I just started to build a dumas cobra and are planning to run it with a titan 550 motor, I was wondering what kind of battery I should use? Also, planning to run it saltwater I was wondering how to seal the hull and what prop to use for fas planeing ride and 10-20min run time?

well I wouldnt advise running in salt water, but I do it sometimes. Your epoxy coat better be thick on the wood hull. Also the boat needs to be really sealed. Your going to need to rinse it off after every run. Your going to want a graupner or dumas prop, probably 3-blade. Titans run 14.4v's right? so youll need 12 cells, preferably gp3800's which you'll need to assemble, with battery bars.

I dont think I can fit 12 cell, what motor/prop/battery combo should I use for run times 7-20min. Needs to be 6-7 cells.

Ill take that back, I think I can.