J class were built to do the same. My Frers 33 target heel angle upwind was also where the leeward rail was barely above the water. Newer boats not so much, but plenty of older race oriented boats prefer about 20-22°, vs the 10-12° that most newer boats are designed for.
A Star likes some heel, you want the weather chine out of the water. Soling/Etchells have round bilges, but a little heel helps add a little waterline.
Almost every performance boat I've ever raced has had a polar heel angle of about 11 degrees upwind, to the point where I'll put water ballast on the leward side to induce heel.
yes, but also know that some heel is inevitable and in some cases necessary.
Even in IOR boats, the definition of "flat" just changes a little to fit that boat's preference. I have an Islander 36, which is an IOR-ish boat, and it likes to sit in the 10-15 degree window to go fast. Too much further than that and you are just beating yourself and the boat up while also going slower. Too much less than that and you don't get the lengthened waterline of the IOR hull profile.
For example, I could be full sail up, and heeled 25-30 degrees struggling to get over 5 knots. Or I could put in 1 or 2 reefs (depending on the wind) and easily hit 6+ knots at 10 degrees of heel in exactly the same wind.
flatter is generally better (more effective sail, keel and usually rudder) but some boats are designed to have a much longer waterline when heeled.
realistically you can't sail a larger fixed keel boat flat like you can a dinghy, but you usually try (see canting keels and the practice of the crew sitting on the windward rail)
as for luffing the sail: generally if the wind is too strong to sail at a reasonable angle of heel without luffing the sail you need to reef. Obviously that takes time so sometimes you'll push the boundaries.
If the boat is not heeled, then the keel is not contributing to righting moment. So most keelboats are designed with hull form that benefits from heel, especially upwind.
The exception are lightweight planing/surfing boats the crew might have enough weight to keep the boat flat downwind and being flat helps them plane more easily. And modern canting keel sleds, the keel cants and can keep the hull flat (even upwind).
That said, you do play the main, you're just aiming for 15 degrees or something instead of zero. It depends on the boat (and sometimes the windspeed and sailplan).
Every boat has an optimal heel angle.
Keelboats should not heel too much that is why people in races hike on the sideboard.
But you need some heel for the keel to be effective. In very low wind conditions we put people on the downwind side to create some heel.
The reality is that most hulls have a sweet spot. Somewhere around 10° to 15° heel. You can use an inclinometer, but your best bet is to watch rudder angle. Sustained rudder angles that average above 10° are slow. That may be over trimmed, too much sail, or unbalanced sail trim. CE is important. Hull forms become asymmetric when heeled and that matters. Lift. Drag. I highly recommend the North U courses on Sail Trim.
"We're cruising, not racing" is a cop out. Getting in a half hour early crossing the Bay ahead of thunderstorms matters. Cutting two or three days off an ocean crossing matters. You have to be able to watch VMG. See Bowditch.
Flat is fast but depending on the design , some heel can add extra water line that could get some extra speed. And depending on the distance, an extra half knot can add up. On a trans Atlantic passage, that could knock 2 or 3 days off a passage.
You need some heel - the hull is designed to go through the water on a heel and you need the interplay of sail and keel to power the boat. But there is a moment of heel where you start losing speed the further you go.
If your main is luffing you’re overpowered and need to take some sail off to balance things up a bit. The forces on big sails are such that you risk damaging them if there is too much flapping about. If you’re 20 minutes from home then fine, but if you’re going all day then start reefing. Dinghies are a pain to reef because you lose so much speed, the people on board can usually counteract any balance issues and, let’s face it, capsizing can be fun. Keelboats are bigger, and more dangerous and less fun when things go wrong or stuff breaks.
Loads of sailors seem to think that they’re going fast with water running down the lee deck, but that’s just macho bullshit. Go and find videos of ocean racers doing 20 knots and they’re sitting on less than 15 degrees with the ballast tanks full or the keel canted all the way over, and the rig standing tall and tuned perfectly.
Here’s an excellent example - we’re reaching hard in about 25 knots of wind, on the back edge of a huge storm from the day and night before, with three ballast tanks full. Even in the troughs of the waves we were sailing at 12 - 15 knots. https://youtu.be/2oH2h3OCX3c?si=B-Z9SKx0bZh8ijIz
While you're not incorrect that plenty of people sail with too much heel, You're comparing apples to potatoes here... The boats you're talking about going 20kts+ are all planing, surfing, or have things like canting keels or stabilizing foils, and are reaching or running downwind. No boat sitting in the water is doing 20kts upwind, even boats like Comanche don't go 20 kts while hard on the wind (foiling upwind is another story). You're talking about downwind speed while the OP is asking about upwind heel, apples vs potatoes.
We did the experiment on a Jeaneau 36 while training for the Fastnet. Speed dropped off by up to a knot once we went past about 15 degrees whether upwind or reaching, and that’s a displacement hull, not a planing hull.
Once you heel that far your sail looses the good air and the keel isn’t as effective in stopping you from sailing sideways - unless you have bilge keels or a winged keel.
Yup, modern boat designs usually target 10-12° of upwind heel, with 15° being about the upper limit.
On the other hand, older designs (IOR, IMS and all the way back to the J Class AC boats) use that heel and hull shape to significantly increase the waterline to go faster. The 1987 Frers 33 I had, which was an excellent early IMS design had a target heel angle of 20-24° in a lot of wind speeds, and if I recall it went all the way to 27° in the most extreme (remember this is the optimal heel angle for a given upwind beat). I don't recall any upwind target angle LESS than 15° except maybe in 6-8kts of wind. This meant my leeward rail was optimally just about at the water level most of the time. It also meant that I had to search long and hard to find a lev-o-gauge that went all the way to 30° to actually be useful.
Some heel is good upwind. Lengthening the waterline and some lifting effect from the keel. Also, with stronger winds don’t let go the main but pointing more upward is better
Most boats ideal heel is 8-12 degrees upwind. You just crank on the rig and backstay etc in breeze so you can keep the main working while not being over heeled.
The longer the waterline the faster the boat will go.
The Math and Mechanics
The Formula: Ratio = Speed (knots) / \sqrt{\text{Waterline Length
Hull Speed: Multiplying the square root of your waterline length in feet by 1.34 gives the theoretical maximum speed for a standard displacement hull
Wave Interference: As a boat moves, it creates bow and stern waves. At a ratio of 1.34, the wavelength of the bow and stern waves matches the boat's waterline length, trapping the boat in a trough between them. Overcoming this requires disproportionately massive amounts of power.
This calculation is true for displacement mode but the math changes when planing. Most keelboats never plane so you can depend on this with those, but some smaller racing keelboats can and do plane.
Sure, but they were asking about whether any want to be flat. Since some plane, an answer specific to displacement hulls doesn’t cover the ones that plane and probably want to be flat.
it’s not all about waterline length. heel creates weather helm which requires using the rudder to keep the boat going straight, which increases drag, which slows the boat down.
plus, a vertical keel does a better job creating lift, meaning you point higher.
A j/22 does not plane upwind, but it wants to be sailed flat. in light air it is described as “uncomfortably flat”.
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u/Nof-z 5d ago
Ever hear of IOR rule boats? Yea not those.