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Old 05-14-2018, 11:15 PM   #1
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Hydraulic bow Thruster, increasing power?

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
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Old 05-15-2018, 04:56 AM   #2
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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. Donít get crazy on the speed though.
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Old 05-15-2018, 05:20 AM   #3
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What do you have for gear controls? Some can be configured to give a quick and easy high idle for just this.
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Old 05-15-2018, 06:02 AM   #4
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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.
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Old 05-15-2018, 07:15 AM   #5
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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.
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Old 05-15-2018, 07:22 AM   #6
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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.
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Old 05-15-2018, 07:25 AM   #7
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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.
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Old 05-15-2018, 07:39 AM   #8
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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.
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Old 05-15-2018, 07:49 AM   #9
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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.
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Old 05-15-2018, 10:38 AM   #10
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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.
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Old 05-15-2018, 11:30 AM   #11
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Unfortunately itís a single lever, it didnít look like ZF had a dual lever single engine control.
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Old 05-16-2018, 05:02 AM   #12
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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.
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Old 05-16-2018, 09:43 AM   #13
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Found the Manual online and looks like this is the perfect answer, Iíll have Hatton configure it later this week. Itís code E6 and all ZF controllers seem to support it.

Thanks TwistedTree!
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Old 05-16-2018, 09:46 AM   #14
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Schweeet!
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Old 05-16-2018, 11:05 AM   #15
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Quote:
Originally Posted by Arthurc View Post
Found the Manual online and looks like this is the perfect answer, Iíll have Hatton configure it later this week. Itís code E6 and all ZF controllers seem to support it.

Thanks TwistedTree!
Gotta love TF.
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Old 05-16-2018, 06:07 PM   #16
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Found the Manual online and looks like this is the perfect answer, Iíll have Hatton configure it later this week. Itís 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.
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Old 05-16-2018, 06:25 PM   #17
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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.
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Old 05-17-2018, 05:48 AM   #18
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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.
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Old 05-20-2018, 01:41 PM   #19
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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 didnít see anything to adjust on it.
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Old 05-20-2018, 02:03 PM   #20
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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.
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