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-   -   Changed Drive Gears - X Dimesion too High ? Looking for Advise (https://www.offshoreonly.com/forums/drives-lower-units/239742-changed-drive-gears-x-dimesion-too-high-looking-advise.html)

Panther 09-28-2010 09:16 AM

Glad to see you're getting the boat dialed in!

When you had the 1.30's did it blow out getting on plane? I don't see how the gear ratio would change your planing ability but who knows! Maybe there is on obstruction that's diverting water away from the prop as slower speeds?

Do you have a picture of the drives level with the bottom of the boat? Have you tried a 5 blade?

JMS322 09-28-2010 11:49 AM


Originally Posted by Panther (Post 3218464)
Glad to see you're getting the boat dialed in!

When you had the 1.30's did it blow out getting on plane? I don't see how the gear ratio would change your planing ability but who knows! Maybe there is on obstruction that's diverting water away from the prop as slower speeds?

Do you have a picture of the drives level with the bottom of the boat? Have you tried a 5 blade?

With the 1.30's I could of gone WOT(not that I would) from a dead stop, with tabs up and it wouldn't blow out the props. With the 1.5's and 4 Blade Bravo Ones..there was NO way to get it on plane. I had to go to 5 blade P5's. My theory is the gear change caused a major increase in leverage to the props.

After crunching some numbers, I'm figuring that the slip has always been a little to high with this boat. Even out of the factory they had to lower the drive 1" to get the boat to plane with the 1.5's and 34 Bravo Ones. With the 1.3's the slip was high too and it also could have used more prop.

The problem is using Bmax shorties when compared to XR shorties is not comparing apples to apples. Bmax shorties do not have full length cav plates. So now we just threw the rules out the window. The quickest and easiest test to prove my theory is going to be, bolt standard length Bmax lowers on, thus lowering the drive 1 1/2 " over what I have now and the standard drive has a full cav plate. If the ability to plane and my speed picks up and my slip goes down, then my theory is right. If not, well then back to the drawing board.

JaayTeee 09-28-2010 12:12 PM

I cant believe the 5 blades didnt fix it.

Bravo's above 32 pitch arent known for their efficiency.

waconda 09-28-2010 12:21 PM

The 5 blades did allow him to get on plane but he had a huge rooster tail.

cowisl 10-01-2010 06:06 PM

Update? Call pat at pmt in fort lauderdale. He should be able to point you in the right direction

JMS322 10-02-2010 01:06 PM


Originally Posted by cowisl (Post 3221343)
Update? Call pat at pmt in fort lauderdale. He should be able to point you in the right direction

Something came up and we're not getting to the lake this weekend. The current plan is to try a set of standard lowers that I'm borrowing from waconda, thus lowering the prop 1 1/2" from where I am now. If that works I will reinstall my -2 shorties with 2" spacers. I will be installing the lowers and testing next thursday. I'll report in after that. I'll trying giving Pat at PMT a call monday and get his opinion. All the logic and slip numbers tell me this is the right move, but only real life testing will confirm it.

bobkatz 10-05-2010 08:14 AM

JMS322,

Not sure if this would work on your bmax's but i have a pair of 2" spacers for a bravo if you would like to try them.

Rob

cowisl 10-05-2010 08:20 AM


Originally Posted by JMS322 (Post 3221711)
Something came up and we're not getting to the lake this weekend. The current plan is to try a set of standard lowers that I'm borrowing from waconda, thus lowering the prop 1 1/2" from where I am now. If that works I will reinstall my -2 shorties with 2" spacers. I will be installing the lowers and testing next thursday. I'll report in after that. I'll trying giving Pat at PMT a call monday and get his opinion. All the logic and slip numbers tell me this is the right move, but only real life testing will confirm it.

I would call him before doing anything. He has the most experience with 38 PP's. Just my .02

JMS322 10-05-2010 10:56 AM


Originally Posted by cowisl (Post 3223385)
I would call him before doing anything. He has the most experience with 38 PP's. Just my .02

I've called him twice, had to leave a message both times.....now if he'd just call me back.

JMS322 10-05-2010 11:57 AM

Had a nice chat with Pat at PMT..... I'm going to try a set of Maximus props before I make any other changes. I hope he's right. I think I have a set of 30's I can borrow, I'll know in an hour.


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