My #1 Gen is a 21.5KW Onan that powers bow thruster via power take off on front of gen. Near the back end of the generator, mounted on a bulkhead is a large (approx 2’x2’) electrical box labeled
“Bow Thruster Gen Unloading Contactor”. Can someone explain the function of the contactor?
Welcome to the Hatteras Owners Forum & Gallery. Sign Up or Login
+ Reply to Thread
Results 1 to 10 of 11
Thread: Hydraulic Bow Thruster question
-
06-05-2022 05:31 PM #1Senior Member
- Join Date
- Jan 2009
- Posts
- 367
Hydraulic Bow Thruster question
Last edited by GCSI; 06-05-2022 at 07:29 PM.
-
06-06-2022 04:21 AM #2
Re: Hydraulic Bow Thruster question
The bow thruster is powered by hydraulic fluid being pushed in circulation by the genset's PTO. The circulation of the fluid from and to the PTO is always the same direction.
Its likely that the contactor is actually a solenoid control that operates a reversing valve located within a manifold nearby and directs the the flow of fluid depending if you wish to go to port or starboard when the dashboard toggle switch is moved/pressed. Regardless of the switch position the flow of oil from and back to the PTO remains the same direction.+++
1984 61MY #353 with 9' cockpit extension.
Sydney, Australia.
-
Re: Hydraulic Bow Thruster question
If it is truly related to unloading, it could kick the pump out of the loop to prevent stalling the genny, or, perhaps it drives a clutch between the pump and genny (my favorite guess). Do you have to "arm" the thruster by flipping on a master switch? Maybe the joystick drives the clutch regardless of the desired direction. It might be obvious if the genny is off, and the thruster joystick causes the solenoid to actuate but that may be inhibited with the genny off.
Regards
Dan
-
Re: Hydraulic Bow Thruster question
2’ x 2’ sounds big for just a contactor…
What brand thruster is it? You don’t have the manuals and diagrams on board?
We have an ABT Trac system on the boat i run. The hydraulic system is powered by a pump on each engine and the starboard gen via a PTO. The 48kw gen will struggle for a couple of seconds when the PTO is engaged if the hydraulic system is activated.
In your case this maybe a circuit to disengage the PTO of gen freq and/or voltage drops below a set value
A hydraulic thruster uses quite a bit of power, I m even surprised it is driven by the gen and not by the mains. Our thruster is obviously pretty big on a 116 but so is the cummins 4BT driving the gen and that’s not enough to run the thruster. The PTO is only used for the zero speed stabs and the windlasses.
Call the thruster manufacturer if you don’t have the diagrams.Pascal
Miami, FL
1970 53 MY #325 Cummins 6CTAs
2014 26' gaff rigged sloop
2007 Sandbarhopper 13
12' Westphal Cat boat
-
06-06-2022 10:56 AM #5Senior Member
- Join Date
- Jan 2009
- Posts
- 367
Re: Hydraulic Bow Thruster question
-
06-06-2022 11:06 AM #6Senior Member
- Join Date
- Jan 2009
- Posts
- 367
Re: Hydraulic Bow Thruster question
The box is 2x2, contactor is within box. ABT System. Normally, thruster will stall the engine if generator has any electrical load.
Consequently, I’ll run house load on Gen 2 and thruster on #1 if thruster is needed. Seems kinda Mickey Mouse that thruster can kill
Gen if Gen has any load. Was thinking function of contactor would be to shed e load while thruster is used and the contactor is wonky.
Plan on calling ABT and will report back.
-
Re: Hydraulic Bow Thruster question
ABT track customer service is very good with phone support. Here in SoFl I used Advantage Marine Service in FTL. He really knows these system.
I don’t understand why they didn’t just put hydraulic pumps on the mains. It must be a pita to have to run both gens when maneuveringPascal
Miami, FL
1970 53 MY #325 Cummins 6CTAs
2014 26' gaff rigged sloop
2007 Sandbarhopper 13
12' Westphal Cat boat
-
06-06-2022 01:49 PM #8Senior Member
- Join Date
- Jun 2012
- Posts
- 520
Re: Hydraulic Bow Thruster question
I would like to install hydraulic pumps for a bow thruster but I don’t have a PTO pad on my transmissions . The only place on a 12V-71 is on the nose of the crankshaft and that would kill accessibility not to mention being expensive to install. As I have two generators , I thought about that installation, but even 20KW doesn’t have that much power at 1800 rpm . A 48 volt Westmar is my next choice.(25 HP)
JMooney
61 MY 1983 #341
“Jerrie”
Miami , FL
-
Re: Hydraulic Bow Thruster question
12V71TA does not offer much with the second cam PTO used for the alternator.
The 12V71TI second cam PTO should be available on the engine not driving the stabilizers pump.
On our partners Hatt, the 48V Westmar works great.
-
06-06-2022 02:10 PM #10Senior Member
- Join Date
- Jun 2012
- Posts
- 520