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Propeller

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gallagh59
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Propeller

Post by gallagh59 » Fri Nov 16, 2018 12:05 pm

My '59 18' Continental calls for a 12x16x1 prop (wheel #670). I purchased the boat with a NiBral 1067 12X14x1 with cupped edge. Should I go back to the original or will the NiBral 1067 fit the bill??? All original 283 cu. in. power. Recommendations???? Thanks!

Riviera Wish
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Re: Propeller

Post by Riviera Wish » Fri Nov 16, 2018 12:43 pm

I am far from an expert on propeller selection but I think I can make a contribution to the selection. The selected propeller should run at the maximum rated horsepower RPM of the engine at wide-open throttle. Diameter of the propeller should be the maximum allowable with proper tip clearance; for your purpose I assume this is 12". Propeller design has made significant advances in the past 50 years so contacting a representative of ,say ACME propellers, would be very enlightening. In previous posts I believe there are names and phone numbers of persons with up to date knowledge of propeller selection for old CC boats. Before contacting these persons you should have some information on the current performance data of your current propeller: actual RPM at wide-open throttle, speed at wide-open throttle, load condition of the boat (average # passengers, etc.).

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mbigpops
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Re: Propeller

Post by mbigpops » Fri Nov 16, 2018 2:24 pm

I went the ACME route and they recommended a prop based on my boat size and engine type and horsepower. I was also pre-warned to order a stock prop so that it could be returned if there were any issues (custom ones are not returnable).

That was some great advice as despite the pitch and diameter being correct on the new prop I had two issues. One was it rode up the shaft too far and was up against the strut (none of the standard props had this issue). Second was due to the curve of the blades they hit the rudder.

I was very disappointed as the ACME reputation for performance seems to be very good.

Mark
1953 CC Rocket Runabout "Rocket Man"

homeiste
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Re: Propeller

Post by homeiste » Sun Nov 18, 2018 8:19 am

I have a 1960 18' Continental w 283, some extra weight from a 5200 bottom. I can't comment on the appropriateness of the NiBral 1067, but I went from the stock CC prop to an Acme prop a couple years ago and love the switch to that prop. Unless you are showing the boat I would stick with a modern one for smoothness and performance. The thread moved towards recommending an ACME prop. Not sure what you would gain versus a NiBral (would depend on its characteristics), but if you choose to explore the ACME route, work directly with ACME (more $ but worth the expertise and free swap). They wanted me to try a 3 blade variable pitch prop as the potential best, but it had too much rake so the blades came too close to the rudder, so we went with a four blade with less rake: No 650, 13 x 12.125 x 1, 0.06 cup. Much smoother, more 'hole shot' (we tube and ski), slightly enhanced top end performance but I rarely' push the 283 up that high anyway. It does move the boat a bit faster at idle speed so I had to adjust low speed maneuvering.
1960 18' Continental
1970 Boston Whaler Sakonnet w/ Bearcat 55 outboard

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WoodenRookie
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Re: Propeller

Post by WoodenRookie » Sun Nov 18, 2018 11:03 am

Bob,
I have an extra 670 you could borrow/test.

Bill
59 18' Continental

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