suggestions/advice anecdotes on how to jury/jerry rig a rudder on an unltd (SIC in this case) when the steering fails.
I am not asking for when the entire rudder fails or falls off - assume one just "bobs" - but rather ideas on how to jam the rudder when the steering has failed (broken screw, snapped cable, cable jumping loose from rudder post, etc). A board is very ungovernable when the rudder is "free" & pivots... being able to jam it gives significant control but how best to achieve that in rough water, 40kts of breeze & crew disappearing over the horizon.
Anticipating your collective wisdom...

I use the tiny plastic wedges you get from the Hardware store that tilers use to keep tiles spaced. Always have 4 of them in the pocket of my boardies. You don't even know they're there.
If needed, you just wedge them in the front of the rudder (between the bottom of the rudder and the board) and the back on both sides and it keeps the rudder fixed in place well enough to get you in.

This has been my solution. I have fixed the 'carbon fixing plate' permanently onto the rudder mechanism (I actually prefer it as occasionally I am standing on it in big conditions and prefer the feel of it. In addition means with a quick look back, I know that the rudder is aligned).

I then keep one of those supplied bolts (though with the plastic head epoxied on) attached to a loop which I keep in my baggies or lifejacket. In two years I have never had any problems but in yesterday's DW race, as murphy would have it (and surprisingly large waves to paddle through on the beach launch), the rudder came loose (I wish SIC would sort out those plastic headed bolts - seems so out of tune of the rest of their board design which is so clever). I first buggered around and stopped 2 times in the first 3 or 4 km to re-align the rudder. Eventually after a bit too many broaches (22-24knot averages in big swell), I decided to toss the race and fix the rudder. Wish I have done so previously as was surprisingly easy to fix and it works very well. The rest of the 7 km was then catch up, nowhere as close to top speed vs the rudder, but still managed a respectable 4min45s km's on 10km.

Without the rudder, on a 17' Bullet, is a bit of a pain as the board is so long, and one definitely misses the tiny run's as well as the ability to quickly change direction when jumping runs (I did not even realise what a benefit it has been), but the flip side is I enjoyed staying on the back of the board and concentrating on enjoying the glides.

But definitely happy with the solution as fixed rudder is still way faster than a 14footer in case of an emergency, and if I had immediately 'fixed' the rudder, it would not have lost me minutes in multiple stops.