Standard is 15 inches, long is 20 inches and extra long is 25 inches. As a former dealer, the question I asked is where you would be sailing. If in the ocean or bays due to following seas or high waves, the 25 inch shaft was recommended but on a lake I suggested the 20 inch shaft. If you feel that a 25 inch shaft is needed, then go with that. The smaller mercurys are built by Tohatsu and that inclludes Nissan. However Honda is a good one as well and invest in the electric start.
If you get the electric start and you have a dual battery system, never switch the battery selector while the motor is running. Otherwise you could destroy the alternator. If you do decide on a dual battery system with battery selector, get the battery selector that has a quick field dissconnect with it as it helps to prevent damaging the alternator if you accidentaly change the battery selector.
Also, all engines now have a zinc attached and you may want to get a spare
Crazy Dave
