Bow thruster noise machine

Out of interest, and without prejudice :rolleyes:, what is the overall weight increase in the nose of a yacht, when one adds a bow thruster?
 
Actually I looked up the weights on the Vetus technical page. At around 26kg for a fairly beefy thruster for a forty footer, it's much lighter than I expected, though perhaps that weight will double when support structures, plumbing and reinforcement around the gaping hole, have been added.

Presumably one only uses a bow thruster when the engine is running? So an additional battery isn't necessary, is it?
 
On a boat big enough to need a bow thruster, I'd be more concerned about the drag from the apertures; the ones with flaps fairing in the hole seem a good idea to me, but they seem quite rare.

I knew someone who ran a Lochin 33 fishing boat as a charter / tax fiddle, the bow thruster on that could be used in-line as emergency ' impulse drive ' propulsion.
 
Seajet said:
On a boat big enough to need a bow thruster, I'd be more concerned about the drag from the apertures; the ones with flaps fairing in the hole seem a good idea to me, but they seem quite rare.
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You cab get bow thrusters that either swing or slide down for use and back up when not in use so no aperture to introduce drag but do make then more complicated .

The trick is to have a lip on the forward edge to deflect the water when moving forward out and past the aperture to reduce the forward movement drag.
 
Our old boat had a bow thruster already on it when we bought it. I did wonder what the point of it was but it did get us out of some tricky situations. But more importantly it gave my wife much more confidence in helming the boat when mooring up. Not that she used it all the time but that it was there was a welcome safety blanket which made our sailing together much better.
As to this thread can anyone imagine some one with a bow thruster starting a thread questioning why people do not have one?
 
This is entirely academic since I neither have, nor have any great desire for, a bow thruster, but the question on cavitation is a good one. I can understand the argument that with limited room for a tunnel the possible sized propeller(s) will inevitably suffer cavitation, but does anyone know whether the swinging-down type (Volvo?) where size is less limited are also affected?

Another idea would be to use a high pressure pump to squirt water rather like a jet ski. Would this give a more efficient and quieter thruster action? Is this produced commercially? I'm thinking of a fire pump with four through hull outlets: appropriate selection giving rotation or sideways translation as required...
 
DaveS said:
Another idea would be to use a high pressure pump to squirt water rather like a jet ski. Would this give a more efficient and quieter thruster action? Is this produced commercially? I'm thinking of a fire pump with four through hull outlets: appropriate selection giving rotation or sideways translation as required...
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The gut who started Vetus did put one on the market but I think it is no longer available as it was not effective. What you need is low pressure high flow where a fire pump type setup is high pressure low flow.

Jet ski's are in effect high flow low pressure as are most jet boats.
 
DaveS,

you can get thrusters like that, with a row of 4 or so jets; they work on suction one side, jets of water the other; good for spraying people if the boat heels a bit, and just as surprisingly noisy as propellor thrusters !

Edit; beaten to it by Roger...
 
Well, if it's the noise that bugs you this version should be silent enough...













bowthruster_zpsa017ad12.png
 
Seajet said:
On a boat big enough to need a bow thruster, I'd be more concerned about the drag from the apertures; the ones with flaps fairing in the hole seem a good idea to me, but they seem quite rare.
Click to expand...

On my mates 55ft (the one that requires your expertise on non bow thruster close quarters marina action...!) you deploy it prior to use and it bleeps to tell you it's engaged from the hull and to remind you to put it away.

So a you get a loud bleep every 3 seconds and a loud Zzzzzzzzzz in use which should get a Javelin going in Southwold.....assuming the 3m draft isn't a problem...
 
Prior to arriving in a marina I report to the captain "thrusters energised" I was never a fan of star treck but it makes me chuckle. As someone else has said it's not a last minute aid it's used early as part of the arrival plan. I noticed when the Harbourmaster launched the Kipper here he made ample use of the bow thruster putting her into the berth and there's no one I respect more for his boat handling than JJ.
 
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