Prop Size for 44 HP Challenger

bartc3

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Oct 10, 2011
11
We are now the proud owners of Tarna, an Alden Challenger. She has a Westerbeke W44B engine and a three bladed prop. I would like to change her over to a two bladed prop. I can't afford a feathering prop at the moment so the best alternative is a two bladed fixed prop. Has anyone had experience with two bladed props on Challengers? I want to get the best performance both for sailing and motoring possible under the circumstances. Thanks
 

jon

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Nov 18, 2008
9
Newport Newport 16 South Haven MI
When it gets daylight I'll walk across the road and see if there any numbers still stamped where I can read them. Muskrat has a 2 blade whweel and a 44B as well. Top rpm is around 3000 though I never run her that hard. At 2000 rpm we do around 6-6.5 knts.
 

TomY

Alden Forum Moderator
Jun 22, 2004
2,663
Alden 38' Challenger yawl Rockport Harbor
I'm interested in this. I have a 3 blade prop on Christmas with a Nissan SD22 that puts out 40 hp. I have a sense due to the depth of the keel at the aperture, prop may not have as large a drag effect as boats with narrower keels or of course with detached rudders in apertures. 2 blade would be better for sure, especially if it's lined up with the keel.
 

JayZ

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Dec 4, 2007
60
Hodgdon Bros. Alden Caravelle Seabrook, Texas
Tom Young said:
I'm interested in this. I have a 3 blade prop on Christmas with a Nissan SD22 that puts out 40 hp. I have a sense due to the depth of the keel at the aperture, prop may not have as large a drag effect as boats with narrower keels or of course with detached rudders in apertures. 2 blade would be better for sure, especially if it's lined up with the keel.
Tom, I totally agree. The fixed 3 blade prop creates a lot of drag on a super slippery modern hull. However with our boats and their attached rudder and prop in the aperature you already have a disturbed area. ...that all said, I have been thinking of putting the 2 blade prop on that the prevous owner included when I purchased Banjo Girl. I thought I'd do some testing hiding it behind the keel and comparing boat speed under sail to the current configuration with the large 3 blade. It might not be the best experiment however because when the previous owner put the larger3 blade prop on he enlarged the aperature and lets just say that it isn't the prettiest nor most symmetrical cut. In fact I have always suspected that enlarging the aperature to fit a larger prop might hurt performance as much or more than the effect of the larger prop.
 

bartc3

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Oct 10, 2011
11
I have been calling around about props. The MaxProp guy seems to think the best alternative is a three blade feathering prop. The cost however is $2800 which is not in the budget at the moment. Our present prop is a three blade fixed prop 16 x 8. The MaxProp guy seems to think this is way off. He said it should be more like 16 x 11. Interestingly our prop was a 16 x 11 and it was repitched to 16 x 8. Most people I talk with think 16 x 8 is too flat a pitch. I wonder why the former owner had the prop repitched? I am going to climb down the cockpit hatch and check the reduction gear to make sure it is 2:1. A 1:1 would explain the prop pitch but I am quite sure the gear is a 2:1. The general rule for changing from three blade to two is to go up a pitch. In other words if our present prop is 16 x 8 we should buy a 16 x 9 fixed two blade prop. The question is what is the correct pitch? It would be interesting to note what others have on Challengers and whether they think what they have is working well especially in a chop or head wind.
 
May 25, 2012
3,844
john alden caravelle 42 sturgeon bay, wis
a two baded "sailing prop" locked vertically is the only way to sail these boats. a feathering prop will not fit in the apreature area nor will a folding prop. alden talks about that this. the gain while sailing hugely off sets any percieved gain motoring. these are sailboats not motorsailors. the difference is most noticable in the light stuff. i raced aeolus and had to switch the boat over from a loaded up cruising boat to a respectable racer and the number one instant improvement was going back to the sailing prop that the design calls for. the helm feel is also improved. aeolus now sails up to the 159 phrf rating i have. this all being said i also found that racing this molich built boat is like doing a irish jig on your mother's dining room table, it's hard not to skuff the surface. three bladed props are for motor boats, jon