23 Sceptre OB on transom vs 23 CC with OB on bracket - impressions.

Fr. Frank · #10 07-22-2020, 08:34 AM

Quote:

Originally Posted by gofastsandman

Big Shrimpin` suggested I try a Mirage + so I found a 15.380x17p.

Denny and I tested many props shortly thereafter. Apollo 4 bl 14.75 x 20,
PT ofs 4 bl 15x15, and the Mirage +, were among the standouts.

76 Red suggested a SST 1 3bl many moons ago. I shrugged this off as not being
serious at all. I now run a 15x16p and can hold plane at 2700 rpm easily.
12 mph all day. I wonder if this is part of the 2 stroke factory exhaust design.

I get ya' Sandy. On my previous Seafari, I started with a 4B 16P over-hub cleaver on a B&B'd XR Merc (prop came with motor). Motor had big 4.75" gearcase, 1.65 gear ratio with a nose-cone and low water pickup. Top speed was about 44 kts (not mph) at 6100 rpm, but fell off plane below 16kts, and very poor holeshot. No trim tabs (Threw a hell of a rooster tail above 40, though).

I switched to a 3B Mirage 17P. Top speed was 42 knots, would hold plane down to about 13 kts and got on plane very quickly.

Got a chance to talk with the guys at PowerTech and bought an OFS 4B 15.5x15P. 1 knot slower than the Mirage, but even better holeshot, much better low-speed control and would hold plane down to 10 kts. Max RPM fell to 5650.

After a couple of months and lots of emails, I traded that back to PT for a one-off custom-built (read non-returnable) Power Tech OFS 3B 15.25Dx16.5P with extended tip cupping because I ran with my motor mount as high as possible. Top speed was now 46 knots at 6050 rpms with light fuel and one person on a cold day. When I put the bimini up and loaded the family top speed was about 42-44 kts, depending on conditions. Time to plane about the same as the Mirage, and would hold plane down to 11 kts in calm water. Ran best in a light chop.
Man, I LOVED that prop!

Swapped the Merc XR motor for a 90hp Opti in '06. Top speed fell to 34kts, but fuel economy went from 1.9 NMPG, to almost 6 NMPG average. Partly because I wasn't tempted to run at 5800-6000 rpms all the time.