When were the first sails that went upwind?

[tudorsailor]

We all know about sails being an aerofoil and allowing upwind sailing. I now know and understand the Bernoulli principal. I have done some Googling but am having difficulty finding out when boats moved from sails that were essentially downwind bags to shaped sails that allowed upwind sailing. In the course of looking for the answer, I have come across this article explaining why a sail is NOT an aerofoil

Can anyone point me in the right direction?

Thanks

TudorSailor

 

[JumbleDuck]

We all know about sails being an aerofoil and allowing upwind sailing. I now know and understand the Bernoulli principal. I have done some Googling but am having difficulty finding out when boats moved from sails that were essentially downwind bags to shaped sails that allowed upwind sailing. In the course of looking for the answer, I have come across this article explaining why a sail is NOT an aerofoil

An odd website in which I would not place a great deal of trust. He seems obsessed with the notion that a single layer of cloth cannot possible be a wing, which is going to come as news to the hang gliding community.

 

[Mrnotming]

Was it the Norsemen who reinforced (in a grid fashion) their sails?
They used walrus hide strips.
Deformation of shape was reduced to windward.
Going to windward angle was more limited, and I'm not sure if the even had used leeboards at this stage, I think not.
There was a program about this some years ago probably BBC.Was there a bit about vessel portage at Scapa Flow also?
I've had a look at your link Tudorsailor, but not read it in detail yet.
From Memory the North Sails manuals either U Smart or U Fast cover this aspect in some detail.
Sorry to say, I now have neither manual, due to these having been loaned and not returned.(no forumite involved, glad to say)

 

[JVL]

I've sailed dhows in east Africa a lot and apart from iron fastenings the design is essentially unchanged for at least 3000 years. They go everywhere at hull speed including upwind,fast efficient and relatively cheap sailed with supreme skill for fishing/trading/journeying ( no Kevlar, laminated sails, electronics or fancy toys)

John

 

[Mrnotming]

Hi JVL, is that also called the claw rig?An emminent person is supposed to have proved that this is the most efficient rig of all?

 

[JVL]

Hi JVL, is that also called the claw rig?An emminent person is supposed to have proved that this is the most efficient rig of all?

The claw or crab claw rig is of pacific origin and is rigged slightly differently , the dhows that I have sailed are what we call lateen rigged ( they just refer to it as the sail)

John

 

[Searush]

Lateen & crab claw rigs have been sailing to windward for several thousand years, I doubt that there is a written & dated record going back that far.

However, the Arab dhows were not good for tacking as they required a large crew & basically lowered the yard & rehoisted on the new tack - see the "Sinbad Voyage" book by Tim Severin. Most of their trading voyages used the 6 monthly Monsoon trade winds to ensure minimal windward sailing, nevertheless they were capable of entering & leaving the "Jaws of Hell" (Bad el Mandab?) in & out of the Red Sea.

Equally, I think that crab claw sails were used on Proas which don't tack as such either, they just swop bow for stern, check out David Lewis's book (don't recall title now) but he is an expert on the navigators of the Pacific who crossed oceans to find tiny islands thousands of years ago & returned safely with the knowledge to pass on to future sailors.

 

[tcm]

We all know about sails being an aerofoil and allowing upwind sailing. I now know and understand the Bernoulli principal. I have done some Googling but am having difficulty finding out when boats moved from sails that were essentially downwind bags to shaped sails that allowed upwind sailing. In the course of looking for the answer, I have come across this article explaining why a sail is NOT an aerofoil

Can anyone point me in the right direction?

Thanks

TudorSailor

Hum, but they don't really go upwind do they? They go off the wind by 20+ degrees. Not much wing effect since the distance travelled by air inside and outside the sail is almost exaccerly the same, so no pressure difference, so no Bernouilli, sorry. Boring old Newton, just resolve the forces. It's "principle" not "principal" btw.

 

[JumbleDuck]

Hum, but they don't really go upwind do they? They go off the wind by 20+ degrees. Not much wing effect since the distance travelled by air inside and outside the sail is almost exaccerly the same, so no pressure difference, so no Bernouilli, sorry. Boring old Newton, just resolve the forces. It's "principle" not "principal" btw.

The idea that the different track lengths on each side of a wing give rise to different speeds and therefore, via Bernouill, to lift is a pernicious myth. Why on earth would two adjacent molecules, separated by the leading edge, feel any need to meet again at the trailing edge?

Aerofoils produce lift by superimposing circulating flow - a vortex - on top of linear flow. Where the two add you get a higher net speed and a reduced pressure; where they oppose each other you get a lower next speed and increased pressure.

 

[tudorsailor]

Lateen & crab claw rigs have been sailing to windward for several thousand years, I doubt that there is a written & dated record going back that far.

However, the Arab dhows were not good for tacking as they required a large crew & basically lowered the yard & rehoisted on the new tack - see the "Sinbad Voyage" book by Tim Severin. Most of their trading voyages used the 6 monthly Monsoon trade winds to ensure minimal windward sailing, nevertheless they were capable of entering & leaving the "Jaws of Hell" (Bad el Mandab?) in & out of the Red Sea.

Equally, I think that crab claw sails were used on Proas which don't tack as such either, they just swop bow for stern, check out David Lewis's book (don't recall title now) but he is an expert on the navigators of the Pacific who crossed oceans to find tiny islands thousands of years ago & returned safely with the knowledge to pass on to future sailors.

But I really am trying to find out - for no particular reason - is when did Europeans start having triangular sails. On further Googling, I have found this summary http://nabataea.net/sailing.html which does give some history and then led me to this wiki page http://en.wikipedia.org/wiki/Caravel. Seems that the key term is Lateen sails which enabled Columbus to cross the Atlantic

Tudorsailor

 

[JVL]

Lateen & crab claw rigs have been sailing to windward for several thousand years, I doubt that there is a written & dated record going back that far.

However, the Arab dhows were not good for tacking as they required a large crew & basically lowered the yard & rehoisted on the new tack - see the "Sinbad Voyage" book by Tim Severin. Most of their trading voyages used the 6 monthly Monsoon trade winds to ensure minimal windward sailing, nevertheless they were capable of entering & leaving the "Jaws of Hell" (Bad el Mandab?) in & out of the Red Sea.

Equally, I think that crab claw sails were used on Proas which don't tack as such either, they just swop bow for stern, check out David Lewis's book (don't recall title now) but he is an expert on the navigators of the Pacific who crossed oceans to find tiny islands thousands of years ago & returned safely with the knowledge to pass on to future sailors.

The dhows that I have sailed in east Africa (Malindi and Lamu) are exactly the same as the Arab dhows the yard as you call it never lowered to tack , the action is thus : bear away to speed up and then luff , one crewman unhitches the tack yard and flicks the yard to the other side of the stump mast, the other crewman shifts the ballast(rice sacks filled with sand) whilst the skipper puts the dhow through the wind. The whole exercise is slick, I've never seen a dhow in irons. The reason for the trading season had nothing to do with windward work it was purely a financial exercise the winter monsoon raises a sea and the summer does not dhows when loaded have a low freeboard and sink when swamped!

John

 

[{151760}]

Hi JVL, is that also called the claw rig?An emminent person is supposed to have proved that this is the most efficient rig of all?

From memory, Marchaj, in "The Aero- and Hydrodynamics of Sailing" says that the Crab Claw rig produces the most thrust. In terms of lift to-to-drag ratio, the Bermudan rig is more efficient.

 

[AndrewB]

But I really am trying to find out - for no particular reason - is when did Europeans start having triangular sails. On further Googling, I have found this summary http://nabataea.net/sailing.html which does give some history and then led me to this wiki page http://en.wikipedia.org/wiki/Caravel. Seems that the key term is Lateen sails which enabled Columbus to cross the Atlantic

Tudorsailor

The earliest fore-aft rigs in Europe designed for windward sailing were probably Roman, possibly Greek. Roman 'Corbita' merchant ships were designed for up-wind sailing carrying a comparatively small crew without oarsmen. Although usually square-sail, there's evidence sprit-sail rigs were also used: this frieze is 3rd Century AD. (Not, of course, triangular sails).

 

[lw395]

1) Square sails are not completely useless upwind.
2) Plenty of fore and aft sails were available in medieval times, but square was a better compromise at the time for bigger ships, making use of known wind patterns, the need to beat was limited.

Sails are indeed different from wings, but not so much in the way Bittle claims.
IMHO, the key difference is that a wing is optimised to use the component roughly at right angles to the flow, i.e. 'lift', whereas a sail, upwind, is trying to optimise the component forward of the flow, i.e. 'drive'. The component at right angles to the flow is generally 'heeling', which you want less of!

Who is this bloke?
What has he done? Designed any good boats or sails?

I suggest reading Bethwaite, his rigs go rather well....
And his comments on gaff rig show a proper understanding of how people used to use them effectively.

 

[JVL]

As to lateen type sails being in use by European vessels Vasco d gamma visited Malindi east Africa in the 1400s and would have certainly returned to Europe understanding dhows and the lateen rig. A museum to to VdGs visit looks out to the lighthouse he had built there local chronicles tell of how he used local skippers as pilots during his visit.

John

 

[prv]

But I really am trying to find out - for no particular reason - is when did Europeans start having triangular sails.

I thought you wanted "upwind", not "triangular"? Plenty of four-cornered sails go upwind, some of them (dipping lugs) rather well. Not to mention gaff rig, which does all right to windward, and sprit sails. Even a square-rigged ship can claw to windward a bit if you board the tacks tight to make a leading edge (on Stavros we used to cheat and use the hydraulic anchor windlass on the fore-course tack!). The Vikings used to do something similar with their square sails, stretching the leading edge (I'm not sure exactly how) with a piece of wood called a vargood.

Pete

 

[Buck Turgidson]

We all know about sails being an aerofoil and allowing upwind sailing. I now know and understand the Bernoulli principal. I have done some Googling but am having difficulty finding out when boats moved from sails that were essentially downwind bags to shaped sails that allowed upwind sailing. In the course of looking for the answer, I have come across this article explaining why a sail is NOT an aerofoil

Can anyone point me in the right direction?

Thanks

TudorSailor

I don't know who he is but he is wrong. Folding a piece of paper and chucking it across the room clearly demonstrates the principle.

 

[Searush]

(snip)

I fear you may be getting reported for pictures of "naughty bits" shortly. :disgust:

 

[oldbilbo]

I understand that 'lateen'-shaped sails have been used on Felucca vessels trading the length of the lower River Nile for several thousands of years. These boats do work to windward against the winds that flow essentially along the river-course, and the river current.

Models of such boats appear within the burial goods of several Pharaohs AIR, and the spars are those of a Felucca. I believe imagery of such boats, with their lateen sails, appears on several temple freizes dating from many hundreds of years BCE, and the early Egyptian civilisation traded food and goods far and wide for centuries before Europeans started to wander the ocean-seas. Consequently, it seems likely that the design of hulls and sails was exported by them to the Red Sea, Arabian Gulf and beyond, rather than in the other direction.