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Old 10-11-2005, 07:48   #16
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"Somewhere in here is the advancement in design that now allows performance cruisers to have monster beams, but still sail to weather.

Capt Lar"
....

The boats that I am talking about, IMS and IRC derived designs really do not have the monster beams that are associated with the more propular value oriented cruising boat designs. The IMS and IRC oriented boats gain pointing ability by having higher efficiency keels (less drag/more lift) , multiple spreader rigs allowing narrower headsail sheeting angles, finer bows (moving the center of beam aft giving them more powerful stern sections but which also gives the visual illusion of greater beam) and lower centers of gravities resulting from their bulb keels which in turn allows then to sail flatter making less leeway. There have also been improvements in sail design that works well with these boats.

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Old 10-11-2005, 08:05   #17
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Jeff H - Would 80's boats such as the Bristol 35.5 and Sabre 36 fit this category ? I am guessing the Sabre has the higher performance keel.
As to keels, I will do a tread. I read your old and extensive post on keel configurations - lotta info, and have some questions.

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Old 10-11-2005, 08:34   #18
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Hi Jeff,

I guess the point I wish to get over is that contrary to your experiences on Solings v Farr 38 (or non-overlapped headsails v genoas) - I've witnessed the Solings practically outpointing the Farrs every time they are up against one another.

Not just sailing parrallel - but the Solings sailing higher - climbing away to windward.

If anyone else who sails on the relatively flat water of the Swan River in WA can testify - bang a fleet of Solings, or Etchells, up wind alongside a fleet of bigger genoa equipped racers (and this happens week in / week out) - and the smaller keel boats outpoint.

I can't debate this as it's not just an opinion, but what one can see happening.

So that's the only point I wished to express.......and I'd agree with all others that sail size / sheeting is only one aspect of a yachts ability to work to windward.

And if we can all agree on what measurement we are talking about - having Cap't Lars compile a chart showing relative angles would be good..................

Cheers
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Old 10-11-2005, 08:47   #19
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IMHO there has been a lot of discussion around a couple of points so far.

1] Pointing ability is controled by sheeting angle

2] Influenced by sail shape especially the main

3] Influenced by hull shape

4] Limited by Keel design

Modern high end racers like TP52s go upwind like bandits. I have observed them sailing in the 25 degree apparent wind angle range at full speed. When I quite racing about 6 years ago or so watching Farr 40s going upwind was scary but these new boats are beyond belief. They use non overlaping jibs with big extended roach mains, sail very flat with high aspect deep keels that contribute to their ability upwind. They also have hull shapes that are very fair and designed not to just push water but flow it and I think even create lift out of the hull.

I think that a semi modern cruiser should be able to effectively sail in the 35-40 degree range. I know that my Moody can sail upwind with a #3 [100%] at a higher apparent wind angle about 35 degrees than it can with a #2 [140%]. Both sails are triradial composits as is the main.

If I drop the 'board' which is more like a lift keel, my draft goes up to 9 ft and VMG to windward goes up by 25% or so.

So I guess this long winded answer is my way of saying that it is not a simple answer.
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Old 10-11-2005, 09:03   #20
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Angle of the dangle

My boat is a 1979 design. The keel is industrial strength of moderate ( not deep ) depth. Therefor the lift generated is not as good as a more modern fin. But Some of the older deeper hulls also develop lift when the hull is heeled to about 15 degrees, whereas a shallow hull generally needs to be sailed flat. Also in heavy going the shallow hull needs more attention to keep it at the appropriate angle, and can slip sideways a bit. So wind and boat speed are factors along with waves.
In smooth water, no current, 5 knots of boat speed, I sight down the main sheet traveller when tacking to make a mark. So that gives me an angle of 90 deprees. Same conditions hop in the Soling, tack before the traveller is square, hop in the Holland 7.6 and tack a few degress before the traveller gets square. The tacking angle is now down to about 80 degrees. So the boats with the more efficient keels have a tighter tacking angle.
Increase the wind and add waves, my boat points higher by about 5 degrees, driven from the hull, nothing to do with sheeting angle. I can now point as high as the smaller boats, and have a greater degree of range of angle. Too high, too low, it does not matter. With the small boats too high, you stop, too low you blow over. Also it is the main that drives the boat up in to the wind, you can mess with the headsail sheeting angle, but the results may not be there. The boom should be near the centerline but the back end of the main should not hook to windward. Some boats will tell you what is going on from the rudder.
For a cruiser I prefer a boat with an efficient keel that can handle solid groundings, for around the buoys I prefer a modern foil, small jib, large main. A small jib can always be sheeted with a shallow angle but that is not the final answer.
Michael
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Old 16-11-2005, 11:41   #21
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First of all, my apologies to the forum. I had completely incorrectly remembered the angle on my windex tracking arms. Originally there was 67 degrees between the arms and I narrowed that to 62 degrees. That would mean an apparent wind angle of roughly 31 degrees in flat water.

With regards to the relative pointing angle of a Soling and a Farr 11.6, I had the chance to experiment a bit with this question over the weekend. In roughly 15 knots of wind (gusts to roughly 17-18) I came from astern and to leeward of a fleet of Solings that were racing. Sailing my normal course I was pretty much sailing parallel to them, neither climbing up on them nor sliding to leeward. I did have greater speed. As I wanted to tack out of the race course I slightly over sheeted and although my speed dropped, I was able to work to windward of the last boat weather of me (he pulled away a little while this was happening). Once I had cleared my air, I resumed my normal course and sail trim and was once again on what appeared to be a parrallel course with a bit more speed. Ultimately as I was gaining on the Soling I tacked away well below their rhumbline. By the time they approached their weather mark, it appeared that I could have easily crossed their fleet. I am not sure how this would compare with lighter winds where I would not be using my blade.

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Old 16-11-2005, 19:24   #22
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Jeff,

I was down in Annapolis working on my boat this past weekend, and was looking up at my Windex trying to gauge the angle at which the arms were set. Your original statement of 36 degrees was starting to look not out of the question, but of course I was looking at something about 45 feet overhead, so who knows? 62 degrees does seem more realistic.

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Old 16-11-2005, 22:51   #23
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Ok, found some designer's polar charts for my machine.



These angles, I believe, are not for apparent wind, they're for true wind angle.

Typical day.. Looks like I'm tacking 'bout 75 degrees.

Now them heel angles are off. We try to never heel the machine over 15 degrees. If it starts leanin' we pinch up into the wind and coast for a bit. So that would put us in a little closer to the wind from about 15kn of wind on up.

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Old 17-11-2005, 00:22   #24
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Ahh! Jim Lee, you've given away my secret

I like to fly my genoa most of the time and rather then watch the telltails, I watch the clinometer and keep the boat at 20-25 degrees by pinching up.

When I have to ease off on the main then it's time to take down the genny.............._/)
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Old 17-11-2005, 00:41   #25
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OK so this sailing part is my weakness. By the chart Jim has shown, can someone explain some points. What is VTW.
And is the heel showing the maximum amount of heel you should have or the optimum amount of heel. And why? Ummm, I have a feeling that is a very big question with bigger answer to match.
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Old 17-11-2005, 00:54   #26
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As far as I can make out, and I ony found this document last night,

VTW : Velocity true wind.
BTW : Bearing true wind.
V : Velocity (Boat speed in knots)
VMG : Velocity made good. How fast your moving directly into the wind. (Upwind componet of your course)
Heel : Heel, and for how people sail J/35s it seems too high.

I don't know where this heeling anlge comes from, 'cause in a blow you sail these machines right on the ragged edge of luffing. Its basically, pull in a -little- power, the heel starts cranking up and you let it point up a tad and coast. Pull in another little nibble of power then let it luff up again.. These little nips of power are really small adjustments. When the boat feels powered up your, pointing too low. Flat is fast on these things.

With less wind, things are done differently. But in the SF Bay its usually sailing when its hootin' out, so that's how I learned.

Now being in the PNW I'm going to have to relearn everything.

Bother!

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Old 18-11-2005, 14:36   #27
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Another Data Point

Just for another data point, here are the optimum upwind "polars" for my Peterson 34, as calculated by the IMS Performance Package (back in 1988):



One interesting thing to note is that the bearing of the apparent wind is essentially constant as the wind speed picks up, while we can sail closer and closer to the true wind as the wind speed increases.

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Old 18-11-2005, 22:55   #28
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Here is an interesting little demo I just stumbled upon.
Just incase this URL doesn't open the demo exactly, look for the sailing simulator.
http://www.nationalgeographic.com/vo...ing/index.html
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Old 22-11-2005, 05:03   #29
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From Sailing Anarchy

http://www.sailinganarchy.com/index.htm

"Ask/Answered

We have gotten an amazing response to our new Better Ask Someone feature that we listed yesterday. Here is the first one, answered by Tim Kernan of Kernan Yacht Design:

Q: I Have a late 1/2 tonner with the genoa tracks next to the cabin sides. Other similar boats have the tracks further outboard by about 3-4" and I was told by a sailmaker that I'd be faster doing the same. I have always been told that tighter sheeting angles allowed one to point higher. What gives?? Should I move the tracks outboard or pull the traveler car higher to keep the slot open??

A: We'll need to know what the actual sheeting angle is, measured from centerline, with the clew as the origin. Older generation wisdom was to shoot for 8 degrees, sometimes you would see it even lower at 7 degrees. Current thinking is up to 10 degrees, but you have to factor in that most current boats are set up with inhaulers. So at standard setting, the slot is more open, but inhaul for height when you need it. Definitely you will need to be able to get to 8 degrees at a minimum for height, particularly on an older generation IOR type hull. It is probably not worth moving the tracks, but your best bet is to check the actual angle, then go from there.

11/17/05"
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Old 22-11-2005, 05:22   #30
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While sheeting angle is a very critical component in determining the pointing angle of a boat, to some extent the way that the jib is cut and its stretch can have even greater impact than generally understood. For a given size sail, windspeed, seastate, and given sheeting angle, differences in camber depth and shape of the sail can affect pointing ability by as much as 5 degrees which is actually an enormous difference.

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