you open the flow to pump more oil volume, your engine will likely drop more rpm to handle that flow. You may not be able to gain anything.
My idle drops about 30 rpm when I engage my hyd thruster. Patience usually wins out but if it's really windy or lots of current I kick up the throttle a bit.

 

[sunchaser]

AC

Good suggestions have been made. In addition, be doubly sure your tach is accurate at low RPMs (photo rach). You sure don't want to think you've bumped up to 800 and it's really 1000 RPM.

BTW, a 15 or so HP electric thruster would be a nice addition. What size is the tunnel? When your vessel was made electric thruster options were not as good as today's offerings.

 

[Arthurc]

Thanks all, as far as the engine and controls is a brand new JD6068 with ZF electronic controls. I haven’t looked into the fast idle option but that’s a good idea. In terms of dropping RPM with the Thruster or pump on that’s not a big issue since it’s all electronic and holds a dead even 600 no matter what’s the load.

I’ll look into the fast idle first, unless anyone knows if that’s doable on the new JD electronic keypad/controls?

I think my tube size on the bow is 8”, but could be 10”, I’d need to measure to be sure. I’m sure the newer units are more efficient but if it’s plenty of power at 800rpm I’m hoping it’s simple versus another big project. I’m actually wondering if the flow control on the pump was changed when the new engine was put on so I asked the installer.

 

[Ski in NC]

Check with JD. On most of these electronic engine there is a high/low idle option. Some you need to purchase a pigtail and a switch to mount on the helm, and pigtail plugs in somewhere. They will know what the options are.

If using a single lever electronic shift/throttle control, as most are set up it is not convenient to bump up rpm while maneuvering.

 

[Arthurc]

Unfortunately it’s a single lever, it didn’t look like ZF had a dual lever single engine control.

 

[twistedtree]

You ZF shifter has a fast idle feature. You press and hold the button for 1/2 sec and it toggles between fast and slow idle. All you need to do is program in the fast idle value. It's an adjustable setting in the ZF control box. If you have the manual, it's in there. I think it's parameter E7 or something close to that. If you don't have the manual, send me a PM with your email address and I'll send it to you, but I found it online somewhere. I've got mine set to 800 rpm vs the normal 650 rpm idle speed. It's a nice boost.

 

[Arthurc]

Found the Manual online and looks like this is the perfect answer, I’ll have Hatton configure it later this week. It’s code E6 and all ZF controllers seem to support it.

Thanks TwistedTree!

 

[Ski in NC]

Schweeet!

 

[Comodave]

Found the Manual online and looks like this is the perfect answer, I’ll have Hatton configure it later this week. It’s code E6 and all ZF controllers seem to support it.

Thanks TwistedTree!

Gotta love TF.

 

[twistedtree]

Found the Manual online and looks like this is the perfect answer, I’ll have Hatton configure it later this week. It’s code E6 and all ZF controllers seem to support it.

Thanks TwistedTree!

It's really easy to configure yourself if you want to save on labor costs. The manual explains it.

 

[johnma]

If changing the setting on your ZF controller doesn't give you the response you need, take a photo of your hydraulic pump and post it. Some pump types such as gear and vane have no settings, however if you have a piston pump it may be pressure and flow compensated and can be adjusted to give you more flow. Before retiring last year I managed a hydraulic repair facility with dozens of US and Middle East locations and can give you detailed help.
John

 

[FF]

Many boats will use the prop to move the stern while docking.

The hassle with increased engine idle speed is the shaft will be turning faster , 20% ?? or more increasing boat speed.

The hassle with kicking in and out of gear is the faster turning shaft and prop are more mass to get spinning , then stopped and reversed, harder on the tranny.

 

[Arthurc]

If changing the setting on your ZF controller doesn't give you the response you need, take a photo of your hydraulic pump and post it. Some pump types such as gear and vane have no settings, however if you have a piston pump it may be pressure and flow compensated and can be adjusted to give you more flow. Before retiring last year I managed a hydraulic repair facility with dozens of US and Middle East locations and can give you detailed help.
John

Here is the pump, I didn’t see anything to adjust on it.

 

[TomandJeri]

It's probably just a gear pump, which is fixed displacement. I don't see any reason they'd have used anything more sophisticated for something like a bow thruster.

 

[BeeJay]

If the hydraulic pump is belt driven maybe you could change the pulley ratio so that the pump revolutions are the same as your 800 rpm engine rpm at your preferred 600 rpm idle speed.

 

[Arthurc]

It’s mounted right off the engine flywheel with an electronic clutch so I think I’ll have to first see if 800 works for windy docking then perhaps upgrade the pump if needed.

 

[TomandJeri]

Check the lines to see if there's a flow control in there somewhere, including in a directional valve manifold. It's possible one was installed to limit the motor speed by diverting some portion of flow to the return (assuming open loop) if operated at a higher pump speed than intended. Assuming the directional valve is solenoid operated, that's one place where one could be incorporated easily, along with a relief valve. If there is such a flow control, a larger pump won't do much good if it spills the excess to tank unless you increase the setting, which may overspeed the motor. Lotta 'ifs'.

 

[Arthurc]

Ill take a look, I traced the lines a while ago and they are pretty simple:
Tank to pump
Pump to solenoid pack (out to motor)
Return to tank via filter located right before the tank.

 

[TomandJeri]

Pump to solenoid pack (out to motor)

I would expect to find, at the very least, a relief valve in that manifold. Possibly a flow control, too, as it's super easy to incorporate all that into a small manifold, especially since the return also passes through that manifold. Look for one or two allen keyed or slotted screws with locknuts. Though it's also possible the relief, if it's there (and it should be), is not adjustable, in which case it might just look like a hex plug.

 

[johnma]

This is a Commercial Intertech gear pump. (now Parker Hannifin) there are no adjustments on the pump. You said the pressure line goes to a manifold with a solenoid valve. Can you post a photo of the manifold? it is possible there is a flow control in the manifold. Also, how is the pump being driven? Belts and pulleys?
This pump has a 2.25" wide gear inside. the largest gear available in this frame size pump is 2.5". Even upgrading to that gear is not going to give you what you need as it would only give you an additional 12-13% of speed not the 30% your trying to get. If your drive is belt and pulleys you can increase the pulley to give you 30% more speed to the pump. Let me know the pulley diameter on the pump and the drive.
The other option is changing the frame size of pump. You could take your pump to Hydraulic Repair and Design in Kent WA, And tell them you need a pump with 30% more capacity and with the same mounting, shaft and ports. Also, you will need to tell them what rotation your pump is turning as it is a bi-rotational pump. The easiest way to do this is mark your ports as to which on goes to the tank and which goes to the valve. Also let them know how much space you have all around the pump so that they don't build you a pump that is too large physically to fit in your available space. The next frame size up from your P50 pump is the P75 and its a lot larger physically.
good luck,
John

 

[FF]

You might also want to look for a fitting or valve that is undersized , reducing the flow.


Sometimes folks will "fix it" with what is on hand not what is correct.

 

[cafesport]

Arthur, it looks like an old working hydraulic system migrated to a new engine and now seems to no longer work. Any other changes made? Was this pump spec’d by naiad to also run a bow thruster, perhaps an hydraulic windlass as well? If so what rpm gives max flow? You probably just need to increase your engine rpm to use these devices, pretty simple really because you won’t be using propulsion when hauling an anchor or moving your boat side ways. FWIW our pump maxes out around 1800 rpm. I’ve only needed that kind of flow for the thruster a few times. For the windlass I like at least 1200 because it makes the rode retrieval much faster. You should be able to achieve this with your controls by holding the “take command button” and advancing the lever out of the neutral detent to any rpm you choose.

 

[Arthurc]

This is a Commercial Intertech gear pump. (now Parker Hannifin) there are no adjustments on the pump. You said the pressure line goes to a manifold with a solenoid valve. Can you post a photo of the manifold? it is possible there is a flow control in the manifold. Also, how is the pump being driven? Belts and pulleys?
This pump has a 2.25" wide gear inside. the largest gear available in this frame size pump is 2.5". Even upgrading to that gear is not going to give you what you need as it would only give you an additional 12-13% of speed not the 30% your trying to get. If your drive is belt and pulleys you can increase the pulley to give you 30% more speed to the pump. Let me know the pulley diameter on the pump and the drive.
The other option is changing the frame size of pump. You could take your pump to Hydraulic Repair and Design in Kent WA, And tell them you need a pump with 30% more capacity and with the same mounting, shaft and ports. Also, you will need to tell them what rotation your pump is turning as it is a bi-rotational pump. The easiest way to do this is mark your ports as to which on goes to the tank and which goes to the valve. Also let them know how much space you have all around the pump so that they don't build you a pump that is too large physically to fit in your available space. The next frame size up from your P50 pump is the P75 and its a lot larger physically.
good luck,
John

Thanks for the details! I’ll post a picture of the solenoids/controls next time I’m at the boat. I’m actually wondering if 13% more would be enough as I now have my rpm bumped up to 775 at high idle and an extra 75 would put me in the 850 range where I really noticed the boost in power. At 600 she is fine on a normal day but in a really strong x wind I don’t know if she would have the power to overcome my large bow/windage...
Pump is on a brand new JD engine, direct mounted via a electronic clutch so no way to change the drive ratio.

 

[twistedtree]

Are the clutch and PTO on the transmission, or on the engine? I'm guessing it's on the transmission?