Dave M

I read that Maximus props come in different diameters. Was this always the case?

I bought a used Maximus, part #48-889964-26. What diameter is this prop? I can't seem to find that part number anywhere.

Dean Ferry

15.5 is stock, at least that's what mine are....

bbladesprops

Actually stock are 15 5/8" diameter.

The first ones we built in 2002 while I was still at Mercury Racing were 15.25" but we settled at 15 5/8" for various reasons.

Most Labbed versions end up at 15.25" but we have done them from 14.5" - 15 5/8".

Brett

Dave M

Thanks Brett!

What do you think about this?

Here's my setup......
2006 Superboat Y2K w/525efi, 1.5R Bravo XR w/ITS.

With the stock 26P maximus @ 5000 RPM = 73 MPH
As you can see, I'm a little light on RPMs. I'm seeing around 11% slip through the RPM range. Planing, low speed, and mid range are pretty good.

With a "labbed" 28P Bravo prop @5350 RPMs= 80.1 MPH.
My slip numbers are considerable higher across the RPM range. My mid-range speeds are down 5+ MPH compared to the Maximus.

I also tested a labbed and stock 30P bravo. The results with the labbed prop where similar to the 28P, just less RPM. The slip was ever higher with the stock prop.

Should I just get the Maximus worked and forget about the Bravos?

Could my drive height be too high for the Bravos?

My realistic expectations are 78-80MPH while maintaining the mid-range.

bbladesprops

I believe we can get 76-77 mph with the Maximus. You might lose 1mph in cruise do to the diameter reduction

Slip is only 2% higher with the Bravo 1 30P than the Maximus.
Depending on your ulimate goal, I like the Maximus for every day and the B1 for top speed.

Having the high cruise speed and 80mph is tough to get.

Brett

Dave M

Thanks Brett!

I'll probably send my Maximus to you over the winter.

What number to you put in the "pitch" field on the prop slip calculator? Do you use the pitch stamped on the prop? I though I remember you saying that for bravo props, you subtracted .5 inch, or something like that.

bbladesprops

For Maximus propellers I use the cast in number.
For B1's I use .7-1.3 inches less pitch depending on the stock to Lab recipe used on the prop.

People would be amazed at the deviations in actual propeller pitch from model to model and manufacturer to manufacturer.
It can get complicated because other factors determine the ultimate rpm level created.

Brett