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Go Back   SailNet Community > On Board > Gear & Maintenance > Bow Thrusters ??
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Thread: Bow Thrusters ?? Reply to Thread
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Topic Review (Newest First)
01-07-2008 05:03 PM
Brezzin I have a thruster on my boat. All though I don't use it all that much, I'm glad it's there. For me it falls in the category of "better to have it and not need it than to need it and not have it."

I don't know any sailor of a 45+ foot boat that at some point would not have benefited by being able to swing the bow around or the crab walk the boat into a tight fuel dock or slip.
01-07-2008 10:38 AM
sailingdog You do know that in really tight spaces you can generally use warps to turn the boat in almost any way you'd possibly need to without a bow thruster. We turned a 50' steel schooner that weighs 28,000 lbs. in a slip way so that she wouldn't have to motor out in reverse against a 15 knot wind.
Quote:
Originally Posted by davekitson View Post
We have a Southerly 35 which has a lifting keel and hence twin rudders. With a center prop we get no prop wash and we also get very little prop walk.
Without a thruster she would be essentially impossible to manoeuvre in a confined space. I one tried turning her without the thruster in a 25 Meter wide channel and it took over 30 backward and forward runs. With a wind or tide it would have been a disaster.
The thruster adds new ways of approaching difficult spaces such as crabbing in slowly (1 to 2 knot) at 15 degrees while keeping the boat parallel to the quay. Much safer in a side wind or current than flying in then jamming on full rudder and prop wash at the last minute then full reverse and hoping not to hit the boat in front and not get blown off!

For many years we had conventional boats with centre rudders and no thruster. I wouldn't easily go back now
01-07-2008 10:08 AM
SEMIJim There's a big ol' jet-powered stinkboat in a yard not far from our sail club, up on the hard, near the road. (That's how I noticed it.) It has a bow thruster in it. I s'pose it's okay for a stinkboat. Seems like a rude thing to do to a sailing vessel, tho. Don't care what anybody says: It can't be good for the boat's sailing performance. To each his own, I guess, but I think if I had to rely on such an obscenity, I'd sell the boat and crew with others.

Jim
01-06-2008 05:33 PM
davekitson We have a Southerly 35 which has a lifting keel and hence twin rudders. With a center prop we get no prop wash and we also get very little prop walk.
Without a thruster she would be essentially impossible to manoeuvre in a confined space. I one tried turning her without the thruster in a 25 Meter wide channel and it took over 30 backward and forward runs. With a wind or tide it would have been a disaster.
The thruster adds new ways of approaching difficult spaces such as crabbing in slowly (1 to 2 knot) at 15 degrees while keeping the boat parallel to the quay. Much safer in a side wind or current than flying in then jamming on full rudder and prop wash at the last minute then full reverse and hoping not to hit the boat in front and not get blown off!

For many years we had conventional boats with centre rudders and no thruster. I wouldn't easily go back now
12-28-2007 11:31 AM
Giulietta Here's a story for you...

An very well know older sailor here, "climbed" the ranks of sailboat size along the years.

His latest boat, a Beneteau Oceanis 50 (sold as a 49) DS, really pretty boat, twin wheels like the big fast boats, enormous saloon, etc. and....state of the art bow thruster.

So here he comes, in his 50 footer, to dock....VRRRRRRRRRRRRRRRRRRRRRR port..VRRRRRRRRRRRRRRRRRRRRRRR right......VRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR RRR Port.......

VRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR starboard....VRRRRRRRRRRRRRRRRRRRRRRRRRRRRR port....

By now, the wind here is not a game...it blows....he couldn't get the boat in, and worse, relying on his state of the art bow thruster.....some more VRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRto starboard....

he is trying to pull his bow across the wind....when normally him of all people would come around, and factor the wind....

not anymore...VRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR and more VRRRRRRRRRRRRRRRRRRRRR

Then..... ouch ouch ouch......the bow Thruster stopped...

Bang crack $$$$$$$$ bling blang $$$$$$$ his bow into another boat's anchor....dent hole.....

Engine in reverse, scratchhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh

8 feet along the side on a pier cleat........

engine forward, his bow into another boat.....

And here you have a really old sailor, with more miles that we all together....

why??? why???? His trusting on the Thruster....that's why....never again....

The bow thruster ceased (SP) and cooked....

Off comes Benetau...guarantee claims..."no no, dear Sir, you only use it a litlle at a time, not for half hour".....

"then why don't yo say so in the manual"????

"Well we install it, but we don't make it"....

"Well its on my new boat I bought from you....fix it or give me a new"...

"well....we'll fix the bow thruster....but not the boat...tough luck".....

A week later, bow thruster fixed....he runa aground...why?? Melted the bow thruster again....

Note BT is of a reputable brand....however, not designed to move a 50 footer into 20 knot winds....

there are many more stories, this one will suffice...

Install it, don't trust it....I guess....

By the way...he now comes in "hot", accounts for the wind, and docks "Ń lŠ old fashion"...first time with his 50 footer...the bow thruster??

I saw it in garage.....smelled burnt.....
12-28-2007 10:36 AM
camaraderie Volkhard...
Funny you bring that up. When I bought my boat it had a Vetus bowthruster from the 80's that worked on just that principle...water jets instead of props. The whole thing was huge and clunky and worked on 24V and did NOT work very well compared to modern prop units. I had it pulled out and sealed the hull and lived quite happily without one. I hope the new ones are more effective than my old one...but the original idea does go back several decades!
I kinda feel like Giu does about thrusters in general...especiallly on under 40' boats...but in some tight, high current docking situations or for "geriatric" situations, they do make some sense. One must consider the electrical draw, the expense, the loss of storage space AND the ability to dock when the thruster fails due a bad connection etc.
12-28-2007 10:29 AM
mallo Hi we fitted a bow thruster in our 48ft steel ketch 7 years ago, we are very pleased with it.
As regarding the hole in the boat it was a bit of a shock when we cut it, however the tube is 8mm thick the hull is only 5mm, we had to take a small frame out to fit it where we wanted to, but the tube is now acting as the frame (the tube is a lot stronger than the frame that was there).
As is mentioned here earlier we formed an eyebrow and we have not noticed any performance loss however itís a huge help in tight marinas.
Our boat was built in 1939, before marinas, she has twin rudders and the prop is situated between them with no effect over them, she has to have about 2Knts of boat speed before you have steerage, makes for interesting handling!!!
We have noticed marinas getting tighter and tighter when we took out mooring we could just about swing her to get out but now with people getting larger boats this isnít possible, so we have to go stern first all the way along the row of boats to get out, this it now possible with the bow thruster.
We donít use it unless we need to or things are going wrongÖ. However itís nice to take control of her when the wind/tide or any other influence decides differently.
I would fit another one tomorrow.
We have also fitted them to other boats, one that jumps to mind was in an 60 ft aluminumn hulled yacht and the customer was very pleased with the outcome, we fitted compensating plates on the inside to stiffen the hull up and eyebrows on the outside.
I do think the fibreglass tubes want to be fitted professionally and agree there is a lot of weight hanging on the tube, but I canít really comment on this as I am a metal man!
We fitted batteries up fairly close to the thruster and we also use this to power the windless on the foredeck, we didnít notice any change in the trim or performance in her, but we did move a spare load of anchor chain that wasnít used further aft (thinking about it the chain probably slightly more than the tube, thruster and batteries.)
Whilst I hear all the professional sailors saying itís not necessary, I agree in some ways but when you are being taken down a marina row in a unknown marina and its blowing a bit its nice to know you are in control of your boat and can always come out stern first if thereís not enough room to turn at the far end, in the early hours of the morning.
Itís not a toy, its another member of crew.
12-28-2007 10:17 AM
Giulietta If You Can't Dock A Boat Without The "geryatric" Aid, Stay Home...

Sailing Isn't For You.
12-28-2007 09:26 AM
petegingras Rockter,
do you have valid concerns, or notice of, regarding failures of bow thrusters?

Your point is any hole in a boat is a source of prospective ocean insurgence. While the tube is “big” it’s glassed to the hull, and the shaft of the thruster is no worse than our stuffing boxes, but in the end it’s a hole yes.

and no it's not a toy, but rather a dockhand you tip in amperage.
12-28-2007 12:46 AM
Rockter A big 'ole in the bow, beaten by a big sea, smashing to weather.
A stiffness discontinuity, the extra drag, the seal around the drive shaft.
The weight of the motor, right at the front.
Cabling, brutal power consumption.
The need to run the motor to take the load off the batteries.

If needs must, then go for it.

I am wary of them.
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