Very close to doing the same thing. Many people will carry on about the dangers of
propane, but not many people seem to think twice about storing dinghy gas. Gas fumes, just like
propane, are heavier than air and will collect in the
bilge. Also having a dinghy motor that doesn't weight 60 lbs would be a huge benefit. I know the battery won't be light, but you can buy multiple smaller sizes, and they are a much easier form factor to handle than an
outboard.
Torqeedo's look great, but like others have said, the
price is frustrating. Seems they could offer something without the integrated Li-ion battery for a lot less.
So why not trolling motors? A 55 lb thrust
salt water Minn Kota MSRP is $380. The Torqeedo 503 (1.5 hp equivalent) is $1,700. The trolling motor is rated at 50 amps @ 12V, so 600W. The 503 is rated at 500W. That matches with thrust, Torqeedo specs say 40 lbs for the 503, but also say it is measured differently than trolling motor thrust, so add 50% to compare, so 60 lbs. The Minn Kota is obviously 55 lbs.
So what is the difference? Seems to come down to the integrated battery and prop. The Torqeedo uses and 8"
pitch prop turning at 700
rpm. Minn Kota props are 4"
pitch and the motors turn 1500
rpm.
Funny enough, that should just about cancel out when it comes to speed (about 4 kts).
For $2,000, you could upgrade to the 1003, which turns that same prop at 1200 rpm for an approximate max speed of 6.5 kts. This seems the more popular
route.
This has led me to wonder if I could retrofit an eBay-special gas outboard prop (commonly available in 5" and 6" pitch) to a trolling motor. Seems like for $400 + batteries, you could get the same result as the $2K Torqeedo.
Of course, for most situations 4kts would be fine. I worry about that one time you have to fight a 5 kt tidal
current.