Bravo III Drive with 4 Blade rear 3 Blade front props performance improvement

[320Bob]

I test drove a Cobalt 242 with a 350 Mag Mercruiser engine with the 4/3 blade combo Bravo 3 and a Crownline 245SS with the same engine but 2 3 blade props yesterday. The performance difference between the two boats was significant which may in part be the hull design but I believe another factor may have been the 4 blade/3 blade prop combination. The Cobalt came on plane much faster with virtually no bow rise and held plane better at 3000 rpm. The other more noticeable difference was the lack of stern wandering at idle speed with the Cobalt which I am wondering if was due to the prop set up. My 1999 Mariah had a 454 and a Bravo III had stern wandering which I assumed was just normal.

I talked to my Sea Ray saleman today and he knew nothing about this prop set being offered by Sea Ray on their Sport Boats. Any of you guys with Sea Rays or other brand Sport Boats and Bravo III drives tried this prop set up and did you observe some of the same things I found yesterday on the Cobalt?

 

[320Bob]

I did a little more research and Mercury offers this configuration as the XR prop set. As I asked before has anyone purchased a Sea Ray or changed out their B3 props to these?

 

[tbirdvet]

I noticed that Mercruiser now uses 4 blade to replace 3 blade on B3. I also see that is what Sea Ray is using on my model (both props). I have not evaluated myself but the tech articles indicate better low speed performance with very little high speed degradation(if any).