Well the bahner is getting closer to getting on the water..has been a long coming and a shit ton of money..after every thing I have came across still don't have a throttle cable...so my question is what length do I need for my 18 ft bahner?

Find some string run it on the path you want it then measure it.

If your throttle is push style or pull style the cable will be significantly different.

Guessing 1 ft short would suck