I am thinking about buying a new Mercury 5 HP 4-stroke for the boat. Do these come with a prop? If they don't, is it difficult to select the correct one (pitch?) for sailboat use? Any thoughts appreciated!! Thanks!!
Prop Selection
- Thread starter SailorDave5050
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You can ask for a four blade small pitch prop. That will give you more thrust for a big boat but less speed for a dink. Tell the dealer what use you plan and he should be able to advise you concerning the correct prop.
Usually, outboards come with a prop. The manufacturer should have a recommended "RPMs at WOT (wide open throttle)". Then it's a matter of seeing if you have the correct prop. If the RPMs is below the recommended at WOT, then you're "overpropped." If the RPMs are higher at wot, then you're "underpopped." A good mechanic knowledgeable about props can help you get it right.
They make ONE really good 3 blade prop for the motor and while 99 dollars might seem high it will make the motor into a tugboat and pushed my 8000# Cal 29 at 4.5 knots with the 4HP motor
http://www.internetoutboards.com/partdetail.asp?id=719
http://www.internetoutboards.com/partdetail.asp?id=719
I don't know much about O/B props other than I tried a few on my 23 foot Aquarius on it's 9.9 hp 2-stroke, and found that going from the original 10 x 10 (if memory serves) 3-blade 'standard' prop to a 5" pitch made relatively little difference in boat speed, though it probably did increase engine top speed. Essentially no difference in reverse, which is what I was looking to improve mostly. Props had the common backswept type blades.
Changed to a 10 x 7 pitch 'high-thrust', with the Mickey Mouse ear blades like the one in the link, and wow, what a difference. Like a tractor, in forward and reverse. I even kept it when I sold the boat, in case I end up with another O/B like that one (Evinrude/Johnson 9.9 or 15 hp 2-stroke).
FWIW.
Changed to a 10 x 7 pitch 'high-thrust', with the Mickey Mouse ear blades like the one in the link, and wow, what a difference. Like a tractor, in forward and reverse. I even kept it when I sold the boat, in case I end up with another O/B like that one (Evinrude/Johnson 9.9 or 15 hp 2-stroke).
FWIW.
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