Model Boat Mayhem

The Shipyard ( Dry Dock ): Builds & Questions => Yachts and Sail R&D: => Topic started by: Patrick Henry on January 21, 2010, 11:39:53 am

Title: Rudder throw on small yachts.
Post by: Patrick Henry on January 21, 2010, 11:39:53 am
Anyone give me an idea as to how much rudder throw I should aim for on my Duplex 575? I guess too much rudder movement will slow the yacht down as it's applied...too little won't turn it?

Would 45 degrees either side of centre be a good start point?


Rich
Title: Re: Rudder throw on small yachts.
Post by: Islander1951 on January 21, 2010, 12:27:09 pm
That's about right, and having a bit too much is better than too little because you control how much you use.
Also having some brakes (hard right,hard left, hard right, etc) can be useful when coming into the bank.
Title: Re: Rudder throw on small yachts.
Post by: Popeye on January 21, 2010, 12:44:57 pm
I was 'taught' that 35 degrees (iether side of Centreline) is the optimum angle.

In the final analysis experiment within the range 35 - 45 degrees to determine what best suits your particular model/s.
Title: Re: Rudder throw on small yachts.
Post by: tigertiger on January 21, 2010, 12:51:44 pm
I was 'taught' that 35 degrees (iether side of Centreline) is the optimum angle.

In the final analysis experiment within the range 35 - 45 degrees to determine what best suits your particular model/s.

35 degrees rings a bell with me as well.

Remember that a race yacht will turn on a sixpence compared to say a working boat. Less rudder is needed.
Title: Re: Rudder throw on small yachts.
Post by: Patrick Henry on January 21, 2010, 01:25:41 pm
That's great, gives me a good point to make a start from.

Gentlemen..thank you all.


Rich
Title: Re: Rudder throw on small yachts.
Post by: BobF on January 21, 2010, 01:33:33 pm
Hi U33,
If you are new to sailing, it is also important that the sails are trimmed so the boat will sail in a straight line without rudder.
Title: Re: Rudder throw on small yachts.
Post by: Patrick Henry on January 21, 2010, 01:36:24 pm
Hello Bob,

I haven't sailed a yacht for years, I did have a 575...ooh, maybe twenty years ago, hence the reason for buying this one. I guess following the plan and the instructions would set the sails correctly?

Rich
Title: Re: Rudder throw on small yachts.
Post by: Popeye on January 21, 2010, 03:17:44 pm
35 degrees rings a bell with me as well.

Remember that a race yacht will turn on a sixpence compared to say a working boat. Less rudder is needed.

What I have found critical in respect of scale yachts is the size of rudder: a scaled down rudder is often too small to effectively control a model so I always make provision  for a slip- on extension  (or two, including a spare)) at the time of the rudder's fabribication. 
Title: Re: Rudder throw on small yachts.
Post by: Patrick Henry on January 21, 2010, 03:51:22 pm
I've made up a new rudder for the 575 as the old one was split, so I've made a slightly longer and slightly narrower one, based on the one fitted to the 590. How it works we shall see later...much later!

Rich
Title: Re: Rudder throw on small yachts.
Post by: Jimmy James on March 03, 2010, 09:00:08 pm
Most scale boats need over sized rudders to give good control with 35 to 45 deg of throw :-))
Freebooter
Title: Re: Rudder throw on small yachts.
Post by: malcolmfrary on March 03, 2010, 10:09:26 pm
If 45deg is too much, the answer in in your right thumb - dont shove it as far.  You can always compensate for too much travel - the same does not apply to too little, you have to do some rebuilding.  Anyway, a rudder with healthy travel is good for sculling it back in when becalmed.
Title: Re: Rudder throw on small yachts.
Post by: Jimmy James on March 07, 2010, 08:28:38 pm
A lot depends on the type of rudder ie: Balanced, Semi Balanced, Plate, Raked, Narrow or broad, But the rule of thumb with a sailing model is over sized is best ---- Remember the model might be to scale but the water and wind isn't  :-)) O0
Freebooter
Title: Re: Rudder throw on small yachts.
Post by: tony23 on March 13, 2010, 06:47:53 pm
 you can have too much rudder travel I know whats been mentioned here that too much can be controlled by the thumb but thats wrong as you will from time to time over kill the rudder with that much travel. Use 30/35 degrees or about 30mm travel each way from centre to be right also for a sailing yacht you should put in between 30-40% expotential in the rudder so it's not so lively as soon as you start the turn that way you will not slow the boat down.