no you dont need two of them. and yes it does plane off. with two people about 550lbs combined weight 40 gals fuel all your basic gear anchor ropes bumpers cooler beer ice ect. with a 13by15 prop planes off about 2800 nice cruise at 3800 wot 5100 willthis go up after break in? will have gps #soon my guess 28 to 30 quiet and seem to be easy on fuel sweet trolling motor so far pretty good first shark trip aug 12