In the 17th and 18th century, the parrel (attaching the yard to the mast) were made different and were not as developed as those of the later 19th century clippers.
See documentation <a href="http://books.google.dk/books?id=c_sJIeR0jeIC&pg=PA141&lpg=PA141&dq=parrel+from+17th&source=bl&ots=S6yk8NCb3X&sig=j6Rs-I_4pHKMVBszPtb9h9_8Tg0&hl=da&sa=X&oi=book_result&resnum=1&ct=result" target="_blank">here</a>
On small ships, the system was even more simple. The yard was mannered to the the mast with rope or held by a chain, so the yard had to be twisted around the mast - therefore the squaresail on a yacht was mostly used when having the wind in from the back.
As such, the yards could only be turned to a certain degree. This made the angle, of which the ship could sail close to the wind, less efficient compared to ships in later periods.
BUT you are right about one thing: Britain was almost the only nation left to use large ships-of-the-line far into the 19th century, so these ships were ofcourse build with modern parrels. Still, they were very slow. They were actually meant to be, as they had to be able to sail at the same speed to stay in line without having to break off due to difference in speed <img src="style_emoticons/<#EMO_DIR#>/smile.gif" style="vertical-align:middle" emoid="
" border="0" alt="smile.gif" />
Offtopic:
This talk of man-o-wars and ships-of-the-line made me realize, how obsolete the ingame shipclass "man-of-war" really is. A man-of-war is really just a term for "a naval ship build for combat", it could be any ship, a brig on a patrolmission, a 3-decker in the Battle of the Nile or a schooner armed for defence purposes, running mail from one island to another. I dont know much of the british classifications in ships-on-the-line other than they were divided into 1st rate, 2nd rate etc, meaning the 1st raters sailed in front, then came the 2nd raters all down to ships armed with only 50 guns. This "international agreed arrangement" was to even out the odds for the ships on both sides, avoiding fights between i.e. a 110-gun 3-decker and 50-gun fregate.
I do think, ships-of-the-line serves a purpose in PotC with the player being able to run up to 4 ships, but renaming the "man-of-war" class would be nice.
See documentation <a href="http://books.google.dk/books?id=c_sJIeR0jeIC&pg=PA141&lpg=PA141&dq=parrel+from+17th&source=bl&ots=S6yk8NCb3X&sig=j6Rs-I_4pHKMVBszPtb9h9_8Tg0&hl=da&sa=X&oi=book_result&resnum=1&ct=result" target="_blank">here</a>
On small ships, the system was even more simple. The yard was mannered to the the mast with rope or held by a chain, so the yard had to be twisted around the mast - therefore the squaresail on a yacht was mostly used when having the wind in from the back.
As such, the yards could only be turned to a certain degree. This made the angle, of which the ship could sail close to the wind, less efficient compared to ships in later periods.
BUT you are right about one thing: Britain was almost the only nation left to use large ships-of-the-line far into the 19th century, so these ships were ofcourse build with modern parrels. Still, they were very slow. They were actually meant to be, as they had to be able to sail at the same speed to stay in line without having to break off due to difference in speed <img src="style_emoticons/<#EMO_DIR#>/smile.gif" style="vertical-align:middle" emoid="

Offtopic:
This talk of man-o-wars and ships-of-the-line made me realize, how obsolete the ingame shipclass "man-of-war" really is. A man-of-war is really just a term for "a naval ship build for combat", it could be any ship, a brig on a patrolmission, a 3-decker in the Battle of the Nile or a schooner armed for defence purposes, running mail from one island to another. I dont know much of the british classifications in ships-on-the-line other than they were divided into 1st rate, 2nd rate etc, meaning the 1st raters sailed in front, then came the 2nd raters all down to ships armed with only 50 guns. This "international agreed arrangement" was to even out the odds for the ships on both sides, avoiding fights between i.e. a 110-gun 3-decker and 50-gun fregate.
I do think, ships-of-the-line serves a purpose in PotC with the player being able to run up to 4 ships, but renaming the "man-of-war" class would be nice.