9.5 Johnson has wake but don't go

[willowcat]

I have a 1968 9.5 Johnson, it locks into gear good, it runs out good, the problem is that when going wide open it throws a large wake and churns up the water but dosn't seem to push the boat along very well. The boat is a small 14' flat bottom so weight isn't a factor, Could it be the prop?

 

[wayne h]

Re: 9.5 Johnson has wake but don't go

what is the hight of the cavataion plate it sounds like u might be pulling air (cavatating) around the prop and just making a good splash

 

[rolmops]

Re: 9.5 Johnson has wake but don't go

Check your trim.It may well be that you are pushing your bow into the water instead of bringing it up to plane

 

[R.Johnson]

Re: 9.5 Johnson has wake but don't go

Are you running a 15" engine on a 20" transom?

 

[fireman57]

Re: 9.5 Johnson has wake but don't go

Could be a spun prop.

 

[mjbrueck]

Re: 9.5 Johnson has wake but don't go

When you say that it "don't go", I assume you mean that it won't plane? Assuming the engine is running properly:<br /><br />If it's cavitating due to being too high on the transom, it will run "normally" at lower rpms, but when you increase throttle the motor will rev but you won't increase speed at all.<br /><br />Since you say it puts out a large wake, it sounds like you're not cavitating. I think you need to work on trim or weight distribution. When giving it full throttle, try moving forward in the boat. Sometimes this is enough to help the motor overcome the bow wave and hop up on plane. After planing, you can then move to the back.<br /><br />If that's the case, you can buy or make a tiller extension to run the boat from the middle seat. Or move all the gear (gas, battery, coolers, etc.) towards the bow.

 

[willowcat]

Re: 9.5 Johnson has wake but don't go

What is the recomended pitch for this prop?<br />It runs like the prop is to small.

 

[v12mac]

Re: 9.5 Johnson has wake but don't go

I agree with Fireman, are you sure you don't have a spun hub? Easy to check. <br />Mac

 

[willowcat]

Re: 9.5 Johnson has wake but don't go

When the motor is out of the water, I put it in gear and try to spin the prop, it will not turn. Only if the motor turns.

 

[willowcat]

Re: 9.5 Johnson has wake but don't go

When the motor is out of the water, I put it in gear and try to spin the prop, it will not turn. Only if the motor turns.

 

[mjbrueck]

Re: 9.5 Johnson has wake but don't go

A 1968 9.5 doesn't use a hubbed prop - it uses a shear pin which wouldn't cause your symptons. I don't know what prop is standard on that motor, but it is probably somewhere around 8x8 to 9x9. <br /><br />Have you tried moving some weight forward? I'll bet you ten pounds of walleye fillets for ten pounds of redfish fillets that it will fix your problem. An old crankshaft-rated 9.5 doesn't give you a lot of power to plane a boat, even if the boat is lightweight. On a 12 foot, 150 pound boat, I have to move forward to get my 18hp to plane, but once it planes I only need 2/3 throttle to hit max rpms.

 

[Paul Moir]

Re: 9.5 Johnson has wake but don't go

It's a common mistake to think that Johnny/Rude pin drive props don't have rubber hubs. They all do - at least since the 40's.<br />To test, mark the pin drive part of the prop against the outside part (the part with the blades cast into it). Then run it. If the marks are no longer aligned, then the hub is spinning. A prop shop can repair the prop by pressing in a new hub.

 

[fireman57]

Re: 9.5 Johnson has wake but don't go

Check the shear pin and make sure that one side isn't broken off letting the whole thing grab slightly at low speed but spin at high speed. If the prop is not spun then your weight distribution and trim should solve your problem.<br />You don't say whether this is a new problem or not. Is this a different engine on your old boat or different boat on your old engine.