T12 has keel following wooden sealing boards which are original I am sure.
In theory they are great for hydrodynamics, water sloshing control and automatic operation.
In reality I am yet to be sure they fully close the keel slot (and thus improves hydrodynamics) but I will check when she is in the water next year.
They also require maintenance every year; due to lots of moving parts combined with antifouling/wear issues.
I may convert the current system of bungees and multiple sheaves to deploy the strips, into something more manual, but more positive. Hopefully this would make them feel more beneficial.
Best of all would be GRP followers, the aft end of which is forced, and then locked down to the hull line with some sort of strut. Possibly you could use a long gas strut with an extended underwater actuator arm. Or a bit of batten with holes in it that you lock into place on the rear bulkhead.
George