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Bow thruster battery advice


Karl

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Hi all, hope you are all keeping well with the current situation we are all facing at the moment. I have a 62ft Piper hull and a Vetus bow thruster which works ok in general but if I get in a bit of a current or slight breeze I struggle to fight against it coming out of my mooring onto the canal. It is being powered by a 110v leisure battery which is in good condition. I wonder though would I be better getting a battery with more amps and power to give the thruster more thrust, so to speak ! I just think compared to some boats I have seen mine appears a bit underpowered when getting into situations when the thruster has its use. Or is it the case where a higher amp battery would not give more power ? The Vetus motor also has a 20 amp fuse mounted in it which blew some time ago and was an absolute nightmare to get to. I don’t want to blow this fuse if I can help it by changing to a bigger amp battery ! 

Your thoughts please would be appreciated. Thanks.

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if you have a 12v thruster and it is powered by a 12v 110Ah battery there is little more you can do apart from keeping the cables from the battery to the thruster as short and as fat as possible and the battery properly charged up.

 

when I had a 57ft widebeam I had a 75kgf Vetus thruster that needed a 400A fuse.    Are you sure the thruster is only fused at 20A ?

 

what is the power (thrust in kgf) rating of the thruster?

where is the battery?

what is the length and size of the cables?

how do you charge the battery?

 

don't get confused by the capacity of the battery - as long as the battery voltage matches the vetus motor then a 110Ah battery should be fine as long as it is close to the motor.

Edited by Murflynn
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A bigger battery will only help the thruster push at full thrust for longer .  It will not give you any more oomph and will take longer to fill up again.

A more powerful (bigger kgf rating ) thruster might help.  Practice and experience are likely to give even better benefits.

 

N

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First of all its not a 110 amp battery, its probably a 12v 110 amp hour battery.

 

Next how do you know the battery is in "good condition". How do you know how well charged it is?

 

A lead acid battery in good condition and well charged can deliver well over 1000 amps if required but note the "good condition" and "well charged" bit. The less well charged and the worse condition the shorter the time such high currents can be delivered.

 

If the batteries are not well charged then the voltage they supply to the thruster will be lower so can push fewer amps through the thruster. This also has the effect of increasing the current drawn from the battery thereby discharging it even more.

 

You can see that once you ensure the thruster propeller is not fouled and  the sheer pin/rubber bush is in good condition my guess is that your battery is not in the condition you think it is. Unless you can ensure the battery is kept fully charged for most of the time a new battery will quickly be destroyed.

 

Voltage reading from the thruster battery as you shut down for the day and just before you start the next day please.

 

 

PS the majority of experienced boaters manage with the thruster that lives on the roof (long shaft/boat pole)

Edited by Tony Brooks
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I found that the volt drop across the split charge diode coupled with the volt drop on the 50 foot of cable meant the battery was never fully charged. So I changed it to a Sterling Zero Volt Drop unit and replaced the 'leisure' battery with a truck starter battery.

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39 minutes ago, pearley said:

I found that the volt drop across the split charge diode coupled with the volt drop on the 50 foot of cable meant the battery was never fully charged. So I changed it to a Sterling Zero Volt Drop unit and replaced the 'leisure' battery with a truck starter battery.

I placed the battery right next to the thruster and laid a couple of welding cables the length of the boat connected to the leisure batteries + and -  .

 

Thruster battery on charge with the leisures.  Because of the long cables the thruster battery charged a bit slower (lower voltage) until the leisures reached float when the thruster battery caught up.

 

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My advice is that in general a bow thruster on a canal boat is only intended for slow speed, close quarters handling and isn't really designed to counter river currents or wind. You should be using your main engine and prop for that, not the bow thruster.

Edited by blackrose
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As others have indicated, the connections from the batteries to the BT motor is important and short fat cables are required. The charging of the BT battery is also a factor. My setup is that the BT batteries share the charge with the start battery through a voltage sensitive relay. So the start battery alternator charge is split between those two banks. The domestic battery alternator just charges the domestic bank. 

 

That setup makes sense because the start battery is usually fully charged anyway meaning that the relay can send the charge to the BT batteries most of the time. The charge cables running the length of my boat are only 16mm2 but that's fine, I don't need thick charge cables with my setup. Why would you want to split the charge between the domestic bank and the BT bank? That doesn't make sense to me.

Edited by blackrose
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In my experience, a bow thruster will not beat a windy day blowing in the opposite direction to where you want to go, if your reversing out of a marina jetty, for instance, coming out great, but as soon as the bow clears the jetty, you have to decide,fight it or turn into it, then reverse. Go with the flow, I can't see a bow thruster beating a wind much over ten miles an hour if reversing. Going forward it may help a bit, but not much over engine thrust steering.

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11 hours ago, Tony Brooks said:

This also has the effect of increasing the current drawn from the battery thereby discharging it even more.

 

Leading to the bow thruster supply fuse blowing, which the OP has already had once. (Assuming he means a 200A fuse blew and needed replacing, not 20A. Especially as it was really hard to gt to. Where was it, OP?)

 

So the battery may not be in good condition at all. 

 

 

 

 

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11 hours ago, Karl said:

. It is being powered by a 110v leisure battery which is in good condition. 

You may be better off  having a starter type battery for a bow thruster. The bigger the CCA rating the better.

Is the battery near the thruster ?

 

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10 hours ago, blackrose said:

My advice is that in general a bow thruster on a canal boat is only intended for slow speed, close quarters handling and isn't really designed to counter river currents or wind. You should be using your main engine and prop for that, not the bow thruster.

 

Totally agree its a manoeuvring aid not a navigation aid - I used to know a boat where the steerer used one all the time to go around bends on a "normal" canal - that's EVERY bend!

 

SHORT cables and proper manufacturers original equipment slow blow fuse if you haven't got one already

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16 minutes ago, Halsey said:

Totally agree its a manoeuvring aid not a navigation aid - I used to know a boat where the steerer used one all the time to go around bends on a "normal" canal - that's EVERY bend!

I was stood having a chat on the bank at Boot Wharf a few years back, with the usual two boats abreast at the wharf and others moored on the towpath side, not leaving much room for passing boats. We started to hear ‘whiiiine... whiiine... whiiine...’ and a boat slowly passed through using his thruster constantly to steer his boat past the wharf. By the time he used it as he reached the bridge it was clear that his thruster battery was about flat. I have no idea how he got around the next bend...

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Learn to control the boat in windy conditions and leave the BT alone. They don't last long if over used. Check that the prop has not got lots of rubbish on it, if you have it will wear through your possibly un-blacked bow  tube and you will sink.

Its a toy for beginner boaters, no working boats ever found the need.

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1 hour ago, Tracy D'arth said:

Learn to control the boat in windy conditions and leave the BT alone. ......................

Its a toy for beginner boaters, no working boats ever found the need.

Totally agree about learning to control your boat.

 

Your second comment, however, is twaddle. A bow thrust a very useful aid for manoeuvring and should be thought of as such, and occasionally very handy.  You dogmatically say that no working boats ever found the need; only because they were't invented in the "olden days". When working boats on the canals first started they never found the need for engines and they stuck to their horses , not surprisingly because engines weren't yet invented, but they soon adopted them when they were.

 

Howard

Edited by howardang
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3 hours ago, Mike the Boilerman said:

 

Leading to the bow thruster supply fuse blowing, which the OP has already had once. (Assuming he means a 200A fuse blew and needed replacing, not 20A. Especially as it was really hard to gt to. Where was it, OP?)

 

So the battery may not be in good condition at all. 

 

 

I suspect the battery is the problem but that then leads on to all sorts of other possible problems others have referred like small cables, lack of charging. etc. I am still awaiting the battery voltage readings that may clarify things.

 

 

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2 hours ago, Tony Brooks said:

I am still awaiting the battery voltage readings that may clarify things.

You might be waiting until the lockdown is lifted Tony.  I read the OP as being something to investigate while he can't go to the boat, so unless @Karl is a liveaboard he won't be taking the readings anytime soon.

Edited by TheBiscuits
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On a fine sunny windless day (the only weather that sees them away from their moorings) nearly every gross gin palace on the Thames enters the locks at a snail's pace, stops in the middle of the lock and then crabs sideways using bow and stern thrusters. 

Groan .......................   groan  ..................................  whine ................................. groan.

Goes without saying that the skipper will be wearing a gold-braided peaked cap and the boat will be flying some posh burgee (Bracknell Rotary or The Royal Meat Purveyor's Yacht Squadron or summat like that).

 

  • Haha 1
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49 minutes ago, Murflynn said:

On a fine sunny windless day (the only weather that sees them away from their moorings) nearly every gross gin palace on the Thames enters the locks at a snail's pace, stops in the middle of the lock and then crabs sideways using bow and stern thrusters. 

Groan .......................   groan  ..................................  whine ................................. groan.

Goes without saying that the skipper will be wearing a gold-braided peaked cap and the boat will be flying some posh burgee (Bracknell Rotary or The Royal Meat Purveyor's Yacht Squadron or summat like that).

 

Reminds me of my first trip on the Thames, in a particularly scruffy narrow boat. I was at the back of a long queue for the lock as the gin palaces in front positioned themselves down either side of the chamber, leaving a narrow boat width gap down the middle. The Lockie looked down the queue then beckoned me forward past all the waiting gin palaces and I slotted into the middle, unable to tie up. Meanwhile chaps in braided caps shouted at me down from their flybridges and over-tanned women made ineffective stabbing motions at my boat with their lightweight aluminium and plastic boat poles as the lock emptied. And as soon as the gap between the bottom gates was wide enough I was away while they waited for the gates to open fully.

And then of course they all stormed past me at speed in a blue diesel haze. And I caught them up again at the next lock.

Happy day's!

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In my case, it's lovely when they all charge past, leaving the river slopping about for a few minutes - then there is guaranteed peace and quiet for half an hour.  Getting to the next lock first and taking time to help the lockie, cruising into the lock and relaxing as the next batch of blue-smoke monsters charge up to the lock like the Epsom Derby front-runners.   Pillocks!

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Just now, robtheplod said:

My bow thruster is useless in windy conditions. Was once stuck as a fuel jetty for 2 hours waiting for wind to drop!

If it happens again, it could be worth trying to 'spring-off', its a common 'lumpy-water' manoeuvre where you can have strong onshore winds and tides pushing you all over the place.

 

https://www.yachtingmonthly.com/sailing-skills/springing-on-and-off-29899

 

 

 

 

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3 minutes ago, Alan de Enfield said:

If it happens again, it could be worth trying to 'spring-off', its a common 'lumpy-water' manoeuvre where you can have strong onshore winds and tides pushing you all over the place.

 

https://www.yachtingmonthly.com/sailing-skills/springing-on-and-off-29899

 

Quite.  A 75 kgf m/s bow thruster is common on a 57' narrowboat - it's about one horsepower. 

 

Most boats that have one of these are likely to have a 43 or 55 hp engine and some rope ...  all the gear as it were!

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Spring off, and on,  are both quite common manouevres for HM' s war canoes.  Neither are likely to be particularly popular with the XO/First Lieutenant or the Buffer because of the damage to paint and squashed fenders which can result.

I think the first time I saw it was HMS Intrepid in a severe gale in Nassau. Got alongside eventually and spent the weekend at 4 hours notice while the seaman department were using hurricane hawsers as springs to try and stop the ship surging backwards and forwards.

I seem to recall that a bottle of local rum there was cheaper than a bottle of Coca-Cola to put in it.

 

N

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