12V vs 24V bow thrusters

[Desolation Dan]

I am going to get a bow thruster for my 26 Monk. I see that Vetus makes both 12V and 24V thrusters. I am leaning to the 24V model but wonder if anyone here has made the choice and why? Also did you wire the thruster to an existing battery bank or install 1 or 2 up front closer to the thruster? I see lots of discussion on here about pros and cons of bow versus stern thrusters but nothing on the voltage issue. I await your comments .Thanks.

 

[O C Diver]

I went from 12 to 24 volt but on a substantially larger boat. Oops, you said 26', the Monk is 36'. I would still go 24 volt and put the batteries in that compartment. The higher voltage cuts the amperage in have. Two 12 volt batteries in series will substantially reduced voltage drop which is better for performance and the motor. If you have an inverter, it's very easy to recharge the batteries with a 6 amp battery charger.

Ted

 

[ScottC]

Definitely use a dedicated battery! Using a big house battery just doen’t cut it . Been there. Done that. Had to re-do that! I use a DC to DC charger from my house battery to the thruster battery, however. It greatly simplified the charging installation.

 

[Codger2]

I went from 12 to 24 volt but on a substantially larger boat....... The higher voltage cuts the amperage in have. Two 12 volt batteries in series will substantially reduced voltage drop which is better for performance and the motor.

I agree but I use 4-6volt AGMs mounted within 4 feet of the thruster.

 

[ScottC]

Agree about the proximity! When I re-did my installation to a dedicated & close battery, I think I must have removed 30-40 lbs of long, heavy cables.

 

[O C Diver]

Yes the goal is to have short battery cables to minimize voltage drop.



Ted

 

[markpierce]

My boat is a 24-volt boat (like its larger Seahorse Marine sisters). Also, have ancillary 12-volt and 110 AC. Bow-mounted 24-volt thruster is about 10 feet from the batteries. No problem. Have not seen the need for a dedicated battery for the thruster. Besides, the engine is normally running and generating electrical power whenever the thruster is used.

 

[Knot Fast]

OC, That's a nice, clean install. But what's that PVC thing in the middle?

Also, good to has an accessible battery switch. Thrusters do occasionally stick "on".
[I bet OC has one]

 

[Comodave]

I put a stern thruster on my 41’ President. It is a Sidepower SE100/185T which is 8 hp. It is a 12 volt unit and it works wonderfully. I have used it in 25+ mph winds and it immediately moves the stern upwind. I don’t see the need for a 24 volt unit in my application.

 

[Ka_sea_ta]

If you don't want to add dedicated batteries for a 24vdc thruster you can use oneof these...https://www.amazon.com/PARALLEL-SWITCH-DOUBLE-1119845-3603872RX/dp/B009VKJ6MI/ref=pd_sbs_263_2/140-6538615-4543824?_encoding=UTF8&pd_rd_i=B009VKJ6MI&pd_rd_r=3cc3b26a-0e57-43d6-a842-6d9284c94ede&pd_rd_w=aHSXF&pd_rd_wg=7qKL2&pf_rd_p=bdc67ba8-ab69-42ee-b8d8-8f5336b36a83&pf_rd_r=ZM8YDASVK1AXW00G622T&psc=1&refRID=ZM8YDASVK1AXW00G622T


It's basically a 24vdc starter solenoid for a 12v tractor.... it parallels the batteries when not energized for charging and general use.... when energized it series the batteries for 24v output.... It's just another way to skin the cat

 

[boatpoker]

Two 12volt starter batteries at the thruster with a series parallel switch and relay. Charging takes place at 12volts from your existing alternator and charger but switches automatically to 24volt output when the thruster is energized.

You can buy a series parallel switch from Vetus for about $1,300 or buy one at a farm supply outfit for about $100.
If uncomfortable with this kind or wiring hire a farm equipment mechanic they do this stuff all the time.

 

[ScottC]

The unit I refer to above is mounted as a stern thruster. Side Power Retractable SR80/185T 12V. Love it. And yes, do mount a local battery switch with it, as Knot Fast suggested. Once every 4-5 months, mine sticks on and I need to "re-boot" it using the battery switch.


To expand a bit on my earlier posts... When I first had this thruster hooked up to my 200Ah 12v AGM house battery, it worked fine. It didn't take many weeks, however, for me to notice that some of the helm instruments did not appreciate the sudden, fluctuation in voltage that accompanied each use of the thruster. It could have been that my house battery was approaching end-of-life anyway. Or, it could have been that attaching the thruster to it pushed it into the grave even faster. I don't know. After learning a little more about the situation, before changing to a dedicated thruster battery, I came to understand that the kind of battery one typically uses for "house" applications is different than the ideal battery type for starting your engines. The thruster creates a short, extremely heavy power demand...just like starting your engine. So, a starter battery is more appropriate for thruster use.

 

[ScottC]

Since you mentioned, specifically, bow thruster in the title of this thread, I will throw in one other comment. My boat came from the factory with a Side Power SE40 Bow Thruster AND a Quick anchor windlass. The local 12v bow thruster battery is also used by the windlass. Nothing else. This has worked well, as these two items are never used at the same time and they have somewhat similar power draw characteristics.

 

[mvweebles]

Surprised by the comments thus far. Not that I don't agree about 24v being worth the cost/complexity/effort on many boats, but this is a 26-footer. 12V is fine but don't cheap-out on the cables.

Peter

 

[O C Diver]

OC, That's a nice, clean install. But what's that PVC thing in the middle?

Also, good to has an accessible battery switch. Thrusters do occasionally stick "on".
[I bet OC has one]

The PVC thing is the oil reservoir. The original one cracked.

Ted

 

[O C Diver]

Surprised by the comments thus far. Not that I don't agree about 24v being worth the cost/complexity/effort on many boats, this is a 26-footer. 12V is fine but don't cheap-out on the cables.

Peter

Hi Peter, I thought that also, but 26 was a typo by the OP. A Monk is almost always a 36' boat, and is so indicated by the OP's information under his username.

Ted

 

[mvweebles]

Hi Peter, I thought that also, but 26 was a typo by the OP. A Monk is almost always a 36' boat, and is so indicated by the OP's information under his username.

Ted

That makes sense - your original response said as much, but I didn't catch it.

Thanks for the clarification. I'm still not sure it makes sense for the OP given the generic value of a Monk 36, it certainly makes more sense than for a 26-footer. A lot depends on his need (some boat/berth combo's really need a thruster) and current config - heavy 2/0 cables are dang expensive; but he likely already has a 12v windlass. Tough call from the bleachers except to state the obvious - starting from scratch, 24v requires a relatively small upgrade of DC-DC inverter which is more than offset by reduced cost of cables. At some point, 12v thruster is too small or cables required are too large. At some point, a hydraulic thruster makes more sense than even a 24v thruster. Etc., etc.

BTW - nice install on your thruster Ted.

Peter

 

[PM]

If you can make your installation as simple and sweet as O.C. shows, go for it.

pete

 

[Desolation Dan]

Hi Peter, I thought that also, but 26 was a typo by the OP. A Monk is almost always a 36' boat, and is so indicated by the OP's information under his username.



Ted

Yes I made a typo. The Monk is 36’. Thanks for your help. And there is an inverter running off a bank of 6 “golf cart” batteries, but they are at least 15’ away from the location of the bow thruster. That is why I am considering going to 24V with designated batteries.

 

[Ski in NC]

I went 12V on my rather light and skinny 38'. Put a dedicated grp 24 starting batt right there so cables were short. Been happy with the performance. Charging is done through 10ga leads to house bank through a 15A breaker with a relay that opens when thruster is running. System works well.

I would not want to increase the complexity in a 36' by putting a 24v system into an otherwise 12v boat. Can be done, probably get a bit better thrust, but is it worth it?? Me thinks not. Can be done with the series/parallel relay as posted above, but that is just another thing to go wrong.

 

[Scottwb96]

I have had both 12v and 24v thrusters. The 24v seems to have a very noticeable "PUSH/JUMP" when activated. Install is fairly straightforward. My boat is a 12V boat but the thruster is isolated in the bow with 2 AGM's wired to 24v. There is also a small 10a 24v charger running in the bow. Keeps all the wiring short and simple.
Hardest part for me was running the wiring for the controller up to the flybridge (THAT SUCKED)...

 

[Screaming04]

If you double the voltage, you half the required amperage for the same size thruster. Higher amperage requires bigger cables and is harder on batteries.

 

[tn6437]

installing aug 3

i am having a vetus bow75 put in my 35 ft senator trawler. i am tired of jockeying around with a single screw. planning on one battery dedicated to the thruster located within a foot or so. between now and then i have to relocate my ac unit to accomodate the thruster.
after the thruster install and ac relocated i will be painting the bottom and installing an autopilot then finally splashing her. i plan a few days making sure all systems are functioning properly after the long spell on the hard (nov til aug) then in september heading out to start the loop. plan to be at the aglca fall rendezvous in october at joe wheeler state park. hope to see some of you there.

 

[Tiffany]

I installed a Lewmar 3.5 HP thruster in my Apollo 32. Heavy cables run up from the house bank seem to work fine. I did not want the additional maintenance of another battery in a location with difficult access. The install works fine, executed by an experience electrical engineer who ensured the voltage was adequate at end of run, by Lewmar specs. Boatyard wanted $12,000, cost me $2,300 all in and professional oversight of the circuitry install and materials.

 

[tn6437]

I installed a Lewmar 3.5 HP thruster in my Apollo 32. Heavy cables run up from the house bank seem to work fine. I did not want the additional maintenance of another battery in a location with difficult access. The install works fine, executed by an experience electrical engineer who ensured the voltage was adequate at end of run, by Lewmar specs. Boatyard wanted $12,000, cost me $2,300 all in and professional oversight of the circuitry install and materials.

where did you find someone to do a bow thruster for $2300. ?? that has to be just the labor i guess, not the parts and labor ?

 

[mvweebles]

where did you find someone to do a bow thruster for $2300. ?? that has to be just the labor i guess, not the parts and labor ?

I just had a thruster installed in Mexico. $3500 labor and fiberglass materials. Nice work - everything was nicely faired-in and painted. Electrics were done as part of a separate rewiring project with a marine electrician. I'd guess in the range of $4k plus thruster/cable/switches/tunnel. Boat was already hauled.

I guess I could have done it myself for a lot less - basic install isn't hard. Making it look good is a different matter for me. Plus, if there are any problems, I have recourse.

Peter

 

[Shifty]

I went from 12 to 24 volt but on a substantially larger boat. Oops, you said 26', the Monk is 36'. I would still go 24 volt and put the batteries in that compartment. The higher voltage cuts the amperage in have. Two 12 volt batteries in series will substantially reduced voltage drop which is better for performance and the motor. If you have an inverter, it's very easy to recharge the batteries with a 6 amp battery charger.

This is how we’re set up on our 45. The stern thruster has a pair of 12V AGMs in series, and there are two more in the bow for the bow thruster and windlass. Both banks are charged by a dedicated 24v charger powered by the inverter. The only longish cable run is from the charger in the laz to the forward batteries.

 

[Tiffany]

where did you find someone to do a bow thruster for $2300. ?? that has to be just the labor i guess, not the parts and labor ?

TN6437, My apologies, I should have written $3,200. I did the tunnel cutting, fitting and fiberglassing myself and assisted the electrician running cables. It is not really as difficult a job, so much as daunting to start cutting big holes in the hull. 3 years now and all well and eliminates many in-and-out problems. A Vetis unit would have added more to the cost. Tunnel placement is critical to effective operation. A CHB close to me has a thruster set too high in the water and blows a jet into the air every time he powers it up. It's difficult to imagine how the boatyard could possibly justify an $8,000, let alone a $12,000 pricing.