Bow thruster powering

Calling all windlass/bow thruster folks - how do you get that much power up forward? I took my bow thruster off the boat to figure out why it doesn't work. I suspect the DC motor is fried - it smoked and dimmed the cabin lights when I tested it back when the boat was in the water. Seems like a fire hazard.

Now I'm getting to the bottom of what to do about it, and come to realize that my whole circuit is completely undersized. Anyone else solve this by putting a battery in their forward cabin? (Anyone else have a bow thruster??) A couple owners ago, someone basically just Tee-d into the windlass circuit (2/0  cable) to power the bow thruster. With smaller, 1/0 cable, even though the bow thruster pulls twice as many amps. I'm skeptical it would work even if the bow thruster motor wasn't cooked. According to Vetus, even the 2/0 is insufficient for a such a long cable run to the thruster. The windlass works fine and I haven't been too worried about it. 

So, as I go down the rabbit hole of replacing the thruster and the circuit, here is a sketch of what I have come up with. If you have a battery up forward, how do you charge it? Are there any problems I should be wary of?
I plan to use a trickle charger from the house, but have an emergency bypass switch in case the battery dies, then I can use the windlass off the alternator (via the house, not directly).
Also, anyone who has a thruster - what is the thrust rating? Do you like it? Do you use it? Should I just glass up the hole and forget about it?

Thanks for any insight!

 


- Grace


 

Hi
After several years of ownership we added an Exturn bowthruster. It is the most expensive upgrade we have done, and the most worthwhile. The bow gets blown around a lot while maneuvering, and the thruster controls that, so don't get rid of yours without careful consideration.
I can't help you with the electrical issues you have because the model we got requires 24 volts, so we have a pair of dedicated batteries for it, installed nearby. However, I will say that it makes sense to power your windless and thruster from a forward mounted dedicated battery, which will reduce the wire lengths and provide a power reserve. Also, it's helpful to move weight forward.
Nothing like 20 knots of wind on the beam to make you love your thruster!

(Part 2)
I placed the thruster batteries in the bottom of the locker opposite the forward head. Because they are wired to provide 24 volts they are charged by an 120 v A.C. charger.

Hello, we’ve owned our Brewer 44 for the past eight years and lived aboard for the past three. We have about 10,000 miles under the keel. In our opinion for a boat this size a thruster is unnecessary and a crutch. We see so many sailors these days who don’t know how to maneuver their boats or use lines properly because they always use their thrusters. Thrusters don’t always work and are ineffective in strong winds.
The best book I know about docking technique without thrusters is “Docking Techniques for Single Engine Boats” by Tom Tursi (American Sailing Association). Buy that book and save your money for something that will make your boat sail better. The drag alone from the thruster itself is slowing you down.

Thank you Mark for the validation!

How do you run the AC charger while you are off the dock? Do you have a generator, or a separate 24V alternator on your engine? I see the benefits of switching to 24V, but not sure how deep I want to go uprooting the system.

Hi Gino,
Thanks so much for your feedback. I will absolutely check out that book!

I hear you on the logic of saving money for things that make the sailing better. I am curious though - where are you sailing mostly? Do you mostly spend time offshore, going anchorage to anchorage, or do you ever go into crowded city marinas and unfamiliar ports? Do you sail singlehanded and how comfortable are you docking singlehanded?

Maybe you can help me suss out how to handle my marina. I have been doing spring line tricks for two years to get in and out, but I haven't figured out a good way to dock without crew or someone to catch me.

The first year, I was in an inside slip with about 3 feet between me and my neighbor, but my finger pier was only 30 feet long. By the time I could reach a cleat to throw a pre-measured spring, I was already in the slip, too late. To get out, I would run a line from transom to aft dock cleat and doubled back to the chock. 1 Crew would ease it out as we backed out of the slip while another held the bow on. Then once we were clear of the neighbors, they'd hold the aft spring fast and I'd back into it to pivot the boat around. Once straight in the fairway (width about 50 ft) the crew would haul the line in like heck. I could do the whole shenanigan myself if someone cast off my bow and walked me back, but holy moly was it stressful to haul 100 feet of line near the prop. 

The second year, I got an outside slip with a 50 ft finger, but sharing a 30ft wide double berth with an Amel Super Maramu (15 ft beam). Accounting for fenders there were about 6" room for error, and I still couldn't back out straight enough without someone holding my bow on. Getting in was no problem until I hit reverse and the bow would blow off unless already sprung.

To top it off, the current induced by the nearby locks can hit 3 kts at peak, blowing sideways across the slips. Sometimes it's useful, like for straightening out in the fairway, and sometimes not.

What would you have done in these situations, if you didn't have crew or a neighbor to cast you off and catch you? How do you keep the bow from blowing off when you arrive in the slip and put it in reverse?

I'll definitely get the book - I would love to be confident enough to enter unfamiliar ports without spending the dough on the thruster - but just curious if you had any thoughts on these situations as someone who has gone 8 years without one.