Any one had experience with "Feathering Props" Should i go with a two blade or a three presently I have a standard 2 blade and seem to do the job very well
Props
- Thread starter PM in TO
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PM - Need to know a little more about how you use the boat to give a good answer. If you race the folding or feathering prop could be worth the other issues. (panic reverse does not work well) Seeing the transmission in the Catalina allows the prop to turn, (free wheel) with no damage when sailing, I give up very little with my three blade fixed, and the boat backs well, and hits hull speed at 2400 rpm when motering.
Check out the Kiwi props...we have one and it backs well and it cost less then the other feathering props. www.kiwiprop.us I would guess on average we gained at least a half knot of sailing speed. In fact this is our second Kiwi...we had one on a Beneteau 331 as well.
I had the Martec on my Catalina 34' like I said except for the lag in backing responce I felt it was a good prop. This prop from Kiwi is pretty interesting looking, will have to do a little more research on it. Thanks for the Post Scott
Russ
Russ
Prop Choices (open your wallet...)
Sorry to (slightly) disagree with another poster...
but about prop choices --
1) Two Blade Fixed: boat builders put them on because they are usually adequate if pitched right. Often the initial pitch is incorrect, but 'close enough' to get the boat up to hull speed. NoteB: if they err, it will normally to over pitch it a bit, so that the boat will hit a quick hull speed in smooth water at lower rpm's and thereby seem to have a quieter diesel installation. Least expensive choice.
2) Three Blade Fixed: more blade area, somewhat intrinsically better ballance, and thereby more thrust even against some wave or wind resistance. Price goes up a bit.
3) Feathering Props: commonly coming in Two Blade, and for more $$, 3 or 4. They solve most of the problems with reverse power, prop walk in reverse, and give you a lot more sailing speed. This solution comes at the expense of complexity, and, well, 'expense'. If you can budget for it, you will likely find that after roller furling jibs and self tailing winches, this is one of the nicest upgrades you can do for your boat.
(Opinions rendered on the hour, deposit one virtual cent!)
4) Folding Props: Since all that the two (or three) blades do is pivot back for very minimal resistance under sail, the cost is intermediate, and the complexity is much reduced. Stopping quick and back up straight are rare happenings -- possible according to some ads but seldom observed in real life.
My experience has been with the 'stock' two blade fixed, a two blade featherer for a decade, and currently a three blade fixed. I have a lot of crew time on another boat with a folder, as well.
Pluses and Mnuses as noted above.
While we love the thrust of the 3 blade fixed, when budget allows we will be putting a 3 blade featherer on.
Happy Motoring,
FO
ps: be aware that some sailors confuse brands with prop type. For instance MARTEC sells both feathering and folding props.
Sorry to (slightly) disagree with another poster...
but about prop choices --
1) Two Blade Fixed: boat builders put them on because they are usually adequate if pitched right. Often the initial pitch is incorrect, but 'close enough' to get the boat up to hull speed. NoteB: if they err, it will normally to over pitch it a bit, so that the boat will hit a quick hull speed in smooth water at lower rpm's and thereby seem to have a quieter diesel installation. Least expensive choice.
2) Three Blade Fixed: more blade area, somewhat intrinsically better ballance, and thereby more thrust even against some wave or wind resistance. Price goes up a bit.
3) Feathering Props: commonly coming in Two Blade, and for more $$, 3 or 4. They solve most of the problems with reverse power, prop walk in reverse, and give you a lot more sailing speed. This solution comes at the expense of complexity, and, well, 'expense'. If you can budget for it, you will likely find that after roller furling jibs and self tailing winches, this is one of the nicest upgrades you can do for your boat.
(Opinions rendered on the hour, deposit one virtual cent!)
4) Folding Props: Since all that the two (or three) blades do is pivot back for very minimal resistance under sail, the cost is intermediate, and the complexity is much reduced. Stopping quick and back up straight are rare happenings -- possible according to some ads but seldom observed in real life.
My experience has been with the 'stock' two blade fixed, a two blade featherer for a decade, and currently a three blade fixed. I have a lot of crew time on another boat with a folder, as well.
Pluses and Mnuses as noted above.
While we love the thrust of the 3 blade fixed, when budget allows we will be putting a 3 blade featherer on.
Happy Motoring,
FO
ps: be aware that some sailors confuse brands with prop type. For instance MARTEC sells both feathering and folding props.
The Kiwi is around $ 1500.00 and motors extremely well in forward and reverse. We went with the 15.50" X 21 and the pitch can be easily adjusted.
We had a martec folder on a C-30 many years ago and we did notice a decline in motoring...especially in reverse but the gain in sailing performance was worth it.
We had a martec folder on a C-30 many years ago and we did notice a decline in motoring...especially in reverse but the gain in sailing performance was worth it.
Long Story,
So you sail with your prop "freewheeling" all the time. I was not aware you could do that without causing issues. This is good to know!
Your better off to stop the prop from windmillling because it causes more drag than while it's stationary. Also, a windmilling prop produces undue wear, regardless if it's on the transmission or the stuffing box. I always put my transmission in reverse while sailing.
Well that is to be debated. Mainsail did a very interesting test reguarding prop drag. For the life of me I can't find it on his site, but here is a link to the Video he created.
http://www.youtube.com/watch?v=jI-UG9RSlJo
You are correct, mine was the folder - 2 blade
Sorry to (slightly) disagree with another poster...
but about prop choices --
1) Two Blade Fixed: boat builders put them on because they are usually adequate if pitched right. Often the initial pitch is incorrect, but 'close enough' to get the boat up to hull speed. NoteB: if they err, it will normally to over pitch it a bit, so that the boat will hit a quick hull speed in smooth water at lower rpm's and thereby seem to have a quieter diesel installation. Least expensive choice.
2) Three Blade Fixed: more blade area, somewhat intrinsically better ballance, and thereby more thrust even against some wave or wind resistance. Price goes up a bit.
3) Feathering Props: commonly coming in Two Blade, and for more $$, 3 or 4. They solve most of the problems with reverse power, prop walk in reverse, and give you a lot more sailing speed. This solution comes at the expense of complexity, and, well, 'expense'. If you can budget for it, you will likely find that after roller furling jibs and self tailing winches, this is one of the nicest upgrades you can do for your boat.
(Opinions rendered on the hour, deposit one virtual cent!)
4) Folding Props: Since all that the two (or three) blades do is pivot back for very minimal resistance under sail, the cost is intermediate, and the complexity is much reduced. Stopping quick and back up straight are rare happenings -- possible according to some ads but seldom observed in real life.
My experience has been with the 'stock' two blade fixed, a two blade featherer for a decade, and currently a three blade fixed. I have a lot of crew time on another boat with a folder, as well.
Pluses and Mnuses as noted above.
While we love the thrust of the 3 blade fixed, when budget allows we will be putting a 3 blade featherer on.
Happy Motoring,
FO
ps: be aware that some sailors confuse brands with prop type. For instance MARTEC sells both feathering and folding props.
Check the manual
This was a surprise to me also, as I had always been taught to sail with the tranny locked in Rev to stop prop freewheeling. While reading the manual on the transmission one snow covered day, OMG reading the maunal, it is stated that the boat can be sailed in netural (out of gear) with no damage to the transmission. :naughty: don't shoot the messenger please...
This was a surprise to me also, as I had always been taught to sail with the tranny locked in Rev to stop prop freewheeling. While reading the manual on the transmission one snow covered day,
OMG reading the maunal, it is stated that the boat can be sailed in netural (out of gear) with no damage to the transmission. :naughty: don't shoot the messenger please...
Witzend, there is a lot of clear evidence that a windmilling prop causes more drag than a stationary prop...certainly in the aviation community, and I believe the same applies to boats. If anyone can proove otherwise, that information would be fun to review and perhaps some text books may need to be re-written. Think of this way: The energy it takes to spin the prop MUST come from somewhere. Now, having said all that, I'm not necessarily saying that you'll notice a difference in boat speed. There are many more variables involved with the outcome of boat speed.
I can't view the youtube video at this time, but I will when I get at chance. I really enjoy the information that Mainsail writes about, so I am interested to hear what he has to say.
I can't view the youtube video at this time, but I will when I get at chance. I really enjoy the information that Mainsail writes about, so I am interested to hear what he has to say.
Yes - But?
In the case of my 3-blade a windmilling prop will have less drag than a locked prop correct? Turning is less resistance than hitting a solid blade. Your correct in that it will use more energery than a folded prop, in your aviation example, the prop is feathered away when it stops turning. We know there is a lot of energy used becuse you can pitch the prop to cause enough force to turn over the engine for an emergency restart. We also know people that generate power off their windmilling prop shaft. This discussion sure beats being out moving the 12" plus snow we got last night.
In the case of my 3-blade a windmilling prop will have less drag than a locked prop correct? Turning is less resistance than hitting a solid blade. Your correct in that it will use more energery than a folded prop, in your aviation example, the prop is feathered away when it stops turning. We know there is a lot of energy used becuse you can pitch the prop to cause enough force to turn over the engine for an emergency restart. We also know people that generate power off their windmilling prop shaft. This discussion sure beats being out moving the 12" plus snow we got last night.
I don't think so...
Long Story, sorry about the 12" of snow, but I think you deserve it more than we do down here. :stirthepot:
Let's not forget that the only reason the prop is spinning because of the fluid flowing across the blades of the prop and Bernoulli's principle causing the motion. It's not as if the prop is spinning through the fluid stream...the prop is spinning because of the fluid stream. Therefore we still have fluid hitting the same amount of surface area. Now that I think of it, the prop motion through the water may be analogous to sialing into the wind and the affect of apparent wind.
In my aviation example I was refering only to fixed pitch propellors, which cannot be feathered. So it is the exact same principle as your 3-blade prop. Many people in aviation compare the additional drag of a windmilling prop to that of a flat disc the same diameter as the prop. But I believe it's well know that the additional drag is even greater than that of a flat disc.
Long Story, sorry about the 12" of snow, but I think you deserve it more than we do down here. :stirthepot:
Let's not forget that the only reason the prop is spinning because of the fluid flowing across the blades of the prop and Bernoulli's principle causing the motion. It's not as if the prop is spinning through the fluid stream...the prop is spinning because of the fluid stream. Therefore we still have fluid hitting the same amount of surface area. Now that I think of it, the prop motion through the water may be analogous to sialing into the wind and the affect of apparent wind.
In my aviation example I was refering only to fixed pitch propellors, which cannot be feathered. So it is the exact same principle as your 3-blade prop. Many people in aviation compare the additional drag of a windmilling prop to that of a flat disc the same diameter as the prop. But I believe it's well know that the additional drag is even greater than that of a flat disc.
I bet people think we just sit on here and chat away, not realizing that we explore areas of science and test out key principals of engineering and physics. To sail it to create upon the canvas of the sea....
Feathering Prop
In spring 2006 we replaced our prop with a 3 blade Max Prop Feathering 15" diameter x 9" pitch. Total price through Defender was $2181. The two blade model was about $800 less. A lot of $ for a prop but both my wife and I agree that it was one of the best improvements we made. Besides adding additional speed while motoring, the best advantage we found was in greatly improved control in reverse. Still some prop walk but when in reverse the blades change pitch so we can come to a stop, when needed, much faster than with the old prop. One thing I have found is to not over-grease the prop as too much grease interferes with the blades setting to the correct pitch.
Went with folding
Last year shifted from the stock 3 blade to Flex-O-Fold 3blade 15x9. Experienced similar benefits - about 3/4 knot speed increase in 4 knot winds, prop walk almost eliminated and hull speed 300 RPM lower. Well worth the cost. Get to raft up happy hour while the food is still out !!
Last year shifted from the stock 3 blade to Flex-O-Fold 3blade 15x9. Experienced similar benefits - about 3/4 knot speed increase in 4 knot winds, prop walk almost eliminated and hull speed 300 RPM lower. Well worth the cost. Get to raft up happy hour while the food is still out !!
Interesting thoughts.........15x11
http://mysite.verizon.net/resqp86c/performancepropellers/id33.html
paulj :troll:
http://mysite.verizon.net/resqp86c/performancepropellers/id33.html
paulj :troll:
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