thicker rudder and a construction idea
Never seen those offsets myself. Only the general dimensions.
You can find controversy as those drawings in the Manual also imply that a wider rudder WAS once planned for the Ariel and maybe the Triton.
But of course the shoe only allows a 1" shaft. And therefor a thin rudder.
Pics of the traditional plank rudder show them to be no more than an 1 1/8" thick. The rudder would have to be almost totally flat and of consistent thickness to be built with the internal fastenings as we know them.
The finished rudder is skinny and relatively light.
There is no reason imco that a heavier rudder couldn't be built.
The only problem is holding back the bulk at the shaft so that the rudder can be swung. The traditional rudder has no problem going the full sweep of the tiller in the cockpit.
Don't know that the extent of that sweep has been translated to how much there is to the rudder on the keel. Any thickness at the shaft obviously will limit its swing because the rudder is inset into a cove on the 'keel post'
Can relieve the rudder wood at the shaft back so that the swing is maintained.
But that will change the flow of the water off the underbody onto the rudder and might create eddies or turbulence over the blade. Don't know.
A thicker rudder will ease the fitting of the planks together.
Imco a rudder made of thicker wood begs that the rudder sides be shaped into a bit of a modern foil.
Imco a keel hang rudder uses only the trailing HALF of the modern wing foil. An easier shape to introduce onto the rudder.
The curving of the trailing half of a foil is rather mild.
However a trailing foil wants to be thin. And that is a real problem with a round rudder.
And maybe the reason round rudders are left flat.
I think a more efficient rudder can be shaped, one that is less likely to cavitate. Don't know if this has been observed as a problem with A/Cs.
With curved sides the thickness can be carried further aft which may allow the third plank out to be fastened differently.
(Slightly different construction method.)
IE, if the third plank does NOT have the long rods that go thru the second and first to the shaft, why can't the third plank be permanently glued* to the second? Could be slipped over a couple blind bronze pins for reinforcement. And if things work out could allow carving down the trailing edge SOME.
When building the plank rudder the nuts on the ends of the the long rod/bolts/allthread need not be buried in counterbore holes. The nut and washer and bolt ends can be notched into the second plank. They would be totally exposed in open square cutouts - tightening, loosening and adjusting at will. When the rudder is finished, the square holes can be filled and faired with non-hardening putty. When painted the holes will have disappeared.
Later when maintenance is needed and the paint is removed, the major fastenings will be right there! The nuts could be backed off and the blade taken off the shaft without an act of congress.
This is imco - I haven't done this, but it appears feasible. Putting this out for discussion.
The traditional rounded rudder however goes back to a time before rudders were hydrodynamic. It might be too difficult to give a foil shape to a round rudder.
Anyway, with thicker planks some more dynamic but mild curves might be added to a new but traditional blade.
Might entice the Ariel/Commander to go a little faster and enjoy a little more control.
???
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* The traditional rudder is NOT glued anywhere - giving individual planks some room to move. The usual 3 planks are generally of equal width, about 6".
The original rudder was assembled DRY, altho they may have used a thin coat of bedding compound on the edges and certainly at the shaft to plank join.
However, in this case, the suggestion is to glue on the 'third plank' - the outer and smaller PROBLEM plank. It interferes with no clamping threaded fasteners, not even screws. It is free to swell and shrink.
The middle plank could be an extra wide plank incorporating the third plank. A two planker,
But clamping nuts and washers introduced into the outer edge of a less wide second plank is easier, The same ease of assembly and disassembly of the rubber blade could be achieved in a very wide plank by mortising out the access holes at about the same distance out if a three planker.
So much easier to bore long centered holes in less wide material.
Resorcinol is the perfect underwater bonding glue for mahogany. Maybe a rubber adhesive could be used....
