As far as Graupner goes, they don't even use a stinger or strut on their hulls. I also don't see trim tabs. There appears to be only one turn fin if I am seeing correctly. A solid straight shaft is used with a solid coupler. Plastic Flexible Rudder.

I'll show him where there are plenty places to purchase quality harware. We simply have not got that far.

Higher Voltage does not increase heat, it is current that controls heat. If there is too much heat you are drawing too many amps.

By The Way, I missed the post where you attached photo's of your prop shaft exiting. If you decide to use a 39mm prop, good luck with achieving any type of speed. That is far too high as only 1/3 of the prop will be in the water. I'd suggest patching the hole and re-mounting it as per my previous recommendations.

Ryan