Best prop for 8.5?

[voytek]

Does anyone know what is the original/recommended prop for an 8.5 with stock Yanmar 1GM? I suspect that mine has been replaced at some point and we're barely getting 5 knots at max rev. Can I install a 3-blade prop? What is everyone else running on? What site/manufacturer would you recommend?

Many thanks,

Voytek

 

[BobM]

That may be close to your max. I can cruise at 5.5 knots at 2800 rpm with a 14hp 2QM15 in a 9.2A with a 2 blade 16R9 prop. Max rpm is 3200. What rpm are you maxing out at? If you can't get max rpm you likely need to replace your exhaust elbow. Is it blowing any smoke? I'd imagine that the original prop is similar in pitch to mine, a 9 or 10 pitch and the diameter is probably around 14 inches. Michigan Wheel made my prop and it is stock. You can contact them. Any of the prop companies will spec a prop out for you via a simple email.

http://www.miwheel.com/Propellers/InboardPropellers/Michigan/Sailboat.aspx

If you want to stay fixed, Campbell Sailer is supposed to be a good prop.

http://www.westbynorth.com/CampbellSailerTests.aspx

I don't know if putting a three blade on your 1 cylinder is going to help you much. Drag is significantly greater for a 3 blade and will hurt light air sailing performance.

Hope this helps.

 

[voytek]

Hi Bob,

Thanks for your detailed response, We'll check out the vendors and see what they can offer but it sounds like there isn't much we can do anyway. We're somewhere in the 2700-3000 rpm range but with the tach working intermittently (yup, will need to look into that) it's hard to tell sometimes. Another option may be a 3-blade folding prop but that's a lot more money plus that diesel may be too smal for that. For now we're putting her up for sale [http://sbo.sailboatowners.com/index.php?option=com_adsmanager&Itemid=284&page=showad&adid=9608], will see what happens...

V.

 

[BobM]

Good luck with the sale. Looks like you did a lot to her. Are you getting out of sailing or moving up?