Talk:Sailing

Multis and monos

The seriousness of this article needs to be cranked up a few notches. I'be begun by removing the outright rant wrt monohulls vz multis:

Multihulls, especially catamarans, sail much faster than monohulls. Unhappily it is common wisdom that in the open ocean, monohulls are the only safe design. Monohulls remain upright because their buoyancy is higher than their center of gravity. In severe storm or wave conditions, a monohull will recover from a capsize well enough for the crew to jury-rig some sails and limp to a port. A multihull will remain capsized and adrift, probably killing its crew.

-- Egil 07:02 Feb 11, 2003 (UTC)

I have read dthat Multi-hulls on the open ocean actually travel slower or at the same speed as monohulls. just adding trivia. -- colinpcarr

I've started to include some basic sailing theory and intend to continue to develop it as time allows. I've also tried to resequence it a bit so that it starts off with the simple stuf and then builds up to the more advanced aspects. I know there's still a lot more to do so if you want to help please "fill your boots" :-) PS If anyone thinks this is NOT the best page for this stuff please let me know. Thanks Julianp

I'll start working. colincarr, multihulls are light, and so they can't really punch through the waves the same way monohulls can. Additionally, if they have to start going through waves, their efficiency is greatly reduced. So, in wavy conditions nearshore or offshore, you'll find traditional multihulls go slower than monohulls. However, advanced multihulls such as SWATH hulls can move fairly fast. You should also mention hydrofoilers (such as the Moth dinghy). (Forgot sig again.) - Dastal 23:06, 15 November 2005 (UTC)[reply]

On the subject of saftey in multihulls versus monohulls, there is some validity to that argument. More specifically, the rule is that any monohull competing in Type 3 or above racing must be able to self-right. That is to say, has to be able to right from the action of the waves alone. Most monohulls acomplish this by being more stable upright then they are capsized. I'm not sure how they apply this rule to offshore dinghy racing. - Dastal 16:40, 17 November 2005 (UTC)[reply]

Overall comments

This page has some good stuff in it, but IMO it is NOT very encyclopedic in style. The Sailing Techniques section reads too much like a How-To manual, I think we would be much better off with a more detatched analysis of sailing theory; basic aero and hydro dynamic forces acting on a boat, the relation between sail trim and relative wind, ect.

Also, this article also focuses pretty much exclusively on recreational bermundian sloops, which is understandable, but it would be nice to try to include (at least implicitly) other types of boats and rigging in the scope of the article.

I would like to hear peoples opinions on this before I start editting. --BadSeed 11:39, 19 July 2005 (UTC)[reply]

I just completed a fairly massive overhaul of the types of sails and layouts, though it's not quite finished. - Dastal 18:10, 16 November 2005 (UTC)[reply]

Sailing skills

First, I think the article is great. What about putting together some practical skills; docking, MOB (man over board), uncapsizing a dinghy, some images for points of sail, etc..

I especially would like to add docking because if there is anyway we could make an impact to "the world of docking", I watch people bounce around their slips all day, I believe everyone would be happier.:-) Colin Carr 15:49, 1 May 2004 (UTC)[reply]

Good ideas. Please go for it Julianp 06:51, 14 May 2004 (UTC)[reply]

Sailing hulls and hull shapes

I added a section on the layout and advantages of multihulls Gary Mulder 18:00, 4 Mar 2005 (UTC)

Sailboat Racing

Also added a short para. with some references to other WP articles on the most major races Gary Mulder 18:00, 4 Mar 2005 (UTC)

Where's the history section?

There's a lot here about modern sailing, but barely a word on the history of sailing. Same goes for sail. Are there really no takers on this aspect of it...? Peter ^Isotalo 7 July 2005 03:09 (UTC)

Ditto! I came for the same thing. Too much emphasis on competition sailing. -Timvasquez
I'll get to work on that as I have time. Cheers. --Dastal 22:44, 15 November 2005 (UTC)[reply]

The physics of sailing

The explanation using wings of airplane can more precisely described with the aerodynamic equation called Bernoulli Equation. It states that when fluid (in this case air) flow faster, the pressure will drop. Due to the difference in air flow on both sides of the sail, the pressure difference causes a resultant force pushing the sail forward.

Actually, this is not entirely correct. According to Sail Power, a major text on the aerodynamics of sailing, it is mostly a rotational effect that creates momentum while sailing upwind. Otherwise factors such as slot width would be unimportant. Moreover, most modern sails are, at most, 3 mm thick. (These are more the high end mylar sheet/kevlar tape sails, though the sails on the Lark-hull dinghies used at Tufts University are certainly no thicker than that, and they are dacron.), creating a minimal pressure differential according to the Bernulli equation. Considering that the sails on 30-40 foot keelboats can generate upwards of 10 tons of force in moderate winds, it would seem that the Bernulli Equation is not the major source of force in sailing. (Edited to add signature.)--Dastal 22:44, 15 November 2005 (UTC)[reply]

Besides this, if this effect did apply, the sail would bow into the wind and it would be possible to sail dead straight into the wind. This is utter nonsense. In all cases, the boat moves because as the wind pushes the sail, only the component of the force on the sail that is parrallel to the keel will have effect. Although the wind pushes the sail from one side of the sail's normal vector, the wind is also deflected to the other side of the normal vector so that the majority of the resulting force on the sail is parallel to the normal vector of the sail. Therefore, the sail will always be limited to an angle between the forward direction of the boat and the source of the wind (for simplicity, I am ignoring effects of frictional drag and bowing of the sail). Furthermore, depending on the angle of incidence of the wind on the sail, the effective area of the sail varies: if the sail is left to point straight away from the wind, then the effective area of the sail is nill. Taking these two statements into account, as the boat is more closely directed into the wind, the sail is more limited to smaller angles and, therefore, smaller effective areas. Thus, the more the boat points into the wind it has less power to move forward, until it must finally stop when it is pointing straight into the wind. In fact, this stop must come sooner because frictional drag and other effects are involved too.

When sailing directly with the wind, the boat approaches the speed of the wind so that the relative speed of the wind to the sail is decreased. Sailing at an angle to the wind, the boat must move faster to effect the same decrease of relative speed because it is only the component of the boat's velocity vector that is parallel to the wind that decreases the relative speed.

Needs a re-org

Hi all, Just thought I'd stick my whisker pole in here... I think that we have the basis of a great article here — or more correctly a series of articles. I think that a fairly major re-org is needed, and I'd start by splitting off at least one "child" article:

Sailing should be a general overview of the sport
Technique of sailing (suggest a better name?) should contain the "physics", and all the how-to stuff
Sailing boats and rigs (suggest a better name?), to discuss boat types (monos, multis, ketches, schooners, etc.) and rigging (bermudan, gaff, junk, sprit, etc.)

And yes, we need a History bit, which could conceivably become a separate article.

Also, we need to mention single-handed versus double-handed and crewed sailing somewhere.

What do folks think of this? Just FYI, I'm working on getting all the single-handed sailing articles up to scratch — see my user page for a list. — Johantheghost 15:26, 7 January 2006 (UTC)[reply]

Reorg or rewrite?

I agree its a bit bitty, and needs some tidying up. But it doesn't seem unwieldy, the bits seem to belong together. Should we try to rearrange the sections, renaming where need be? I don't really see the need for child articles, someone needing to find out about sailing could reallywant ot know about principles, skills, history, etc,. and therefore have his/her need met by looking up one article. Is there a coherent case for splitting up what we've got? Perhaps the history of sailing would be good, as its a bit of a specialist topic.

TonyClarke 19:26, 7 January 2006 (UTC)[reply]

What is a knockdown?

Hi all, I just removed this from the article:

... if however the boat heels beyond a certain point of stability, it can be knocked-down or capsize. A boat is said to have been knocked-down when the tip of the mast touches the water. When a boat floats fully inverted it is said to be capsized.

I believe this is incorrect, or at least misleading; in this definition, a gentle capsize in a dinghy on a duck pond would be called a knockdown. I don't believe that a knockdown is simply when the mast tip touches the water. In all the sailing literature I've read, a knockdown happens when sailing in the ocean, when the boat is hit by a steep following wave and violently thrown on to her side. The key is the violent part; a dinghy will capsize very gently if you simply sheet in and sit on the wrong side, but a knockdown is something that can cause a dismasting.

Now, this is my understanding, but before editing the article, I'd like to have other views, since I've never seen an actual definition of a knockdown, and how it relates to a broach. — Johan the Ghost _seance 10:48, 15 March 2006 (UTC)[reply]

That does sound overly scientific and not in agreement with standard usage among recreational sailors in my area. To me, knockdown always implies a sudden change in trim past equalibrium; the boat heels significantly farther than it should (though not necessarily as far as the mast touching the water) and doesn't immediately right itself. Dinghy sailors and those in small monohulls (20-35 feet) would call a knockdown what happens when a sudden gust overwhelms the boat, usually because the sails can't be eased fast enough. "Man, when that squall hit us, we took a knockdown and the genoa track blew out." When reaching with a spinnaker, a knockdown can be caused by a gust or windshift; the boat is overcanvassed for the new speed/direction, and the spinnaker has too high a center of gravity and holds the boat down.

A knockdown can also be caused by a wave in the open ocean, a much more serious situation, but I don't think it's limited to that. Otherwise, we need a new term for small boats getting pushed over almost onto their sides (from which they recover eventually, though dinghies are more likely to actually "capsize" -- sails flat on the water, needing to be righted -- at that point of heel).

A broach happens when a boat suddenly accelerates, causing it to turn (upwind) and to heel onto its leeward side (centripetal force and hydrodynamics play roles here; the boat gets too much lift off the keel, causing it to turn, and the turning and acceleration cause it to heel more, as I understand it in simple terms). It can be caused by a following wave suddenly accelerating the hull, or by a wind gust, usually under spinnaker. After a broach, a boat is square to the wind and held down on its side; all heck breaks loose. In that sense, a broach could be considered a specific kind of knockdown, perhaps.

Others may have more precise definitions, but sailors aren't linguists. DavidH 21:55, 15 March 2006 (UTC)[reply]

That all sounds good to me; I'm obviously more familiar with the ocean side of things, but I guess the common thread is that "knockdown" implies some degree of suddenness / violence. Your point about capsize not being synonymous with upside-down is also good; a capsize, to me, is simply when a boat is rolled beyond her point of self-righting. For a keelboat, this usually means upside-down, but for a dinghy it will usually be what you said — 90° over, sails flat on the water. — Johan the Ghost _seance 12:19, 16 March 2006 (UTC)[reply]

Since I started it I feel I'd better take this chance to be heard. Unequivocally a boat is NOT capsized UNLESS the boat is inverted. All else can follow from there. Since a boat on its beam ends is NOT inverted, you cannot say it is capsized. If dinghy sailors in lakes in some parts of the country (world) have been saying they are 'capsized' when in fact they have not inverted their dinghies, then they have been mistaken. I suggest this is clear as per the article on Capsize - to wit: "Capsizing refers to when a boat is inverted such that the bottom of the boat is on top. The term is also used to describe a boat that has broached, pitch poled, rolled, or sunk."

Now the definition of a 'knockdown' is simple - it is when the beam ends (topsides or sides of the hull) are touching the water. This would be a 90 degree shift from the boats normal trim. The mast at this point may or may not actually touch the water depending on if the sails are bent on, how bendy the mast is, etc. Once the boat passes 90 degrees and reaches (say) 95 degrees surely the mast is now touching the water regardless and yet you still cannot say the boat is capsized.

Being knocked down has nothing to do with suddeness or strength of wind or wave, it merely describes the orientation of the vessel relative to its normal axis. Ahem. Even a boat with its mast pointing at 145 or 165 degrees is not technically capsized - it has to be 180 degrees inverted. — Preceding unsigned comment added by Jordanbigel (talk • contribs)

That sounds like a non-sailor's definition to me. I can't imagine a sailor insisting on using a protractor before deciding that a boat is capsized. Anyhow, US Sailing should know:

A small boat is said to capsize when it rolls over upside down or on its side with its mast and sails in the water. Turtling is a type of capsizing but only refers to the turning of the boat completely upside down with its sails and mast pointing vertically toward the sea bottom. Capsizes usually occur when a sudden guest of wind catches the skipper and crew off guard.[1]

And Safer Sailing:

As most sailors learn at some point in their sailing career, a knockdown occurs when an exceptionally large gust of wind, perhaps in combination with a wave, knocks your boat over onto its side with the sails parallel to the water.[2]

From ESPN's Americas Cup pages:

Broach: When a keelboat sailing on a run capsizes from a strong puff of wind or gets knocked down by a wave. Also called a Knockdown or a Wipeout.[3]

From Sailors Choice:

BROACH: To go over violently toward the wind and lose steering , a "knock down"[4]

From what I can see, "capsize" means what I thought: you've tipped over beyond the boat's righting angle, so you stay down. "Knockdown" seems to have different meanings to dinghy versus ocean sailors, but the common thread seems to be getting pushed over to mast-on-the-water or more. In a dinghy, that may be from just a puff, but for a heavy-displacement ocean boat (like mine) it would have to be something much more scary. "Turtled" is perfectly clear: upside-down. — Johan the Ghost _seance 15:12, 28 March 2006 (UTC)[reply]

Capsize just means that the boat is over and staying over. A turtled boat is still capsized. With a dinghy you just lever it over and you are back in sailing trim. A keel boat will NEVER capsize unless there are dire circumstances (Such as dropping the keel). keel boats are what is called "Self righting". That means that at any angle they heel too, including right down to 90 degrees, they will right themselves once preasure is taken off the sails. When this happens it is called a knockdown. The keel boat heals over to the point that the sails stop functioning and the boat then rights itself. What causes a kockdown is ussually a "Broach". This is when, on a reach, the boat heals to leaward and the tip of the boom hits the water. This will often cause the main to tighten up to the wind, with crew being unable to sheet out due to water preasure on the boom. The boat heads up into the wind as it heals over and it's profile in the water changes (same theroy as roll tacking) and is ussually "knocked down" before it can recover. Please note that broaching is EXTREAMLY dangerious and a condition to be avoided at ALL costs. This is also how you commonly break masts at sea.

Apparent Wind

Added a bit about apparent wind when going downwind as it's a significant factor there. (not sure about my wording of it - maybe someone literate could improve?) Singlefin 16:30, 21 March 2006 (UTC)[reply]

another method of reefing

when i used to sail Optimists i remember we used to reef them by ommiting the sprit, folding the sail over and attatching the folded peice with a special elastic cord. Is this a common enough method of reefing to go in the reefing section of this article? Plugwash 19:01, 9 May 2006 (UTC)[reply]

This needs to be rewritten

This needs to be rewritten. I have added some lines to "The Physics of Sailing" to correct terms. Who else here is a sailing instructor? I belive we should be taking material from the CYA White Sail handbook and US Sailing's program and rewriting them to fit this article. Any thoughts on contacting these organization and requesting permission to reprint the information here? That would be by far the easiest method of a rewrite. If that is not a good idea, I think that we have to determine a level that we are going to write too. If we are only going to to write to a White Sail III level then mentions of the Spin and the physics of sailing may be too much. But if we are going to write up at the bronze level this is all in, only leaving out the technicalities of racing (Silver Sail).

I also note a great lack in informative diagrams. In the physics of sailing section there should be at LEAST a diagram of the Bernonli and Venturi effects as well as how to determine the Centre of Lateral Resistance and the centre of effort and how they cancil each other out to create forward momentium. This would be a far clearer explination then trying to say "the force exerted on the sail is represented by a vector comming off at 90 degrees from the boom. As the sail is sheeted in and the boat heads up into the wind, the effort exerted on the boat from the sail becomes more lateral and creates leaway. The centreboard, or keel acts exerting force at 90 degrees from the centre of lateral resistance canciling out lateral movment and converting the force acting on the sails into forward momentium."

I want to do a full rewrite but could use the help of any other instructors that might be out there.

Peace!

Agreed, this very much needs to be rewritten. Would love to see some history, be great if we could find someone who could fill that in to work with. Some parts are nice, but it is erratic, and the introduction needs work. Some specific items from intro, perhaps they could be altered? Perhaps it could also be a bit shorter.

"strafing to the sides?", how about slips to the sides or leeway?
"...it is pushed in the direction that it bows."
.."if the sail is pointed just as the boat, then the boat will only be pushed sideways" - This is not true. Depending on the camber

I unfortunatly can't help until the fall, so havn't wanted to suggest a rewrite or cleanup, but agree it is need. --Augustz 03:56, 14 May 2006 (UTC)[reply]