I have a Furlex Furler for the genny on my CD27. I have noticed that many times, especially in stronger winds, if the genny isn't trimmed just right, the entire forestay/furler assembly starts to oscillate. That forestay can be moving quite a bit and quickly too. In the past if the genny wasn't trimmed correctly the sail alone would just luff heavily in the stronger winds but the forestay would pretty much stay put.
The bottom of the furlex is attached to the stemhead on my boat. That stemhead has three holes in it. I have a feeling that the furlex was not secured to the same hole in the stemhead as last year. A couple of questions;
1. Is the forestay oscillation due to insufficient tension on the forestay?
2. The holes on the stemhead are very close together. Nevertheless, could securing the furlex to a different hole cause this?
3. How does one go about tightening a forestay inside a furler/foil?
I did it to some extent last year by tightening the backstay thereby indirectly tightening the forestay. There is a rigging screw beneath the drum on the furlex but I'm not sure if taking up the "slack" on it, thereby also tightening the forestay, is what it is intended for.
Also, I was able to use a loos guage on the backstay but I cannot find an area on the forestay to use the guage because of the furler's foil. When I tightened last year I may have overtightened and the furlex was much harder to turn and use.
When the oscillations are quite strong and fast, I worry about the wire "cycling" like working a paper clip wire, and eventually weakening an even breaking. Not a comforting thought.
If any of you know what I am talking about and have a solution, I will forever be in your debt.
Warren Kaplan
Sine Qua Non
CD27 #166 1980
Oyster Bay Harbor, NY
Setsail728@aol.com
Forestay Oscillations
Moderator: Jim Walsh
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John D
Re: Forestay Oscillations
Hi Warren,
I'm going to try, but I can't guarantee this analogy is going to fly. Think of your forestay as a string on a guitar.If the string is loose and floppy, you get no oscillations or sound at all. As the guitar string is tightened somewhat, it straightens out, but still no oscillations, no sound. Tighten it some more and the string starts to oscillate, creating some sound. The more you tighten it, the greater the amount of oscillation, the higher the tone. You can control the degree of oscillation and pitch by the tautness of the string.
Consequently, by loosening the string/forestay , the ocillating decreases. Just my stab at explanation. Good luck.
John D
in beautiful sunny, breezy
Oswego, NY
(maybe I should have said cello)
I'm going to try, but I can't guarantee this analogy is going to fly. Think of your forestay as a string on a guitar.If the string is loose and floppy, you get no oscillations or sound at all. As the guitar string is tightened somewhat, it straightens out, but still no oscillations, no sound. Tighten it some more and the string starts to oscillate, creating some sound. The more you tighten it, the greater the amount of oscillation, the higher the tone. You can control the degree of oscillation and pitch by the tautness of the string.
Consequently, by loosening the string/forestay , the ocillating decreases. Just my stab at explanation. Good luck.
John D
in beautiful sunny, breezy
Oswego, NY
(maybe I should have said cello)
Warren Kaplan wrote: I have a Furlex Furler for the genny on my CD27. I have noticed that many times, especially in stronger winds, if the genny isn't trimmed just right, the entire forestay/furler assembly starts to oscillate. That forestay can be moving quite a bit and quickly too. In the past if the genny wasn't trimmed correctly the sail alone would just luff heavily in the stronger winds but the forestay would pretty much stay put.
The bottom of the furlex is attached to the stemhead on my boat. That stemhead has three holes in it. I have a feeling that the furlex was not secured to the same hole in the stemhead as last year. A couple of questions;
1. Is the forestay oscillation due to insufficient tension on the forestay?
2. The holes on the stemhead are very close together. Nevertheless, could securing the furlex to a different hole cause this?
3. How does one go about tightening a forestay inside a furler/foil?
I did it to some extent last year by tightening the backstay thereby indirectly tightening the forestay. There is a rigging screw beneath the drum on the furlex but I'm not sure if taking up the "slack" on it, thereby also tightening the forestay, is what it is intended for.
Also, I was able to use a loos guage on the backstay but I cannot find an area on the forestay to use the guage because of the furler's foil. When I tightened last year I may have overtightened and the furlex was much harder to turn and use.
When the oscillations are quite strong and fast, I worry about the wire "cycling" like working a paper clip wire, and eventually weakening an even breaking. Not a comforting thought.
If any of you know what I am talking about and have a solution, I will forever be in your debt.
Warren Kaplan
Sine Qua Non
CD27 #166 1980
Oyster Bay Harbor, NY
-
Larry DeMers
Re: Forestay Oscillations
Greetings Warren,
My feeling is that the rig is not tuned right. With my Hood Roller/Furler, I get oscillations while at anchor, if the winds pipe up into the 30kts. range. I have a specific fix for that. But in your situation, the whole furler extrusion is moving while sailing to weather.
This seems to be a too loose headstay situation. My reasoning is as follows:
When the wind encounters a round object, it flows around that object unevenly, creating a pressure differential on one side verses the other. The side that has a more negative pressure on it will allow the furler to move slightly in that direction, and then this movement changes the dynamic situation of the furlers shape, which likely changes which side which has the low pressure on it, and reversing the side that the furler tends to move towards.
In short..it oscillates back and forth. Loosening the stay tension will allow wider and wider movement (lower and lower oscillation frequency), which then flexes the components far more and harder.
Tightening the stay tension raises the oscillation frequency until that frequency is above the natural resonance of the stay, which will quiet it's oscillation movements down.
What we do is leave the forestay tension set the same..we never play with it. We set the fore-aft upper stay tension using the backstay tension only (and with the lower shrouds loose). Since the position of the forestay turnbuckle has not moved, the rig will tension to last years setting just fine using the backstay only. Measure the tension with your Loos gauge on the back stay, and set to the same tension as the Port/Starboard uppers -a little less than mid scale.
Then do the lower stays to take out the S-Curve on the mast.
Longwinded, but I hope it helps.
Cheers,
Larry DeMers
s/v DeLaMer
CD30c Lake Superior
ldemers@wwt.net
My feeling is that the rig is not tuned right. With my Hood Roller/Furler, I get oscillations while at anchor, if the winds pipe up into the 30kts. range. I have a specific fix for that. But in your situation, the whole furler extrusion is moving while sailing to weather.
This seems to be a too loose headstay situation. My reasoning is as follows:
When the wind encounters a round object, it flows around that object unevenly, creating a pressure differential on one side verses the other. The side that has a more negative pressure on it will allow the furler to move slightly in that direction, and then this movement changes the dynamic situation of the furlers shape, which likely changes which side which has the low pressure on it, and reversing the side that the furler tends to move towards.
In short..it oscillates back and forth. Loosening the stay tension will allow wider and wider movement (lower and lower oscillation frequency), which then flexes the components far more and harder.
Tightening the stay tension raises the oscillation frequency until that frequency is above the natural resonance of the stay, which will quiet it's oscillation movements down.
What we do is leave the forestay tension set the same..we never play with it. We set the fore-aft upper stay tension using the backstay tension only (and with the lower shrouds loose). Since the position of the forestay turnbuckle has not moved, the rig will tension to last years setting just fine using the backstay only. Measure the tension with your Loos gauge on the back stay, and set to the same tension as the Port/Starboard uppers -a little less than mid scale.
Then do the lower stays to take out the S-Curve on the mast.
Longwinded, but I hope it helps.
Cheers,
Larry DeMers
s/v DeLaMer
CD30c Lake Superior
Warren Kaplan wrote: I have a Furlex Furler for the genny on my CD27. I have noticed that many times, especially in stronger winds, if the genny isn't trimmed just right, the entire forestay/furler assembly starts to oscillate. That forestay can be moving quite a bit and quickly too. In the past if the genny wasn't trimmed correctly the sail alone would just luff heavily in the stronger winds but the forestay would pretty much stay put.
The bottom of the furlex is attached to the stemhead on my boat. That stemhead has three holes in it. I have a feeling that the furlex was not secured to the same hole in the stemhead as last year. A couple of questions;
1. Is the forestay oscillation due to insufficient tension on the forestay?
2. The holes on the stemhead are very close together. Nevertheless, could securing the furlex to a different hole cause this?
3. How does one go about tightening a forestay inside a furler/foil?
I did it to some extent last year by tightening the backstay thereby indirectly tightening the forestay. There is a rigging screw beneath the drum on the furlex but I'm not sure if taking up the "slack" on it, thereby also tightening the forestay, is what it is intended for.
Also, I was able to use a loos guage on the backstay but I cannot find an area on the forestay to use the guage because of the furler's foil. When I tightened last year I may have overtightened and the furlex was much harder to turn and use.
When the oscillations are quite strong and fast, I worry about the wire "cycling" like working a paper clip wire, and eventually weakening an even breaking. Not a comforting thought.
If any of you know what I am talking about and have a solution, I will forever be in your debt.
Warren Kaplan
Sine Qua Non
CD27 #166 1980
Oyster Bay Harbor, NY
ldemers@wwt.net
-
Melissa Abato
Re: Forestay Oscillations
Hi Warren,
Last year our staysail was too loose. We had a similar symptom, but you could also tell it was too loose when not sailing as well. Stays do stretch over time. I don't know about the Furlex Furler, but our new ProFurl furlers allow you to adjust the tension while connected. You can loosen some screws, move the drum up (over the extrusion) and turn the turnbuckles. You can't get a Loos gauge on it, but you can do it by trial and error. If you cannot do that, you could try moving it to the forwardmost hole. That will buy you a little tension. You'll probably have to loosen your backstay and uppers to do this though. (Use a halyard secured to the pulpit to support the mast while you move the stay).
Melissa Abato
CD36 Mahalo
mla I'm Sick Of Spam @ charter.net
Last year our staysail was too loose. We had a similar symptom, but you could also tell it was too loose when not sailing as well. Stays do stretch over time. I don't know about the Furlex Furler, but our new ProFurl furlers allow you to adjust the tension while connected. You can loosen some screws, move the drum up (over the extrusion) and turn the turnbuckles. You can't get a Loos gauge on it, but you can do it by trial and error. If you cannot do that, you could try moving it to the forwardmost hole. That will buy you a little tension. You'll probably have to loosen your backstay and uppers to do this though. (Use a halyard secured to the pulpit to support the mast while you move the stay).
Melissa Abato
CD36 Mahalo
mla I'm Sick Of Spam @ charter.net
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Warren Kaplan
Re: Forestay Oscillations
Thanks everyone for your input. I was up at the boat this afternoon doing something else. I had a chance to run this by the rigger. He too thinks that the stay is probably too loose. Since he rigged it he said he will go out and take a look at it during the next couple of days. He also mentioned taking up on the backstay to indirectly increase tension on the forestay. The furlex also has a rigging screw and I think you can use that to make "fine adjustments" to the tension on the stay. I have to get my loos guage back on the backstay and the shrouds. I did the job a few weeks back but somehow I think I have to do it again. I'll let you know how it comes out.Warren Kaplan wrote: I have a Furlex Furler for the genny on my CD27. I have noticed that many times, especially in stronger winds, if the genny isn't trimmed just right, the entire forestay/furler assembly starts to oscillate. That forestay can be moving quite a bit and quickly too. In the past if the genny wasn't trimmed correctly the sail alone would just luff heavily in the stronger winds but the forestay would pretty much stay put.
The bottom of the furlex is attached to the stemhead on my boat. That stemhead has three holes in it. I have a feeling that the furlex was not secured to the same hole in the stemhead as last year. A couple of questions;
1. Is the forestay oscillation due to insufficient tension on the forestay?
2. The holes on the stemhead are very close together. Nevertheless, could securing the furlex to a different hole cause this?
3. How does one go about tightening a forestay inside a furler/foil?
I did it to some extent last year by tightening the backstay thereby indirectly tightening the forestay. There is a rigging screw beneath the drum on the furlex but I'm not sure if taking up the "slack" on it, thereby also tightening the forestay, is what it is intended for.
Also, I was able to use a loos guage on the backstay but I cannot find an area on the forestay to use the guage because of the furler's foil. When I tightened last year I may have overtightened and the furlex was much harder to turn and use.
When the oscillations are quite strong and fast, I worry about the wire "cycling" like working a paper clip wire, and eventually weakening an even breaking. Not a comforting thought.
If any of you know what I am talking about and have a solution, I will forever be in your debt.
Warren Kaplan
Sine Qua Non
CD27 #166 1980
Oyster Bay Harbor, NY
Thanks again,
Warren Kaplan
Sine Qua Non
CD27
Oyster Bay Harbor, NY
Setsail728@aol.com
-
Daniel
Re: Forestay Oscillations
Larry, In all due respect I would like to differ with part of your answer. I feel that when the wind encounters a round object, the pressure is equal on either side of the object. If you were to light a candle and place it behind a jar and then blew at the center of the jar, the candle would be blown out.
If you blew through a tube at the jar slightly to the right of center, then you would have unequal pressure on opposite sides of the jar and the candle flame would lean towards the left. Dan
If you blew through a tube at the jar slightly to the right of center, then you would have unequal pressure on opposite sides of the jar and the candle flame would lean towards the left. Dan
Larry DeMers wrote: My feeling is that the rig is not tuned right. With my Hood Roller/Furler, I get oscillations while at anchor, if the winds pipe up into the 30kts. range. I have a specific fix for that. But in your situation, the whole furler extrusion is moving while sailing to weather.
This seems to be a too loose headstay situation. My reasoning is as follows:
When the wind encounters a round object, it flows around that object unevenly, creating a pressure differential on one side verses the other. The side that has a more negative pressure on it will allow the furler to move slightly in that direction, and then this movement changes the dynamic situation of the furlers shape, which likely changes which side which has the low pressure on it, and reversing the side that the furler tends to move towards.
In short..it oscillates back and forth. Loosening the stay tension will allow wider and wider movement (lower and lower oscillation frequency), which then flexes the components far more and harder.
Tightening the stay tension raises the oscillation frequency until that frequency is above the natural resonance of the stay, which will quiet it's oscillation movements down.
What we do is leave the forestay tension set the same..we never play with it. We set the fore-aft upper stay tension using the backstay tension only (and with the lower shrouds loose). Since the position of the forestay turnbuckle has not moved, the rig will tension to last years setting just fine using the backstay only. Measure the tension with your Loos gauge on the back stay, and set to the same tension as the Port/Starboard uppers -a little less than mid scale.
Then do the lower stays to take out the S-Curve on the mast.
Longwinded, but I hope it helps.
Cheers,
Larry DeMers
s/v DeLaMer
CD30c Lake Superior
Warren Kaplan wrote: I have a Furlex Furler for the genny on my CD27. I have noticed that many times, especially in stronger winds, if the genny isn't trimmed just right, the entire forestay/furler assembly starts to oscillate. That forestay can be moving quite a bit and quickly too. In the past if the genny wasn't trimmed correctly the sail alone would just luff heavily in the stronger winds but the forestay would pretty much stay put.
The bottom of the furlex is attached to the stemhead on my boat. That stemhead has three holes in it. I have a feeling that the furlex was not secured to the same hole in the stemhead as last year. A couple of questions;
1. Is the forestay oscillation due to insufficient tension on the forestay?
2. The holes on the stemhead are very close together. Nevertheless, could securing the furlex to a different hole cause this?
3. How does one go about tightening a forestay inside a furler/foil?
I did it to some extent last year by tightening the backstay thereby indirectly tightening the forestay. There is a rigging screw beneath the drum on the furlex but I'm not sure if taking up the "slack" on it, thereby also tightening the forestay, is what it is intended for.
Also, I was able to use a loos guage on the backstay but I cannot find an area on the forestay to use the guage because of the furler's foil. When I tightened last year I may have overtightened and the furlex was much harder to turn and use.
When the oscillations are quite strong and fast, I worry about the wire "cycling" like working a paper clip wire, and eventually weakening an even breaking. Not a comforting thought.
If any of you know what I am talking about and have a solution, I will forever be in your debt.
Warren Kaplan
Sine Qua Non
CD27 #166 1980
Oyster Bay Harbor, NY
-
tjr818
- Posts: 1851
- Joined: Oct 13th, '07, 13:42
- Location: Previously owned 1980 CD 27 Slainte, Hull #185. NO.1257949
Tuning
Okay, I know this post is old, but so am I. I am new to the CD27 and this sound exactly like the problem I am having. In certain wind conditions, at certain points of sail I too get these jib/forestay oscillations. I am using my working jib and an older Harken MKII furler. I do not have a Loos gauge. is forestay tension the problem? How much should I be able to move the backstay from side to side? How about the upper shrouds?
Tim
Nonsuch 26 Ultra,
Previously, Sláinte a CD27
Nonsuch 26 Ultra,
Previously, Sláinte a CD27
gauges not really necessary - use your eyes
I'll probably get flamed here with diffening opinions, BUT...
take your boat out on a nice, strong windy day. with everthing hauled way in, giving you max heel, you wamt the downwind shrouds under minimal tension - not loose, but not at all TIGHT...if they're tight in those conditions, you have them too tight. normally lou will find them flopping around. you want to take out the slack, so that when the wind dies down or you tack or whatever, you are not shocking the shrouds - slamming them from no load to loaded.
once you have that done, and are back on your mooring, eyeball the deflection you get with a fair pull on an upper shroud - personally i can move them about 2 inches , at arm level above deck.
your backstay should carry the same amount of tension
matt
take your boat out on a nice, strong windy day. with everthing hauled way in, giving you max heel, you wamt the downwind shrouds under minimal tension - not loose, but not at all TIGHT...if they're tight in those conditions, you have them too tight. normally lou will find them flopping around. you want to take out the slack, so that when the wind dies down or you tack or whatever, you are not shocking the shrouds - slamming them from no load to loaded.
once you have that done, and are back on your mooring, eyeball the deflection you get with a fair pull on an upper shroud - personally i can move them about 2 inches , at arm level above deck.
your backstay should carry the same amount of tension
matt
-
tjr818
- Posts: 1851
- Joined: Oct 13th, '07, 13:42
- Location: Previously owned 1980 CD 27 Slainte, Hull #185. NO.1257949
Re: gauges not really necessary - use your eyes
mattlydon wrote:I'll probably get flamed here with diffening opinions, BUT...
take your boat out on a nice, strong windy day. with everthing hauled way in, giving you max heel, you wamt the downwind shrouds under minimal tension - not loose, but not at all TIGHT...if they're tight in those conditions, you have them too tight. normally lou will find them flopping around. you want to take out the slack, so that when the wind dies down or you tack or whatever, you are not shocking the shrouds - slamming them from no load to loaded.
once you have that done, and are back on your mooring, eyeball the deflection you get with a fair pull on an upper shroud - personally i can move them about 2 inches , at arm level above deck.
your backstay should carry the same amount of tension
matt
Okay! I did that today. SE winds at 15-20. I ran downwind under mainsail alone at 5.5 kts. Coming about under mainsail alone we were having a good time, but tacking was difficult. I unfurled about 2/3rds of the working jib and we were flying. No oscillations. Trying a s hard as we could, we could heel over at a steady 30-35 degrees at that point the leeward shrouds were VERY, VERY loose. I could rattle them back and forth 4 " either way. Is that too loose? What should I try next? This wonderful breeze isn't going to last much longer, another two or three days at the most.
Thanks,
Tim
Nonsuch 26 Ultra,
Previously, Sláinte a CD27
Nonsuch 26 Ultra,
Previously, Sláinte a CD27
-
tjr818
- Posts: 1851
- Joined: Oct 13th, '07, 13:42
- Location: Previously owned 1980 CD 27 Slainte, Hull #185. NO.1257949
Back Stay tension
Okay, so tacking back and forth I can adjust the shrouds so that they don't flop around too much. How do I judge the tension in the forestay & backstay?
Tim
Nonsuch 26 Ultra,
Previously, Sláinte a CD27
Nonsuch 26 Ultra,
Previously, Sláinte a CD27
-
Maine_Buzzard
- Posts: 506
- Joined: Dec 22nd, '10, 21:15
- Location: Feet Dry, Olympia, WA