It strikes me that a lot of people here are from the British Isles and that seafaring knowledge is common; but in other nations like mine, there be a lot o' landlocked lubbers and city slickers. I've read a lot of sea stories, built a dozen ship models, taken a sailing class in college, and owned two sailboats. So in the interest o' bein' helpful here's some terminology according to my knowledge. And anything I get wrong I hope will get corrected. I APOLOGIZE IF THIS IS A BIT LONG-WINDED

the Tropics - latitudes near the equator. Ships coming to Britain from the south Atlantic pass thru here, and the sailors are glad because they'll soon be home. Also it's a little warmer.

a-foaming along - a ship going fast churns the water, making white foam

every stitch drawing - this means they've put on every sail (sails are stitched) because a breeze is blowing. If it were blowing harder they'd have to take in some sails. If it were blowing less they'd be going slower. So it's right at the point in between; rather thrilling.

the Trade blowing strong - the trade winds blow in the tropics from east to west. If you want to go fast in a sailboat you don't want the wind directly behind you; you can only go as fast as the wind, or a little slower. You don't want it directly in your face; a lot of these big ships didn't sail very close into the wind, but only maybe 45 degrees. So if the wind's from the north they have to sail northwest, then northeast, back and forth, which is called tacking. You want the wind from say the east; then you angle your sails and you can actually go north faster than the wind speed. Really thrilling.

The white caps all breaking in spray - a stiff wind stirs up waves, and if there's two or more sets of waves in different directions, they add and subtract constructively. So you get triangular points to the waves. They can get so pointy the top falls over, making white foam, also the wind whips these tops.

For the girls have got hold of her towrope today - as said above, the girls are the winds driving the ship; it's poetic, as if there are invisible women pulling the ship forward by a rope, real fast.

Haul away - various things on these old sailboats had to be moved around by pulling with ropes. A group of sailors would provide the force needed by pulling together in a line.

logging sixteen - to measure the speed of a ship, they'd throw a line out the stern with a drag of some kind, called a log - anciently it probly was a small log - and as it dragged the line out, you count the knots as they go out during a space of time which is timed with a sandglass. Thus the speed of a ship be still measured in knots, which many today suppose to mean 'nautical miles per hour'. Sixteen knots is an astonishing speed for a big sailing ship.

The wind in her royals - the royals are the highest sails up there in the sky, there might be five or six ranks of sails - main, top, topgallants, ?, royals. I forget all the names.

a bone in her mouth - as the bow of the ship shoves thru the water, the water is flung out of the way on either side, so the ship is likened to a dog with a white bone in its mouth. Anything else that you think isn't relevant.

a wake like a millrace - the wake is the foamy water left behind the ship. When the ship goes fast, it's really dazzling to watch the wake rush out behind so fast. A mill race is of course a channel where water was diverted from a stream, shooting down to turn the water wheel on a mill.

she rolls on her way - the ship moving thru the waves rocks back and forth. It makes some people seasick but not us jolly sailors.

the poop - from a French word meaning the back of the ship; the rear deck. Modern cognates... we won't go there

fore an' aft - obvious

put by his sextant - a sextant is used to measure the elevation of a star or planet above the horizon, which gives information as to where you are. To 'put it by' is to lay it down.

charters - hired to carry cargo or maybe people

nitrates - used to make gunpowder by civilized nations, so they can fight wars and fire salutes and stuff. It could be used for fertilizer, if there's any left.

dipped her yards under - these sailing ships had masts, which are the vertical poles, and yards, which crossed the masts and held the sails out open, if they were 'square rigged'. If the yards are dipping under, the ship is laying way over in the wind, almost on her side.

hove to - means turned so the wind doesn't fill the sails, but blows along their surface. So no thrust; ship stops almost. Intentional.

off the Horn - Cape Horn, southern tip of S.America

fog and floes - in Arctic/Antarctic areas, you get fog and floating ice...

drifted forlorn - and no wind. Everything motionless, and cold. So, not happy

Becalmed in the Doldrums a week - this is an area in the middle of the Atlantic, where sometimes the wind dies for days at a time.

shanty - sailor's song, as everybody here knows. Cognate with 'chant'.

sheet - not the sails, but the rope(s) that tighten the sails.

stay - ropes that guy up the masts from the front.

shroud - ropes that guy up the masts on either side, toward the back. Usually with crossed ropes, forming a ladder. So sailors can climb up to work the sails at the risk of their lives, which they love to do, especially in strong, cold wind and driving sleet.

halyard - ropes that control the angle of the yards.

chops of the Channel - choppy seas in the English Channel. I guess; never been there. Or it could be the name of a pork dish.

tug hawser - a tow rope for a tug to pull a ship into the harbor. I think this tug must have been a rowed galley.

The mate's "That'll do" - means the voyage is finished, everything secured.

fourteen months pay - yikes, that's a long voyage! Whalers tho might be out 3 years. And the custom is to drink and gamble and give gifts to friendly women, so you have to go to sea again to make more money; rinse & repeat