use of carbon fibre to control the rudder?

Discuss the IOM class rules and interpretations

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Dave Pickett
Posts: 107
Joined: 18 Oct 2010, 19:33
Sail number: GBR3845
Club: Eastbourne
Design: TS2 and Shiraz

use of carbon fibre to control the rudder?

Post by Dave Pickett » 06 Apr 2011, 22:27

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
Posts: 354
Joined: 21 Apr 2007, 17:54
Sail number: CAN 46
Club: VMSS
Design: V8
Location: Vancouver Island, BC, Canada

Re: use of carbon fibre to control the rudder?

Post by Barry Fox CAN262 » 06 Apr 2011, 23:28

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.
Barry Fox
CAN 46
Vancouver Island, BC, Canada

Dave Pickett
Posts: 107
Joined: 18 Oct 2010, 19:33
Sail number: GBR3845
Club: Eastbourne
Design: TS2 and Shiraz

Re: use of carbon fibre to control the rudder?

Post by Dave Pickett » 07 Apr 2011, 13:58

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
Posts: 271
Joined: 06 Jan 2006, 00:47
Sail number: CAN 307
Design: V8
Location: CAN

Re: use of carbon fibre to control the rudder?

Post by Hiljoball » 07 Apr 2011, 15:40

Dave Pickett wrote: - 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
John Ball
CRYA #895
IOM CAN 307 V8
In my private capacity

Barry Fox CAN262
Posts: 354
Joined: 21 Apr 2007, 17:54
Sail number: CAN 46
Club: VMSS
Design: V8
Location: Vancouver Island, BC, Canada

Re: use of carbon fibre to control the rudder?

Post by Barry Fox CAN262 » 08 Apr 2011, 06:38

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).
Barry Fox
CAN 46
Vancouver Island, BC, Canada

Dave Pickett
Posts: 107
Joined: 18 Oct 2010, 19:33
Sail number: GBR3845
Club: Eastbourne
Design: TS2 and Shiraz

Re: use of carbon fibre to control the rudder?

Post by Dave Pickett » 08 Apr 2011, 15:06

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
USA NCA Officer
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Club: Famous Potatoes Sailin Club
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Re: use of carbon fibre to control the rudder?

Post by Bruce Andersen » 10 Apr 2011, 00:33

might look into dual rods (push-pull) if you're worried about a single push rod bending too much
Bruce Andersen - USA 16

Patrick Parisienne
Posts: 10
Joined: 01 Sep 2010, 09:04
Sail number: AUS 38
Club: Albert Park Model Yacht Club
Design: Obsession

Re: use of carbon fibre to control the rudder?

Post by Patrick Parisienne » 12 Apr 2011, 10:04

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

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