help please BRAVO III duo prop gears ratio?

[Gregs2222]

Need help to find gears ratio in my new boat larson 290 w/single merc 7.4 and bravo III duo props . I'm new w/ this boat and i looking for any information about this engine and outdrive( on alpha one impeller is inside but bravo III?where?)boat is new for me but is 1997.

 

[Bondo]

Re: help please BRAVO III duo prop gears ratio?

( on alpha one impeller is inside but bravo III?where?)

Ayuh,... Look for a belt driven pump, lower forward starboard side of the Motor....

The drive ratio maybe stamped into the drive, near the serial numbers...

 

[HT32BSX115]

Re: help please BRAVO III duo prop gears ratio?

larson 290

Howdy,

If there's still a sticker on the left upper gear box with the serial number on it it may also have the ratio stamped there too...

If that's a 29ft boat, it probably has a 2.20:1 ratio drive. What is the pitch of your props?

 

[Gregs2222]

Re: help please BRAVO III duo prop gears ratio?

it's 24

 

[Gregs2222]

Re: help please BRAVO III duo prop gears ratio?

i just bought this boat( good price = more problems). on ebay i found lover piece for 1200$ . Boat is from 1998 and is 590h on it - never rebuild .

 

[90stingray]

Re: help please BRAVO III duo prop gears ratio?

i just bought this boat( good price = more problems). on ebay i found lover piece for 1200$ . Boat is from 1998 and is 590h on it - never rebuild .

What problems do you have? Something wrong with your Bravo3?

 

[HT32BSX115]

Re: help please BRAVO III duo prop gears ratio?

it's 24

You can estimate your drive ratio if you can measure your speed and RPM accurately, your hull (bottom) is clean, and the engine is running correctly.

Using a prop slip calculator , 24p props and approx 12% slip, you should do around 33mph at 3500 RPM if your drive ratio is 2.20:1

If it's 2.00:1 (which may be unlikely in a boat that big) you'll be a little bit faster (3 or 4 MPH)

It's also easy to do it by removing the sparkplugs.... turn the engine either by hand or the starter, while someone gently places the drive in gear......once in gear turn the engine exactly 2 revolutions and have someone determine if the prop turns exactly 1 turn (2.00:1) or slightly less than one turn(2.20:1)

Don't shift the drive unless the engine is turning.