18 x 12 or 18 x 14?

[daw3f]

Hi,
I own a 2000 Moody 42 centre cockpit with a 50hp Volvo MD22L driving a 120SE saildrive 2.2:1 reduction. I'm looking at repropping with a 2 blade folding Gori. Lots of info out there but I'm concerned that 18 x 12 might be too fine. Please advise.

[DougR]

Based on the info I can find for your boat, my prop program says the optimum fixed blade prop would be a 20.7 X 11.2 x 2, resulting in 41% efficiency and 1020 lbs of thrust.

However if you are limited to 18 inches of diameter then you should have an 18 X 13.5 x 2, giving 38% efficiency and 934 lbs of thrust.

I would consult with Gori as they know how their props stack up against fixed blade props for blade area, efficiency, etc.

DougR

[daw3f]

Thanks. Looks like the 18 x 12 I'm looking at is too fine. I'll keep searching.

[Jim Cate]

Originally Posted by daw3f

Thanks. Looks like the 18 x 12 I'm looking at is too fine. I'll keep searching.

As long as you are still searching, you should consider a Flex-O-Fold prop. They score better in tests than Goris, and from personal experience, they are longer lived.

Jim

[daw3f]

Thanks. Anyone have experience with Eliche Radice folding props?

[GordMay]

Greetings and welcome aboard the CF, daw.

[Cadence]

Originally Posted by DougR

Based on the info I can find for your boat, my prop program says the optimum fixed blade prop would be a 20.7 X 11.2 x 2, resulting in 41% efficiency and 1020 lbs of thrust.

However if you are limited to 18 inches of diameter then you should have an 18 X 13.5 x 2, giving 38% efficiency and 934 lbs of thrust.

I would consult with Gori as they know how their props stack up against fixed blade props for blade area, efficiency, etc.

DougR

Doug, It sounds like a realistic program as to efficiency.

[daw3f]

What is the downside if I go for the 18 x 12? It's selling for less than half price.

[daw3f]

Also noticed corrosion where the exhaust elbow connects to the engine. Do I need a whole new elbow or can I just clean it up and replace the gasket?