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Old 04-09-2010, 18:55   #1
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Bow Thrusters

What are the negatives with bow thrusters, beyond the extra cost? If you don't have one on your motor boat, do you wish you did. If you do, do you wish you didn't have it? Thanks.
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Old 04-09-2010, 19:06   #2
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There are no negatives to having extra control, only poor choices or installation
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Old 04-09-2010, 19:06   #3
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G'day, mate. Another 2 (in our case) props to keep clean to work efficiently. In the end, we're glad the previous owner put it in. Cheers.
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Old 04-09-2010, 19:20   #4
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I can't imagine that a serious racer would accept this disruption in hull performance.

e.


I've found times when maneuvering with troublesome wind and current that I would do better with a bow thruster, but it's not on my wish list. There's is much to be said for simplicity and the willingness to warp around pilings and use the skills to do well without. Though, to be clear, my vessel is certainly not a performance racer and there would be a great advantage to push that button and see the bow behave.
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Old 04-09-2010, 20:25   #5
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Once you get over a certain size, you really need a bow thruster. My 48' ketch would be all but imposable to warp around, just too much windage and mass to reliably preform, let alone comfortably.

The racer/cruiser can also employ one of the drop down types, which retains all of the wetted surface and well designed systems have no appreciable drag. Naturally the dedicated racer will never permit their hull to be molested in such a fashion.
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Old 04-09-2010, 21:11   #6
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It's one more thing you get to buy/repair/maintain/clean if you get a big boat.

I'm guessing 90% of people with bow thrusters think warping is something from star trek.
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Old 04-09-2010, 21:16   #7
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a bow thruster is the next best thing to Volvo's IPS system
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Old 05-09-2010, 09:12   #8
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Bow thrusters on pleasure boats seem to work in relatively light winds but have little value in heavy winds when the ability to maneuver the yacht is most important. I cannot count the number of times we have watched boats blown sideways past our slip in cross winds with some skipper desperately pushing his thruster button and the device whining away at high speed accomplishing nothing. Better to learn how to manage the boat, IMHO.

FWIW...
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Old 05-09-2010, 09:19   #9
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Quote:
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I'm guessing 90% of people with bow thrusters think warping is something from star trek.
Warp 4 is 2 springs, bow, and sternlines. I see where you're coming from
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Old 05-09-2010, 09:20   #10
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Bowthrusters for ships or other vessels that are too large to be pulled by hand are a great thing. Sometimes they save the cost of hiring an extra tug. But for small boats they are a substitute for good seamanship. No offense, but I do not think they are needed at all on smaller boats where if you get a crew member or two up on the foredeck and with proper line handling you can do anything a bow thruster can do. All they do is add weight, increase drag, make your boat more complex and reduce your buoyancy forward by putting a hole through your bow.
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Old 05-09-2010, 09:27   #11
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I have an old 3 blade fixed prop. By using the prop walk I can get around pretty well. Mine will crawl to port in reverse. So I reverse and throw a little throttle on and the tail end pulls over to port. Washing the rudder with prop wash is another way to shove the tail end around. It might be nice on occassion to be able to walk the bow either way but not so much that Im going to make the investment. Using prop wash and rotation of the prop works for my peterson 44.
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Old 05-09-2010, 09:32   #12
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Reminds me of the song "the Gambler." "Boy if you're going to do it, learn to do it right."

Too many installations are just not well thought out, not large enough nor adequately powered. If one is seriously thinking about a thruster, install one with enough "guts" to do the job required.

GET A BIG ONE or just maybe you really do not need one. Use at least 24vdc to power it!!! The voltage drop between the batteries and the load can be a significant portion of the total voltage. Some of the thrusters I looked at when I was considering a thruster required over 600 amperes..........THAT IS A HUGE AMOUNT OF CURRENT.

I further suggest that one consult an electrical engineer or at least a knowledgeable electrician (sometimes hard to find!) to aid in the installation's design.

If it is not designed properly, it will not work properly and that will be when it is most needed.

Foggy

EDIT: I considered installing one on my 40' Silverton aftcabin, my first power boat. I was advised to first "learn the boat." My boat has twin 454 engines, it did not take long to learn the benefits of twin engines. I became a believer that a thruster was not needed.
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Old 05-09-2010, 09:39   #13
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Bow thrusters, unless they're the type that retract into the hull, affect performance and speed. I've seen numbers as high as 0.5kt for the non-retracting models. They add weight to a generally overloaded bow area and are a significant hole in the hull. They also consume valuable interior space that could be used for storage.

Their effectiveness is compensated by boat speed, windage, underbody design, and thruster design. They require considerable power - comparable to windlasses in many cases. They require maintenance. They are neither cheap to purchase nor install.

Many of today's thrusters are designed for intermittent use (30sec on, 3 min off) and have thermal switches to protect the motor (and warranty). Use of the thruster requires timing, well thought out maneuvers, and common sense.

It makes a number of movements easier and safer but at the cost of loss of skills. There are times when the use of a thruster is not good seamanship and should be considered an assistant rather than a requirement.

They are considered standard equipment on the big boats, but then we've got 50-75hp hydraulically operated, no time limit, thrusters in addition to twin screws to move us safely around. With the incredible windage that these large motor yachts have, having a bit of independent bow control can be a real asset.
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Old 05-09-2010, 09:56   #14
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It's one more thing you get to buy/repair/maintain/clean if you get a big boat.

I'm guessing 90% of people with bow thrusters think warping is something from star trek.
Where we sail -- vicious tidal currents, often a lot of wind, tight manuevering -- if you don't know how to warp off, you are dead meat (or more literally, quickly uninsurable). It's not really a substitute for a bow thruster, it's just basic boat handling when you have currents to deal with.

Getting back to the OP's question:

The biggest downside of bowthrusters is that you will never want to be without one again. They are completely addictive. They profoundly change your options with regard to maneuvering. You can move the boat sideways with a little practice, and you can turn and position the boat in completely different ways. It does take practice, however -- use of a bow thruster to its full potential is more complex than warping off.

It's not the function of warping off they duplicate, but much more the function of man-handling the boat using the crew. A boat small enough to be moved by a couple pairs of strong hands possibly does not need a bow thruster. After a certain point, however, hands will not do anything. Our boat displaces about 24 tons all up and you cannot influence her path in relationship to a dock with your hands.

Another downside is supposed to be some loss of performance from the drag created by the tunnel, but we haven't notice it.

Concerning the post about the supposed uselessness of yacht bow thrusters in any kind of wind: this is not generally true and certainly not for us. I suppose it depends on not having an undersized thruster. We have a 12hp Sleipner and just last weekend were using it in Yarmouth in very close quarters in a full gale, 40+ winds, with a current running to boot. There was mass confusion as boats were running en masse for shelter into this very tiny, very tight little harbor. We would NEVER have managed without it!

As to whether using a bow thruster is bad seamanship or not, here I have a pretty strong opinion: good seamanship is having the absolute maximum control possible over your boat using all means at your disposal, period. Poor seamanship, on the contrary, would be to increase risks in your maneuvers by not using a bow thruster you had on board.

A rather different question is whether you have become a poor seaman by using a thruster as a crutch to avoid learning how to handle your boat. Actually, I think this is also a myth. Thrusters require more skill to use effectively, than warps, and will not really make up for your lack of ability in handling your boat. In fact, a thruster in the wrong hands can make as big a mess as anything else. A poor seaman is going to be just as poor, with or without a thruster, in my humble opinion.
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Old 05-09-2010, 10:36   #15
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The biggest downside of bowthrusters is that you will never want to be without one again. They are completely addictive. They profoundly change your options with regard to maneuvering. You can move the boat sideways with a little practice, and you can turn and position the boat in completely different ways. It does take practice, however -- use of a bow thruster to its full potential is more complex than warping off.
But the real question is.... should one have bow thrusters in a twin engined cat? (ducking and running really, really fast )
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