Changing from 3 to 4 blade prop. Any suggestions??

[whit71]

I recently bought a 2000 Four Winns 180 horizon with 4.3 GL Volvo SX (1.79 gear ratio) it has alum. Volvo prop 14 1/4 x 21 that looks like it was run aground there is about a 1/2" mising off of each blade. Boat is running 41 mph (GPS) at 4800 rpm Volvo recommends 4200-4600 on the GL 2bbl carb. Im looking for more pull out of the hole and more stability on plane the boat rides ok but if you trim up a hair to much it porposes like crazy I put a hydrofoil to get more lift it helped but I still want more stability. I know i want a 4 blade SS been loking at the Stiletto Bay Pro II I think I want the 22 pitch to lower the top end rpm, but Im worried i'll lose bottom end. This may sound crazy but could the 4800 rpm be from the 1/2" of prop missing from the blades? I just can't afford to buy the wrong prop to much money to throw away, and the boat is from out of town there is know Volvo dealer in the area to try a loaner prop. Any help would be appreciated. THANKS

 

[180shabah]

Re: Changing from 3 to 4 blade prop. Any suggestions??

A chewed up prop will throw the numbers off.

What is attracting you to SS?

A GOOD aluminum prop can give almost as good performance, and cost a LOT less.

 

[whit71]

Re: Changing from 3 to 4 blade prop. Any suggestions??

I was leaning to SS for less flex in the blades at higher speeds. what is your opionon on changing pitch when changing number of blades? I figured the missing metal may be the reason for more RPM's. I like what ive read about the Bay Pro II and i either have to go to a 22" or 20" to get a 21" gotta go to a Bay Pro III. Dont know how that would work on my runabout..

 

[180shabah]

Re: Changing from 3 to 4 blade prop. Any suggestions??

You DO NOT want a BayPro III.

IMHO, you would get more bang for your buck getting rid of the red-neck wing and replacing it with a set of tabs and a 21" Amita4. I know it is aluminum, but all that hype about blade flex is seriously exaggerated. Yes SS has thinner blades that make them more efficient, but unless you run WOT all the time, you'll never know.

Maybe your pockets are deeper than mine, get the tabs and SS

Either way, stability and 'foil on an I/O just don't go together.

 

[Dhadley]

Re: Changing from 3 to 4 blade prop. Any suggestions??

Ok, lets back up a minute. The Bay Pro III is designed for higher X dimensions which is not normally associated with a stern drive. The Bay Pro II is basically aimed at drives running a little deeper which lends itself to stern drives. If - IF - your stern drive happended to have a fairly high X dimension the the Bay Pro III may - may - be a good choice. A lot depends on hull design.

The cup placement is different between the BP II and the BP III. Most stern drives will benifit from the stern lift of a BP II. Some will benifit from the overall lift of a BP III.

A relatively short boat with a lot of iron in the stern probably is better suited to a stern lifting prop. SS props are a lot more advanced than aluminum props for a lot of reasons, thinner blades are the least of the advantages. Most have blades as thick as aluminum props, some thicker.

 

[whit71]

Re: Changing from 3 to 4 blade prop. Any suggestions??

Thanks for all of yall's advice. I bit the bullet and ordered the Bay pro II 20",and I will definetly test with and without the foil when I get the new prop. I'll let ya'll know how it runs. I dont expect to get the prop till mid next week so probaly be after the 4th before I report back so have a safe holliday and watch out for the idiots. Cause aint nothing like the 4th to bring out every dumba-- that cant drive a car much less a boat!!

 

[whit71]

Re: Changing from 3 to 4 blade prop. Any suggestions??

So I havent got my new prop yet but deciced to head down to the river saturday with the family backed the boat in trimmed down started up backed off the ramp and the trim quit working. Gotta love owning a boat its always something. got so agrivated I havent looked at it yet just loosened pressure line lifted up the outdrive and strapped it to the boat. Gotta check it out tonite crossing my fingers its a relay but I really doubt it. figure i'll be buying a new pump!!