I am in the process of tuning my rig and all things look good except for the back stay. I have the mast set up with a 3 degree tilt to the stern and about 3 inches of (bow) in the middle. The back stay at this point could be removed and the mast would stay put. Here is the question: How much do you tension the back stay or do you leave it sloppy? Any thoughts? thanks, Stu
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Backstay
Your job is done......the backstay on the Mac really has no other purpose than for safety when raising the mast. The upper shrouds create the forestay tension and mast bend and the lower shrouds freeze the middle of the mast into that "bow" you describe......you can firm up the backstay if you want to keep it from being too loose but not enough to create more mast bend which would loosen he tension on the upper shrouds.
Your job is done......the backstay on the Mac really has no other purpose than for safety when raising the mast. The upper shrouds create the forestay tension and mast bend and the lower shrouds freeze the middle of the mast into that "bow" you describe......you can firm up the backstay if you want to keep it from being too loose but not enough to create more mast bend which would loosen he tension on the upper shrouds.
Tuning
When I had that much rake in the mast I had so much weather helm it would over power the OEM rudder. Now have less rake and Ida rudder
When I had that much rake in the mast I had so much weather helm it would over power the OEM rudder. Now have less rake and Ida rudder
Mast Bend
Stuart, Can you get the mast to have the aft incline without the bend in the middle? The bow is the weak point for compression forces on the mast. I had to make a new forestay to create enough aft slant, but I imagine it is possible to get the correct lean by adding a quick disconnect forestay lever by Johnson. Once I got the desired incline (in my case 6 inches), then I tightened up the side wires to get them tight, but I maintained a straight`mast all the time. It becomes progressively more difficult to attach the stemhead turnbuckle as you tighten the sidestays, but deal with it. While it is true that in lighter wind conditions the backstay can be loosened to allow the other wires to take the load, when the wind picks up, an adjustable backstay can depower the mainsail. This occurs when the mainsail is flattened by pulling the upper part aft when the backstay is tensioned. It can have enough effect to put off reefing and is quickly removed if the wind dies off, if you install an adjustable backstay. I am concerned about your mast and the bow in it statically. Adjust your mast until it is straight with whatever slant you desire or you may break it. I used a plum bob on my main halyard to mark the difference in mast angle as I was getting ready to swage the forward wire. Swage tools (the kind that you tighten bolts to make the swage) are not very exspensive, and they allow you to make the longer nose wire you will need, as well as create the thimble eye in your backstay for a small block and tackle for your adjustable backstay. And get rid of the pigtail. John S Boise
Stuart, Can you get the mast to have the aft incline without the bend in the middle? The bow is the weak point for compression forces on the mast. I had to make a new forestay to create enough aft slant, but I imagine it is possible to get the correct lean by adding a quick disconnect forestay lever by Johnson. Once I got the desired incline (in my case 6 inches), then I tightened up the side wires to get them tight, but I maintained a straight`mast all the time. It becomes progressively more difficult to attach the stemhead turnbuckle as you tighten the sidestays, but deal with it. While it is true that in lighter wind conditions the backstay can be loosened to allow the other wires to take the load, when the wind picks up, an adjustable backstay can depower the mainsail. This occurs when the mainsail is flattened by pulling the upper part aft when the backstay is tensioned. It can have enough effect to put off reefing and is quickly removed if the wind dies off, if you install an adjustable backstay. I am concerned about your mast and the bow in it statically. Adjust your mast until it is straight with whatever slant you desire or you may break it. I used a plum bob on my main halyard to mark the difference in mast angle as I was getting ready to swage the forward wire. Swage tools (the kind that you tighten bolts to make the swage) are not very exspensive, and they allow you to make the longer nose wire you will need, as well as create the thimble eye in your backstay for a small block and tackle for your adjustable backstay. And get rid of the pigtail. John S Boise
I disagree
I totally disagree with the last post. Mast bend is disirable..2-3" allows the shape and cut of the mainsail to be taken advantage of. If you have roller furling, the turnbuckle under the furler is used only to adjust the rake to whatever you desire...be it 2 degrees as most have it or the 6 degrees set at the factory. the upper shrouds create the mast bend and lower shrouds freeze it in position. If you desire to use an adjustable backstay, it can be used to create more mast bend to help flatten the mainsail.
I totally disagree with the last post. Mast bend is disirable..2-3" allows the shape and cut of the mainsail to be taken advantage of. If you have roller furling, the turnbuckle under the furler is used only to adjust the rake to whatever you desire...be it 2 degrees as most have it or the 6 degrees set at the factory. the upper shrouds create the mast bend and lower shrouds freeze it in position. If you desire to use an adjustable backstay, it can be used to create more mast bend to help flatten the mainsail.
Mast Bend
In order for your sail to match a bend in your mast, you must have the sailmaker cut the sail to accomodate that bend. I don't think we are talking about a sail cut specifically for any mast bend. Trying to bend or incline 6 degrees is going to be difficult to measure, and it begs the question "6 degrees from what line?". The local racing fleet of Mac D models have determined that a certain amount of aft mast lean is beneficial to the fractional rig on the D model. What I was hinting at is the fact that you are not going to be able to arrive at 6 inches of aft inclination without cutting a new piece of wire for the nose wire. If you can afford to and if you are inclined to, you can set up your rig this way when you re-rig your boat. That way, you can have tight shrouds, the correct aft inclination and a STRAIGHT mast. Please feel free to cause any bend in your mast that you wish. I only bend mine above the hounds when I pull on the adjustable aft wire, otherwise, I keep a straight mast. Just out of curiousity, where is the bend located in your mast? How did you arrive at the idea that 2-3 inches of mast bend is beneficial to sail shape? Don't get me wrong, I bend my mast, but only with the adjustable backstay. I do not have a furler.
In order for your sail to match a bend in your mast, you must have the sailmaker cut the sail to accomodate that bend. I don't think we are talking about a sail cut specifically for any mast bend. Trying to bend or incline 6 degrees is going to be difficult to measure, and it begs the question "6 degrees from what line?". The local racing fleet of Mac D models have determined that a certain amount of aft mast lean is beneficial to the fractional rig on the D model. What I was hinting at is the fact that you are not going to be able to arrive at 6 inches of aft inclination without cutting a new piece of wire for the nose wire. If you can afford to and if you are inclined to, you can set up your rig this way when you re-rig your boat. That way, you can have tight shrouds, the correct aft inclination and a STRAIGHT mast. Please feel free to cause any bend in your mast that you wish. I only bend mine above the hounds when I pull on the adjustable aft wire, otherwise, I keep a straight mast. Just out of curiousity, where is the bend located in your mast? How did you arrive at the idea that 2-3 inches of mast bend is beneficial to sail shape? Don't get me wrong, I bend my mast, but only with the adjustable backstay. I do not have a furler.
manual
The owners manual has some comments regarding mast position. I'm not saying anyone is wrong, but I agree with John S' technique. I have an adjustable backstay too. Note the distinctions between "Rake" and "Bend": "MAST RAKE: The mast, when set properly, should lean about 3 degrees to the rear of the boat from vertical. When properly tuned, all of the mast support wires should be quite snug. Use the following sequence to set the rigging. REAR SUPPORT WIRE: (BACKSTAY)Adjust the rear mast support wire to give the mast the proper fore and aft position. FORWARD SUPPORT WIRE (FORESTAY)Take up the slack in the forward mast support wire by adjusting the turnbuckle. At this point, tighten it enough to give a slight forward bend to the center of the mast. TOP SIDE SUPPORT WIRE: (UPPER SHROUD) Adjust the top side mast support wires so that the mast is straight from side to side. Try to make them snug. MIDDLE SIDE SUPPORT WIRES: (LOWER SHROUDS)Adjust the middle side support wires as described above. Don’t get them too tight or the center of the mast will be pulled toward the rear of the boat."
The owners manual has some comments regarding mast position. I'm not saying anyone is wrong, but I agree with John S' technique. I have an adjustable backstay too. Note the distinctions between "Rake" and "Bend": "MAST RAKE: The mast, when set properly, should lean about 3 degrees to the rear of the boat from vertical. When properly tuned, all of the mast support wires should be quite snug. Use the following sequence to set the rigging. REAR SUPPORT WIRE: (BACKSTAY)Adjust the rear mast support wire to give the mast the proper fore and aft position. FORWARD SUPPORT WIRE (FORESTAY)Take up the slack in the forward mast support wire by adjusting the turnbuckle. At this point, tighten it enough to give a slight forward bend to the center of the mast. TOP SIDE SUPPORT WIRE: (UPPER SHROUD) Adjust the top side mast support wires so that the mast is straight from side to side. Try to make them snug. MIDDLE SIDE SUPPORT WIRES: (LOWER SHROUDS)Adjust the middle side support wires as described above. Don’t get them too tight or the center of the mast will be pulled toward the rear of the boat."
Mast bend
All generic mainsails have a certain amount of depth or chordline built into them....unless you have a specific custom built sail that is flatter....ie. racing sails. Now, to address some of you comments.. 1."Trying to bend or incline 6 degrees is going to be difficult to measure, and it begs the question "6 degrees from what line?". a. Your speaking of two different things...mast rake and mast bend are two different things....mast rake is the amount of incline measured from the mast against being verticle when the boat is in the water.....it is measured in degrees and not inches, Mast bend is the amount of bend invoked by tensioning the upper shrouds....about 2-3" is good, and can be measured with the halyard held at the base of the mast.....yes this does create compression on the mast and if you had a giant hand and pressded down on the top of the mast you could create more mast bend....to prevent this further movement....you use the lower shrouds to prevent this by pulling the middle of mast back to prevent further bending...ie. freezing in positon. 2. "Just out of curiousity, where is the bend located in your mast? How did you arrive at the idea that 2-3 inches of mast bend is beneficial to sail shape? Don't get me wrong, I bend my mast, but only with the adjustable backstay. I do not have a furler." a. My mast bend is basically in the center of the mast.......a certain amount of mast bend helps flatten the belly of the sail...if you were to lay a sail out flat on a large flat surface, you'd notice that the middle of the sail would seem to have a bit more bagginess to it....thats because there is extra material in the center.....if you pulled the center from the luff and leech, you'd notice that the luff is no longer a straight line but more of a slight curve. If you only bend your mast from the backstay, you are in effect reducing the shrould tension and on a reach, you'd notice the lower shrouds of the leeward side go slack to an extent. this amount of wobble in the middle of the mast is not the most effcient to getting the most out of the boat.
All generic mainsails have a certain amount of depth or chordline built into them....unless you have a specific custom built sail that is flatter....ie. racing sails. Now, to address some of you comments.. 1."Trying to bend or incline 6 degrees is going to be difficult to measure, and it begs the question "6 degrees from what line?". a. Your speaking of two different things...mast rake and mast bend are two different things....mast rake is the amount of incline measured from the mast against being verticle when the boat is in the water.....it is measured in degrees and not inches, Mast bend is the amount of bend invoked by tensioning the upper shrouds....about 2-3" is good, and can be measured with the halyard held at the base of the mast.....yes this does create compression on the mast and if you had a giant hand and pressded down on the top of the mast you could create more mast bend....to prevent this further movement....you use the lower shrouds to prevent this by pulling the middle of mast back to prevent further bending...ie. freezing in positon. 2. "Just out of curiousity, where is the bend located in your mast? How did you arrive at the idea that 2-3 inches of mast bend is beneficial to sail shape? Don't get me wrong, I bend my mast, but only with the adjustable backstay. I do not have a furler." a. My mast bend is basically in the center of the mast.......a certain amount of mast bend helps flatten the belly of the sail...if you were to lay a sail out flat on a large flat surface, you'd notice that the middle of the sail would seem to have a bit more bagginess to it....thats because there is extra material in the center.....if you pulled the center from the luff and leech, you'd notice that the luff is no longer a straight line but more of a slight curve. If you only bend your mast from the backstay, you are in effect reducing the shrould tension and on a reach, you'd notice the lower shrouds of the leeward side go slack to an extent. this amount of wobble in the middle of the mast is not the most effcient to getting the most out of the boat.
Setup
Okay, I'm not saying that what I'm describing is THE WAY, but A WAY. When setting up, the forestay and backstay only aid in getting the mast in positon of the desired amount of rake......Macgregor says 6-10 degrees which is excessive for most people because it invokes too much weather helm. Most peoploe find that 2-3 degrees mast rake gives a small but desirable amount of weather helm. I noticed that you said you do not have a RF and have replaced your foretay.....I bet at one time it did have a turnbuckle on it. I set mine to 2-3 degrees while the boat sits in the water because 2-3 degrees on the trailor means nothing to the attitude of the boat on the water. I then get my boat back on the trailer and sight up the mast from the rear to make sure it is centered from side to side...at this point the lower and upper shrouds have little tension on them other than to support the mast and the mast is still straight when viewd form the side. Then I began to tighten the upper shrouds to invoke mast bend.....when doing this, I watch for two things...the amount of mast bend and shroud tension using a Loos Gauge. Once they are where I want them. I use the lowers to to about 10 percent of breaking strength to feeze the amout of mast bend and to prevent the the mast from bending any more..but not enough to create the letter "S" just enough to support the bend in position.
Okay, I'm not saying that what I'm describing is THE WAY, but A WAY. When setting up, the forestay and backstay only aid in getting the mast in positon of the desired amount of rake......Macgregor says 6-10 degrees which is excessive for most people because it invokes too much weather helm. Most peoploe find that 2-3 degrees mast rake gives a small but desirable amount of weather helm. I noticed that you said you do not have a RF and have replaced your foretay.....I bet at one time it did have a turnbuckle on it. I set mine to 2-3 degrees while the boat sits in the water because 2-3 degrees on the trailor means nothing to the attitude of the boat on the water. I then get my boat back on the trailer and sight up the mast from the rear to make sure it is centered from side to side...at this point the lower and upper shrouds have little tension on them other than to support the mast and the mast is still straight when viewd form the side. Then I began to tighten the upper shrouds to invoke mast bend.....when doing this, I watch for two things...the amount of mast bend and shroud tension using a Loos Gauge. Once they are where I want them. I use the lowers to to about 10 percent of breaking strength to feeze the amout of mast bend and to prevent the the mast from bending any more..but not enough to create the letter "S" just enough to support the bend in position.
John S
John, reading your post over again, I believe we are in the same book but on different pages. The adjustable backstay, which I may install one day, will create mastbend and will pull the center of the mainsail and help flatten it...that is a true statement. The mast does require a certain amount of static bend to help with sail shape because of the amount of draft built into the sail. 2-3 degrees is recommneded by Macgrgor for the stock mainsail. A custome made one could be made in which you decide how much draft is pre-built into it and this would dictate how much mast bend you wanted. Without static mast bend, the stock main would be really full and create a ton of power but at the cost of speed unless you yanked back on the backstay....this setup I describe allows you to get the main pretty flat with the outhaul and halyard and still have the entire standing rigging pretty firm.
John, reading your post over again, I believe we are in the same book but on different pages. The adjustable backstay, which I may install one day, will create mastbend and will pull the center of the mainsail and help flatten it...that is a true statement. The mast does require a certain amount of static bend to help with sail shape because of the amount of draft built into the sail. 2-3 degrees is recommneded by Macgrgor for the stock mainsail. A custome made one could be made in which you decide how much draft is pre-built into it and this would dictate how much mast bend you wanted. Without static mast bend, the stock main would be really full and create a ton of power but at the cost of speed unless you yanked back on the backstay....this setup I describe allows you to get the main pretty flat with the outhaul and halyard and still have the entire standing rigging pretty firm.
Timm
Timm, Thanks for the tuning suggestions. I will check my rig today, as I am about to go sailing. I do still have a tbuckle on my forestay, if nothing else it is necessary for me to connect up my rig. I think I shall have to get a Loos gauge and set up my mast at least once as you say. I did not make an error when I stated that my mast was raked 6 inches. I measured this by hanging a plumb bob from my main halyard, after first squaring up the boat with a level. Found perpendicular with the plum bob and then raked the mast an additional 6 inches. This amount of rake requires cutting a new wire as it cannot be accomodated by forestay adjustment alone. This amount of rake may not be for you. By the way, as it sits, my D can sail for a while on most points of sail by roping the tiller into the center. I often single hand (and I will be in about an hour) and I find that the tiller controls of my boat have no unnecessary weather helm. I also have learned to disregard most of what Macgregor prints about their boat setup- like most of the Macgregor boats it is just a starting point. Thanks John S
Timm, Thanks for the tuning suggestions. I will check my rig today, as I am about to go sailing. I do still have a tbuckle on my forestay, if nothing else it is necessary for me to connect up my rig. I think I shall have to get a Loos gauge and set up my mast at least once as you say. I did not make an error when I stated that my mast was raked 6 inches. I measured this by hanging a plumb bob from my main halyard, after first squaring up the boat with a level. Found perpendicular with the plum bob and then raked the mast an additional 6 inches. This amount of rake requires cutting a new wire as it cannot be accomodated by forestay adjustment alone. This amount of rake may not be for you. By the way, as it sits, my D can sail for a while on most points of sail by roping the tiller into the center. I often single hand (and I will be in about an hour) and I find that the tiller controls of my boat have no unnecessary weather helm. I also have learned to disregard most of what Macgregor prints about their boat setup- like most of the Macgregor boats it is just a starting point. Thanks John S
John S
John, I see you have an D, I am speaking of an X in my setup. I have seen people use a 4" level against a verticle mast and the rake for an X is something like 1 5/8" away from verticle....I'm sure the D is going to be different from the X. If you make it to the Chesapeake Bay, first beer is on me. Enjoy the season and be safe.
John, I see you have an D, I am speaking of an X in my setup. I have seen people use a 4" level against a verticle mast and the rake for an X is something like 1 5/8" away from verticle....I'm sure the D is going to be different from the X. If you make it to the Chesapeake Bay, first beer is on me. Enjoy the season and be safe.
How do you level your boat?
Timm, I read your recent discussion about tuning your X. Very interesting. Did you mean 1 5/8" with a 4' level? Where do you put the level to horizontally level your boat? Thanks Timm.
Timm, I read your recent discussion about tuning your X. Very interesting. Did you mean 1 5/8" with a 4' level? Where do you put the level to horizontally level your boat? Thanks Timm.
Level
I have never done this my self, but have read about using a 4' level fore of the mast and at the top of the level the distance is something like 1 5/8" to the edge of the mast with the level being verticle. I'm not a math whiz but someone who is could give you the exact number with geomentry.
I have never done this my self, but have read about using a 4' level fore of the mast and at the top of the level the distance is something like 1 5/8" to the edge of the mast with the level being verticle. I'm not a math whiz but someone who is could give you the exact number with geomentry.
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