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Old 10-23-2021, 07:07 AM   #1
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Bow Thruster

We are considering adding a Bow Thruster to our single screw GB 36. Is a pretty much standard 12 volt / 120 volt 30 amp boat. Any thoughts on 12 volt vs 24 volt thruster? Batteries and thruster will be self contained in the bow. So will make for short cable runs.

Also wondering about charging off 100 amp Balmar with an ACR vs dedicated 120 volt battery charger.

Thoughts are appreciated
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Old 10-23-2021, 07:57 AM   #2
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I would go 24 volt. Half the amperage for the same thrust. Lower voltage drop because of less amperage means the motor runs more efficiently and generates less heat.

I prefer the dedicated battery charger if you run a pure sine wave inverter or the generator while underway.

Ted
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Old 10-23-2021, 07:57 AM   #3
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My preference is 12v volt for simplicity. I installed a AGM 12v 2’ from the thruster. It is all stand alone. I added a 10 dedicated amp charger . It is completely isolated from any other system. It moves my 13,k boat with ease. I added a guest battery switch to make for a mechanical disconnect should anything happen.
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Old 10-23-2021, 10:58 AM   #4
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Our NT 37 has a bow bank (two g31 Deka AGM's in parallel for 12V, for both windlass and bow thruster) just a few feet of 2/0 cable from the thruster. Charged by a Blue Seas ACR from the house bank. Simple, works like a charm, and runs the thruster for many seconds with no problem.
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Old 10-23-2021, 12:04 PM   #5
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Quote:
Originally Posted by Arc View Post
My preference is 12v volt for simplicity. I installed a AGM 12v 2í from the thruster. It is all stand alone. I added a 10 dedicated amp charger . It is completely isolated from any other system. It moves my 13,k boat with ease. I added a guest battery switch to make for a mechanical disconnect should anything happen.

Aside from needing more batteries to make 24V, what would make a 12V version -- as in your installation, and OP's similar bow location -- simpler than a 24V version of the same?

-Chris
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Old 10-23-2021, 02:30 PM   #6
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I am installing a somewhat over sized thruster. The people that I am purchasing it from seem to think that 24 volts is the correct application for that particular thruster. Pricing is the same other then a minimum of 2 batteries for 24 volts. Also a dedicated charger seems best.

Thanks for everyone’s input. .
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Old 10-23-2021, 02:37 PM   #7
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I am putting both bow and stern thrusters on our ďnewĒ boat. They are both 24 volt. The only problem is that I couldnít find any 24 volt Promariner chargers so I had to buy Mastervolt. Our boat was at the top end for 12 volt thrusters and near the bottom end for 24 volt thrusters. The difference in cost was $1000 for both and 2 batteries. To me that was a no brainer to go with the larger thrusters.
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Old 10-23-2021, 05:32 PM   #8
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10000% go 24v. To simplify, just put a small charger dedicated for those batteries up in the bow. Run it through your regular AC. A LOT less cable/config to worry about... But whatever you do, 24v all the way!!!
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Old 10-23-2021, 05:36 PM   #9
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Yes, I am putting in 2 24 volt 20 amp chargers, one for bow and one for stern. Much easier than trying to run heavy cables forward.
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Old 10-23-2021, 05:46 PM   #10
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Comodave- YEP! So much easier and efficient!
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Old 10-23-2021, 06:15 PM   #11
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Just make sure that you secure the batteries in the bow really well. I am putting in 2 AGMs and bought some Atwood battery trays. I am using them but am not really impressed with them. The batteries slide back and forth 3/4Ē which is technically ok by ABYC standards but I donít want them moving at all so I cut a piece of Starboard to shim the tray so the batteries donít move at all. Also the top that holds the batteries down is flimsy so I added a piece of Starboard across the top to hold the batteries down. And I will be through bolting the trays instead of just screwing them down.
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Old 10-23-2021, 07:40 PM   #12
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Just make sure that you secure the batteries in the bow really well. I am putting in 2 AGMs and bought some Atwood battery trays. I am using them but am not really impressed with them. The batteries slide back and forth 3/4” which is technically ok by ABYC standards but I don’t want them moving at all so I cut a piece of Starboard to shim the tray so the batteries don’t move at all. Also the top that holds the batteries down is flimsy so I added a piece of Starboard across the top to hold the batteries down. And I will be through bolting the trays instead of just screwing them down.
NICE! Those def aren't moving! Mine are also through-bolted. I used foam from gym floor mats on my outside edges. Piece of duct tape on one side makes sure they dont move and I can use a smaller piece 2"x2" square. Keeps them secure but also doesn't "insulate" them and keeps a buffer of air around the batteries. Also keeps the batteries from having any sort of "abrasion point" since they will def. get some motion in the bow from waves, but also micro-vibration...
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Old 10-27-2021, 06:05 AM   #13
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Just be sure to read the use booklet before buying a thruster.

Many are very very limited in terms of operating time ( in seconds) vs cooling time.
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Old 10-27-2021, 06:34 AM   #14
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While I understand the reflex to recommend 24v, much depends on geometry- bear in mind,, this is a 36 foot boat. For my Willard 36, I went the 2x12v AGM parallel (12v) route. Distance from forward batteries to thruster is under 5-feet. Also powers existing 12v windlass. My house bank is LiFePO4 so have a DC-DC charger for the AGM banks. While I have a generator, it is used only occasionally. Powering a 120vac charger would be problematic. While going 24v reduces cable complexity for the thruster, keeping 12v for the windlass cables increases length and complexity there. For a new build, would go 24v both windlass and thruster.

And let's not forget that the GB36 is a pretty mannerly boat. I would not expect it to require excessive amounts of thrust.

Regardless good luck with the install. I happen to like thrusters. Anything that makes a boat easier to use is good value.

Peter
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Old 10-27-2021, 07:41 AM   #15
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Quote:
Originally Posted by ranger42c View Post
Aside from needing more batteries to make 24V, what would make a 12V version -- as in your installation, and OP's similar bow location -- simpler than a 24V version of the same?



-Chris
I would think charging is the biggest consideration for simplicity. AC chargers are one thing but what about when you are cruising away from dock and don't want to run gennie to get back to 100% charge.
DC to DC charger may be the simplest as how ever you charge house or start it then takes care of the thruster.
Just remember that AGM need to be brought back to 100% SOC at least periodically (several days to week).
Cable size a Neg w 12V but with short runs not a big deal.
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Old 10-27-2021, 08:01 AM   #16
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Quote:
Originally Posted by Arc View Post
My preference is 12v volt for simplicity. I installed a AGM 12v 2í from the thruster. It is all stand alone. I added a 10 dedicated amp charger . It is completely isolated from any other system. It moves my 13,k boat with ease. I added a guest battery switch to make for a mechanical disconnect should anything happen.
Quote:
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Aside from needing more batteries to make 24V, what would make a 12V version -- as in your installation, and OP's similar bow location -- simpler than a 24V version of the same?
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I would think charging is the biggest consideration for simplicity. AC chargers are one thing but what about when you are cruising away from dock and don't want to run gennie to get back to 100% charge.
DC to DC charger may be the simplest as how ever you charge house or start it then takes care of the thruster.
Just remember that AGM need to be brought back to 100% SOC at least periodically (several days to week).
Cable size a Neg w 12V but with short runs not a big deal.

Arc said his is an isolated system, with it's own nearby battery and charger... and his preference for "12 volt for simplicity." Sounds like a good set-up, but...

I just wondered what would make 12V simpler than 24V in a similar isolated system -- own battery bank, own charger -- aside from having to add battery to get to 24V.

-Chris
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Old 10-27-2021, 09:08 AM   #17
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Originally Posted by O C Diver View Post
I would go 24 volt. Half the amperage for the same thrust. Lower voltage drop because of less amperage means the motor runs more efficiently and generates less heat.

I prefer the dedicated battery charger if you run a pure sine wave inverter or the generator while underway.

Ted
Thumbs up. Having run a GB36 extensively, I wholeheartedly agree with adding a BT. 24V for the isolated system you propose would be good because the GB is not a light boat, and 24V would drive a smallish BT harder than 12V power. Do you foresee any need to charge the 24V system underway? I would think not.
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Old 10-27-2021, 09:12 AM   #18
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Originally Posted by ranger42c View Post
Arc said his is an isolated system, with it's own nearby battery and charger... and his preference for "12 volt for simplicity." Sounds like a good set-up, but...



I just wondered what would make 12V simpler than 24V in a similar isolated system -- own battery bank, own charger -- aside from having to add battery to get to 24V.



-Chris
Wasn't clear if only recharges at the dock or when gen runs. I am glad I charge mine while underway using a charge relay... easy w 12V requires another charger (DC TO DC) if 24V
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Old 10-27-2021, 09:58 AM   #19
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Thumbs up. Having run a GB36 extensively, I wholeheartedly agree with adding a BT. 24V for the isolated system you propose would be good because the GB is not a light boat, and 24V would drive a smallish BT harder than 12V power. Do you foresee any need to charge the 24V system underway? I would think not.
IMO, it's too easy to have recharging underway, not to do it. Performance is always better with maximum voltage (fully charged battery).

Ted
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Old 10-27-2021, 11:07 AM   #20
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Our last boat had a stern thruster and we only charged the battery when we were on shore power or had the generator running. We never had any issues with the battery being discharged. You only run the thruster for brief times.
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