Foiling Moth

The MIT Sailing Pavilion has a Hydrofoiling Mach 2 Moth that uses wing-like foils to lift the hull out of the water. This 11 foot, 65 pound dinghy "flies" above the water is only sailed by the most advanced sailors.

Requirements to Sail

• Must have full membership (Normal Sailing Card)
• Must have Helmsman rating
• Must have permission from Sailing Master Fran Charles or Varsity Sailing Coach Matt Lindblad
• Must have rating
  • Moth: Basic
    • Buddy system: Must sail with moth qualified buddy that is also motorboat capable
    • Recommendation - on breezier days, 3 people buddy systems are more ideal
• Moth: Advanced
  • May choose to sail moth without chase boat

Safety For You (& The Boat)

• Don’t hang on to the tiller extension if you lose control or crash - it snaps over the wing easily.
• Do hold on the main sheet in a crash, if reasonable - the boat can easily sail 100 feet on its own (sometimes still foiling).
• Think of an exit strategy for any potential crash (especially if it’s windy). Try to get yourself clear of the boat so that you don’t hurt yourself or the boat.
• Don’t step on the hull, except the chine (corner).
• Do step on the centerboard (right next to the hull) to right the boat after a capsize - it’s much stronger than the hull.
• Watch out for the trailing (back edges) of the foils, and the ends - they are sharp.
• Watch out for the wand if swimming around the bow - it’s difficult to see in the water, pretty long, and very fragile.
• Watch out for falling off the wing through the sail (it has torn before), try to let yourself down carefully.
• Be extra mindful of traffic - that can be the scariest part when you’re first getting up. Purposefully crashing to windward and using your body to slow down can be an effective stopping method sometimes.
• Be extra mindful of being smooth with the tiller, especially as you move your body around the boat. Since the boat goes so fast and the rudder is long, the rudder cassette and pin get very loaded up when there are erratic rudder movements. These sort of movements also can make you crash…

Rigging the Foiling Moth

Rough sequence:

• Make sure the line going across the back from wingbar to wingbar is very tight. This keeps load off of the wingbar joints.
• Rig up sail (CST mast with red KA10, Mach2 mast with blue KA16)
  • Check that the battens are snug (use a metric allen key from shop to adjust tensioners)
  • put together mast, slide into luff pocket, put on cambers
• move sail on top of boat, attach spreaders/shrouds
  • Make sure the shrouds and forestay are properly seated in the ends of the “star” spreaders. Also make sure the shaft collars are set so that the star is roughly horizontal and symmetric port/stbd.
• pull up rig, place onto mast step, then tighten forestay pretty tight and tie off
• rig up boom (attach gooseneck first, make sure outhaul not tangled with downhaul)
• make sure vang all the way loose, attach clew of sail to boom and then attach outhaul
• flip boat over on its side -- orient so that you can tip it over foils first into the water with the boat pointed upwind
  • can either get someone to help lift, or flip boat over with trolley and then carefully lift trolley off
• insert main foil, put in pin (center hole)
• rig up the rudder
  • Make sure the tiller is lead through the bungee. This keeps the tiller centered if you let go, and also makes it harder to move the tiller too erratically.
• Put electrical tape over the breather holes. There is one on the stbd side of the transom, and one on the vertical section of the cockpit near the mast step. (Open these back up when you return to the dock)
  • The holes should be reopened to let the pressure equalize once the boat has been in the water for a few minutes. This can easily be done on the dock or while the boat is capsized to port.
• untie wand keeper, then screw in wand linkage to the top of the main vertical. This should be the last thing you do when putting the boat in the water and the first thing you do when the boat comes out of the water to prevent people on the dock from tripping over and damaging the wand.
  • A good rule of thumb for setting up the main foil ride height is that the horizontal flap should have a slight negative angle of attack when the wand is fully extended. This is ~5-7mm of pushrod showing
• Slide then tip the boat into the water, being careful of the wand and linkages. Try to lift the boat when tipping it upright instead of rotating it about the wingbar on the dock.