Thrusters vs twins

FF said:

usually thrusters that are overheating are because of..


.Someone read Da Book and is using the TIME limits the unit mfg suggests?

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That is a good point, FF. Just like my manual on my engines say you can run at WOT for 1 hour out of every 8. It doesn't mean I am gonna jack up the throttle every eighth hour just because the manual says I can....

Arch said:

I have a single and a Vetus 12 volt stern thruster. Manual indicates I can get 2 minutes of use per hour.

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Good point! My thruster (SidePower) manual states continuous operation should not exceed 3 minutes. Do you realize just how long that is? In 7 years of using my thruster, I have never had it quit due to excessive heat. Heavy usage for me is 15 seconds!

I was reading an owner's manual for a MAN 1200 HP V-12 diesel and the manufacturer suggested this was a good engine to use for a bow thruster. Yes there would not be a concern for overheating an electric bow thruster if you had room for one of these....
Most of us might remember reading an owners manual for a car or truck. It is usually suggested that if the engine does not start right away if you are doing extended cranking, to let the starter cool off before trying again.
Most thruster motors are simply starter motors for big diesels. Some thrusters have a fan built in to help dissipate heat but most do not so a light touch with short bursts will help to make sure it will not overheat when you need it.
I love this bow thruster below, I think this picture came from some one on this forum in the past.

Fighting that same concern, with a electric bow thruster, even using it in short burst, I have on two occasions tripped by circuit breaker. having twins and pretty big wheels we don't use it often, but it is nice to have it for insurance. If I was paying the ticket for a new one I too would go Hydraulic but like most things it came with the boat, so I was thrilled.

I've checked the connections and they are all clean, the breaker is correctly sized according the manufactures specs, so not sure what we are doing wrong. We try to use in it only in short burst less then 5 sec, but usually by the 3rd burst, you can count on resetting the breaker....which is of course down three sets of stairs by the thruster.

Suggestions ?

Dswizzler said:

Fighting that same concern, with a electric bow thruster, even using it in short burst, I have on two occasions tripped by circuit breaker. having twins and pretty big wheels we don't use it often, but it is nice to have it for insurance. If I was paying the ticket for a new one I too would go Hydraulic but like most things it came with the boat, so I was thrilled.

I've checked the connections and they are all clean, the breaker is correctly sized according the manufactures specs, so not sure what we are doing wrong. We try to use in it only in short burst less then 5 sec, but usually by the 3rd burst, you can count on resetting the breaker....which is of course down three sets of stairs by the thruster.

Suggestions ?

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I'm thinking that while the breaker is sized correctly as per manual, the wiring between the breaker and thruster may be to small a gauge which is causing them to heat up which is leading to breaker trip...next time you use the thruster feel the wires to see if they feel inordinately hot...

Hi Tom Isee you have a stern thruster, WOW we are considering installing one. Where does the hydraulic come from? Is there a PTO off of the Transmission?

Irdiverdan said:

I'm thinking the while the breaker is sized correctly as per manual, the wiring between the breaker and thruster may be to small a gauge which is causing them to heat up which is leading to breaker trip...next time you use the thruster feel the wires to see if they feel inordinately hot...

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If the thruster is a starter motor for a diesel, the cable size should be considerably large especially if the run from it and the battery is a long distance. Possibly even using welding cable.

Nothing will kill an electric motor like voltage and amp loss.

Tom B , can you contact me about the stern thruster we ahve basically the same boat im a 35 SENATOR

beachbum29 said:

the cable size should be considerably large especially if the run from it and the battery is a long distance.
Nothing will kill an electric motor like voltage and amp loss.

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My dock mates thruster was doing the same thing. He solved it by installing a dedicated 4D flooded battery within a couple of feet of the thruster and eliminating the 12' battery cable run. His biggest issue was venting the battery gases. Problem solved.

RickB said:

Because little boats typically use a DC series wound starter motor that produces a great deal of power from a small package with no provision for cooling.

Your cruise ship has 3 bow thrusters, they are variable speed AC powered and are air/water cooled and are rated for continuous operation. They cost more than your bow thruster.

Note the two gray pipes attached to the header on the right side of the photo. The motor housing contains fans that circulate cooling air across the fins of that water cooled heat exchanger.

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Thanks RickB for the info & photos. I'd always assumed - based on what is often touted as the best solution for recreational boats - that the large ship thrusters would have been hydraulic.

Dswizzler said:

Fighting that same concern, with a electric bow thruster, even using it in short burst, I have on two occasions tripped by circuit breaker. having twins and pretty big wheels we don't use it often, but it is nice to have it for insurance. If I was paying the ticket for a new one I too would go Hydraulic but like most things it came with the boat, so I was thrilled.

I've checked the connections and they are all clean, the breaker is correctly sized according the manufactures specs, so not sure what we are doing wrong. We try to use in it only in short burst less then 5 sec, but usually by the 3rd burst, you can count on resetting the breaker....which is of course down three sets of stairs by the thruster.

Suggestions ?

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That does sound like it could be a wiring problem. Ours uses 2 AWG wire, which is pretty darn thick. Contact the manufacturer and check your wiring.

Dswizzler said:

Fighting that same concern, with a electric bow thruster, even using it in short burst, I have on two occasions tripped by circuit breaker. having twins and pretty big wheels we don't use it often, but it is nice to have it for insurance. If I was paying the ticket for a new one I too would go Hydraulic but like most things it came with the boat, so I was thrilled.

I've checked the connections and they are all clean, the breaker is correctly sized according the manufactures specs, so not sure what we are doing wrong. We try to use in it only in short burst less then 5 sec, but usually by the 3rd burst, you can count on resetting the breaker....which is of course down three sets of stairs by the thruster.

Suggestions ?

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I would suggest checking the thruster mechanism for a bad bearing, anything fouling the blades, or proper lubrication. Amp draw can go way up if there is any drag on its operation.

Tucker, photo of interesting bow thruster, via Rick B.

Edelweiss said:

My dock mates thruster was doing the same thing. He solved it by installing a dedicated 4D flooded battery within a couple of feet of the thruster and eliminating the 12' battery cable run. His biggest issue was venting the battery gases. Problem solved.

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Am I understanding that the thruster is connected directly to the battery...if so battery gases may be the least of his worries......as Bluto mentions below...

Bluto said:

I would suggest checking the thruster mechanism for a bad bearing, anything fouling the blades, or proper lubrication. Amp draw can go way up if there is any drag on its operation.

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If the amp draw gets really high with no protection, I'm thinking fire is a concern...

Come on. Each circuit needs protection.

Irdiverdan said:

Am I understanding that the thruster is connected directly to the battery...if so battery gase may be the least of his worries......as Bluto mentions below... If the amp draw gets really high with no protection, I'm thinking fire is a concern...

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No, they have a control box between the thruster and the battery, mine has 2 breakers for the counter rotating props.

Actually starter circuits don't need protection if the battery is close enough.

I don't necessarily consider a thruster a starting circuit even if it is a glorified starter motor...

2 ga wire isn't very big if the run is more than a few feet...2/0 is more like what ay be used.

Is the run time limit cumulative, do 4 15 second uses over say 2 minutes, reach a one use minute limit? I guess I`m asking about recovery time before next use. I don`t have thrusters, but now and then think about it, and how it would work in practice. Maybe the manual tells you.

Irdiverdan said:

Am I understanding that the thruster is connected directly to the battery...if so battery gases may be the least of his worries......as Bluto mentions below...

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We don't need no stinking breaker..man!!

This is a 55' boat; he moved the thruster battery from the engine room (a new dedicated battery) to a compartment in the bow which is 12' closer to the breaker, solenoid and thruster.

psneeld said:

2 ga wire isn't very big if the run is more than a few feet...2/0 is more like what ay be used.

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Actually, you are right, I believe it is 2/0.

psneeld said:

Actually starter circuits don't need protection if the battery is close enough.

I don't necessarily consider a thruster a starting circuit even if it is a glorified starter motor...

2 ga wire isn't very big if the run is more than a few feet...2/0 is more like what ay be used.

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Edelweiss said:

We don't need no stinking breaker..man!!

This is a 55' boat; he moved the thruster battery from the engine room (a new dedicated battery) to a compartment in the bow which is 12' closer to the breaker, solenoid and thruster.

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There should always be protection in every circuit to protect you and the boat if some type of failure occurs.

I.e. solenoid jams and motor stays engaged.

As Dr. Ruth used to say...."Always use protection"...

bluebyu said:

Tucker, photo of interesting bow thruster, via Rick B.

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That wasn't my photo. I used a similar one for an avitar for a time but that photo is the result of someone else's great sense of humor.

Jwnall (OP) doesn't have a thruster. That boat doesn't need one, she can spin on a dime and you can get it in to the tiniest opening. I'd drive it at 5:15 pm on I-95 between Fort Lauderdale and Miami.

Dougcole said:

I'd drive it at 5:15 pm on I-95 between Fort Lauderdale and Miami.

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A few more years, with the oceans continuing to rise, and you will probably be able to do exactly that!

John