I've been looking around to upgrade my hull to something a bit bigger. One boat I looked at has a Johnson 50hp Seahorse. This engine starts good, and on earmuffs runs cleanly though the rev range. BUT put it in water and in gear, it just stutters when you give it some gas. You need to give a little throttle, it stutters then cleans up, and then you give it a bit more, once again stuttering then cleaning up, all the way to full throttle.
