jon boat will not plane out

[joshcw25]

Hi everyone,

I have a grizzly 1448 jon boat with a Suzuki 15 hp tiller steer. With me alone in the boat it will run 25 mph. With a fishing partner I can barely get on plane. If I do get on plane it will run 21 mph with 2 people in the boat. I just can't see me getting such good top end speed but not even planing out with one more person. The boat has a long transoms and calls for a 20 " shaft motor. The cavitation plate sits about 2 inches below the hull. I am thinking I may need a jack plate or some kind of tilt and trim. Any other suggestions? I have tried all the simple things hydrofoil, every motor position, ect. . Anyone have any ideas?

 

[DuckHunterJon]

Re: jon boat will not plane out

Start with the simple stuff. Is the motor running up to snuff? Do you know what RPM's you are getting (makeing sure you are reacing WOT)? Have you tried playing with the trim? My father used to have a 14' starcraft v bottom with an 18 HP on it, it would plane easily with 4 of us on board. I would think the grizzly would be lighter and flatter.

 

[Home Cookin']

Re: jon boat will not plane out

drive over shallow water to get some lift.
Have the passenger moveback or forward until you get it.

 

[Texasmark]

Re: jon boat will not plane out

I remember seeing OMC sales brochures of engines back in the 50's and the anti-vent plate was like 2" below the transom. I don't know why that was other than it may have had something to do with the location of part of the water intake system. Obviously that creates a lot more drag. Now-a-days it's more like even with or an inch above sort of thing since water inlets are designed lower on the skeg.

Your problem sounds like you have too much pitch for the heavier load. Coming out of the hole puts extra demands on the engine for the required hp to get up on plane. Once going, the resistance to the engine is significantly reduced and with the current prop it can go ahead and develop it's hp.

So, I'd lighten the load, move about to get on plane, or get a prop with less pitch (2" less). If your engine had mechanical or fuel problems, I'd say that you couldn't get the top end that you do.

Less pitch will usually reduce your top end, but not necessarily. If, in lightening the load on the engine, it increases rpm's then it's a question of will the rpm increase make up for the 2" theoretical loss in forward motion per rev. Only way to know is to try it.

Mark

 

[southkogs]

Re: jon boat will not plane out

15 hp on a 14ft john boat should have no problem planing out. We run a 14ft open fiberglass boat with an Evinrude 9.9 and that thing runs along on plane just fine. Unless the motor is in need of serious servicing, I'm thinking you've got a trim issue. Sounds like a weight forward problem of plowing.

If it works fine with just you in the boat, figure out besides the other person what gets added against the CG when you load up. Move your load closer to the CG and see what happens. Might adjust your trim on the motor for a little bow up attitude and see how it runs. Though, when you change back to one person, you may have to knock it back down. You'll know if it starts porpoising on you.

 

[joshcw25]

Re: jon boat will not plane out

Thanks everyone for the advice. I just recently had my mechanic go over the motor inside and out. Everything is fine . I know some guys that run jack plates on their jon. boats and set the motor back up to 8 inches and these guys fly. I have tried every tilt position on the motor. We fish these little jon boat tournaments with a 10 hp limit so we all try to get an extra edge. With just me in the boat there is only 1 or 2 boats that can catch me but with 2 people in my boat I will have bigger boats loaded down with gear passing me its really odd how it does so good with me in it but goes down the drain when I add a fishing partner. Im not sure what pitch my prop is but maybe I should give that a try

 

[dragginanchor]

Re: jon boat will not plane out

throw a 25 on there and that should be enough. overpower by about 33% and its about right like on my 12ft. sea nymph..perfect with 1 fishing buddy and gear.

 

[DuckHunterJon]

Re: jon boat will not plane out

Just curious how you fish 10 hp limit tourney's with a 15? Different stickers?