Bravo 1 / Hydromotive Prop question
 

On my 91 Formula 272 SR1 W/ twin 454 Mags, I currently run Mirage 25p's .
I am changing to 4 blades. I am stuck inbetween the Bravo 1 24P and the Hydromotive QUAD IV-X 24P. Has anyone compared these two props on their boat??

What would be the answer to the question above? Had 4 blade props on my previous boat and I loved the midrange speed gains , thinking about 24p , getting 5000 rpm with mirage 23 p ,too high for my 330s

Props are cheap buy a set of each used here in the swap shop and test them out, and then sell the set you don't want. Every boat is different and the best way to know is to test on your boat.

I agree, just got a set of 23's mirage but going too high rpm for my 330's when trim

I had the same boat as a 1988. I tried a set of 26 bravo 1's but the boat lost a few mph. I went from 55 to 53.

Props I've owned the past 5 years (just qualifying my response):
22 B1
24 B1
24 B1
25 Rev 4
25 QIV-X
26 B1
26 B1 labbed
26 QIV-X

Hydromotives are going to be a true 15" diameter and true 24P.

Bravo 24's are going to be 15" at best but most likely a tad less (advertised at 15.25") and some where around 1 pitch shy of stamped pitch. I've only had 1 set measured for pitch and they were just shy of 1P shy but have heard this about B1's for years before testing the method myself.

Just using common mans prop math (some people say 150-200RPM per blade/pitch so using 175):

Hydro: Add 175RPM for lower pitch, subtract 175 for extra blade is a net of 0 RPM from your 25P 3 blade.

Bravo: Add 350RPM for lower pitch (since measures more like a 23 than a 24) and subtract 175 for extra blade is 175RPM higher RPM from your 25P 3 blade.

Do you have a 175RPM window available?

If it were me, I'd go with the Bravo 1's. They will be easier on your drives and can be bought (used) or sold easier than Hydros.

[QUOTE=marylandmark;3847439]Props I've owned the past 5 years (just qualifying my response):
22 B1
24 B1
24 B1
25 Rev 4
25 QIV-X
26 B1
26 B1 labbed
26 QIV-X

Hydromotives are going to be a true 15" diameter and true 24P.

Bravo 24's are going to be 15" at best but most likely a tad less (advertised at 15.25") and some where around 1 pitch shy of stamped pitch. I've only had 1 set measured for pitch and they were just shy of 1P shy but have heard this about B1's for years before testing the method myself.

Just using common mans prop math (some people say 150-200RPM per blade/pitch so using 175):

Hydro: Add 175RPM for lower pitch, subtract 175 for extra blade is a net of 0 RPM from your 25P 3 blade.

Bravo: Add 350RPM for lower pitch (since measures more like a 23 than a 24) and subtract 175 for extra blade is 175RPM higher RPM from your 25P 3 blade.

Do you have a 175RPM window available?

If it were me, I'd go with the Bravo 1's. They will be easier on your drives and can be bought (used) or sold easier than Hydros.

Thank you for your clear explanation.
I have a set of B1 26's , I will try them to see how fast I can turn those.

Do you think it will be too much pitch for the 330's ? Otherwise I will try trading them for 24's

Did you have small blocks ? 53mph sounds low , if I get that with the 26's it won't work for me

It was with 454's. The whole boat was a turd, bad engine, cracked exhaust, wet and rotted. Amazing what a nice paint job will hide lol. But, I did loose top speed with the 4 blade bravo props, but it planed off with ease. I needed to play with the one engine throttle to get the boat to plane off with the 3 blade props, but with the 4 blades it just went.

BBlades has a prop test program which allows you to try out different props without buying, Brett Anderson owner is a great prop guy for answers. I found that with a brovo 1 on my Donzi I had too much transome lift, I changed to Hydromotive and eliminated the cavation problem I had. The hydromotive has less of a difuser onit which gives less transome lift.