3 phase motor for bow thruster

Rob, one of the many reasons that hydraulics are used on bow thrusters, and other auxilliary machinery, is that the motor only needs to be started once - whilst you're still tied up.

No matter how you start it, a motor that size will cause your genny to strain a little on startup (due to very high inrush currents), and then there is the possibility of the motor stalling out the generator just when you need it most (ie. whilst manuvering).

If you *really* want to go electric, you might like to install another generator (a dedicated one just for the thruster woud be nice.. :-)

Cameron:-)

| > I am thinking of using a 3 phase 7.5kW 2840 rpm motor to power a bow | > thruster propeller as my generator has a 3 phase output and can accept | > loads up to 8kW using starting and running capacitors. It should also | > be simpler than a hydraulic installation. When started it will be | > against a stationary propeller - so I am hoping to be able to use a | > DOL system so that I do not have starting delays. | >

| > Grateful for any advice on pitfalls etc. | | Rob, one of the many reasons that hydraulics are used on bow thrusters, and | other auxilliary machinery, is that the motor only needs to be started | once - whilst you're still tied up. | | No matter how you start it, a motor that size will cause your genny to | strain a little on startup (due to very high inrush currents), and then | there is the possibility of the motor stalling out the generator just when | you need it most (ie. whilst manuvering). | | If you *really* want to go electric, you might like to install another | generator (a dedicated one just for the thruster woud be nice.. :-) | | Cameron:-) |

Ditto for Cameron's comments. and you might also consider the use of a small Variable Speed drive. THis will eliminate the starting unrush currents as well as giving you a little more control over the amount of thrust you are applying to the bow.

I am not a "Boat Man" So am not really sure if variable thrust at the bow is a desirable thing or not.

Tom Grayson

It's a nice idea, but it depends who he's registered with.

If it's the ABS he will have to sweet-talk an inspector *and then* upgrade the generator (not necessarily in that order ;-) If it's RINa or Lloyds, IMHO it would be way simpler to put a hydraulic system in and forget about it.

The first step is for the OP to read the regs (there is more than one) for himself:

Cameron:-)