Long answer - a lot. It depends what the sail was designed for. We now have 7.0s that rig on 430s. Years ago, a number of sailmakers made entire quivers from 7.5 to 4.5 (and smaller) that rigged on 460s. Traditionally, mid 4s to mid 5s rigged on 430s but that's like saying most cars used to run on gas when you are at the pump with your '86 Benz diesel.
In 2000 most sails rigged 7.5 - 490. 6.5 460, 4.7-5.5 430. Again, most sails. Today, you must look at the sailmaker's recommendation. There is a trend to use shorter and shorter masts and Mr. Ezzy who likes to mix top and bottoms.
if the mast is too stiff, it takes a ton of downhaul and the sail is lifeless as there is no spring to the mast. If it's too soft, it bends way too easily and the sail gets tons of wrinkles when you pump it. If the person is smaller than average, err towards a smaller mast.
If this is your old Bic/UP sails, 430 is probably the best guess.
So, if I would look for smaller sail to rig on my 430, I could go with lowest 4.7 and up? There is a reason I have this question, when I was rigging my 6.0 on 430, I had to use very long extension to meet Ezzy's recommendations and to me mechanically looking, mast extension looks like week link, can extensions break bottom of the mast, since I am using long extension and on top of that you have to use a lot of tension for downhaul.
If the recommended size for that sail is 430, use the 430. The extension will be fine. Probably the smallest size sail you can get on a 430cm is a 5.2-5.0 (at least for sails less than 10 years)
So, if I would look for smaller sail to rig on my 430, I could go with lowest 4.7 and up? There is a reason I have this question, when I was rigging my 6.0 on 430, I had to use very long extension to meet Ezzy's recommendations and to me mechanically looking, mast extension looks like week link, can extensions break bottom of the mast, since I am using long extension and on top of that you have to use a lot of tension for downhaul.
Depends on the sail. Generic 15-20 yr old sail - probably. The newer the sail, the better chance it will use a 400 instead of a 430.
Extensions are built with much more strenuous conditions in mind than most of us sail in. Chinook and others have figured out where to put that top hole in their extensions after years of people trashing stuff in Hawaii, the Gorge, etc. I'm not saying stuff can't break but there's a certain amount of engineering plus real world experience that goes into this stuff.
Also, remember that most of the force at the bottom of the mast and the extension is in compression rather than bending: top of the mast to the downhaul pulleys. There is some bending force but that is more in the center of the mast rather than the ends.
For an experiment, take a drink straw and push on the ends towards each other so it gently bends. It will eventually break in the middle, not the ends.
I have broken many masts. Every sailor I know has broken masts as well. I've never broken an extension yet and don't know anyone that ever did. I think almost everyone broke right above where it was connected to the boom. (I've known of masts that break where the two halves go together because they were put together only part way.)
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What happens in a black hole stays in a black hole.
Ok, maybe I articulated wrong. I meant extension breaks bottom of the mast. Randy, just like you said that you seen masts break in middle where they are slit together, it is same thing as sliding extension in the mast not deep enough. The longer extension you have, the less extensions sliding part you have inserted in the mast. Its like you would insert your extension in the mast only 2 inches or so, I think bottom of the mast will break after downhaul.
Ok, maybe I articulated wrong. I meant extension breaks bottom of the mast. Randy, just like you said that you seen masts break in middle where they are slit together, it is same thing as sliding extension in the mast not deep enough. The longer extension you have, the less extensions sliding part you have inserted in the mast. Its like you would insert your extension in the mast only 2 inches or so, I think bottom of the mast will break after downhaul.
webguy wrote:
Extensions are built with much more strenuous conditions in mind than most of us sail in. Chinook and others have figured out where to put that top hole in their extensions after years of people trashing stuff in Hawaii, the Gorge, etc. I'm not saying stuff can't break but there's a certain amount of engineering plus real world experience that goes into this stuff.
No need to worry about using the top hole if you need to. It will be fine...
Quick answer: yes.
Long answer - a lot. It depends what the sail was designed for. We now have 7.0s that rig on 430s. Years ago, a number of sailmakers made entire quivers from 7.5 to 4.5 (and smaller) that rigged on 460s. Traditionally, mid 4s to mid 5s rigged on 430s but that's like saying most cars used to run on gas when you are at the pump with your '86 Benz diesel.
In 2000 most sails rigged 7.5 - 490. 6.5 460, 4.7-5.5 430. Again, most sails. Today, you must look at the sailmaker's recommendation. There is a trend to use shorter and shorter masts and Mr. Ezzy who likes to mix top and bottoms.
if the mast is too stiff, it takes a ton of downhaul and the sail is lifeless as there is no spring to the mast. If it's too soft, it bends way too easily and the sail gets tons of wrinkles when you pump it. If the person is smaller than average, err towards a smaller mast.
If this is your old Bic/UP sails, 430 is probably the best guess.
So, if I would look for smaller sail to rig on my 430, I could go with lowest 4.7 and up? There is a reason I have this question, when I was rigging my 6.0 on 430, I had to use very long extension to meet Ezzy's recommendations and to me mechanically looking, mast extension looks like week link, can extensions break bottom of the mast, since I am using long extension and on top of that you have to use a lot of tension for downhaul.
If the recommended size for that sail is 430, use the 430. The extension will be fine. Probably the smallest size sail you can get on a 430cm is a 5.2-5.0 (at least for sails less than 10 years)
Depends on the sail. Generic 15-20 yr old sail - probably. The newer the sail, the better chance it will use a 400 instead of a 430.
Extensions are built with much more strenuous conditions in mind than most of us sail in. Chinook and others have figured out where to put that top hole in their extensions after years of people trashing stuff in Hawaii, the Gorge, etc. I'm not saying stuff can't break but there's a certain amount of engineering plus real world experience that goes into this stuff.
Also, remember that most of the force at the bottom of the mast and the extension is in compression rather than bending: top of the mast to the downhaul pulleys. There is some bending force but that is more in the center of the mast rather than the ends.
For an experiment, take a drink straw and push on the ends towards each other so it gently bends. It will eventually break in the middle, not the ends.
(Not an engineer but play one on TV)
I have broken many masts. Every sailor I know has broken masts as well. I've never broken an extension yet and don't know anyone that ever did. I think almost everyone broke right above where it was connected to the boom. (I've known of masts that break where the two halves go together because they were put together only part way.)
What happens in a black hole stays in a black hole.
Ok, maybe I articulated wrong. I meant extension breaks bottom of the mast. Randy, just like you said that you seen masts break in middle where they are slit together, it is same thing as sliding extension in the mast not deep enough. The longer extension you have, the less extensions sliding part you have inserted in the mast. Its like you would insert your extension in the mast only 2 inches or so, I think bottom of the mast will break after downhaul.
No need to worry about using the top hole if you need to. It will be fine...
Edit: Apparently most of these pics came from here: MASTS – What Does It All Mean?