FoilingMultihulls

dense af

These 12 UFO foilers are now crammed into the box called OZ Invader 1, bound from New England to the land of vegemite and croc pies.  From Fulcrum Speedworks: “Gerben’s use of high density shipping make these unquestionably the most cost-effective UFOs ever shipped down under. Join us in tracking the ship (Seatrade Orange) as the boats surge towards New South Wales.”

It remains fascinating and exciting to track the progress made by a handful of young sailing nerds as they crack the long-impossible ‘people’s foiler’ market, and maybe the coolest part is the way the boat’s sailing characteristics are being developed transparently and collectively, with the SA Forum a sort of ‘clearing house’ for the sailors and builders.  Case in point?  Dave and Nick have come up with some new tricks to making the little boat go, and both explained their techniques today.  Here’s a sample (go to the thread for the ongoing discussion):

If the boat starts trying to foil “to infinity and beyond” you need to get the bow down. That means add rudder lift or reduce mainfoil lift by going pin forward. You can also move weight forward, but for starters I’d suggest sitting on the middle pad and adjusting the foils. Upwind you’ll move forward, so you only have one butt cheek on the middle pad, and downwind you’ll move aft similarly, but you never sit fully on the front pad. (Disclaimer: “Moth” mode where you do sit fully on the front pad and bias the lift to the mainfoil might be a fast mode, but its not the easiest or most stable for a beginner.) Based on the windspeed you should have been in the second “pinhole” (really a dimple) from the bow for mainfoil AoA. You might have even been able to go all the way forward with the mainfoil pin, but at 200 lbs I think you’d want to wait for a little more breeze to do that. 

Heisman tack is the way to go when not foiling even in heavier wind. You move towards the middle of the boat as you pull the sail over the top of your head. In light air you’ll stay on the old windward side with weight aft as the bow gets down to your new course. However, in bigger breeze and waves you’ll move across quicker and put your weight a little more forward. If you get stuck in irons and have to back out of a tack, move weight forward if the boat starts dig the sterns in. If you keep weight aft while backing down in bigger waves, you’ll reverse pitchpole over the stern. 

Flatter water is your friend as a beginner. Ideally, you want 10-12 knots and less than 1 foot of chop to make your UFO as easy as possible to foil, but I’m guessing those conditions show up at the SF city front approximately never. So let’s talk about waves. The bigger risk in waves once you get the weight placement and foil tune lined up is launching the boat right out of the water going up a steep wave, not stuffing the bows as you’re already experienced. As a beginner I’d focus on reaching along perpendicular to the waves. The easiest point of sail to get a UFO on the foils is bearing away below a beam reach, but I’d suggest you stay parallel to the chop to start to take waves out of the equation as much as possible. Keeping the ride height on the lower side as you’ve already done, will help with getting launched off waves. As you get comfortable move to working on weather heel and then making VMG upwind.

Waves are much easier to foil through upwind. You’ll you want to steer for low spots in the waves like you would in any other boat. You can also move weight fore-aft and ooch the bow down over the crests. At lower ride heights you’ll bash the windward hull through the crests and at full ride height you’ll be able to keep your hulls dry. The boat will sail like any other dinghy in terms of technique in waves, only you’ll be hovering a couple feet over the water. Additionally, due to windward heel your rudder is no longer just a steering control; it’s also a pitch control. Heading up pushes the bow down and bearing away lifts the bow up. So now in concert with all your wave steering and old-fashioned dinghy kinetics you can play pitch with the rudder. Simply, this means heading up slightly over the crests of particularly bad pieces of chop as you ooch the bow down and do everything else you can to keep the boat planted.

Finally, there’s a dirty trick for foiling upwind in waves. It’s very simple. Add rudder lift. You’ll know when you’ve added enough, because the boat will be absurdly easy to sail upwind in waves. It’s a truly amazing feeling, because most of the stuff I told you above about pitch-stabilizing the boat in waves can be ignored without crashing. When I first really discovered this mode I was running into 4-6 feet of wind against current chop on LI Sound in 12-14 knots of breeze off of Stamford, CT. The mode was so stable, I started pointing the bow directly at the biggest waves to see if I would get launched and crash back down. Again and again I cruised straight through particularly nasty pieces of chop until I finally found a particularly steep 6-footer that caused the boat to launch and crash. Note, I didn’t ooch the bow down over the crest or use my rudder to pitch-stabilize the boat. Either would have kept the boat on its feet even on the particularly big and steep wave.

Sailing in the super rudder lift mode is truly ethereal, but it does have two downsides. One, you’ll have trouble getting foiling, because the boat will pitch bow down and try to dig the bows. You’ll need to move weight aggressively aft to resist this and try to foil parallel to the wave sets, so you don’t dig the bows into the face of the chop. Once you’re up and flying you can turn upwind, and if you have the boat set up right you will know. Two, it will be impossible to sail downwind in waves in this mode. You’ll need to take a couple of turns off the rudder before you try to make VMG downwind on the foils. 

You’ll note I’ve said nothing about foiling downwind in big waves and nasty chop. Unfortunately, there’s no dirty tuning trick to make it easy. You just have to practice, practice, practice until you begin to acquire ninja skills. All the same physics and techniques apply as upwind. You’ll reach along the wave troughs and push the bow down through the low spots in the waves. Additionally, you’ll start to notice that your speed and the frequency at which you’re hitting the waves is very important. If you’re slow and you try to go low over the crest of a wave you’ll more likely than not get launched. If you’re fast and carrying apparent low, you can crush right through a wave set and maintain stability. Basically, there’s a lag in the flap control system, so if you punch through the crest of the wave quickly and the wand starts going forward again, the flap never gets pushed down long enough to launch you. However, if you linger on the backside of wave either due to speed or angle, then its off to “infinity and beyond” followed by a large splash.

-Nick

P.S. When you dig the bows, release the mainsheet and head up. Most of the time you’ll be fine. You can get green water on the second pad and survive as long as you ease the mainsheet immediately.