Originally Posted by colemj
The first part is understandable, but how do you reinforce rudder shafts without changing their dimensions and requiring a complete redesign/refit of the steering?
I don't know exactly what he did . . . but three possibilities come to mind.
1. I am assuming these are carbon shafts, and there are lots of grades of carbon/epoxy. In particular there are some epoxy
nano resins that greatly increase laminate 'toughness'. That would be an easy upgrade.
2. It may normally be a hollow shaft, and if so there would be room within the spec dimensions to make thicker walls
3. They could have had the shaft diameters increased with correspondingly larger rudder bearings and tiller arms. That would not be all that hard or expensive. We in fact did it on Hawk, increasing the rudder shaft diameter from 4" to 5", which provides an extraordinary amount of extra strength.
Note: the owner is probably not short of funds, as he is described as a "swiss hedge fund investor". He might well have asked a NA 'what can I do to get stronger rudders' and they might well have done all three above.
With carbon rudders in the ice, I might be tempted to carry a spare, as their failure model is essentially only to explode. I think a 'cassette system' would be the most preferred solution in this case, but that's way more design and engineering change to most existing designs, and probably usually not as practical a change as the above three.
Metal rudders have much nicer failure modes (bending and denting rather than shattering) . . . . but heavy. A light carbon rudder for Hawk is about 40lbs, where as our 'ice class' aluminum
one is +100lbs, so you could carry a spare carbon one and still be ahead on weight (but of course changing it in arctic waters would possible but no picnic.