Composite rudder stocks

[james h]

Hi
I have a 2008 Leopard 46 that needs new rudder stocks
Has anyone ever considered doing these in G11 composite?
It’s strong as hell and not prone to corrosion
Good idea or bad?
JH

[tcpbob]

yeah, i have composite rudder stocks but no idea what G11 is. they have been ok except they had to be altered at the top as the pin split them. the fix was quick and easy so all good now. my cat is rather light weight compared to a leopard but if stock is the right dimension and thickness... should be ok.

[Chotu]

I think maybe OP means G10 tubing or shaft.

[Breaking Waves]

Originally Posted by Chotu

I think maybe OP means G10 tubing or shaft.

G11 is a thing . I see there is even g12 and g13 which I did not know.

For the OP - it is really simply a matter of proper engineering - understand the loads and make it strong enough and it will be ok. Carbon would be the preferred performance solution but short of that, you can do pretty much what you want so long as it is properly engineered. Some high production boats have had e-glass shafts, some of them have broken but root cause generally because of poor lamination rather than the fiber.

[redneckrob]

Originally Posted by Breaking Waves

G11 is a thing . I see there is even g12 and g13 which I did not know.

For the OP - it is really simply a matter of proper engineering - understand the loads and make it strong enough and it will be ok. Carbon would be the preferred performance solution but short of that, you can do pretty much what you want so long as it is properly engineered. Some high production boats have had e-glass shafts, some of them have broken but root cause generally because of poor lamination rather than the fiber.

When you say e-glass shafts do you mean the prop shaft? Do you remember what models, the gearhead in me is intrigued and wants to learn more!

[cal40john]

Probably people have figured out how to properly engineer it, but this always makes me think of Fastnet 79 where several composite shafts broke.

https://www.boatdesign.net/threads/c...-shafts.16573/

[mlydon]

Out of curiosity, what are the original stocks made of?

[fxykty]

SS or Aluminium shafts are well known and easy to engineer, while composite shafts are still custom jobs that depend on the skills of the builder. Why not replace with a copy (or upgraded copy) of the original shafts?

[Tetepare]

G11 is still substantially heavier than foam cored.

[malbert73]

I’m having a replacement rudder made by OEM manufacturer (tartan) after my original 1987 rudder is showing signs of water ingress and internal corrosion. They are making it with a sleeved carbon fiber rudderpost (as they do for all of their current models in the past decade).
Benefits are a stronger rudderpost, but mostly that the rudderpost can actually be bonded to the blade in a monocoque way to prevent water ingress.
A metal post will always eventually leak water into the blade but with flexing of the blade while sailing.