BRACKET OWNERS

[fillet1]

Ok, Ive got some hours on the boat now and have a few questions for you.

I have a 1999 Johnson Ocean Pro 115
I cruise at around 4000 which gives me 22kts.
WOT at 5500 gives 27-28 kts with people, gear and bimini/full curtains.

The speed is fine for me. I fished three full days in the bay, moving from spot to spot, running a couple miles out and back etc and when I filled the tank it took only 17 gallons. That is more efficient then I expected.

If I trim up at all the motor cavitates very easily. If I make a sharp tun at higher speeds, the prop cavitates.

I was thinking of bolting on a hydrofoil, (I ordered one and then cancelled the order) but I cant help but think that I should drop the motor a notch or two to give the wheel a better bite?

I think the problem stems from the fact that I have a light 115 hp 4cyl engine v 6 cyl on the bracket. The heavier motor would weigh down the a$$ end of the boat a little more? (Incidentially, a heavier motor would help my scuppers drain a little better too)

My question is whether the hydrofoil will help the cavitaion problems. It does not cavitate constantly, just occcasionally. I am hamstrung with the trim control in all but flat conditions though. The hydrofoil would be the easy fix. To drop the motor would be a PIA at this point. I dont even know if there is any room to drop it on the motor and I would have to pull the boat etc.

How about I just fill the livewell with sandbags to make the stern heavier ;D ;D ;D

I have a 200 mercury on the back of my boat without the bracket But with mine trimed up it will cavitate also in turns. Not all the time but it does.

[CT_V-20]

Fillet, what length is your shaft? With my Sea Drive, which was an XXL shaft (25") I had no cavitation and it was effectively a 115 like yours so the weights should be the same. The new motor I bought is a 25" shaft as well. But I would imagine that if I trimmed my 25" shaft high enough, then I would cavitate with that too - on turns especially.

[fillet1]

Its a 25 inch shaft.

[chumbucket]

fillet1, I don't think a hydrofoil will help that situation. They are designed to lift the stern, not keep it down. I think you may be right with the weight issue or perhaps they mounted the bracket a bit too high when things were changed over. Possibly? ???
One thing you may want to try is a four bladed prop. You'd get better holeshots and better bite in turns. Maybe a bit (negligable) off the top end.

[CT_V-20]

That is odd fillet because you've got a big enough shaft for sure. *??? Can a jack plate be used on a bracket?

[macojoe]

I have the 175 on the bracket, and when I get the thing moving and get into the turns it will do the same as yours.
I run the hydrofoil and it helps get me on plain fast!! I think its great!! But I stii cavatate.

I get 34mph at 5000, And I am also very good on gas!! I think I am close to 3 mpg.

[chesapeake724]

I don't have a bracket, but I'll give my two cents anyway... ;D

Is it possible your motor is mounted too high? I ask this because you shouldn't be getting cavitation when you trim only a little bit up. If it's an option, I might drop the motor one set of bolt holes and see what happens.

The other thing I'm thinking is that you're under-propped. The WOT sounds right, but cruising at 4k rpm sounds a little high. If you get the same diameter prop and go up in pitch by 2", that might cure you. (Yeah, I know, I'm not the one writing the check, so it's easy for me to propose it.) More pitch should give you more bite, as it sounds like whenever you put an extra load on the motor (like carving a turn or lifting the bow out of the water), the prop isn't gripping the water and you're getting cavitation. Going up in pitch will cut down your WOT rpms, but how often do you go WOT? Is 5100rpms still in the recommended range for WOT? It should knock down your cruising rpms to a more comfortable 3600.

FWIW...YMMV

[reelapeelin]

I think that motor's gotta come down some...it just ain't gettin' enough BITE...extra weight may help, but sounds counter-productive and only a band-aide...

F1, I don't have a bracket, but everything you describe spells "prop too high"...

[jaysea]

hi,ithink you should lower the motor ,also i dont know where you have your transducers mounted ,they mite be giving you some air in the path of your prop,just a little some thing to check into,