Some Fireflies (post Fairey) have a lined case with a laminate lining. I don't think this is too bad an idea. I reckon it must make it easier to pull up the plate and should last longer as it provides good protection to the wood.
Do you still have the little roller or bearing that sits on the bolt and takes the plate on it? These are a sod to replace if lost or worn out. If you have the original one.....then it might be a bit on the wide side if you are re-building your case and trying to build it as thin as the class rules allow. You used to be able to get them from Tony Pink who had had some made up in nylon at Hillhead marine.
Ed,s queries though I don't claim to be a rule expert or measurer. I took a quick look at the class rules relating to the plate and would note the following:
1) A "non-metallic" liner is permitted to the inside of the plate case of
not more than 1.5mm thickness. I think this rule was introduces to allow racing pundits who had lined their plates with formica to stay in class.
2) The Internal width of the plate case is 16mm +/- 3mm. (A surprising degree of tolerance I thought. Presumably A minimum of 13mm is desirable but anything less
willdisqualify the boat even if you try to line the measurers pockets with gold. (Which as noted in (1) would also be an illegal plate case liner)
3) The Plate thickness may be between 7.7-8.3 mm. Presumably to allow for anodising processes.
4) If you have a "Slotted" plate the rules appear to specify that you
must have the roller. The new fireflies have no slot. Just a bolt hole so there is no possibility of fore and aft movement and I suspect a much bigger jolt when yu run aground. The advantage is that they dont drop out when you turn turtle which is much more likely in a Mark4/plastic boat as they are so much more bouyant on the capsize. I live just round the corner from Hillhead marina and could check out the supply if you like. (Unfortunately Mr Pink has passed on and his wife (who was always good for a wind up if you talked about the new mirror bermudan rig!) sold the business but the new chap is very keen and may be able to help.
5) finally, No restriction of the plate movement is allowed. ie: I suspect anything that allows a hint of a "jybing" plate will not be acceptable, although I wouldn't put it past some clever fellow to build up layers of epoxy on the inside of the plate to allow some degree of windward feathering to improve upwind performance. Remember these are relatively slow boats so small improvements in boat speed are critical.
). 
