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View Full Version : 19' Ragazza wot/prop question Please



Leakyz
08-08-2011, 02:20 PM
So I have been all over this website using the search function and reading but i cant find the answers i need so, I figure ill just ask and see what everyone/anyone thinks. I will spare you all the whole story about the truck loads of problems that have to be sorted out after you buy what was a "turn key boat"

So its a 1989 donzi ragazza bowrider
It has a 3 year old mercruiser 4.3 (that was purchased new)
The omc cobra drive and Ive determined the final gear ratio to be approx 1.6-1.7

the boat has a 4 blade alumin 15x16 prop now and with 2 people on board I am seeing a max rpm of about 3800 and with 4 people about 3500. I thought this prop would easily allow me 4500-4800 but no way. Any help,advice, critisism, anything is appreciated

guy also gave me a 3 blade stainless prop 14 1/2x19 I assume that would be worse though..

Thanks in advance

Phil S
08-08-2011, 09:38 PM
On my 17', 4.3 OMC, with a 14.5 x 19 ss, it spins to about 4,800 - 4,900 rpms. 15 x 16 aluminum I'm pretty sure is not the right prop for your boat. I also have a 23 pitch ss that I run on it when we're not skiing / tubing. No hole shot with that one and it drops the rpm down to around 4200-4300, but I know my tach gauge is not that accurate. I'd put the 19 pitch on it and try it.

Good luck with it...and post back what you find.

Regards,
Phil S.

Leakyz
08-09-2011, 09:31 AM
Thanks for the response, the whole prop world with diameters, pitches, blade count, material and style is a land only accessible by those who are pure genius with several phd's or people who are on the brink of madness and about to be commited..........

ps when i use the prop calculators online most say my boat will top out at 28mph what is that?!