ChrisC
  • ChrisC
  • Advanced Member Topic Starter
2009-01-22T16:09:18Z
Previous topics have mentioned the use of a rudder addition that is short enough to allow the boat to dry out on a mooring but long enough to provide some directional stability when the boat is floating with the keel down only a foot. Has anyone got any info on the actual arrangements of such a keel stub, please, such as dimensions, material used, method of attachment/deployment etc.

Many thanks

Chris Cobb

235/48 "Tarakihi"

Geoff Harwood
2009-01-28T17:36:08Z
On my 21, which I think has the same rudder arrangement as the 235, I made my "harbour rudder" the same size and shape as the stock and pivoted on the same bolt as the main rudder but outside the stock so that it lies alongside the stock when up. The original 10mm plywood one broke so the current one is 10mm PVC.
ChrisC
  • ChrisC
  • Advanced Member Topic Starter
2009-01-29T15:18:05Z
Geoff,

Thanks for info - I'm surprised that 10mm PVC is stronger that ply. Did the ply blade break across the pivot hole? How far did the blade extend? We leave about a foot of keel down, so I was thinking that a blade extending to match this depth below the hull would be about right i.e. probably about 2 feet in the water.

How do you stop the blade dropping down when not in use? Is the pivot nut sufficiently tight to prevent this?

I know that boats with rudders that lift vertically use a shorter stub rudder when on a drying mooring. I thought that I might try to contrive something similar for the 235 by attaching some slides on one side of the stainless steel rudder housing but this is still at the "idea" stage pending some inspiration on how to attach the guides to the rudder box and also making them stand off sufficiently so that the stub rudder clears the pivot nut. I don't think slotting the stub to clear the nut would be very strong or hydro-dynamically efficient!

Chris Cobb

235/48 "Tarakihi"

Geoff Harwood
2009-01-30T15:34:03Z
Chris,

The PVC is the stuff that they make big photo processing tanks out of - not the soffit stuff that's either foam or hollow. It would take some breaking. The ply version snapped off at the stress concentration at the bottom of the stock.

Mine is 21 inches long from the bolt to the bottom and is just about level with the bottom of the motor skeg. It stays up by gravity since the bolt is well aft of its G of G.

Harry Wyatt made a drop-in-a-slot harbour blade for his 27 Ariel of Wick which gave me the original idea. I don't remember how he got it past the bolt head.

Cheers, Geoff