Bravo 3 with Different Pitch Props Front and Rear

[Sadler]

A friend I was boating with last weekend told me he noticed the props on his 1997 270DA Bravo 3 (7.4l engine)were different pitches, one a 22 pitch and the other a 24 pitch. I told him they should be the same pitch and 24 pitch is the SR recommended pitch for his boat/engine combo. Got an email from him today that said "Checked with a prop shop and the searay dealer and there told me that it was not uncommon to have different size props on the brovo 3. They also told me if the top end was within the rpm range that the prop size was right." This sounds wrong to me; although they might "work" and result in some average pitch, different pitches would mean slippage would be higher than usual and you'd have loss of performance and efficiency. I'd be interested in your opinions on this.

 

[jason78]

I think a quick call to Mercury might be in order. This sounds like one of those things where opinions may vary but the final answer will probably need to come from the company who designs and manufactures them.

 

[Henry Boyd]

Here is the Sea ray prop chart for that boat. http://www.searay.com/boat_graphics/electronic_brochure/Company1729/1C1_25_74DEIP4PX0S.pdf

in 97 the 7.4 either had a matched 24 p set, or a matched 26 p set depending on hp rating.

Henry

 

[Tail Chaser 661]

Pitches should be the same. The Dia's are not from what I have read.

 

[Sadler]

Here is the Sea ray prop chart for that boat. http://www.searay.com/boat_graphics/electronic_brochure/Company1729/1C1_25_74DEIP4PX0S.pdf

in 97 the 7.4 either had a matched 24 p set, or a matched 26 p set depending on hp rating.

Henry

His is the 300 hp engine, so the 24p set is the one.

 

[tbirdvet]

I have same pitch but different diameters

 

[Sadler]

I have same pitch but different diameters

Yes, that's normal that the diameters are different, but the pitches not matching up, and the SR dealer and a prop shop saying it's normal, is what is strange.

 

[jason78]

and the SR dealer and a prop shop saying it's normal, is what is strange.

Please see post #2. I think your friend should just place a call to Merc. They designed and manufacture the Bravo 3, not his local Sea Ray Dealer. Maybe they are right, maybe they are wrong. There is only one source who can tell him for sure.

IMO, this situation is easily resolved with a telephone call. :thumbsup:

Please keep us posted.

 

[Lazy Daze]

I've only ever seen the same pitches being used. But, hey, maybe someone figured out something new - maybe it actually performs better. Either way, start with the advice given in Post #2 and again in post #8. My gut tells me that Merc will just go by the book on this one, but it's the most logical place to start. Then, see if your friend can borrow a matching set and test it out. Compare the two set-ups.

 

[Great lakes pirate]

When I bought my boat, each drive had a 22p on the front and a 24p on the rear. I called mercruiser and asked them if this was OK. They said it was fine to have different pitches front to rear. I ended up changing the front to match the rear and noticed little to no change in performance. My canvas guy has a single big block maxum and has the same set up as I did and says it made a big differance. I would buy another 24 and put it on and run it. If you like the performace keep it. If not sell it back on Ebay.

 

[Woody]

My props are the same pitch on mine. Has anyone tried the 4 x 3 props on their B3?

 

[magster65]

Good or bad?
I have conflicting perspectives;

First;
Wouldn't that just make the prop with more pitch have more load on it... applying more load to that shaft and bearings? I think the key to longevity on this planet (with anything) is balance.

Second; The inner (aft prop) shaft having smaller bearings than the outer... Merc uses a smaller diameter prop to equalize the wear on the shafts? In that case... would a prop swap to one size bigger make any significant difference since they're not really balanced anyways?

Good or bad idea... I can't decide...

 

[Sadler]

Thanks everyone for the good comments and suggestions. I've forwarded this thread to my friend and I'll report back any developments.