Hello all, I have an Aquacraft Wildcat I am upgrading and below is where I am at. I am loosing prop shafts and need advice how to prevent this in future. I do not know if it is a normal wear & tear issue or do I need to upgrade based on my upgrades... I am waiting on a new flexshaft and I have to fiberglass the wildcat hull before she will be ready again but will be fun making her over.

Wildcat - Hull untouched, stock driveshaft, Atomik Vr500 2000Kv outrunner, Proboat Stilleto 60amp Esc, removed one turn fin, aquacraft screw type coupler

Props used:
Grimracer - 44x66, 42x66, 40x52(trip) & 40x57(trip) - all useless
Octura - 440(trip), 442, 645

Octura props worked well after many many balancing/sharpening attempts... Bought a grimracer prop balancer instead of the little cheap one & it has been much better for this. Eventually got the boat to stay fairly manageable at full throttle and it ran very well. Only used 3s(Floureon 30c 4500mah). It ran the best on the Octura 645 but halfway through the run it tore the prop shaft off at the coupler. Lost the prop as well of course on the FIRST RUN!! It did have dents from screws using the old coupler so that may have weakened it? But have no idea. I have to fiberglass it before I run it again as it has a tear in the rear starboard corner that will not hold together by plugging it. I do have some gflex thickened epoxy I could use to plug it but i think I will be better off laying glass on the hull except the bottoms of the sponsons(has run pads) to give strength with the new speeds I expect out of this boat.

SO I would like to run the bigger prop but think this will be an issue with the stock flex cables. Any recs would be greatly appreciated!