Cal 34 3 Blade prop size?

[SantaAna12]

I am looking to add a three bladed prop, for better handling and uphill trips. Google shows very little for my boat....I posted on yahoo cal groups (900+)....not much coming back. I own a Cal 34 MkIII with a Westerbeke 30 (4-91) driving a stock prop of 16X12X1 LH. Is there a direct size relationship to the stock prop? Or do I keep asking other Cal owners? (I own the original owners manual listing options...no go...just a Martec folding).

[tommays]

Talk to a GOOD prop person with current prop and RPM as there is a good bit of black magic in changing and getting the end result you want

[SantaAna12]

Thank you Tommays. I will give the SF prop shop a call that others recommended here. I was hoping to catch someone with a sister ship (there is a 15 inch 3blade in the Craigslist here that I was hoping to use), but it might not be the smartest choice. Anyways.....your advice will probably save me time and aggravation, thus giving me more time to sail.

[JimsCAL]

You can ask for a recommendation from one of the online propeller vendors like these guys.

West by North Enterprises - Propeller Recommendations

[SantaAna12]

thank you JimsCal. I am hesitant to ask though, as I am looking for a used prop, and do not want to waste anyones time. I was hoping that someone could tell me that if you had a 16X8X1 LH two blade, you could buy a 16X8X1 LH three blade. I saw a used three blade 15X8X1 in our craigslist......I guess I will let it go and keep my eyes and ears open on this, while making do with my two blade. Appreciate the tip though, I saved it in my favorites for later searches.

[Faster]

The 15" 3 blade may well do a fine job for you... years back we went from 18x12 2 blade to a 17x11 three blade with good results on a previous boat.

But you'd be best to consult someone properly - it's more about the engine/gear combo than the boat itself (other than its displacement)

[LakeSuperiorGeezer]

I would stay with the original propeller. It was selected to transfer peak engine horsepower to optimum propulsion. The two blade can also be positioned behind the deadwood for reduced drag. The two blade is also 2% more efficient than the three. Consider a controllable pitch propeller like the Autoprop if you want better performance.

[Waltthesalt]

Michigan wheel has a good free computer service just give them the numbers. Doesn't mean you have to buy thier prop. but you will get the specs. David Gerr's Propeller Handbook will walk you thru the calculations. I found that Michigan Wheel would have less blade area than IO calculated.

[SantaAna12]

Thank you Walt. I looked at the site....U.S., U.K., and Dubai....interesting. I will have some time this weekend.....gonna plug in the numbers. I have to put on the wetsuit and measure some for that criteria.
Geezer I appreciate yours as well.....I am looking for better backing under power, as the inner harbor I have to negotiate here is all about the narrow channel, and sharing with some mid sized commercial vessels. So.....I am still in the hunt for an affordable 3 blade option, or if need be, the best value.
Fair Winds......

[Faster]

West by North (linked to above) offers the Campbell Sailer prop... a lower drag fixed prop available in 2 and 3 blades that many have had success with. We made the change from a Martec folder (worn, floppy and shaky) to a 3 blade Campbell and had good results with it. I believe the cost would be somewhere around $800 (we paid under $700CDN 10 years ago)

Go ahead and use the estimator service on their site - Norm won't mind.