EPROPULSION NAVY 6
 
If you've already read about the Navy 3 then you'd probably assume the 6 is just a more powerful version of the same thing. Not unreasonably, they look the same! But if you look more carefully the "bulb" or motor housing at the bottom of the leg is strangely much smaller... because the motor isn't down there on the Navy 6. The bulb actually only contains a right angle gearbox, the motor is up the top with a drive shaft running down inside the leg.
 
That does mean it's a bit noisier than the Navy 3 but the smaller bulb means less drag, and it has a very innovative (and award winning) closed-loop cooling system that makes it very efficient. Closed loop cooling is advantageous because it means no intake to block, and less internal corrosion etc, and it's possible on an electric motor because they generate much less heat than combustion engines.
 
Double the power and less drag, plus the option for a higher pitch propeller, all add up to mean the Navy 6 will get some small boats up to planing speeds - maxing out at about 14.5 knots. You still need to be careful of weight though and if planing is not part of the plan then you'd be better off with the low pitch propeller which is slower but makes use of all that torque that's available. 
 
The Navy 6 price is for the motor only, you then need to choose whether you want a tiller or a remote control, and decide what you're going to do about batteries. To make the best of the motor you really need lithium batteries (allowing a higher discharge rate for longer) and, assuming you go with the Epropulsion Navy batteries, at least two of them connected in parallel.