You really want a twin step 35 running flat so the hull can do its job creating stable handling. I believe my props were standard length with the diffusers cut off, I'll see if current owner could post a pic of them.

I believe that the nosecones really helped my boat. If you put shorties on you will either want a different prop or you'll want to space down. Running a -2 lower may gain a little top speed but getting up on plane and rough water drivability will be sacrificed.

Bblades for sure can help you get a prop dialed in after you decide on a lower and propshaft height.

Also, I emptied my PM's.

Sorry, missed this.
Based on what I've read, the nose cones do help >90mph. The water is much cleaner when it arrives at the prop with the cones. Unfortunately, the cones were already installed on that boat when I bought it, so I really can't judge personally.
I worked with Brett (BBlades) when I purchased the 32 Maximus props - the diffuser was cut off, and I believe they were 15 5/8" diameter. This 575 boat was about (estimated) 1200hp, maybe a bit more, when we sold it.

Good luck with your project and keep us posted on your results.
Terry

When I bought my boat (2001 Lightning) it had 500 efi with Vortex supercharges and was either 725 or 750 hp (it been 10 years ago with lots of changes along they way) it had standard bravo and was undrivable past 95 (still had power but would chine walk violently). The first thing I did was put on a set of sportmaster with standard length lowers and used 30 or 31 pitch (had both) P4X (i think that is what hydromotive called there 4 blade round ear propeller) and boat would run 102. Later that year I borrowed a set of 2 shorty imco and used mercury labbed 32 pitch maximus and the boat ran 108. I bought a set of the imco shorties and later ran a set of hydro p5x 31 to 110. Always used 1.36 or 1.34 depending on bravo or xr. KellyO is correct that my boat is not really easy to get on plane and plain sucks in the ocean (prpoellers will not stayed hooked up).
If you want the bow of the boat to fly, cut the duffeser off and make the hub as short as possible (making it even harder to get on plane).
Be prepared to break alot of drives along the way,
Good luck. Allen

What does your boat look like? I just want to make sure I don't pick a race with you when I'm on Old Hickory next month! lol!

Sound's like a fun boat!

Terry

Have you guys with cut diffusers with twins that are having a hard time planing blocked the airflow thru the exhaust passage ? A few of us have with single engines with great results. Tinkerer with a Bravo 2"above transon in 26' cat and me to a small boat with alpha ss. Neither of the boats could get on plane with the diffusers cut until blocking the airflow thru the prop.. Oh,both boats thru hull exhaust...so just outside air going thru prop.

I haven't heard of anyone else trying,thus why bringing it up. .We usually bring this up in single engine threads.

How is this done?

I looked up my notes and 2 of my props do plane (one doesn't) but they slip like a mofo. They even slip bad while on plane to say thru 3/4 throttle and then start to grab. With the exhaust passage plugged, they act totally normal....no extra slippage anywhere.

Anyway, I (we) normally talk about this when a boat acts pretty normal with props with diffusers on,and then don't with diffusers off.

I'll PM Tinkerer to this thread in case he want's to add more or erc.

As far as the Alpha One's and Alpha SS's, a pvc rubber cap fits their openings. A 2" one if anyone can believe that.

Nice Looking corn crop. You cut silage or harvest? If I remember correctly you have a dairy farm so I'm guessing silage?