Weight at minute.
So they have a 1 lb tank screwed to the motor. So if we put a 20 lb barbecue tank in the boat, the range is quite a bit further.
Just recently filled our 20 lb grill tank. Was about $38 total. And weighed in the neighborhood of 34 lbs. I am not sure what the range would be on a 20 lb bottle. Probably quite a bit considering those chinese motors are small (10 hp and less).
So if I took my 9.9 'Rude and put a gallon of gas in the 3 gallon tank, and ran it about 9 miles wide open (roughly the mileage it takes to run a full gallon out of it), it's STILL cheaper than propane. $3.10 a gallon + 2.5 oz of oil (which is basically a few pennies), so figure $3.50 a gal for premix fuel. And it's only about 6 lbs of fuel + 5 lb for the tank (total 11 lbs). And I can fill it ANYWHERE along the way, or stop at the marina and pay $5.50 a gallon for 50:1 premix, which in that case is still probably cheaper in the long run.
Interesting concept, but a flop in my opinion, as long as gasoline is "cheap" (which is currently still about $2 too high per gallon).
Nat Gas is the same way. Trucks have been converting recently here. Lots of them. Up to $10,000 investment to convert one, depending on the model. How long does it take to get a return on that investment? Considering the range on gasoline is about 350 miles and the range on nat gas is about 150. Nat gas is 1.99/gge as of yesterday; gasoline 2.98/gal. Kind of like diesel vs gas. Only fleet vehicles actually see a return; the rest of us are wasting our money.
Then the issues with propane (or LP as we called it for years). LP tends to create acids in the crankcase, and we all know that outboards tend to sit around a lot. Letting an LP engine sit without fresh oil is a no-no. Have seen it with Fork Lifts that have set for long periods of time. I believe engine oils are really the culprit in those cases as most people just use the cheapest or easiest they can find. Some oils don't work well with LP. Also valve seats....LP has almost zero lubrication for the seats, and in cases like these, I really like to see HARD seats (stellite). Lots of headaches with propane for sure. Not worth it in my opinion. Same for nat gas. Nat gas is for heating houses and making electricity, at least until an internal combustion engine is actually DESIGNED to run it, and last 200,000+ miles.
I just can't see LP or nat gas being feasable for small outboards. Larger cruise boats and freighters, perhaps. Especially considering the "clean burn" characteristics and the relative difference between small outboards and a big V8 (or V12, V16, V20, etc).