Best type of wood for rudder

[shaqra]

Hi
I'm thinking of getting a spare rudder made during the winter, which type of hard wood would be most suitable?? Its for an Etap22.
Thanks

 

[richardabeattie]

grp

 

[shaqra]

Its already made of GRP with a foam like filling. I have repaired it a number of times, i.e cracked at the seams, its 1982 vintage. I would like to get made a stronger one to be on the safe side.

 

[simonfraser]

ply / epoxy

 

[Alfie168]

Seconded Definitely ply/epoxy sheathed.

Tim

 

[VicS]

[ QUOTE ]
Definitely ply

[/ QUOTE ] Bearing in mind that fact that only half the plies would have their grain running down the blade if it is cut "with the grain" would you cut it at 45º to the grain to improve its strength.
The reason I ask is that I was recently invited to comment on a rudder that had been modified from a fixed solid wood blade to a lifting blade (pivotted) which had failed due to the fracture of one of the ply cheeks. That was in fact only a contributing fact the whole thing was badly made and quite obviously not strong enough. I suggested that it would have been stronger if the cheeks had been cut diagonally. In the event the replacement was made to the original fixed design as far as I know.

 

[oldsaltoz]

G'day Paddy,

Have you looked at the total cost of a spare rudder? Will you need a new rudder stock as well? could be expensive.

If the existing rudder is splitting at the seams I would be looking for a cause.
Are you cleaning down properly prior to repairing,

Are you using an epoxy resin AND cloth designed for epoxy resins (Not CSM).

I have yet to see the rudder that could not be made stronger if not bullet proof by adding more glass.

Avagoodweekend......

 

[William_H]

For the rudder blade I would suggest wood with fibreglass sheath. Now what I have in mind is fairly thin wood and massive layers of fibreglass. Like fibreglass 1/4 inch thick. This could more correctly be described as a fibreglass rudder the wood only being a retained male mold.
If the fibreglass is this thick it can be made from polyester resin. being so thick it doesn't matter if doesn't bond with the wood.(and you can use any type of wood) If you are going to rely on the wood for strength then you need to use epoxy.
For added strength you could get some carbon fibre cloth and strip the threads out so they can be all laid lenght wise on each side of the balde. (between layers of glass) Stiffness is needed in the top half of the balde.

If you need to replace the cheeks of a swing rudder. You might consider welded stainless steel tubing. Mine is made of cast aluminium.
If you use wood then the greatest stress is in the direction of steering the boat trying to open the cheeks apart. I actually fit a bolt through the after part of the cheeks to clamp them together to reduce play and stiffen the whole thing but then I don't raise the rudder except to bring home at winter.
Anyway cheeks can be stiffened on the outside with wood or even welded steel reinforcing which must extend around the front (hull side) of the cheeks to hold the cheeks together.

There is a lot of strain on my rudder being about 1 metre of cantilever rudder from pintles above water line and about 30cms apart.
Incidentally I increased the depth of my rudder and also the "balance" ie area forward of the pintles for vastly improved steering control especially with a shy spinnacker and gunwhale awash.
The manufacture of a rudder balde will involve lots of layers of f/g with shaping smoothing before finishing so it may be expensive to get someone else to do it but ideal for DIY.
PM me if you want to discuss. olewill

 

[oldharry]

I made a new rudder for my Eventide out of 50mm Iroko, as recommended by our local wooden boat building expert.

However, I too am puzzled why you are unable to repair the existing GRP rudder. It sounds a bit as though you are not building up the repair sufficiently.

I would suggest grinding off all the various attempts to repair to get back to the original moulding, then go over the seams with glass woven tape, at least 4 layers, possibly six (GRP experts around to advise?) and using tape wide enough to allow at least 50mm overlap each side to ensure a good strong repair.

I have repaired two rudders that have had seam failure this way which are AFAIK still as good as new.

A lot simpler than starting again!

 

[shaqra]

Thanks one and all for your valuable information. Yes, I realise now, I am not putting on enough resin. Will re-do it during the winter. Thanks again to all.