I have recently aquire a legend 40 sloop 1986. I would like to know a pro and con of adding a 3 blade prop to my boat. With the motor in gear any thing over 2200 RPM dose not increese my speed. Will a three blade give me more speed and handling. If any one hase added a 3lade what pro size and pitch should I use. Thanks see you on the bay.
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Good question.
I posed this question to someone that I consider an expert, Ike Torresen(Related Link). I asked him if he thought a 3-blade would improve my chances in the Detroit River between lakes Erie and St. Clair. His answer was that if I have the right 2-blade then I would probably not notice the difference. Backing up would be a decided improvement however. Notice he said the "right" 2-blade. I have a folding 2-blade(Fold-O-Flex) and motor at 6 knots in average seas at 2200. That is with a heavy H37C and the original 20hp(2QM20). But when I cruise the ICW I may switch anyway just for the security in reverse. There has been a lot written here on HOW about the subject. Some have had excellent results with 2-blade props that were modified.
I posed this question to someone that I consider an expert, Ike Torresen(Related Link). I asked him if he thought a 3-blade would improve my chances in the Detroit River between lakes Erie and St. Clair. His answer was that if I have the right 2-blade then I would probably not notice the difference. Backing up would be a decided improvement however. Notice he said the "right" 2-blade. I have a folding 2-blade(Fold-O-Flex) and motor at 6 knots in average seas at 2200. That is with a heavy H37C and the original 20hp(2QM20). But when I cruise the ICW I may switch anyway just for the security in reverse. There has been a lot written here on HOW about the subject. Some have had excellent results with 2-blade props that were modified.
vibration
For me, the tremendous increase in performance after switching my h410 to a three-blade prop was a secondary benefit to the fact that it no longer vibrated at certain speeds.
For me, the tremendous increase in performance after switching my h410 to a three-blade prop was a secondary benefit to the fact that it no longer vibrated at certain speeds.
my reasons for a 3 blade
I put a 3 blade on my 81' H30 because the boat had a hard time fighting the tide in certain parts of the harbor. We would go out and the wind would die, and it would take a long time to motor through certain areas because of the tide surge. The 3 blade does provide a lot more thrust and makes the boat more responsive under power (stop means stop now, go means go now, etc). Prop walk is also less, simply because the boat gains speed in reverse faster, so the helm becomes usable sooner than than it did with the 2 blade. It does have vibration at some RPM's, but I can work around that. I have lost boat speed because of it, but not a lot. If I used the boat more I would probably invest in a folding prop, but for me the simplicity of the fixed 3 blade ws the best way to go. When I switched, I dropped 1 inch off both diameter and pitch.
I put a 3 blade on my 81' H30 because the boat had a hard time fighting the tide in certain parts of the harbor. We would go out and the wind would die, and it would take a long time to motor through certain areas because of the tide surge. The 3 blade does provide a lot more thrust and makes the boat more responsive under power (stop means stop now, go means go now, etc). Prop walk is also less, simply because the boat gains speed in reverse faster, so the helm becomes usable sooner than than it did with the 2 blade. It does have vibration at some RPM's, but I can work around that. I have lost boat speed because of it, but not a lot. If I used the boat more I would probably invest in a folding prop, but for me the simplicity of the fixed 3 blade ws the best way to go. When I switched, I dropped 1 inch off both diameter and pitch.
Speed at 2200 rpm
Joe, I wonder how fast you are going at 2200 rpm? If you are making hull speed which I would guess to be 7.8 knots, then you probably can't do much better. But, if you can take the engine to 3600 rpm and not increase the speed or make hull speed, that seems strange. A 3 blade prop will normally give you more thrust and less vibration and possibly have less prop walk. I replaced a 2 blade prop on a 37 Hunter with a Campbell Sailor and gained about one knot at the same rpms and could make hull speed easier. It did have a lot less vibration and did back better. My present boat a Hunter 420 has a 3 blade Max Prop which has a lot of thrust. I need to add more pitch the next time I haul the boat because I can take the engine to over 4000 rpm and not make hull speed at 3400 to 3600 rpm. If you are a cruiser (all destinations are up-wind), I would recommend a 3 blade prop. If you only daysail and race, get a folding/feathering prop. Bill
Joe, I wonder how fast you are going at 2200 rpm? If you are making hull speed which I would guess to be 7.8 knots, then you probably can't do much better. But, if you can take the engine to 3600 rpm and not increase the speed or make hull speed, that seems strange. A 3 blade prop will normally give you more thrust and less vibration and possibly have less prop walk. I replaced a 2 blade prop on a 37 Hunter with a Campbell Sailor and gained about one knot at the same rpms and could make hull speed easier. It did have a lot less vibration and did back better. My present boat a Hunter 420 has a 3 blade Max Prop which has a lot of thrust. I need to add more pitch the next time I haul the boat because I can take the engine to over 4000 rpm and not make hull speed at 3400 to 3600 rpm. If you are a cruiser (all destinations are up-wind), I would recommend a 3 blade prop. If you only daysail and race, get a folding/feathering prop. Bill
I Love My 3 Blade Sailer
I switched to a three blade Michigan Sailer form a two blade on my 1992 H35.5 Yes, I lost a slight amount of boat speed under sail, but I don't race, so who cares? Much improved maneuverability forward and reverse; actually less vibration than two blade also and certainly more punch going in and out of inlets! Go to the Michigan Wheel web site, they will fill you in on their prop types for sailboats [MP, Sailer etc] pros and cons etc. They will even spec out the correct size and pitch if you give them the technical info they request. Good Luck Fred Miller sv M/Squared By the way my Sailer was about $350.00
I switched to a three blade Michigan Sailer form a two blade on my 1992 H35.5 Yes, I lost a slight amount of boat speed under sail, but I don't race, so who cares? Much improved maneuverability forward and reverse; actually less vibration than two blade also and certainly more punch going in and out of inlets! Go to the Michigan Wheel web site, they will fill you in on their prop types for sailboats [MP, Sailer etc] pros and cons etc. They will even spec out the correct size and pitch if you give them the technical info they request. Good Luck Fred Miller sv M/Squared By the way my Sailer was about $350.00
hmmmm
We have an 86 H40 with a 2 blade prop and it motors wonderfully, no problems... touch wood. We get all the speed we need even in pretty heavy tidal currents (like in the Pacific NW San Juan Islands) when others are having trouble. We make great headway at 2200 RPMs and if we are fighting a heavy current go up to 24 to 28 or even 3000 and still get there fast. We also have a heavy current in our home port at the Columbia River. May evenutally put a folding or feathering prop on.... but that will be one more thing to maintain!
We have an 86 H40 with a 2 blade prop and it motors wonderfully, no problems... touch wood. We get all the speed we need even in pretty heavy tidal currents (like in the Pacific NW San Juan Islands) when others are having trouble. We make great headway at 2200 RPMs and if we are fighting a heavy current go up to 24 to 28 or even 3000 and still get there fast. We also have a heavy current in our home port at the Columbia River. May evenutally put a folding or feathering prop on.... but that will be one more thing to maintain!
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