Battle of Trafalgar

[Mohit Pandey]

Buffy- Socratic method question: What happens to waves traveling through a viscous medium over distance?
When you toss a stone in the water, it locally produces turbulence. What happens to it?

It would slow down.

Qfwfg--Nothing abnormal, it's a physics question.

I think I am not understanding completely, especially its Physics.

[modest]

Becca,

The relevant property of ocean swells here is that the longer the wavelength, the faster the wave. A distant storm will make swells of different wavelengths. As the waves propagate leeward they group according to speed. A person standing on shore (or in Nelson’s fleet) will first notice the longer-wavelength, less frequency, rounder waves. They will become more frequent, steeper, and shorter in wavelength as the slower waves arrive. This is an indication that the pressure system causing the swells is nearly upon you.

Spain is known for good Atlantic surfing swells in Autumn and the battle was in October, so this seems the likely cause.

Hope this helps.

-modest

[Qfwfq]

Originally Posted by LaurieAG

Apart from the loss of HMS Eurydice the wind was very dispersive to the French and Spanish fleets...

You were still being dispersive Laurie, by which I meant you were not being helpful to Becca at all.

My little riddle was that Buffy should have said "dispersive medium" instead of "viscous medium", see the answer Modest gave. His first sentence is saying that the propagation is dispersive. That is the only relevant thing.

BTW, even in the days of sail, I don't think that battles were so totally decided by who was weatherward and who was leeward. No doubt admirals had to keep these things in mind, but also many other things too, and they knew their stuff. It was a matter of who knew their stuff better. It wasn't Becca's problem anyway, you were dragging off the point completely.

[LaurieAG]

Originally Posted by Qfwfq

BTW, even in the days of sail, I don't think that battles were so totally decided by who was weatherward and who was leeward. No doubt admirals had to keep these things in mind, but also many other things too, and they knew their stuff.

Hi Qfwfq,

THE BATTLE OF TRAFALGAR 1805 LORD NELSON 1758 TO 1805 ADMIRAL OF THE BRITISH FLEET AND NAPOLEON BONAPARTE

Naval tactical background

During the 1700s naval battle tactics developed from the free-for-all melées of the 1600s where the admiral commanding a fleet had little or no control of the disposition and actions of his ships. The concept of the line of battle was developed where every ship of the line had its predetermined position in the line of battle and the fleet attempted to stay in this formation during the battle. Both admirals would attempt to form up into long lines. The two lines would then manoeuvre, sometimes for days, in an effort to close to within gunfire range often seeking the advantage of the weather gauge. Each ship was then supposed to attack its opposite number in the enemy line. This led to battles of attrition where lines of ships battered at each other until one side withdrew, at which point both would limp home for repairs.

Weather gage - Wikipedia, the free encyclopedia

To have the weather gage describes the favorable position of a sailing vessel relative to another with respect to the wind. The term is from the Age of Sail, and is now antiquated. It is any position upwind of the other vessel. An upwind vessel is able to maneuver at will toward any downwind point, since in doing so the relative wind moves aft. A vessel downwind of another, however, in attempting to attack upwind, is constrained to trim sail as the relative wind moves forward and cannot point too far into the wind for fear of being headed. In sailing warfare, when beating to windward, the vessel heels under the sideward pressure of the wind. This restricts gunnery, as cannon on the windward side are now elevated, while the leeward gun ports aim into the sea, or in heavy weather may be awash. A ship with the weather gage, turning downwind to attack, may alter course at will in order to bring starboard and port guns to appropriate elevations.

[Qfwfq]

Laurie, as usual, there's no point insisting when you've been shown totally off the point. You simply didn't get what Becca was asking for help on.

And are you also unable to see that, in what I said, I had left plenty room enough for the stuff you are quoting? Can you not see that the very sentence you bolded even supports my point? Do you ever get things straight? If you're unable to be of help, avoid replying to those who ask for it.

[Becca]

turns out i was sort of right in the first place. it was almost a trick question. there was a storm (i wouldn't worry about the historical accuracy too much) and it moved towards the fleets. by the morning of the battle it was close enough for the ships to be hit by the short frequency waves.

tut.

[modest]

Originally Posted by Becca

turns out i was sort of right in the first place. it was almost a trick question. there was a storm (i wouldn't worry about the historical accuracy too much) and it moved towards the fleets. by the morning of the battle it was close enough for the ships to be hit by the short frequency waves.

tut.

Well, not so much a trick question. As Qfwfq hinted at, then pointedly hinted at, then (left with no choice) pointedly beat someone about the head with - there is a relevant bit of physics behind this phenomenon. Dispersion in fluid dynamics. And, when we're talking about ocean swells, it can happen in the absence of a storm - given the right wind conditions.

[Qfwfq]

Originally Posted by Becca

...and it moved towards the fleets.

Actually Becca it might not have moved closer. As Modest already said, the longer waves on water surface travel faster, at a large distance they'll arrive sooner. This kind of difference can occur with other kinds of wave propagation too and it must be the reason for what I once described about an earthquake I felt.

[LaurieAG]

Originally Posted by Becca

turns out i was sort of right in the first place. it was almost a trick question. there was a storm (i wouldn't worry about the historical accuracy too much) and it moved towards the fleets. by the morning of the battle it was close enough for the ships to be hit by the short frequency waves.

tut.

Hi Becca,

Teachers should make questions more relevant to history than what was contained in the question you describe, especially science teachers.

BTW, the short frequency waves didn't sink any ships (apart from HMS Eurydice as I referred to before) or win the battle, the fleet on the weather guage (not a barometer) could come to the attack quite easily with a following wind while the other fleet couldn't do it as easily against the wind as identified in the Battle of Trafalgar website. It's not surprising that after Trafalgar this tactic became almost standard for naval warfare.

[modest]

Originally Posted by LaurieAG

Teachers should make questions more relevant to history than what was contained in the question you describe, especially science teachers.

I can't think of a better historical example of this physics problem (especially for someone in the UK) Granted, I'm not a historian. What example were you thinking of?

-modest