Model Boat Mayhem - Forum

Please login or register.

Login with username, password and session length.
Pages: [1]   Go Down

Author Topic: Graupner Bow Thruster  (Read 3272 times)

ianb

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 76
  • Location: Japan
Graupner Bow Thruster
« on: March 17, 2008, 10:24:37 AM »

I installed a Graupner bow thruster in my Aziz.

First I ran it on 7.2V, as rated by Graupner, using bang bang actuation. No ESC.

The output was very impressive, to say the least, but I think that the scream of the motor could be heard in the next village. It was rather embarrassing!

I cut the supply back to 6V, lots of power but still very noisy.

The main drive motors, Graupner 720 BB Torque, are almost silent.

Can anyone suggest a way to quieten the thruster down or will I have to live with it? I don't see any way to soft mount the motor, so that avenue seems to be out.

Thanks

Ian
Logged

barriew

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 2,009
  • Location: Thaxted, Essex
Re: Graupner Bow Thruster
« Reply #1 on: March 17, 2008, 11:32:38 AM »

I think full size bow thrusters can be noisy :) I've been on a couple of small cruise boats where the thruster was extremely noisy. Particularly the Lord of the Glens which sails the Caledonian Canal and makes almost constant use of the thruster to navigate the narrow channel ;)

Barrie
Logged

FullLeatherJacket

  • Guest
Re: Graupner Bow Thruster
« Reply #2 on: March 17, 2008, 12:55:34 PM »

Ian

Those Speed 400 motors are as noisy as hell, largely because of the revs they do. At those speeds they are very efficient, but slow them down and they lose power drastically. I would say that the only feasible solution would be to fit over-size tubes in the hull and then soft-mount the actual thruster unit into them e.g. by using silicone sealant instead of P38 or epoxy. Either that or maybe chop a short length out of the existing tubes between the motor unit and the hull and re-plumb with some soft rubber tubing and hose-clips. A bit late now for your Aziz, but maybe some daring young thing out there might experiment and let us know the result.

I'll endorse Barrie's comments about full-size units. We had our first cruise on Emerald, and our cabin was well down towards the bow. At about 5am every day the ship came into a new harbour and that bl00dy thruster nearly frit me to death when it went off!

FLJ
Logged

boatmadman

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 2,721
  • Location: South Cumbria
Re: Graupner Bow Thruster
« Reply #3 on: March 17, 2008, 02:13:54 PM »

And those thrusters suck serious power, I was on a 27000t tanker with one, it had its own dedicated steam turbine gen set to power it. When it started you could see the boiler pressure vanishing!

Ian
Logged
if at first you dont succeed.....have a beer.....

catengineman

  • Guest
Re: Graupner Bow Thruster
« Reply #4 on: March 17, 2008, 03:17:06 PM »

As said before most B thruster units are noisy :(

The latest idea is to inject air into the truster tube thus creating a damper action reducing the noise.

Yes I know it sounds way out but it works, its not enough air to cause loss of thrust through cavitation but just enough to stop the water hammer effect from within the thruster tube.

As for in the model world I have yet to get my Tito Neri thruster quiet. I run it through an ESC now and with 6 volts but at the full power end it's well like a jumbo landing ;D

Wrapping foam around the tube and bottom of the motor has helped
R,
Logged

ianb

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 76
  • Location: Japan
Re: Graupner Bow Thruster
« Reply #5 on: March 18, 2008, 11:50:02 AM »

Well, it seems that:
a/ Full size and model bow thrusters are noisy
b/ If I cut the voltage I cut the efficiency
c/ I may have to live with it

I may take FLJ's suggestion and cut the tubes on either side of the motor and fit soft tubing as an isolator. At least then I could get at the motor mounting screws if service is required!

I'll also try wrapping foam around the tubes and motor bottom as suggested by catengineman.

I do feel that Graupner could put a warning on the Bow Thruster box "This unit is really noisy". Doesn't the EC regulate that sort of thing yet?

Thank you very much for your replies.

Ian
Logged

FullLeatherJacket

  • Guest
Re: Graupner Bow Thruster
« Reply #6 on: March 18, 2008, 12:46:51 PM »

I do feel that Graupner could put a warning on the Bow Thruster box "This unit is really noisy". Doesn't the EC regulate that sort of thing yet?
Ian

Only if it contains lead or interferes with that 21st century Grand Deity, the mobile phone, apparently.........
FLJ
(Cynical? Moi??)
Logged

portside II

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,519
  • tugs at rest
  • Location: Howden.East Riding of Yorkshire.England Near the banks of the river Ouse
    • goole model boat club indi site
Re: Graupner Bow Thruster
« Reply #7 on: March 18, 2008, 05:19:32 PM »

I had the same prob with that thruster on one of my boats .
the soloution i found was to fit an esc in to regulate the speed and the noise ,
worked for me.
daz
Logged
I like to build my boats to play with, not to just look pretty,so they dont !

boatmadman

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 2,721
  • Location: South Cumbria
Re: Graupner Bow Thruster
« Reply #8 on: March 18, 2008, 11:33:37 PM »

Hmm I just bought one of those at Epic last weekend, although I always intended to use an esc on it.  O0
Logged
if at first you dont succeed.....have a beer.....

catengineman

  • Guest
Re: Graupner Bow Thruster
« Reply #9 on: March 20, 2008, 04:50:33 PM »

In reply to ianb,

Yes the B thrusters are noisy
With an ESC in the system you wont loose too much power and I found that it was more to scale than the full power on from battery mode did.
Afraid that we do tend to live with the noise but I seldom need to use the B thrust anyway, other than the occasional burst to correct my crap steerage :D

R,
Logged

Ghost in the shell

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 2,707
  • Go Nuclear! you'll love it
Re: Graupner Bow Thruster
« Reply #10 on: March 20, 2008, 11:05:45 PM »

another source of the noise is probably from the paddle wheel that they have, water washing over the ends of the blades as they spin round
Logged
"xxxxx" the tree huggers, GO NUCLEAR

ianb

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 76
  • Location: Japan
Re: Graupner Bow Thruster
« Reply #11 on: March 21, 2008, 01:47:25 AM »

Well, I re-connected my bow thruster using 6V output and an ESC. That was easy using the Action P93 and, no, I don't have any shares in Action Electronics!

I then cut the center section of the bow thruster free and put soft rubber tubing to isolate the motor from the hull. So far no leaks, but I'm keeping my fingers crossed.

The results of these mods were:
       much improved control over the thruster output
       plenty of power if needed
       significantly quieter operation
       a  modeller who isn't embarrassed to use the bow thruster because of the ungodly noise

This happy camper thanks you for all your advice and help.

Ian
Logged
Pages: [1]   Go Up