use of carbon fibre to control the rudder?

[Dave Pickett]

Can someone confirm whether I can use a carbon fibre rod between the servo and rudder as a control rod? Couldnt see anything that referred to this in the rules!

[Barry Fox CAN262]

From my understanding, not the official word, for your boat, based on the pictures I have seen on another posting, the answer would be no because it will go through the deck/hull to get to an above deck rudder arm on the rudder shaft.

D.2.3 FITTINGS
Fittings are unrestricted except that:
(a) Fittings that can contribute to the stiffness and/or strength and/or
watertight integrity of the hull shall be of materials permitted by D.2.1.
(b) Ball and/or roller bearings may only be used for: sheet control line blocks,
mainsail boom sheet blocks and headsail boom sheet blocks.
(c) Fittings shall not project outboard of the hull shell or deck.

It is a fitting and by going through the deck it can (will) contribute to the watertight integrity of the hull so it must be of one of the approved materials.

That's how it was explained to me.

[Dave Pickett]

Thanks Barry. Thats the problem with rules I guess - I am sure it could be arugued that the control rod does not stiffen the hull and equally coming through the decks it has a negative impact on water tightness!

no matter, seems I have 2 options:

- use a metal control rod above decks
- use carbon fibre rod below decks, which would involve shortening the rudder tube significantly. This could be addressed by using a ball race or similar bearing above decks - quite like the idea of this.....will think on.

[Hiljoball]

- use carbon fibre rod below decks, which would involve shortening the rudder tube significantly. This could be addressed by using a ball race or similar bearing above decks - quite like the idea of this.....will think on.

Ball race on rudder is not allowed. (See IOM class rules D 2.3.b which lists various sheet control fittings as allowed to use ball bearings - the absence of permission for the rudder post is the issue)

John

[Barry Fox CAN262]

I use this stuff all the time to come up through the deck.

http://www.sullivanproducts.com/GoldnRodContent.htm

hobby shops that do model airplanes should probably have it. On line you can get it from places like Tower Hobbies (and many others).

[Dave Pickett]

Ah I was reading D2.4 ball bearings may be used in the rudder control unit and the sheet control unit.......

I was taking the control unit to mean the servo and linkage etc, if they mean SERVO why the hell dont they say SERVO!!!!!!

anyway yes I have used flexible controls back in my model aircraft days and it is a solution, but not my favourite as it does absorb some of the servo effort.

I may still look at the carbon fibre rod under deck with some other form of bearing on top of the deck, or indeed a flexible control.

Thanks for your clarification guys.........

[Bruce Andersen]

might look into dual rods (push-pull) if you're worried about a single push rod bending too much

[Patrick Parisienne]

I wouldn't bother with a push-pull arrangement, a single arm will be fine. The rudder in an IOM doesn't come under very big loads. As you can see, a 1.6 mm stainless steel wire suffices for many IOM designs worldwide, so a single carbon (or fibreglass) rod will be fine.....

I use a single carbon rod (6mm square) in my Ten Rater. Even with the speed, and loads associated with these rockets, in 2 seasons of racing, I've never had any dramas with bending, even though the arm is 400mm long.

Cheers,

Pat