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A windex tracks only apparent wind. In fact, all wind sensors on a boat sense only apparent wind. You have to remove the ship's own vector (via GPS) to get true wind, and the only way to do that is either 1) estimation based on experience 2) Vector math on paper 3) with a wind sensor input to your chart-plotter.

Apparent wind can easily feel like 20 degrees off the bow while pointing. Quite routinely in fact. Using my wind instrument and chart-plotter in San Diego bay, I go into irons between 40 and 50 degrees to true wind, depending on the boat's speed (faster = better pointing). But yes, the apparent wind in those situations is usually about 20..25 degrees.

bscott wrote:I gave up using a Windex many years go when an Osprey decided to perch on it. I use Davis shroud tell tails about 8' up the shrouds from my cabin top. I see 20-25 apparent on the windward TT provide all my 110 jib and main tell tails are streaming back and we do not exceed 15 heel. All bets are off heeling beyond 20.

Mast rake, halyard and sheet tension, CB/DB position, sail quality, etc, etc will also determine your pointing. None of this really matters unless you are running the markers--sailing off the wind is alot more fun and faster too

Bob

I recently added the shroud tell tails. It's great. Less strain on the neck - especially with the bimini up.

Re pointing in flat water
I don't have a windex on mine so I can't give the exact angle but I've been very pleased as long as one is careful not to stall the boat, and allow her to pick up speed after going about. Lots of fun in the bay I usually day sail in. Shell pretty much do anything that's reasonsble to ask of a sailboat, and in some cases more. Some of the places I sail are pretty shallow. Obviously with no board and the rudders up she points less well!

You have to show a GPS track to demonstrate pointing, not report a windex angle . I can guarantee you a stock Mac powersailor will not sail a 60 degree tack angle to either true or apparent wind.

those terms are way beyond me, but since you know what your'e talking about regarding GPS could you tell me what Bearing means, on my gps chart thing it gives my heading,speed,temperature which i'm familiar with but the last thing is bearing, I've tried adding and subtracking from heading but nothing seems to make any mathmatical sense.

Catigale wrote:You have to show a GPS track to demonstrate pointing, not report a windex angle . I can guarantee you a stock Mac powersailor will not sail a 60 degree tack angle to either true or apparent wind.

Unless your GPS has wind direction and velocity, how does it calculate pointing angles?

Bob

The GPS doesn't. We do, by looking at your GPS track on both tacks, moving the courses to the compass rose on the chart, and taking the difference in the track over ground.

Remember that the direction your boat points to, and the direction made good, are two different things...especially on a Mac..

raycarlson wrote:those terms are way beyond me, but since you know what your'e talking about regarding GPS could you tell me what Bearing means, on my gps chart thing it gives my heading,speed,temperature which i'm familiar with but the last thing is bearing, I've tried adding and subtracking from heading but nothing seems to make any mathmatical sense.

Bearing: The compass direction one vessel is from another object
Heading: The magnetic compass direction a vessel is traveling as measured in degrees
" Gunner, target is bearing 090, Helmsman maintain heading 010."

GPS: Heading is the compass direction you are going
Bearing is the compass direction to a set way-point
Bob

May I offer this one slight expansion to your explanation?
Heading is the compass direction the pointy end of your boat is pointing, not necessarily the direction your boat is actually going. There is leeway, your boat slipping sideways through the water because the wind is pushing it sideways (toward the lee), and current, which will move you along with the water you are sitting on, and possibly other factors which influence which direction the boat is actually MOVING, but the pointy end still points in a single compass direction, called the heading. You can set the heading at 90-degrees, but if the wind is pushing from the south, you'll actually be moving less than 90-degrees, let's say 86-degrees if you actually plotted your real course. But the bow is still pointing at 90-degrees the whole time, you're just slipping sideways as you move forward. So if you wanted the boat to actually MOVE at 90-degrees, with the wind coming from the south, you'd actually have to set a compass heading of say, 93 or 94-degrees to compensate for your leeway.

....ergo my comment on GPS tracks vs Windex angle above....

Over sheeting the sails is probably the most detrimental thing on the M that I've found. On any boat actually but the M is very picky about it. Not only does it encourage heeling, but As soon as speed drops, you go sideways even though the boat seems aimed at the mark. If you can't hold the course without over sheeting the sails, fall off a few degrees, keep up the speed and make an extra tack. In anything other then flat water these boats need to be sailed a bit loose. Experience will help you a lot because just how loose depends on wind strength and wave conditions. In flat water with good wind I can tighten the sheets in more then in choppy water and lighter winds. if I'm close hauled in 10 k of wind and two foot chop, the main would probably be just shy of touching the spreader bar, and the main sheet block would be about 3/4 of the way to leeward on the track. The jib would be trimmed to match. If I had rf the genoa would be rolled in a bit to reduce heeling to around 20 degrees. The weird thing with the M is that you want it to heel a little because it changes the underwater profile from a powereing to sailing shape, but too much heel makes the boat slide sideways more.

You should induce heeling in all sail boats in light air to let gravity help with sail shape. In really light air with little headway you can "roll tack" a Mac like a dinghy.

Bob

jbousquin wrote:

Ixneigh wrote:One caveat: these boats do point really well in flat waters. With a true gaff you would lose some of that.

I've thought that perhaps my Windex was being unduly influenced by apparent wind in some cases, but I had someone else sailing my boat this weekend, and she also commented on how close my boat was seeming to sail to the wind. I'm talking regularly sailing 20 to 25 degrees off the wind. I've posted this before, and have been laughed off the forum for it! But I'm actually being serious -- I can't figure it out, but sometimes, my Windex will be pointing upwards of 20 to 15 degrees, and I'm still making way.

If anyone has insight into either a) what I'm seeing/not seeing that would suggest the Windex is only tracking apparent and not real wind, and I'm actually not as close as I think or b) other tales of sailing closer to the wind than the Mac is known for, I'd love to hear it. Thanks, Joe

Do you use GPS? If so, take note of your heading while sailing close hauled. Tack, and then note your heading. By counting the degrees and dividing by 2, you will get your ability to sail close to the wind. Post your results. It will be nowhere close to 25 degrees, and most likely closer to 50 or 55 degrees.

Sounds dumb, but I have used a free Jogtracker app on my phone to record speed, path, and direction when sailing my . It lets you post to social media as well.The only caveat is that it doesn't account for the currents on the hudson. Going out today, will see how close 'Breaking Wind' points.

Do you use GPS? If so, take note of your heading while sailing close hauled. Tack, and then note your heading. By counting the degrees and dividing by 2, you will get your ability to sail close to the wind. Post your results. It will be nowhere close to 25 degrees, and most likely closer to 50 or 55 degrees.

See GPS track below from a recent sail on SF Bay. All upwind tacks are close hauled. Looks like she tacks through about 60 degrees. Conditions were moderate chop (about 2 ft waves from an ebb tide), and wind 10-15 kts. Main was single reefed.

Note this is actual track, and not boat heading (sideslip included).

Roger