[Amel Yacht Owners] Fixed prop
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Patrick McAneny
Just as I sent my question about fixed vs. unfixed props to the group , my wife sent me the results of her google search . Yachting monthly said that this subject had been debated for decades so they conducted tests that determined that a spinning prop produced less than half the drag of a fixed prop. That at seven knots you would lose approx. one knot while fixed. That seems to jive with what I experienced. Pat
-----Original Message----- From: sailw32@... [amelyachtowners] <amelyachtowners@...> To: amelyachtowners Sent: Wed, Jun 3, 2015 9:26 am Subject: [Amel Yacht Owners] Fixed prop We have a fixed prop due to the original owner opting for the prop driven alternator , which I have dismantled since my solar panels and wind generator supplies all the electric I need. I have been told, that it is more efficient from the standpoint of drag for a prop to be fixed opposed to be freewheeling, from a pilot who's opinion I respect. While sailing I do not like to switch in and out of gear due to the loud clunk that sounds as though it could damage the transmission, so its hard to experiment to draw conclusions. However we just sailed back from the BVIs via Bermuda and we were in gear fixed and then I put it in neutral and it seemed that we picked up a knot. I never put it back in gear as we were sailing too fast and for the next three days we averaged 173 nms. with true wind avg. 12 - 16 . Could someone that is knowledgeable about props and drag tell me which is more efficient ? I am also concerned about wear on the transmis sion while freewheeling .
Thanks, Pat SM Shenanigans
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Germain Jean-Pierre <jgermain@...>
Hi Pat,
I am a pilot too.. though you probably have no reason to respect my opinion. :-) From a fluid dynamics POV, a feathered prop is better than a turning propeller. And a turning prop has less drag than a stopped prop. For this reason, I would not install a shaft generator on Eleuthera because of the “relative” fragility of the SM dual 90 degree gearbox and the propeller drag if left to windmill. Cheers, Jean-Pierre Germain SY Eleuthera, SM 007.
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hanspeter baettig
Hello Pat After 20 Years experience with fix pro against maxpro you will not lose 1 knot, Trust me. A propos to engage the fix pro during sailing, I do it like that ; even with downwind sail I luv until I do not have more then 1 knots spead against the Wind even in Heavy weather. Then I put the gear in inverse without any clunk ( Capt. Amel advice) Hanspeter SM 16, Tamango 2 Göcek, Turkey Von meinem iPhone gesendet Am 03.06.2015 um 16:21 schrieb "Patrick Mcaneny sailw32@... [amelyachtowners]" <amelyachtowners@...>:
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Germain Jean-Pierre <jgermain@...>
Hey Hans Peter,
Now I know why Bernard is faster than you in his Maramu. :-) :-) Jean-Pierre SY Eleuthera, SM007
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Patrick McAneny
I just read another study that also determined that a fixed prop created more than twice as much drag as a freewheeling prop. But what I want to relate is that this article claimed that Yanmar and Volvo both believe that the transmissions should be in neutral to prevent damage and could cause warranty issues .I do not know if that is true ,if concerned you may want to speak to a rep. Pat
-----Original Message----- From: Patrick Mcaneny sailw32@... [amelyachtowners] To: amelyachtowners Sent: Wed, Jun 3, 2015 10:21 am Subject: Re: [Amel Yacht Owners] Fixed prop
Just as I sent my question about fixed vs. unfixed props to the group , my wife sent me the results of her google search . Yachting monthly said that this subject had been debated for decades so they conducted tests that determined that a spinning prop produced less than half the drag of a fixed prop. That at seven knots you would lose approx. one knot while fixed. That seems to jive with what I experienced. Pat
-----Original Message-----
From: sailw32@... [amelyachtowners] <amelyachtowners@...> To: amelyachtowners <amelyachtowners@...> Sent: Wed, Jun 3, 2015 9:26 am Subject: [Amel Yacht Owners] Fixed prop
We have a fixed prop due to the original owner opting for the prop driven alternator , which I have dismantled since my solar panels and wind generator supplies all the electric I need. I have been told, that it is more efficient from the standpoint of drag for a prop to be fixed opposed to be freewheeling, from a pilot who's opinion I respect. While sailing I do not like to switch in and out of gear due to the loud clunk that sounds as though it could damage the transmission, so its hard to experiment to draw conclusions. However we just sailed back from the BVIs via Bermuda and we were in gear fixed and then I put it in neutral and it seemed that we picked up a knot. I never put it back in gear as we were sailing too fast and for the next three days we averaged 173 nms. with true wind avg. 12 - 16 . Could someone that is knowledgeable about props and drag tell me which is more efficient ? I am also concerned about wear on the transmis sion while freewheeling .
Thanks, Pat SM Shenanigans
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Interesting Pat, Seems to me that a freewheeling prop could wear out the drive, while a prop that is not turning wouldn't cause any damage at all unless you hit something with it (highly unlikely on our boats). It's hard to evaluate the difference between a fixed prop, freewheeling fixed pitch prop, and folding or feathering prop, as wind and wave conditions are always changing. I used a fixed pitch prop for a year and always put the engine in gear while sailing. When I put my feathering MaxProp on I think I gained an average of about a half knot while sailing in varied conditions. I always put the transmission in gear long enough to feather the prop, then put it back in neutral while sailing. If it's OK to let it freewheel, there must not be a significant difference in boat speed...so maybe I wasted a bundle on my MaxProp, eh? Kent SM243 Kristy On Jun 3, 2015, at 1:56 PM, Patrick Mcaneny sailw32@... [amelyachtowners] <amelyachtowners@...> wrote:
I just read another study that also determined that a fixed prop created more than twice as much drag as a freewheeling prop. But what I want to relate is that this article claimed that Yanmar and Volvo both believe that the transmissions should be in neutral to prevent damage and could cause warranty issues .I do not know if that is true ,if concerned you may want to speak to a rep. Pat
-----Original Message-----
From: Patrick Mcaneny sailw32@... [amelyachtowners] <amelyachtowners@...> To: amelyachtowners <amelyachtowners@...> Sent: Wed, Jun 3, 2015 10:21 am Subject: Re: [Amel Yacht Owners] Fixed prop
Just as I sent my question about fixed vs. unfixed props to the group , my wife sent me the results of her google search . Yachting monthly said that this subject had been debated for decades so they conducted tests that determined that a spinning prop produced less than half the drag of a fixed prop. That at seven knots you would lose approx. one knot while fixed. That seems to jive with what I experienced. Pat
-----Original Message-----
From: sailw32@... [amelyachtowners] <amelyachtowners@...> To: amelyachtowners <amelyachtowners@...> Sent: Wed, Jun 3, 2015 9:26 am Subject: [Amel Yacht Owners] Fixed prop
We have a fixed prop due to the original owner opting for the prop driven alternator , which I have dismantled since my solar panels and wind generator supplies all the electric I need. I have been told, that it is more efficient from the standpoint of drag for a prop to be fixed opposed to be freewheeling, from a pilot who's opinion I respect. While sailing I do not like to switch in and out of gear due to the loud clunk that sounds as though it could damage the transmission, so its hard to experiment to draw conclusions. However we just sailed back from the BVIs via Bermuda and we were in gear fixed and then I put it in neutral and it seemed that we picked up a knot. I never put it back in gear as we were sailing too fast and for the next three days we averaged 173 nms. with true wind avg. 12 - 16 . Could someone that is knowledgeable about props and drag tell me which is more efficient ? I am also concerned about wear on the transmis sion while freewheeling .
Thanks, Pat SM Shenanigans
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sailormon <kimberlite@...>
I notice a ½ knot difference when the engine is running in neutral and the autoprop is freewheeling. When the engine is stopped the brake locks the shaft and I gain ½ a knot.
When I used to build race cars we always disconnected the drive shaft as many transmissions are lubricated by the fluid / lubricant being splashed on the mechanism by the engine driving the gears. Many times people who did not do this blew the rear seals on their transmissions. I do not know if the same holds true for my tranny. But I am happy to have the shaft brake. Fair Winds Eric Kimberlite Amel Super Maramu #376
From: amelyachtowners@... [mailto:amelyachtowners@...]
Sent: Wednesday, June 03, 2015 3:11 PM To: amelyachtowners@... Subject: Re: [Amel Yacht Owners] Fixed prop
Interesting Pat, Seems to me that a freewheeling prop could wear out the drive, while a prop that is not turning wouldn't cause any damage at all unless you hit something with it (highly unlikely on our boats).
It's hard to evaluate the difference between a fixed prop, freewheeling fixed pitch prop, and folding or feathering prop, as wind and wave conditions are always changing. I used a fixed pitch prop for a year and always put the engine in gear while sailing. When I put my feathering MaxProp on I think I gained an average of about a half knot while sailing in varied conditions. I always put the transmission in gear long enough to feather the prop, then put it back in neutral while sailing. If it's OK to let it freewheel, there must not be a significant difference in boat speed...so maybe I wasted a bundle on my MaxProp, eh? Kent SM243 Kristy
I just read another study that also determined that a fixed prop created more than twice as much drag as a freewheeling prop. But what I want to relate is that this article claimed that Yanmar and Volvo both believe that the transmissions should be in neutral to prevent damage and could cause warranty issues .I do not know if that is true ,if concerned you may want to speak to a rep. Pat
-----Original Message-----
Just as I sent my question about fixed vs. unfixed props to the group , my wife sent me the results of her google search . Yachting monthly said that this subject had been debated for decades so they conducted tests that determined that a spinning prop produced less than half the drag of a fixed prop. That at seven knots you would lose approx. one knot while fixed. That seems to jive with what I experienced. Pat
-----Original Message-----
We have a fixed prop due to the original owner opting for the prop driven alternator , which I have dismantled since my solar panels and wind generator supplies all the electric I need. I have been told, that it is more efficient from the standpoint of drag for a prop to be fixed opposed to be freewheeling, from a pilot who's opinion I respect. While sailing I do not like to switch in and out of gear due to the loud clunk that sounds as though it could damage the transmission, so its hard to experiment to draw conclusions. However we just sailed back from the BVIs via Bermuda and we were in gear fixed and then I put it in neutral and it seemed that we picked up a knot. I never put it back in gear as we were sailing too fast and for the next three days we averaged 173 nms. with true wind avg. 12 - 16 . Could someone that is knowledgeable about props and drag tell me which is more efficient ? I am also concerned about wear on the transmis sion while freewheeling . Thanks, Pat SM Shenanigans |
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Patrick McAneny
Kent, No you probably did not waste your money, the test results showed that a feathering prop decreased drag significantly over a spinning fixed prop and a folding prop's drag could not even be measured it was so low. I will have Diane post the test . It showed that the Flexofold had best thrust and very low drag, wonder if they would fit on a SM. Pat
-----Original Message----- From: Kent Robertson karkauai@... [amelyachtowners] To: amelyachtowners <amelyachtowners@...> Sent: Wed, Jun 3, 2015 3:11 pm Subject: Re: [Amel Yacht Owners] Fixed prop
Interesting Pat,
Seems to me that a freewheeling prop could wear out the drive, while a prop that is not turning wouldn't cause any damage at all unless you hit something with it (highly unlikely on our boats).
It's hard to evaluate the difference between a fixed prop, freewheeling fixed pitch prop, and folding or feathering prop, as wind and wave conditions are always changing. I used a fixed pitch prop for a year and always put the engine in gear while sailing. When I put my feathering MaxProp on I think I gained an average of about a half knot while sailing in varied conditions. I always put the transmission in gear long enough to feather the prop, then put it back in neutral while sailing.
If it's OK to let it freewheel, there must not be a significant difference in boat speed...so maybe I wasted a bundle on my MaxProp, eh?
Kent
SM243
Kristy
Sent from my iPhon e On Jun 3, 2015, at 1:56 PM, Patrick Mcaneny sailw32@... [amelyachtowners] < amelyachtowners@...> wrote:
I just read another study that also determined that a fixed prop created more than twice as much drag as a freewheeling prop. But what I want to relate is that this article claimed that Yanmar and Volvo both believe that the transmissions should be in neutral to prevent damage and could cause warranty issues .I do not know if that is true ,if concerned you may want to speak to a rep. Pat
-----Original Message-----
From: Patrick Mcaneny sailw32@... [amelyachtowners] < amelyachtowners@...> To: amelyachtowners < amelyachtowners@...> Sent: Wed, Jun 3, 2015 10:21 am Subject: Re: [Amel Yacht Owners] Fixed prop
Just as I sent my question about fixed vs. unfixed props to the group , my wife sent me the results of her google search . Yachting monthly said that this subject had been debated for decades so they conducted tests that determined that a spinning prop produced less than half the drag of a fixed prop. That at seven knots you would lose approx. one knot while fixed. That seems to jive with what I experienced. Pat
-----Original Message-----
From: sailw32@... [amelyachtowners] < amelyachtowners@...> To: amelyachtowners < amelyachtowners@...> Sent: Wed, Jun 3, 2015 9:26 am Subject: [Amel Yacht Owners] Fixed prop
We have a fixed prop due to the original owner opting for the prop driven alternator , which I have dismantled since my solar panels and wind generator supplies all the electric I need. I have been told, that it is more efficient from the standpoint of drag for a prop to be fixed opposed to be freewheeling, from a pilot who's opinion I respect. While sailing I do not like to switch in and out of gear due to the loud clunk that sounds as though it could damage the transmission, so its hard to experiment to draw conclusions. However we just sailed back from the BVIs via Bermuda and we were in gear fixed and then I put it in neutral and it seemed that we picked up a knot. I never put it back in gear as we were sailing too fast and for the next three days we averaged 173 nms. with true wind avg. 12 - 16 . Could someone that is knowledgeable about props and drag tell me which is more efficient ? I am also concerned about wear on the transmis sion while freewheeling .
Thanks, Pat SM Shenanigans
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Patrick McAneny
Jean, I have read on this site that no damage is done by allowing the prop to freewheel, indeed Amel sold the boat with a shaft charging system which requires the prop to freewheel. However, I have always worried about wear , it just seems logical that if something is moving ,its wearing. I would value knowing what Oliver's thoughts are on this. Pat SM #123
-----Original Message----- From: Germain Jean-Pierre jgermain@... [amelyachtowners] To: amelyachtowners Sent: Wed, Jun 3, 2015 11:02 am Subject: Re: [Amel Yacht Owners] Fixed prop Hi Pat,
I am a pilot too.. though you probably have no reason to respect my opinion. :-)
From a fluid dynamics POV, a feathered prop is better than a turning propeller. And a turning prop has less drag than a stopped prop.
For this reason, I would not install a shaft generator on Eleuthera because of the “relative” fragility of the SM dual 90 degree gearbox and the propeller drag if left to windmill.
Cheers,
Jean-Pierre Germain
SY Eleuthera, SM 007.
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Patrick McAneny
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-----Original Message----- From: Patrick Mcaneny To: amelyachtowners Sent: Thu, Jun 4, 2015 7:47 am Subject: Re: [Amel Yacht Owners] Fixed prop
Kent, No you probably did not waste your money, the test results showed that a feathering prop decreased drag significantly over a spinning fixed prop and a folding prop's drag could not even be measured it was so low. I will have Diane post the test . It showed that the Flexofold had best thrust and very low drag, wonder if they would fit on a SM. Pat
-----Original Message-----
From: Kent Robertson karkauai@... [amelyachtowners] <amelyachtowners@...> To: amelyachtowners <amelyachtowners@...> Sent: Wed, Jun 3, 2015 3:11 pm Subject: Re: [Amel Yacht Owners] Fixed prop
Interesting Pat,
Seems to me that a freewheeling prop could wear out the drive, while a prop that is not turning wouldn't cause any damage at all unless you hit something with it (highly unlikely on our boats).
It's hard to evaluate the difference between a fixed prop, freewheeling fixed pitch prop, and folding or feathering prop, as wind and wave conditions are always changing. I used a fixed pitch prop for a year and always put the engine in gear while sailing. When I put my feathering MaxProp on I think I gained an average of about a half knot while sailing in varied conditions. I always put the transmission in gear long enough to feather the prop, then put it back in neutral while sailing.
If it's OK to let it freewheel, there must not be a significant difference in boat speed...so maybe I wasted a bundle on my MaxProp, eh?
Kent
SM243
Kristy
Sent from my iPhon e On Jun 3, 2015, at 1:56 PM, Patrick Mcaneny sailw32@... [amelyachtowners] < amelyachtowners@...> wrote:
I just read another study that also determined that a fixed prop created more than twice as much drag as a freewheeling prop. But what I want to relate is that this article claimed that Yanmar and Volvo both believe that the transmissions should be in neutral to prevent damage and could cause warranty issues .I do not know if that is true ,if concerned you may want to speak to a rep. Pat
-----Original Message-----
From: Patrick Mcaneny sailw32@... [amelyachtowners] < amelyachtowners@...> To: amelyachtowners < amelyachtowners@...> Sent: Wed, Jun 3, 2015 10:21 am Subject: Re: [Amel Yacht Owners] Fixed prop
Just as I sent my question about fixed vs. unfixed props to the group , my wife sent me the results of her google search . Yachting monthly said that this subject had been debated for decades so they conducted tests that determined that a spinning prop produced less than half the drag of a fixed prop. That at seven knots you would lose approx. one knot while fixed. That seems to jive with what I experienced. Pat
-----Original Message-----
From: sailw32@... [amelyachtowners] < amelyachtowners@...> To: amelyachtowners < amelyachtowners@...> Sent: Wed, Jun 3, 2015 9:26 am Subject: [Amel Yacht Owners] Fixed prop
We have a fixed prop due to the original owner opting for the prop driven alternator , which I have dismantled since my solar panels and wind generator supplies all the electric I need. I have been told, that it is more efficient from the standpoint of drag for a prop to be fixed opposed to be freewheeling, from a pilot who's opinion I respect. While sailing I do not like to switch in and out of gear due to the loud clunk that sounds as though it could damage the transmission, so its hard to experiment to draw conclusions. However we just sailed back from the BVIs via Bermuda and we were in gear fixed and then I put it in neutral and it seemed that we picked up a knot. I never put it back in gear as we were sailing too fast and for the next three days we averaged 173 nms. with true wind avg. 12 - 16 . Could someone that is knowledgeable about props and drag tell me which is more efficient ? I am also concerned about wear on the transmis sion while freewheeling .
Thanks, Pat SM Shenanigans
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Thanks for posting this interesting article. They say that a full keel mitigates the drag, so I wonder how much difference it makes with our non-fin/modified full keel. My experience with the fixed vs MaxProp is not a scientific evaluation, but does seem to indicate roughly half-know better speed under sail with the MaxProp. The article shows a fairly large side thrust with the MaxProp, but I haven't noticed much propwalk with the AutoProp, fixed, or MaxProp. Kent SM243 Kristy From: "Patrick Mcaneny sailw32@... [amelyachtowners]" To: amelyachtowners@... Sent: Thursday, June 4, 2015 8:52 AM Subject: Re: [Amel Yacht Owners] Fixed prop -----Original Message----- From: Patrick Mcaneny To: amelyachtowners Sent: Thu, Jun 4, 2015 7:47 am Subject: Re: [Amel Yacht Owners] Fixed prop
Kent, No you probably did not waste your money, the test results showed that a feathering prop decreased drag significantly over a spinning fixed prop and a folding prop's drag could not even be measured it was so low. I will have Diane post the test . It showed that the Flexofold had best thrust and very low drag, wonder if they would fit on a SM. Pat
-----Original Message-----
From: Kent Robertson karkauai@... [amelyachtowners] <amelyachtowners@...> To: amelyachtowners <amelyachtowners@...> Sent: Wed, Jun 3, 2015 3:11 pm Subject: Re: [Amel Yacht Owners] Fixed prop
Interesting Pat,
Seems to me that a freewheeling prop could wear out the drive, while a prop that is not turning wouldn't cause any damage at all unless you hit something with it (highly unlikely on our boats).
It's hard to evaluate the difference between a fixed prop, freewheeling fixed pitch prop, and folding or feathering prop, as wind and wave conditions are always changing. I used a fixed pitch prop for a year and always put the engine in gear while sailing. When I put my feathering MaxProp on I think I gained an average of about a half knot while sailing in varied conditions. I always put the transmission in gear long enough to feather the prop, then put it back in neutral while sailing.
If it's OK to let it freewheel, there must not be a significant difference in boat speed...so maybe I wasted a bundle on my MaxProp, eh?
Kent
SM243
Kristy
Sent from my iPhon e On Jun 3, 2015, at 1:56 PM, Patrick Mcaneny sailw32@... [amelyachtowners] < amelyachtowners@...> wrote:
I just read another study that also determined that a fixed prop created more than twice as much drag as a freewheeling prop. But what I want to relate is that this article claimed that Yanmar and Volvo both believe that the transmissions should be in neutral to prevent damage and could cause warranty issues .I do not know if that is true ,if concerned you may want to speak to a rep. Pat
-----Original Message-----
From: Patrick Mcaneny sailw32@... [amelyachtowners] < amelyachtowners@...> To: amelyachtowners < amelyachtowners@...> Sent: Wed, Jun 3, 2015 10:21 am Subject: Re: [Amel Yacht Owners] Fixed prop
Just as I sent my question about fixed vs. unfixed props to the group , my wife sent me the results of her google search . Yachting monthly said that this subject had been debated for decades so they conducted tests that determined that a spinning prop produced less than half the drag of a fixed prop. That at seven knots you would lose approx. one knot while fixed. That seems to jive with what I experienced. Pat
-----Original Message-----
From: sailw32@... [amelyachtowners] < amelyachtowners@...> To: amelyachtowners < amelyachtowners@...> Sent: Wed, Jun 3, 2015 9:26 am Subject: [Amel Yacht Owners] Fixed prop
We have a fixed prop due to the original owner opting for the prop driven alternator , which I have dismantled since my solar panels and wind generator supplies all the electric I need. I have been told, that it is more efficient from the standpoint of drag for a prop to be fixed opposed to be freewheeling, from a pilot who's opinion I respect. While sailing I do not like to switch in and out of gear due to the loud clunk that sounds as though it could damage the transmission, so its hard to experiment to draw conclusions. However we just sailed back from the BVIs via Bermuda and we were in gear fixed and then I put it in neutral and it seemed that we picked up a knot. I never put it back in gear as we were sailing too fast and for the next three days we averaged 173 nms. with true wind avg. 12 - 16 . Could someone that is knowledgeable about props and drag tell me which is more efficient ? I am also concerned about wear on the transmis sion while freewheeling .
Thanks, Pat SM Shenanigans
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Ric Gottschalk <ric@...>
Pat, Why not use the prop to generate electricity? On my Santorin I have to take the key out of the ignition to turn on the Prop alternator. It produces a significant charge and I rarely have to run the engine or generator on a passage. Saves fuel, engine use and is quiet. Or you can spend $4000.00 plus on the new folding prop. Your lucky. Ric Bali Hai SN24 Annapolis
From: amelyachtowners@... [mailto:amelyachtowners@...]
Sent: Thursday, June 04, 2015 8:53 AM To: amelyachtowners@... Subject: Re: [Amel Yacht Owners] Fixed prop
-----Original Message----- Kent, No you probably did not waste your money, the test results showed that a feathering prop decreased drag significantly over a spinning fixed prop and a folding prop's drag could not even be measured it was so low. I will have Diane post the test . It showed that the Flexofold had best thrust and very low drag, wonder if they would fit on a SM. Pat
-----Original Message-----
Interesting Pat, Seems to me that a freewheeling prop could wear out the drive, while a prop that is not turning wouldn't cause any damage at all unless you hit something with it (highly unlikely on our boats).
It's hard to evaluate the difference between a fixed prop, freewheeling fixed pitch prop, and folding or feathering prop, as wind and wave conditions are always changing. I used a fixed pitch prop for a year and always put the engine in gear while sailing. When I put my feathering MaxProp on I think I gained an average of about a half knot while sailing in varied conditions. I always put the transmission in gear long enough to feather the prop, then put it back in neutral while sailing. If it's OK to let it freewheel, there must not be a significant difference in boat speed...so maybe I wasted a bundle on my MaxProp, eh? Kent SM243 Kristy
I just read another study that also determined that a fixed prop created more than twice as much drag as a freewheeling prop. But what I want to relate is that this article claimed that Yanmar and Volvo both believe that the transmissions should be in neutral to prevent damage and could cause warranty issues .I do not know if that is true ,if concerned you may want to speak to a rep. Pat
-----Original Message-----
Just as I sent my question about fixed vs. unfixed props to the group , my wife sent me the results of her google search . Yachting monthly said that this subject had been debated for decades so they conducted tests that determined that a spinning prop produced less than half the drag of a fixed prop. That at seven knots you would lose approx. one knot while fixed. That seems to jive with what I experienced. Pat
-----Original Message-----
We have a fixed prop due to the original owner opting for the prop driven alternator , which I have dismantled since my solar panels and wind generator supplies all the electric I need. I have been told, that it is more efficient from the standpoint of drag for a prop to be fixed opposed to be freewheeling, from a pilot who's opinion I respect. While sailing I do not like to switch in and out of gear due to the loud clunk that sounds as though it could damage the transmission, so its hard to experiment to draw conclusions. However we just sailed back from the BVIs via Bermuda and we were in gear fixed and then I put it in neutral and it seemed that we picked up a knot. I never put it back in gear as we were sailing too fast and for the next three days we averaged 173 nms. with true wind avg. 12 - 16 . Could someone that is knowledgeable about props and drag tell me which is more efficient ? I am also concerned about wear on the transmis sion while freewheeling . Thanks, Pat SM Shenanigans
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Chris Smither <yachtakwaaba@...>
Hi Sailing across the Pacific...our shaft alternator on Santorin Sloop Akwaaba...meant we could have " sold electricity!" The shaft alternator is a great addition to power generation. The prop was " feathered " and we had the Amel pole system with twin headsails for most of the trip. Chris Smither Santorin 027 On 4 Jun 2015, at 20:55, Ric Gottschalk ric@... [amelyachtowners] <amelyachtowners@...> wrote:
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Patrick McAneny
Ric, I had a problem getting the alt. to produce, when I turned the key the green lite would not come on, I guess the alt. did not get current to excite ?? However , I added an arch with three solar panel and a wind gen. and just spent six months on anchor and sailed about 4,500 nm. and never started my generator other than to make water. However I do think its a slick system and would have used it if I had not added the panels. Pat
-----Original Message----- From: Ric Gottschalk ric@... [amelyachtowners] To: 'amelyachtowners@...' Sent: Thu, Jun 4, 2015 9:56 am Subject: RE: [Amel Yacht Owners] Fixed prop Pat,
Why not use the prop to generate electricity? On my Santorin I have to take the key out of the ignition to turn on the Prop alternator. It produces a significant charge and I rarely have to run the engine or generator on a passage. Saves fuel, engine use and is quiet. Or you can spend $4000.00 plus on the new folding prop. Your lucky.
Ric Bali Hai SN24
Annapolis
From: amelyachtowners@... [mailto:amelyachtowners@...]
Sent: Thursday, June 04, 2015 8:53 AM To: amelyachtowners@... Subject: Re: [Amel Yacht Owners] Fixed prop -----Original Message-----
From: Patrick Mcaneny <sailw32@...> To: amelyachtowners <amelyachtowners@...> Sent: Thu, Jun 4, 2015 7:47 am Subject: Re: [Amel Yacht Owners] Fixed prop Kent, No you probably did not waste your money, the test results showed that a feathering prop decreased drag significantly over a spinning fixed prop and a folding prop's drag could not even be measured it was so low. I will have Diane post the test . It showed that the Flexofold had best thrust and very low drag, wonder if they would fit on a SM. Pat
-----Original Message-----
From: Kent Robertson karkauai@... [amelyachtowners] <amelyachtowners@...> To: amelyachtowners <amelyachtowners@...> Sent: Wed, Jun 3, 2015 3:11 pm Subject: Re: [Amel Yacht Owners] Fixed prop Interesting Pat,
Seems to me that a freewheeling prop could wear out the drive, while a prop that is not turning wouldn't cause any damage at all unless you hit something with it (highly unlikely on our boats).
It's hard to evaluate the difference between a fixed prop, freewheeling fixed pitch prop, and folding or feathering prop, as wind and wave conditions are always changing. I used a fixed pitch prop for a year and always put the engine in gear while sailing. When I put my feathering MaxProp on I think I gained an average of about a half knot while sailing in varied conditions. I always put the transmission in gear long enough to feather the prop, then put it back in neutral while sailing.
If it's OK to let it freewheel, there must not be a significant difference in boat speed...so maybe I wasted a bundle on my MaxProp, eh?
Kent
SM243
Kristy
Sent from my iPhon e On Jun 3, 2015, at 1:56 PM, Patrick Mcaneny sailw32@... [amelyachtowners] < amelyachtowners@...> wrote: I just read another study that also determined that a fixed prop created more than twice as much drag as a freewheeling prop. But what I want to relate is that this article claimed that Yanmar and Volvo both believe that the transmissions should be in neutral to prevent damage and could cause warranty issues .I do not know if that is true ,if concerned you may want to speak to a rep. Pat
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From: Patrick Mcaneny sailw32@... [amelyachtowners] < amelyachtowners@...> To: amelyachtowners < amelyachtowners@...> Sent: Wed, Jun 3, 2015 10:21 am Subject: Re: [Amel Yacht Owners] Fixed prop Just as I sent my question about fixed vs. unfixed props to the group , my wife sent me the results of her google search . Yachting monthly said that this subject had been debated for decades so they conducted tests that determined that a spinning prop produced less than half the drag of a fixed prop. That at seven knots you would lose approx. one knot while fixed. That seems to jive with what I experienced. Pat
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From: sailw32@... [amelyachtowners] < amelyachtowners@...> To: amelyachtowners < amelyachtowners@...> Sent: Wed, Jun 3, 2015 9:26 am Subject: [Amel Yacht Owners] Fixed prop We have a fixed prop due to the original owner opting for the prop driven alternator , which I have dismantled since my solar panels and wind generator supplies all the electric I need. I have been told, that it is more efficient from the standpoint of drag for a prop to be fixed opposed to be freewheeling, from a pilot who's opinion I respect. While sailing I do not like to switch in and out of gear due to the loud clunk that sounds as though it could damage the transmission, so its hard to experiment to draw conclusions. However we just sailed back from the BVIs via Bermuda and we were in gear fixed and then I put it in neutral and it seemed that we picked up a knot. I never put it back in gear as we were sailing too fast and for the next three days we averaged 173 nms. with true wind avg. 12 - 16 . Could someone that is knowledgeable about props and drag tell me which is more efficient ? I am also concerned about wear on the transmis sion while freewheeling .
Thanks, Pat SM Shenanigans
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Jean-Pierre Massicotte <jp_nikan@...>
On Vanille a Santorin 1992, we always use our shaft alternator, was greatest thing on the Pacific crossing from Ecuador to New Zealand. If one of you are thinking of getting one running unit out of the boat we would be more than happy to buy it from you. I think if Henri Amel proposed that solution for a long time it was a reliable and safe option in relation to the Amel drive and the transmission. In my case free spinning mean about 3/4 knot faster than block prop. A significant difference over time on long passage. Excuse my poor English Jean-Pierre Massicotte Le 2015-06-05 à 04:47, Patrick Mcaneny sailw32@... [amelyachtowners] <amelyachtowners@...> a écrit :
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