Electric outboards have been in the market for more than ten years, they have a very low maintenance cost, they are completely silent and produce no emisions whatsoever, not to mention the fact that you won't have to put gas ever again. The question is, why aren't these incredible engines more popular among fishermen?
The main reasons are the high initial investment and their limited range due to the weight and size of the battery bank. Torqeedo, which is the leader brand in electric outboards, sells their "Deep Blue" model engine (comparable to an 80 HP gas engine) for 20,000 US dollars, and the battery bank costs around the same.
The battery types used are:
Lead-acid batteries, with low specific energy of 33 to 42 Wh/kg. If quickly discharged they loose 40% of capacity when discharged fully within 1 hour, but they are very cheap.
Nickel-cadmium batteries have specific energy of 40 to 60 Wh/kg, but are rarely used today due to environmental concerns and strong memory effect.
Nickel-metal hydride batteries have specific energy of 60 to 120 Wh/kg, contain no cadmium or mercury, have relatively low self-discharge and almost no memory effect. They provide compromise between cost and performances.
Lithium polymer, Lithium-ion and other newer battery technologies have specific energy of 100 to 265 (or even more) Wh/kg, but at much higher cost per stored Wh.
Charging the batteries with a photovoltaic (converting solar energy into direct current electricity) system, wind turbines and towed generators (when traveling under sails or anchored in strong current) can make the system independent of any external energy source. For longer trips, the system can have a range-extending gasoline or diesel generator which recharges the batteries.
There is an evident shift worldwide towards cleaner and more efective ways of transportation, besides, technology is always improving very quickly, so hopefully we should be able to afford our electric outboard soon enough with the capacity for a full fishing day, or two?