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Author Topic:   Back-up Prop Questions
TheSkipper posted 06-15-2002 09:56 AM ET (US)   Profile for TheSkipper  
I have a 135 Optimax on my Dauntless 180, which has a 15.25 x 17 SS Mirage Plus prop. This prop works perfectly for my set-up (about 42 mph at 5500 rpm). I would like to purchase a back-up/replacement prop. The cheapest I was able to find a second Mirage Plus for was $439. Various other stainless steel props retail for around $299. However, when looking at other brands, I was not able to find a prop with a 15.25 diameter. My questions are: 1. If I buy another stainless steel prop with a smaller diameter (14.25 or 14.5), should I get a larger pitch (19 or 21)? 2. If I am able to find an aluminum prop with 15.25 diameter, should I get a larger pitch, and if so, how much larger? Any help will be appreciated.
Clark Roberts posted 06-15-2002 04:10 PM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Suggest you not sweat the diameter and don't increase pitch... Clark ... Spruce Creek Navy
180 posted 06-17-2002 02:13 PM ET (US)     Profile for 180  Send Email to 180     
why do you want another prop?
Just curious.
TheSkipper posted 06-17-2002 02:53 PM ET (US)     Profile for TheSkipper    
I nicked one of the blades on my Mirage Plus in unfamiliar shallow water. I would like to purchase a replacement to use while I have the Mirage Plus repaired, and also to use as a back-up. I am leaning toward an aluminum replacement. That way, if I ever plan to go into unfamiliar shallow water again, I can use the aluminum prop with less potential of doing serious damage to the lower unit if I happen to hit bottom again. I'm not really concerned about top speed. I just don't want to end up with a prop that will allow the engine to rev to high. That way I won't have to worry about friends or relatives over-revving the engine when I'm not around. (Also, a minor correction to my original post - with the OEM prop I get about 42 mph at about 5300 rpm).
bsmotril posted 06-17-2002 03:04 PM ET (US)     Profile for bsmotril  Send Email to bsmotril     
Pick up a Merc Aluminum prop in the same pitch. Don't worry about the diameter. The RPMs will be within 1-200 of each other based on my experience with doing this on a Merc 175 that also had a Mirage 17" original prop.
TheSkipper posted 06-24-2002 09:17 AM ET (US)     Profile for TheSkipper    
Well, I purchased a 15 x 17 Mercury Quicksilver aluminum prop. At 5300 rpm, I am only getting about 37 mph. This is about a 5 mph decrease from the stainless steel prop. Also, the engine will now rev to the redline - 6000 rpm - while in gear.
bsmotril posted 06-24-2002 10:14 PM ET (US)     Profile for bsmotril  Send Email to bsmotril     
Is the aluminum prop the same diameter as your stainless one? That is a pretty drastic change in RPM and does not mirror my experience at all. The prop I bought was back in '94. I wonder if anything has changed on the design. If the dealer won't let you swap for an 18 or 19 inch one, I would take it to a prop shop and have them add some cup to the blade edges. That should help with the rpm.
Boston Marine posted 06-25-2002 12:02 AM ET (US)     Profile for Boston Marine    
You might want to check out this companies propeller line.

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