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www.sname.org/sname/mt April 2013 charts on page 59 are from an upwind mainsail clew load anal- ysis of a 60 m sloop. Six sail sets were dened for an upwind sailing condition ranging from tight trim in sail set one to looser trim in sail set six. Going from sail set one to six the main trav- eler is eased six degrees and the twist in the main and jib are increased by 50%. Sail twist refers to how tightly the sections of a sail are trimmed relative to the bottom of the sail, and easing the sheets has the eect of increasing ying shape twist. In this study, we were interested in estimating the mainsail clew load at 33 knots apparent wind speed with various settings and deter- mining up to what wind speed the various settings could safely be used. It was found that the tightest conguration could han- dle an apparent wind of 30 knots before becoming overpowered, while the loosest trim to be carried was up to a nearly 40 knot apparent wind speed. Detailed studies like this are only possible when all relevant geometry and loads are taken into account. High-load design solutions rough experience with current generation sailing mega yachts and aided by detailed structural studies such as coupled CFD- FEA analysis, sailing mega yacht designers have found a number of practical and innovative ways to handle these huge loads. e use of rotating freestanding rigs, such as the DynaRigs used on Maltese Falcon , is one way to greatly reduce the compression loads that the rigging imparts on the hull. Conventional masts are thin columns that are supported with support stays. In order to produce the wanted lateral and lon- gitudinal support, the stays also impart a large compression force on the mast and large internal structures are needed to handle such loads. One way of reducing compression loads is to use a freestanding mast. Freestanding masts can be thought of as cantilever beams that support bending using their inher- ent stiness, not the support of wires. e down side of large freestanding masts is that they need to be extremely strong. Maltese Falcon , for example, has a 6 in. wall thickness at the base of her carbon masts. Rotating freestanding rigs are designed to rotate all at once around a central bearing. is creates challenging engineer- ing for the bearing and mast designs but creates simple sail controls and no need for sheets to control the sails. One of the biggest hazards to crews of large sailing yachts is ogging sails and sheets, and rotating masts solve this problem. Well thought-out sail furling systems are important for deal- ing with the large loads present on sailing super yachts. At this scale, it is not practical to have sails that are raised and low- ered each time a boat goes sailing. Instead, the sails are furled along mandrels that are recessed in cavities in the mast and booms and along foils on the head stays. Furling systems today are robust and capable of furling sails when needed with lit- tle human intervention. Captive winch systems, such as those found on commercial ships, are used both in the furling and sail sheet handling on large sailing yachts. Downwind sail handling at this scale is a much greater chal- lenge than upwind sail handling. Unlike upwind sails, which are relatively stier and supported in all the corners and along at least one edge of the sail, downwind sails such as spinna- kers are usually only supported in the corners. Spinnakers act like parachutes, or as drag devices instead as wings like upwind sails. is means they work in a very turbulent, unsteady ow eld. In order to y or properly inate, the control lines attached to a spinnaker must be constantly adjusted to account for the changing ow. If the control lines are not adjusted perfectly, the spinnaker will collapse and re-inate, creating hazardous con- ditions for the crew and boat. Because of the sail handling problems spinnakers can cre- ate, they are used only in light to moderate conditions on large yachts. Hybrid upwind-downwind sails, known as code zeros, have been developed that have large areas like spinnakers but are more controllable, like a conventional headsail. Code zeros are supported only in the corners like spinnakers but have a strong torque rope attached to their leading edge that acts like a stay, supporting the sail when loaded. When you are done Non-linear FEA analysis of a bending mainsail furling mandrel. In this case, a non-linear model was needed because the ?exibility in the mandrel caused very dierent initial and ?nal loading states. THE MEGA MODEL