How did the sails on a square-rigged ship work compared to a sloop dinghy?
Posted by RoboJ1M@reddit | sailing | View on Reddit | 30 comments
My wife and I learned to sail 1 hander dinghies about 15 years ago, single mast, a mainsail and a jib.
I understand the physics of converting wind energy into motive force for the boat, depending on what point you're sailing.
What I don't get is square rigged ships, as far as I know there is no aerofoil comment of a square sail, it's you typical "bed sheet on a mast, winds behind you" type affair.
Never mind hauling, how do you even reach with a square sail? And hauling, just looks impossible.
But I'm guessing I'm wrong and lacking knowledge because if it didn't work it wouldn't have been used for so many ships for so long all across the globe.
So yeah, that's the question, how did they get useful work across the points of sail from square-rigged ships?
A second sub question, were large square-rigged ocean-going ships ever obsoleted by large fully sloop-rigged ocean-going ships?
Icy-Artist1888@reddit
Its totally different.
Here is an amazing video showing whats involved in tacking the Star of India. I found this extremely interesting...
https://youtu.be/BxCKGS_bLKI?feature=shared
tench745@reddit
Was about to post the same video.
ceciltech@reddit
thank you for posting that, great video.
boatstrings@reddit
(I built several sails for USCGC Eagle.) While it's true they are best suited for down wind sailing, if you (starboard tack) pull the port sides of the yards aft (all the yards can be done simultaneously) and then tighten the starboard sides of the yard down, you effectively create a foil shape giving you the ability to sail on a close reach.
Random_Reddit99@reddit
this. unlike in most movies or children's books that use vfx tallships drawn by people who have no idea how squares work, squares can be braced around to create lift while reaching.
squares were built for crossing oceans on the trades, primarily being used much like a modern boat's spinnaker, while still having fore-and-aft staysails and jibs for reaching in coastal areas.
RoboJ1M@reddit (OP)
What's USCGC Eagle? Is that a sail company? Or a ship?
Avisauridae@reddit
Here's the Eagle on a close reach
She's the US Coast Guard training ship and a nice Barque she is!
elprophet@reddit
That's a link to a general google search, which does have some reaching (but also some bare poles) pics. https://www.news.uscg.mil/Press-Releases/Article/3537305/eagle-ride-in-opportunity-as-tall-ship-returns-to-new-london-oct-3/ might be the one you were specifically thinking of?
I'd love an overhead (drone, plane, or helicopter) showing just what the angles of the wind, waves, hull, and spars are...
mr_muffinhead@reddit
German sailing ship from the 30's. USA seized it after WW2 and it's now a USCG ship as the name suggests (United States Coast Guard) (training).
boatstrings@reddit
Barque Eagle is the U.S. Coast Guard Academy's training ship.
RoboJ1M@reddit (OP)
So the plan view of this sail while be an arrow shadow like this 👉 > but asymmetric to create a longer path to bring, ugh, I forget the name of the law, the aerofoil law that creates pressure on the outside of the long side.
Avisauridae@reddit
You are thinking of Bernoulli's principal, but lift (contrary to popular belief) isn't generated by a longer path.
For more on this, check out NASA: https://www.grc.nasa.gov/www/k-12/VirtualAero/BottleRocket/airplane/wrong1.html
J4pes@reddit
Sails that go side-side, carry you downwind. Sails that go fore-aft, carry you upwind.
ppitm@reddit
Uh, yeah it was. You're just mistaken that large square riggers weren't as fast or faster.
J4pes@reddit
The longer vessel you mean, yes.
ppitm@reddit
Longer means larger, in a world with no external ballast.
J4pes@reddit
When we are talking tallships, larger is pretty vague.
Ithvan@reddit
1: Not too sure what the other commenters are smoking, as square sails do, in fact, generate lift. Basically, you want your squares braced as square as possible, as that way you create the most forward movement. But you can sail close-hauled. It depends ship to ship and your drift is terrifying, but I've gone 65-70° to the wind.
2: They did exist, IIRC if you look on Wikipedia under "Bermuda rig" there's a 19th-century painting of a three-master with that kind of sails. But up until the end of working sailing ships, the standard was square sails. Look up some pictures of the Kruzenshtern, that's what ships sailing in the 1930s-1950s looked like.
elprophet@reddit
I've been in modern "floating apartment" catamarans that struggled to maintain COG 120° haha
I should get better sources for this, but I expect (from a combination of reading and first principles) that on a fully crewed sailing vessel, square rigging provides increased adaptability and redundancy. Putting all of your two massive sails on one mast pole and one boom is all the eggs in a basket. Having three masts of two or three sections, which could be replaced with a spar in an emergency, and multiple reefing options, is much more rigorous. But it requires a crew of 20 to 200 men to manage!
Space_Pirate_R@reddit
It's easier to manage. Divide and conquer.
ppitm@reddit
And if it's a large ship, having a single sail per mast wouldn't be feasible in the first place.
ncbluetj@reddit
No, you are correct. Most square riggers cannot go upwind to any useful degree. They can reach, and maybe crab their way upwind a bit, but you are not making much meaningful progress to windward unless you have a fore and aft rig.
Square riggers mostly followed the trade winds, so they did not need to go upwind. They had to wait for favorable wind direction to leave port, and being trapped against a lee shore was a serious danger.
brutallyhonestharvey@reddit
This is incorrect. Square rigged ships could tack upwind, just not as efficiently as modern Bermuda rigs can. They also tended to have several fore and aft sails (jibs, spanker, staysails) that were useful in upwind sailing. Their most efficient point of sailing was typically a broad reach, where the square sails were providing lift instead of direct downwind where they were being pushed and sails tended to becalm the ones in front of them. The problem with lee shores for square riggers is leeway and tides/currents, often those would be enough to more than offset the gain in distance to windward and cause the ship to run aground, but that is not to say that square riggers were incapable of tacking to windward at all.
ppitm@reddit
Whatever you think "useful degree means." We are talking 70 degrees versus the 50 degrees of a fore-and-aft rig of similar vintage. Not the 30 degrees of a modern racer.
There are no trade winds in Europe, the Baltic, or the Mediterranean. Square riggers spent a plurality of the time sailing close-hauled.
SwvellyBents@reddit
Square riggers and the various other clipper rigs basically always ran downwind. Hence the trade wind routes. Broad reaching was the best they could hope for even when it looked like they were close hauled.
You're right. Square sails had no actual lift component. They were obstructions to the wind. It was very inefficient but that was the tech back then.
ppitm@reddit
Glorious, glorious downvotes
ppitm@reddit
The sails work exactly the same way. They're just a different shape and have different ropes controlling the shape.
Lussypicker1969@reddit
So I see a whole lot of misinformation.
I sailed on square rigged ships such as the Stad Amsterdam and I can tell you.. we are able to sail all the same directions as any other sailing vessel.
The squad rigged sails can be changed to accommodate different headings.
I’m not a native speaker so I can better show you it in a video
As you can see the sails are changed to a position that the vessel can have a upwind course
Fred_Derf_Jnr@reddit
Square sails do have a slight lift component, however they are very inefficient, as they aren’t able to sail very close to the wind, so can easily get stuck in a bay as they are also very slow to tack and so lose a lot of ground in the manoeuvre.
The Trade Winds are the downwind routes that the clippers sailed to get to their destinations.
Half-Borg@reddit
There are 2 options
1) Sail where the wind is going
2) Wait for the wind to change
There is a reason why almost all ships are sloops nowadays.