I will be at the boat this weekend, I will get serial #s and hering diameter. Thanks for the input.
Rick

Brett;
#1 prop from you is BB1158 30p L; Hits rev limit at 80mph
#2 prop from you is BB1304 30p L; WOT 5200rpm at 77mph
Both props run nice and Plane quickly. only issue is top speed.

Julie;
Herring prop is 15.5 x 27" 5 blade L; hits rev limit with WOT 5400rpm at 82mph.

Again with no post of better speeds with same set up, is this it? Thanks
Rick

The Semi Cleaver blade design is the best for top end speed on your hull. This is what you are seeing with your current propellers.

There is more there with the 27 5 blade. Since you are in the rev limiter a 28 may give you more top end speed. If you were able to turn a simmilar prop as the Hering at the same rpm it wold be worth an extra 3 mph.

OK,

Since you are running 575's, Your rev limiter is 5400. The first post states 5200 on the limiter and 80 with the one 30 B1 Labs we did. I'm guessing you meant 5400. In the last post you said on the limiter and didn't give a rpm for that propeller so again the asumption of 5400. The other propeller is at 5200 and 77 mph. Both equate to 19% slip which is too high for the boat. The way we built these propellers is different from prop to prop yet the inefficiancy is still there and identical. The 5200 propeller should have been more efficiant than the the other. This tells us the X dimention is too high or C.G. is off for these particular propellers. Stick them a inch deeper and you'll see much different and better numbers.

I don't believe the "semi" cleaver design has a darn thing to do with the better top end speed of the 5 blade. In fact I'm possitive it doesn't. The reason the 5 blade is faster is because it is hooked up better! It has .5" larger diameter, more square centimeters of blade area and a shorter duration between loads. If the 30 B1 was at 12% slip, you would have a WOT speed of 86.27 mph. The slip isn't because the prop has slip built into it, the boat is telling us it need more blade area, a deeper prop shaft or the bottom and or drive needs to be adjusted.

Easiest fix is a 15.25x28 5 blade.

Brett,

Is there anything we can do with the 2 Bblades props to improve the prop slip, or can we trade them towards a 18p 5-blade?
Rick

There are minor tweaks we can do to the 4 blades that may help, but as I stated before, the performance numbers are the same with 2 different custom Labbed Bravo 1's you requested with your set up. The larger blade area 5 blade propeller is band aiding the slip issue. I would investigate X dimention, blade area and diameter changes.

Has anyone tried the 1" spacer and what was the results?
I would like to get the prop slip under control before adding more HP.
Rick