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Quote:

Originally Posted by SB (Post 4660415)

I'm not sure what the exhaust tunnel is. Transom assembly or at/in the drive itself ?

The drive has a passage for thru prop exhaust. That needs to be blocked or the prop will suck too much air especially getting on plane.

Boatally Insane,

have ve you tried LH ve RH of same pitch to see if handling/porpoising is any different? They say different characteristics for each.

Quote:

Originally Posted by Powerquest230 (Post 4660753)

Boatally Insane,

have ve you tried LH ve RH of same pitch to see if handling/porpoising is any different? They say different characteristics for each.

Close... I was running a RH 25 P5X and now have a LH 28 P5X.
Only difference is the direction the boat lists when I'm by myself..
Have yet to try the LH with a passenger to see if it'll be level now...

Quote:

Originally Posted by Tinkerer (Post 4660183)

Did you try the -2 IMCO shortie without the spacer and the big prop?

I only tried it as a -1 and a 28 P5X and it didn't work well..

Don't really want to try bigger diameter props with the XR and 1000hp..

Quote:

Originally Posted by Tinkerer (Post 4640238)

That and I would try a one inch shortie drive. The IMCO drive is the best drive for your application. did you try a labbed BRAVO 26 ???
If you can get on plane with a 4 blade prop it should be faster than the 5 blade. Also that 5 blade is causing a lot of transom lift.
One other thing you could try is to cut the bell off of the back of your 5 blade. This should lower the back of the boat so that you don't need to trim as much.
I could not run a 5 blade because it caused too much transom lift even with the bell cut off.

would my 5 blade be the reason for my aggressive walk at any speed above 85?

Quote:

Originally Posted by Royalflush280 (Post 4681024)

would my 5 blade be the reason for my aggressive walk at any speed above 85?

It all depends on the boat and how far your prop shaft is below the running surface at speed.
The closer the prop shaft is to the surface of the water or the more blades the prop has increases the transom lift.
On my boat the drive rides on top of the water going under the boat. ( the bullet sits on top of the water )
The bullet and the flare at the back of the prop act as a ski and causes transom lift. The higher the bullet is but yet not fully surfaced the more transom lift.
Transom lift counteracts trim for bow lift. This will cause you to trim more than is safe and can cause an ill handling boat at speed.

Boatally insane
You say that you are using a lot of trim.- but from what you have listed you are not.
If 5 is neutral than any trim setting below 5 is negative trim.
Any number above 5 is positive trim.
Once I am on plane I always trim to neutral for best speed at a certain RPM.
A setting of 5.5 to 6 is probably still parallel to the water surface due to the angle of the hull to the water because the bow has risen.
My drive is fully surfaced and at top speed I run only 5.5 to 6 with 5 being neutral on my boat also.
If that is all that you are trimming that is less than most V bottom boats.

Quote:

Originally Posted by Tinkerer (Post 4681228)

yeah it makes perfect sense, I just feel like as soon as I get into it I’ll start bringing my drive up and as soon as I do I’m countersteering it to keep it balanced. My 95 thoroughbred never had that issue . I ran a 4 blade hydromotive on that, but the boat didn’t also have the power I’ve gotten into with my new one. I got to run the boat twice at the end of summer so I’m sure I just need more wheel time. I had my motor pulled this winter and had custom fabbed heavy duty race motor mounts installed. I got the phone call today that they set the motor back on her today and it’s starting to come back together! I’m new to oso if I knew how to post pictures I would

Quote:

Originally Posted by Tinkerer (Post 4660365)

SB - I did the same thing with my -3 IMCO shortie lower. I used a piece of lexon to seal off the exhaust passageway in the lower. This Mod made a noticeable improvement in planning.

Anyone have a photo of how they blocked of the exhaust hole

When you separate the top and bottom halves of the drive You will see a huge hole that goes down the back of the drive. I just cut a piece of Lexan and used 5300 to seal it in place. No air flow trough prop now.
This will help the prop hook up to get on plane.
There are a lot of little things that can be done for few $ and little time that will help a boat get on plane.
My Daytona wouldn't begin to get on plane with a 4 blade prop and barely get on plane with the 5 blade.
I shortened the trim rams 3/4 inch and modified other parts to allow the drive to tuck under more. ( more negative trim ) This allows the prop to be deeper in the water and also causes the prop to push up on the back of the boat more than with the normal trim level.