Sailing by Compass
Part 2: Compass ZOOM

Pictured here, the minus and plus signs are circled in red with yellow arrows. Clicking the plus sign will zoom the compass in, clicking the minus sign will zoom the compass out. When the compass is zoomed in, you can see only nearby items. When compass is zoomed out, you can see only larger enemies (such as ships.)
When the compas is zoomed all the way in, as in the example above in Tormenta cave, you can see individual enemies as red dots. All land-based gameplay defaults to this compass zoom setting. Zooming out to the middle setting on land is rarely useful; zooming out to the maximum setting does not ever seem useful, on land.
At sea, the compass is correctly zoomed all the way out, so that you can see ships on the compass. This is true, even after boarding a flagship (if you zoomed the compass in, while on board the flagship.)
Boss Battle
The rest of my compass zoom observations, are relevant only to the boss battle. There are very few situations where the game requires you to understand (and change) the compass zoom.
After the officers are defeated on the Black Pearl, you are instructed to take the wheel. Your compass is zoomed to the middle setting at this point. Generally, this is useless; you need to know where your crew is and that they are ready, before heading out to the frigates. Zoom the compass in all the way.
Seen here is a pretty typical situation: pirates milling about like ants on the compass, unsure where they should be. Higher-level pirates (boss battle vets) are on port side cannons, waiting for the lower-level pirates to find a cannon (any cannon!) The captain wisely waited for them to all get on cannons before proceeding. (Before the autumn of 2008, cannon ammo could charge all the way up, making that pause even more crucial.)
When I drive, I ask all pirates to get to the port side (left) of the Black Pearl, before engaging the frigates, for several reasons. #1) The left-forward frigate is the hardest to hit and hardest to sink of the four. #2) If the right-side frigates are sunk first,
everyone will run to the left side...meaning that when the 4th frigate finally is sunk,
everyone will be on the wrong side. When the last frigate is down, everyone but the captain should be on a right side cannon, to shoot at the first fort. #3) As of late-fall 2008, it takes 9 to 10 seconds to switch cannons. At that stage of the boss battle, 10 seconds can be fatal (with a large crew.)
If I am just a gunner and the captain asks everyone to get on the right side, before the frigates, I'll usually log out/close the game. Such a request is a sure sign that the crew will all go to jail; logging out before the Black Pearl sinks will prevent my pirate from getting "groggy." (The other indicator that the boss battle is doomed, is when a low level pirate grabs the wheel and barges forward before anyone is ready.)
After the frigates, I will zoom to the middle setting, back in to check crew position, back to middle, back in to check crew again, back to middle. If you are using broadsides to hit the middle bridge of the first three (you should) then having compass on middle setting helps you aim. The two pictures above show the position of the Black Pearl, relative to some of the middle forts. Note that I back up, for both middle pairs, so that only the left fort (of each pair) can hit the Black Pearl.
When all the bridges are destroyed, I'll zoom the compass back out, all the way, for the sea battle with Goliath.
Ooops. I mean, I'll zoom all the way IN first, to make sure the crew has moved from the starboard side cannons over to port side cannons and are all ready to go. Then I'll zoom back out.
Before December 2008, you used to be able to see Goliath on compass, before passing the last forts. In the picture above, the two red dots on the left-edge of the compass represent Goliath. Once you pass the last forts, the third cut-scene starts and Goliath appears next to you (approximately where it appears in this picture.)
Note that if the captain turns left, (even a tiny hair to the left) you should logout quickly.
There is a law against turning left: captains that turn left, go to jail. The battle with Goliath is a measure of cannon range: the sooner you get out of range, the less damage you will take. If you go
straight or even to the right a little, you can use full sail/ramming speed to avoid taking even a single hit from Goliath. Once you have enough distance for Goliath's red dots to drop off the compass, you can stop and turn...your gunners have much better range than Goliath's explosive-firing front cannons. (Stopping and turning too soon can be just as bad as turning left.)
Note that it is possible to survive, if you turn left, sometimes. But that depends on: #1) having a very large and very strong crew, #2) having 40% or more hull remaining after the bridges & forts. When you turn left, you guarantee that Goliath will hit the Black Pearl at least once, with double explosive. So, 100% of the time, it is foolish to turn left when Goliath is still on-compass.