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Does a bow thruster slow you down?

8K views 16 replies 12 participants last post by  PorFin 
#1 ·
I get it...I mean, that it helps you dock. And I get the thrill of a new gadget. I even get the silent, perverse thrill of having people at the dock notice I've got a new toy. But when the 'oooh's' and 'aaaaahs' fade, and the ego returns to it's slightly swollen normal size, does the hole in the bow make the boat go slower than it did before it was there? If so, by how much?

Oh, and for the engineers that circle here, above us, casting pearls of wisdom and math (and I do thank you)....by "by how much" I don't want a quantum mechanics level explaination. I just mean, like, ummm, noticably? or not?

Thank you, friends.
 
#3 ·
I don't have one so this is second hand info. I have asked a couple of people that have bow thrusters if it slows them down and both have said "not noticeably". I have read reports that say they do cause some turbulence in the flow along the hull, which seems reasonable, and so they probably do result in some loss of speed.
 
#10 ·
technology is creating a whole new generation of the helpless. Did it all start with the TV remote control? cars and boats now can self park (if you get the option$ included)
 
#11 ·
I can't say I've ever noticed a difference, certainly not one that isn't far overwhelmed by sail selection or trim.

Ironic that you've suggested oohs and ahhs from onlookers, when most criticize them as cheating. Your thread has already solicited some of that sentiment. However, I invite anyone one of them to back my 45,000lb, 54ft boat into its slip with a 15kt crosswind, raised deck and my neighbor about 5 ft off the other side, without one.

I will acknowledge that it shouldn't require non-stop adjustments, which do make it seem like the captain doesn't quite have control. A bit to offset prop walk when getting into reverse, if you don't actually desire the prop walk for the circumstance. Then a bit more to push the bow into the wind and make a nice turn into a crosswind slip, should be all it needs.

That said, I have a friend who swears that, when in reverse, the thruster is now the rudder. He keeps the helm centered and steers with the thruster. Personally, I don't consider that cheating, while it isn't quite my method.

p.s. raise that crosswind to 20+kts and my boat can't be held or turned against the crosswind in reverse, even with the thruster running non-stop.
 
#12 ·
Ironic that you've suggested oohs and ahhs from onlookers, when most criticize them as cheating. Your thread has already solicited some of that sentiment.
Just disguised jealousy Minne, I wouldn't pay any attention :) .

I really can't imagine that there could be a noticeable loss of performance except in an all out racing boat. I know for a fact that I avoid going into some places because of the lack of maneuverability, but boats with bow thrusters are able to whip in and out seemingly without a thought.
 
#16 ·
We have a bow thruster on our 43'er which was factory installed, so I do not have a before and after speed comparison. I will say that it might have a slight impact as after all there is a hole in the hull which is likely to impact water flow past the bow. That said I have no problem exceeding hull speed so any difference it might make I could care less about. As for it being a new trend I for one love having it. Yes it becomes pretty much useless in winds above 15kts but it certainly is more of a help than hinderance. I'm one of the people who use it as a rudder which adds to the ability to put the boat just about anyplace. Combine it with prop walk and you can just about spin it on it's axis. It's the same principle the Dock and Go systems are using. I also occasionally dock without it just to avoid total dependency on it. I have had the thermal fuse trip on it docking in heavy winds so it's best to keep the docking skills sharp. Bottom line is it's a great addition which I wouldn't be without.
 
#17 ·
Don't have one, but there have been many times I wished we did. Full keeled cruiser, 28K lbs loaded, pretty high freeboard, roller furled genoa and a boom flaked staysail -- it all adds up to "high adventure" when maneuvering in close qtrs. I'd happily trade off the minor loss in speed for the reciprocal loss in anxiety. Just saying.
 
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