I just upgraded the motor on my jon boat from a 25 to a 40.When I took it for a test run yesterday I discovered that the 40 really wants to bury the bow of the boat and it digs and bites really badso much so that it almost makes it dangerous to drive because the smallest movement makes the boat jerk left or right really hard. Even trimming the motor all the way up doesnt really help. It could have done this with the 25 but with the lack of power I may not have noticed as much. Heres my question: The motor is a short shaft, it is currently mounted with the cavitation plate even with the bottom of the boatDo I need to raise motorif so, how much? Any help is appreciated?
I always heard from level on up to maybe 2" above the bottom. If you trim it up the bow should come on up. Bow diving on a v-front jon usually happens when you run flat and not trimmed up enough. You have some sort of trim issue IMO. And/or Maybe a bent / hook in last 2’ of back of bottom of the boat? That can mess up the handling too. I had a 30 on the back of a 13.5’ v-bow jon that did that. Will scare the crap out of you. (well it was rated for an 18) You had to get the weight just right in the boat for it to ride right. Was over-powered and too much weight in the motor. Throws the balance/handling of the boat off.
How long and what size is the jon boat?
J Ford
I would raise the motor at least an inch, that will help a lot. Also move any loose weight, coolers, tanks or whatever further aft. Bow down trim can be very dangerous.
Capt. Larry Teuton
Cracker Built Custom Boats
Small craft surveying and repair
the cavitation plate should be flush with the surface of the water while under way at WOT
quote:
Originally posted by jfordI always heard from level on up to maybe 2" above the bottom. If you trim it up the bow should come on up. Bow diving on a v-front jon usually happens when you run flat and not trimmed up enough. You have some sort of trim issue IMO. And/or Maybe a bent / hook in last 2’ of back of bottom of the boat? That can mess up the handling too. I had a 30 on the back of a 13.5’ v-bow jon that did that. Will scare the crap out of you. (well it was rated for an 18) You had to get the weight just right in the boat for it to ride right. Was over-powered and too much weight in the motor. Throws the balance/handling of the boat off.
How long and what size is the jon boat?J Ford
Since I’ve posted this, I discovered there is a bad hook on the back three inches of the boat…basically acting like a big trim tab. I’m going to work it out and try again. I believe that should solve most of the problem and the rest I hope to work out with a jack plate.