Foiling in a Light Breeze

Here's the post from the forums about light/moderate breeze sail setup. There are a lot of good tips from Dave on the SA thread, so check that out if you haven't already.

First comment, when Dave says add 15 turns to the gaff batten, they are half turns equal to 180 degrees. He assumes you're starting from a reasonable full batten tension, where it's not loose anymore and has just enough tension to pop back and forth.

The instructions also require a Spinlock RigSense tuning gauge, but if you don't have that just pull on the shroud tension as tight as possible once you have the cunningham and outhaul connected, but not tightened. Then bring the end of the bolt rope on the sails tack down to 5.5 inches from the mast collar. Finally, pull on the outhaul until the clew (measuring from the edge of the eyelet) is about 4 inches from the u-bolt in the end of the boom. If you want more power ease the outhaul and leave everything else the same. This will also add more twist to the sail, which will make the trimming more forgiving. To depower and twist off the sail just add cunningham to bend the mast back and stretch the luff.

With twist some part of the sail will likely be trimmed correctly as the boat accelerates and apparent wind moves forward even if you don't adjust your mainsheet correctly. Additionally, in marginal conditions (under 10 knots for your weight) some pumping and kinetics will be very helpful to get you up on the foils. The technique takes time to teach yourself. It took me a number of days sailing to work out marginal breeze launches. When you're pumping 4+ feet of mainsheet (use both hands) and the apparent wind is shifting with acceleration and deceleration even an expert needs some twist in the sail to keep the flow attached.

10-14 knots sounds like enough breeze to get the boat foiling for your weight even if the sail tuning was a bit off. So make sure your foil trim is correct. I'm assuming you had the mainfoil in the middle pin setting, this is the max AoA that's useful. You want the rudder 7 turns from the end of the range (this is the middle). If you think you need more rudder lift to fly, add AoA 1 turn at a time. If you've added three turns on AoA from the middle, you're close to the end of the useful range, so consider looking elsewhere. Finally, when your mainfoil is assembled the pushrod should be just above, but not pushing down on the flap.

http://forums.sailinganarchy.com/index.php?/topic/176284-steve-and-dave-clarks-unidentified-foiling-object/&do=findComment&comment=5994506

If you have a big gap between the push rod and the flap, you need to adjust the calibration. This requires pulling the gearing out of the wand and adjusting the calibration. Good explanation of how that works here. FYI, this is not the official class website, but something one of the early owners put together.

Hope this helps. If you have any more questions, let me know.

-Nick

Nick Burroughs

Fulcrum Speedworks llc

+1 401 552 3801

nick.ufosailing@gmail.com


Maintaining the mast step

Obviously, don't have a bunch of sand in your mast step, but the broader obvious wisdom is that there's a lot of torque in the spar and helping to resolve it is good maintenance. The boom wants to rotate the spar and the bearing at the mast step doesn't, with varying degrees of aggression. I just saw this personally in a highly aggressive state and it wasn't pretty.

So here's the tip to lower the odds of this happening to other spars in the field: Grease your mast lowers at the step. Essentially, all the points where it makes contact with the hull and tries to turn. My grease of choice is tallow. This is otherwise known as rendered animal fat  over the years this stuff has shown stunning results in a variety of applications I've used it in. Plus it's less horrible for the ocean than most synthetic greases and is so thick and greasy that seawater takes a long time to wash it off. The objective should be to make sure that the mast lower rotates cleanly while you ease, even if you have tons of Cunningham on. We're working on increasing the bearing area at the deck plate on future boats as well to address this risk structurally.


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