Yep, the rudder is carved from 8mm ply down to an airfoil shape of about 3mm maximum thikness and the turn fin is 1,5 mm ply. The rudder is strong enough to have been digging the lake's bottom when returning to the shore (no damage yet-fewwwww...) but I don't know if the turn fin will handle the forces appearing at higher speeds (cause I'm planning to go brushless)
The strut is fixed, simply epoxied on the hull and that might be a weak point when it comes to tuning.
By the way, I found at my local store the Supervee27 brushless motor and ESC as spares, total price with cooling jackets should be about 150$ and I'm thinking of that option. I am now using 6 cell packs on this boat, but if I go for the Supervee powerplant I could find place for two 5cell packs in the rigger's hull, making for a total of 10 cells. I think it shouldn't be bad in terms of power, considering that the boat weighs in at 1 kg with the 6cell pack and with 10 cells it would be 1,25kg to say the most (while the supervee27 uses 12 cells, but weighs almost the double!). My concern has to do with boyancy: will it jump out of the water when I hit the gas or will it become a U-boat-rigger and head for the bottom of the lake?...
Does anyone have experience with overpowered, overweight hydros or riggers? I should first look for some feedback before investing, I guess..

Be well, be fast!
Andreas