What props on non-stepped boat?
 

Curious what props people are running on non-stepped twin engine boats.

I've run Mirage and Mirage Plus on my Scarab. Now I'm running Bravo 1's on my Apache.

Is anyone running 5 blades on a non-stepped hull? What are the results?

Re: What props on non-stepped boat?
 

Did the boat run faster with the Mirage Plus's or the bravo's?

Re: What props on non-stepped boat?
 

The 5B props are available in 2 blade designs. The "Round ear", P5-X works well on non-stepped hulls. Typically the semi-cleaver blades do not as a rule of thumb.

Julie

Re: What props on non-stepped boat?
 

I only ran the Mirage's on my Scarab.

I'm spinning 32 Bravo 1's right now with 1.50 gear ratio to 5400, I have no plans on trying a 3 blade prob on this boat.

Re: What props on non-stepped boat?
 

Thanks, maybe they round-ear will be worth a shot.


Top end isn't as important to me as cruise. I can run 52 mph at 3200 rpms, 55 at 3400 and 60 mph at 3600.

I'm curious what a P5-X or a Miximus would net me.

Someone suggested cutting the difusor ring off my B-1's but I'm reluctant because I have some blow-out comming on plane.

Re: What props on non-stepped boat?
 

If you have a dificult time getting on plane then I would not recommend that you cut the ring off. This typically will make it more difficult to get on plane. The 5B propellers will provide better cruise speeds than a 3B or a 4B propeller. Your theoretical speed is 106 MPH which of course doesn't account for slip. What is your WOT MPH via GPS? We can take a look at your propellers efficiency and go from there.

Julie

Re: What props on non-stepped boat?
 

We have had our best success with 3 and 4 blade props on straight deep V's.

This doesn't mean a 5BL won't push the boat. You need to determine your goals. Rarely has a 5 blade prop beaten a 3 or 4 blade on top end with a big deep V. There are exceptions to the rule however. Big slip % is really the only factor. Your mid range numbers are telling me you will definitely improve your cruise speeds, but will more than likely loose mph on the top. We have been doing some great things with the 5BL Maximus and have picked up big numbers in the low and mid range while maintaining top end figures.

As far as the diffuser rings are concerned. I'm assuming the blow out occurs "only" as the bow comes back down to the horizon. If this is true, cutting the diffuser wont hurt your hole shot and could even give you 1-2 mph on the top. If it is occurring through out the planing process, we should discuss other issues.

Re: What props on non-stepped boat?
 

Thanks for the feedback.

The blow out occurs half way on plane, roughly 2200 rpms, as the bow is rising. Then jumps to 3000 rpms, then the bow rolls over and hooks up.

With tabs all the way down, drives in, it gets on plane but if the tabs are up forget about it.

The X is set pretty conservative so I don't see drive height being an issue.

Re: What props on non-stepped boat?
 

I haven't had a chance to do a WOT run because I don't have my fuel system set up properly. I need to run a secondary electric fuel pump to keep up with everything. I'm only running 3 lbs of fuel press at 5000 rpms so I'm not going to run WOT until I get the fuel pumps in place.

My assumption on top end is mid 90's. I know I'm running solidly in the 80's at about 4700 rpms.

Re: What props on non-stepped boat?
 

As I said I would not cut the rings off in your case. I think that once you get the fuel system issues resolved, you can take a step forward with your dial-in work. Record your WOT RPM and MPH via gps and we can go from there. I think the drive height is going to dictate whether your boat will work well with the 5B props.

Julie