Some of those pontificating on the abandoning of the Alpha 42 "Be Good Too" have stated that no boat should go offshore without a standby system for steering.
We have sailed offshore quite a lot, and have met many others doing same, and I have never seen such an animal
Lots of us have standby tillers which will take over if the wheel, hydraulics, cables or whatever break, but I have yet to see a valid substitute for a broken off or irreparably jammed rudder.
We did once steer our (then 90% complete) 47 footer 3 miles across a calm lake at 3 knots with a rudder made of a 16 foot 2 by 4 lashed to the transom with a "blade" made of 2 ft by 4 ft plywood.
It worked, but was amazingly heavy to steer, despite an 6 foot long tiller arm, and only marginally effective. It would have been useless in a seaway.

Does anyone have a practical solution for jury rigging a rudder?
(Sail balance and drogues are well documented, and useful, so no need to discuss here)