bow thruster wiring

Sammy Lou

Sammy Lou

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Hi all,

Job for the winter holiday is to continue with my bow thruster installation. Tunnel is in, thruster is fixed and now I need to do the wiring. I've been using the last working day to draw up a sketch & wondered if any electrical experts would be kind enough to take a look before I go and buy the wiring/terminals/fuses etc (batteries and CVSR are already bought). Please be gentle though as I'm a mechanical minded guy and electric are not my strong point.

Thanks,Regards and Merry Christmas to all

bow thruster wiring.jpg
 
I'm a great believer in the keep it simple principal, especially on boats.
First suggestion - don't use fuses, circuit breaker much better and saves you carrying spare fuses.
On the basis that you are almost always going to use your thruster when the engine is on, why do you want need extra batteries?
( I'll not go down the route of the arguments about charging different battery types in parallel)
If it were me, with the money I saved on the batteries & CVSR, I'd buy bigger cables and perhaps an addition matched services battery.

It's also worth noting that some yacht manufacturers wire up items like anchor windlasses so that you only use them with the engine running.
Might be worth considering this as an option.
 
J
Bav32 said:
I'm a great believer in the keep it simple principal, especially on boats.
First suggestion - don't use fuses, circuit breaker much better and saves you carrying spare fuses.
On the basis that you are almost always going to use your thruster when the engine is on, why do you want need extra batteries?
( I'll not go down the route of the arguments about charging different battery types in parallel)
If it were me, with the money I saved on the batteries & CVSR, I'd buy bigger cables and perhaps an addition matched services battery.

It's also worth noting that some yacht manufacturers wire up items like anchor windlasses so that you only use them with the engine running.
Might be worth considering this as an option.
Click to expand...

Tend to agree. If you feel you need extra battery capacity, why not simply expand your domestic bank? You can then make use of the extra capacity for normal domestic tasks as well as for the thruster when required.
 
I'm going to disagree with the two guys above.... I think your arrangement looks sensible to me.

Running the thruster off the remote bank would require cables running that could handle the entire load of the thruster, and that would probably cost more than an additional battery.

I've planned a similar set up, but have used a Sterling B2B rather than a VSR... but same principle.
 
For windlasses, I much prefer the simplicity of a pair of thick cables from the domestic bank and no batteries and other gear up front. However, last time someone asked about bow thrusters and I worked out the figures, the additional power demands of the thruster over the windlass made a bow battery the sensible choice.

Pete
 
prv said:
For windlasses, I much prefer the simplicity of a pair of thick cables from the domestic bank and no batteries and other gear up front. However, last time someone asked about bow thrusters and I worked out the figures, the additional power demands of the thruster over the windlass made a bow battery the sensible choice.

Pete
Click to expand...
Exactly. I have heavy cables directly wired for my windlass, and upon fitting a bowthruster, these make great cables to connect the bow battery up.... more than enough to charge the battery, but at 50mm2 and 8m long, still very much on the light side for running a bowthruster directly.
 
Some of the thinking for why the installation has ended up this way:

I wanted to keep the cable size down. If I had run the cables from the starter battery then Vetus recommend guage 0000. Having short wiring from the battery is how Vetus recommends it done. The 50mm might be a little light but I’ll see how it goes.

Once you get to doing it with a dedicated bow thruster battery then you need to charge it. Sterling recommends the CVSR so as the bow thruster current (up to 550A) cannot be drawn from the starter battery.

The space that I have over the tunnel is about 210mm deep therefore to use this space for the batteries means that the battery could not be more than 100ah. Vetus recommend 120ah - 225ah for the 75kg/f thruster. Therefore two 100ah AGM are needed.

Thanks for the help so far.
 
Phoenix of Hamble said:
Exactly. I have heavy cables directly wired for my windlass, and upon fitting a bowthruster, these make great cables to connect the bow battery up.... more than enough to charge the battery, but at 50mm2 and 8m long, still very much on the light side for running a bowthruster directly.
Click to expand...

This is what I had, and to boost the capacity of the 50mm2 cables (as Vetus specified 70mm cables for the run), I added an 85Ah battery up forward. Therefore getting diversity with 50mm cables and battery. With this arrangement, I have had absolutely no problems.

At the engine/battery end, there is a 250A circuit breaker feeding the 50mm +ve cable going forward. At the forward end, there is another isolator to isolate the forward battery from the aft batteries (in case the aft 250A cut. brkr. is left on. Also forward is a 75Amp cut. brkr. for the windlass, and another isolator to isolate the bow thruster. There is a 300A fuse for the bow thruster - Vetus spec.

Sounds complicate, but all cables, batteries and windlass/bow thruster can be isolated from each other and everything else.
 
Battery up front and a VSR from the alternator is the job. Otherwise as POH has said you need massive cables, plus you end up with an emergency starter battery up forward with cables back to the VSR you could jump from those direct to the starter motor.
 
This shows my bow thruster installation and wiring with control relay for windlass.

I favour driving both from house batteries hence the use of large bus bars as shown cover in blue insulating tape.

WEB0952_zpsb1a8f912.jpg
 
martinriches said:
You could fit a24v bow thruster and a step up transformer from the house batteries. That is the arraignment on my boat.


Martin
Click to expand...

A DC to DC converter for 12 VDC to 24VDC for the required power for a bow thruster would be very costly. Transformers are only for AC power not DC.

VETUS do have a switch that can provide 24VDC by temporary connecting 2 12VDC batteries in series for the bow thruster when in use but reconnect to 12VDC when Thruster is switch off
 
Rogershaw said:
A DC to DC converter for 12 VDC to 24VDC for the required power for a bow thruster would be very costly. Transformers are only for AC power not DC.

VETUS do have a switch that can provide 24VDC by temporary connecting 2 12VDC batteries in series for the bow thruster when in use but reconnect to 12VDC when Thruster is switch off
Click to expand...

I have realised that is how mine works as well. It is a Bosh switch made for use with a 24v starter motor.

Martin
 
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