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

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.

Phil S.

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?!