Model Boat Mayhem

The Shipyard ( Dry Dock ): Builds & Questions => Yachts and Sail => Topic started by: Lochen on February 09, 2010, 03:48:29 PM

Title: Rudder only servo.........?
Post by: Lochen on February 09, 2010, 03:48:29 PM
Ive seen a picture somewhere (only now I cant remember where, or find it) of an rc yacht with only a rudder servo...............

I have this 40" model I was given which is currently fitted with a Braine steering gear. I rigged it the other day and took it to the local pond. Dull or what? Put it in the water, walk to the other side, turn it around, walk to the other side, turn it arou.................

Anyways.........the yacht looked marvellously majestic under sail but wouldnt it be nicer if she was controlled from the bank.... So I got to thinking about this rig I'd seen where a servo is connected to the Braine gear and controls only the rudder (presumabely the sails are just set to 'requirements of the wind'). At the end of the session, theservo fitting is removed and the yacht returns to 'original' build.

Has anyone done this? Is it feasible to have rudder control only? I assume sailing a model follows the same principles a sailing the real thing, bring her head through the wind and let everything 'slide' over to the other tack.

Does anyone have any pictures of a similar rig?

Reason I ask is that Ive more or less established that the hull was probably built in the 1920s ad I dont want to be drilling it and permanently fitting stuf to it

Many thanks in anticipation.

Title: Re: Rudder only servo.........?
Post by: malcolmfrary on February 09, 2010, 09:02:45 PM
If you've managed to get a Braine gear working properly first go, well done.  In fact, very well done.  Normally its a fact of life that a boat so equipped will only sail straight and true when it will give you the longest possible walk, or if its breezy, run, because it "knows" that you have to go 400 yards for every 100 it does.
Usually the rudder on a self steering boat is intended as a trim tab to keep the boat sailing straight, rather than steering.  Having said that, many sail their yachts with steering only.  There is a body of guys at Fleetwood who insist on it as a local class rule, usually involving multi masted boats using redundant racing hulls. 
It might be a good idea to start with the sails let out to about 25-35 degrees as a starting point.  Like that, you should be able to perform all the usual manoeuvres reasonably.
Title: Re: Rudder only servo.........?
Post by: Lochen on February 12, 2010, 07:59:13 PM
Thanks for this information. Braine gear working first time?? went in a straight line in light airs for the length of the pond after a bit of fiddling to stop it going in circles. Then it went the length in the opposite direction.

It seemed odd though, the only way to make the rudder less affected (so it would traverse a straight course) was to adjust the steering lines so the yacht ended up close hauled and hence no further adjustment was available via the main sheet. (ah, I've just remembered, there is no elastic to centre the rudder, this could be it?)

My guess is that this definiton of 'correct setup' is by fluke and the elastic is the issue here. I've scoured the internet to no avail.

Title: Re: Rudder only servo.........?
Post by: malcolmfrary on February 12, 2010, 10:32:08 PM
The elastic band, or spring, or similar, is crucial, and leads to much trial and error.  The idea of self steering in those days was to sail close hauled on one tack or the other to get one way up the pond, then unhitch it to run downwind.  It could be that the setup is inherently fairly stable.  The fin, or keel, is probably a long shallow one.  This is a great aid to straight running, but inhibits steering somewhat.  Adding a radio box to work the tiller might not give the full control of a full RC yacht, but you should be able to offer it meaningful suggestions.