Bow Thrusters at dawn!

[huzar30]

There must be some technical explanation - why are bow thrusters so noisy? People reverse from their berths with almost no noise, but as soon as the bow thruster comes on, there's a heck of a racket. Why?

 

[Scotty_Tradewind]

There must be some technical explanation - why are bow thrusters so noisy? People reverse from their berths with almost no noise, but as soon as the bow thruster comes on, there's a heck of a racket. Why?

yes, what a confounded racket.
Sounds like a 'self destruct m\chine'.

Isn't there a different type to the propeller models that forces water via an impeller..... that is much quieter?
Thought i saw one in a mag' advertised once.

 

[footsoldier]

That's a question that has always puzzled me too, but I've always been too embarrassed to display my ignorance. Glad you asked first.

One of the better informed forumites will be along soon to throw light on the mystery.

 

[Daedelus]

To give you fair warning that he's needing assistance to manouevre and thereby a chance to get a fender in place. Thought that was obvious.

 

[s/v moondancer]

Its in a big sounding box like a drum. Try getting in the anchor locker when it's running.

At low speeds, in our 'gin palace' using the rudder in reverse is a random event, I use the bowthruster to tweek the bow one way and the stern goes the other

 

[Powersalt]

I am sure there are more learned on this forum than me but I was led to believe the bow thruster is and electric motor driving a small propellor at very high revs inside a tube. As such it creates a lot of air and cavitation which causes the noise.

 

[Doghousekeeper]

I am sure there are more learned on this forum than me but I was led to believe the bow thruster is and electric motor driving a small propellor at very high revs inside a tube. As such it creates a lot of air and cavitation which causes the noise.

My understanding is that this is correct in principle, but the technical term for this effect, I believe, is "ventilation" rather than "cavition"

 

[markdj]

Usually, a very noisy bow thruster is due to little or no fairing on the openings. This causes cavitation and alot of water turbulence around the tunnel openings. If the tunnel openings are faired by about 10% this increases thrust and reduces cavitation.

Mark
www.boatdoctorni.com

 

[Scotty_Tradewind]

On a yacht where the hole for the drain pipe thinghy goes through, does this cause a slowing effect? I go slow enough as it is, I wouldn't want anything else to cause resistance. :-0

 

[Twister_Ken]

I thought it was because they're fitted with the motors from food processors.