12v Boat with 24v bow thruster

[Dockhead]

Originally Posted by piloto

For awhile I thought I wasn’t going to see this suggestion. I have a step up transformer (or step down) from a company named Vanner that has a current capability of 20A on the 12V side. I’m thinking there must be a variety of capacities of these devices around.

That suggestion was made upthread, but apparently no one knows if a big enough one for a 15hp thruster is feasible in terms of cost and size.


A big advantage to doing it this way (as was pointed out upthread) is that a step-down converter will have much less voltage sag than a battery at that voltage, which will improve the operation of the thruster.


Worth looking to see if such a converter exists, I would say.

[Shaneesprit]

I am wondering on your logic here - you want 3 times the power but want to run it off of 2 small batteries - doesn’t make sense
Going from 5hp to 15hp is likely to require a lot more than 3 times the electrical supply.
Do you think you can boil a kettle from the solar panel on your calculator? Being at least a little tongue in cheak

[jordanbigel]

Ok, so, a lot of responses here came in a second wave which were a bit repetitive.

To start, no, I am not trying to run it off of two tiny batteries - I have a single 12v 4D (200ah) battery now, adding a second would give me two 4D batteries or 200amps @24v. And yes, I am aware of the serial-parallel switch idea, which I spent a good deal of time researching. And I also am now aware of the fact that you can wire 2 batteries in series and pull 24v off of the pair, and at the same time wire a 12v load direct to 1 of the 2 batteries, that was brought up early in the thread. And yes. I gave a lot of thought to each of these options and tried to work out the costs and pros/cons of each.

To the contributer who opined that he has a fifty-something foot boat and he has a 12v thruster and its fine, what can I say, on my hull the 12v 5hp thruster is really only useful in a limited set of scenarios based on my experience with my boat. Shrug. Wish it were different. I also compared SidePower thrusters and they offer a slightly more powerful 12v thruster, but the tunnel size is wrong so that would add a huge amount of cost.

But, in the end, I realized that the price estimates I was working off for the 2 thruster options were way off, ie. I had been proceeding based on bad info on the cost of the 2 thrusters, it turned out the cost of both was much higher than I thought. Because of the much much higher cost of the 24v thruster and the related upgrades required, we decided the cost was too high (considering all the other major projects we are undertaking this year).

So, I ordered a replacement 12v thruster. I have a slot to haul-out in mid-December when it will go it.

On the bright side, unlike the 20 year old thruster which is being replaced, the new model thruster, from Wesmar, can be upgraded to the 24v version (which it turns out is actually 13hp not 15hp, but whatever) by just changing out the motor.

[Dieseldude]

Lots of good suggestions here. If you decide to upgrade your alternator to 24 volts, you may not need to replace the whole alternator. It might be possible to obtain a 24 volt regulator for the same alternator that was originally equipped with the 12 volt regulator. You would need to check with the manufacturer if the old 12 volt alternator can handle 24 volts. This specification might be available on the manufacturer's web site. If the original arrangement was a regulator mounted right on the alternator, and a 24 volt direct replacement is not available, an externally mounted 24 volt regulator might be sourced.

[millsie]

Just fit a 12v thruster .
surely a new thruster would be more efficient than the old one.
It worked previously why would it not now.
cheaper and easier , you can still use the dedicated alternator from the main engine, As you should be running your main engine when using thruster .

[malcolm.northey]

Originally Posted by jordanbigel

So,my boat is all 12v and I have a dead 12v bow thruster (5hp). The unit is over 20 years old and they say they cannot repair it (parts not available).

I can replace it with the same unit, but, they (Wesmar) now offer a new thruster which has 15hp equivalent thrust compared to the old 5hp one I have, but with the same prop size (8") same tunnel (215mm), etc. - except it's 24v only. There are some other possible 12v options I am looking into which might fit the tunnel (SidePower).

Currently, I have a dedicated 4D AGM battery in the forward cabin just inches away from the bow thruster. It is charged by a dedicated alternator (a small-case Balmar 150amp deal with its own MC-614 regulator). This battery also feeds the windlass also 12v (Maxwell).

I'm trying to see if there is a way to run the 24v thruster without spending too much $$ and I don't see any way to do it. I could replace the 4D with a pair of smaller batteries and wire them in series to make 24v, and then I would have to replace the alternator with a 24v alternator - but even if I did that what about the windlass? Maybe some kind of DC-DC step down converter which can feed the windlass 12v from the 24v bank? This is starting to get out of hand!

I wouldn't even be considering this except the current 5hp unit is totally under-powered (at the time it was the largest unit available for the tunnel which was already in the boat with a dead thruster when I bought it) - and I knew it was underpowered, but figured it was better than nothing. In reality, it's been barely better than nothing. It is helpful in a limited set of conditions and circumstances, but a 15hp thruster would be a game-changer in terms of close quarters maneuverability, which is why I am considering it.

Is there a better way? Will this even work? Thanks in advance!

From Australia
The option I use is a series parallel switch ,they have been around for years I currently use one on my bow jet since my yacht is 24V but it was better to use 48v (much less current = longer operation without cooking motor) so the Series parallel switch did the job.
The company is Albright International in the Uk although my bow jet came from Holland
the system uses 12v to trigger the operation of the switch from the bow jet controller. It then links 2 batteries in your case 12v batteries into series so you get 24v for the bow thruster.
The batteries when the bow thruster is not working are returned to a parallel connection and supply 12v and are charged as two 12v batteries you need a minimum of 2 batteries.
hope that helps