Anyone know if there's a forumula for calculating saila rea from the IJPE stats? Been There, you got that calc in your hip pocket??
Sail area formula
- Thread starter Phil Herring
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Ballpark estimates
Phil, All you have would be 1/2 bases(J and E) times the respective heights (I and P)and add them together. Unfortunately this does not account for jibs greater than 100% and full roach mains that are greater than the triangular area formed by the boom and mast.
Phil, All you have would be 1/2 bases(J and E) times the respective heights (I and P)and add them together. Unfortunately this does not account for jibs greater than 100% and full roach mains that are greater than the triangular area formed by the boom and mast.
Sail areas: Jeff is right
100% sail area is defined as (P*E + I*J)/2. On yawls, the mizzen triangle counts half. This calculation does not account for main roach, hollow leech, huge genoas, mizzen staysails, stayless headsails, etc. Note that I*J/2 is the area of the foretriangle, while luff*LP/2 is the sail area for any jib with straight leech and foot. You almost never see a jib whose shape matches the foretriangle, because its foot would wipe the foredeck on each tack. 100% jibs typically have their foot off the deck a bit, and overlap the mast a bit. Same SA as the foretriangle, but a different shape. The intended purpose of comparing 100% SA to 100% SA is to get some notion of what the rig provides, independent of the fact that two owners of the same boat fly very different canvass. It also makes sense to compare the actual working sail offered on different boats, and to ask the builder for options, since it is expensive to add sails to an existing suite. The important thing is to know the question you are trying to answer. Do you want to compare rig potential? Race rating? The sails on three different candidate boats? Select the right measure to answer the question, and apply the same measure to each boat. Big luff mains are nice. Triangles are an inefficient shape for air foils. Trapezoidal and oval are better. Luff adds power without raising center of effort. While you can have some luff with a backstay, the ability to have really big luff is the advantage to a B&R rig. If you're buying a new Hunter, don't lose this advantage by choosing in mast furling. Then you have all the disadvantages of B&R, without its big win.
100% sail area is defined as (P*E + I*J)/2. On yawls, the mizzen triangle counts half. This calculation does not account for main roach, hollow leech, huge genoas, mizzen staysails, stayless headsails, etc. Note that I*J/2 is the area of the foretriangle, while luff*LP/2 is the sail area for any jib with straight leech and foot. You almost never see a jib whose shape matches the foretriangle, because its foot would wipe the foredeck on each tack. 100% jibs typically have their foot off the deck a bit, and overlap the mast a bit. Same SA as the foretriangle, but a different shape. The intended purpose of comparing 100% SA to 100% SA is to get some notion of what the rig provides, independent of the fact that two owners of the same boat fly very different canvass. It also makes sense to compare the actual working sail offered on different boats, and to ask the builder for options, since it is expensive to add sails to an existing suite. The important thing is to know the question you are trying to answer. Do you want to compare rig potential? Race rating? The sails on three different candidate boats? Select the right measure to answer the question, and apply the same measure to each boat. Big luff mains are nice. Triangles are an inefficient shape for air foils. Trapezoidal and oval are better. Luff adds power without raising center of effort. While you can have some luff with a backstay, the ability to have really big luff is the advantage to a B&R rig. If you're buying a new Hunter, don't lose this advantage by choosing in mast furling. Then you have all the disadvantages of B&R, without its big win.
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