Anna,
You might find this book of interest, and at quite a reasonable price:
http://www.amazon.co.uk/Shipwrecks-Revo ... 730&sr=1-1I haven't read it, but from the reviews, it would seem as though the author has done some serious research. I would imagine he might include some info on any regulations or conventions of the time, although I'm not so sure there were that many.
Brian Lavery in his 'Nelson's Navy' gives some pages to it, under 'Disaster at Sea'. Between 1793 and 1815, he notes that 101 rated ships were lost all told, but that only 7 were lost from the weather alone. The majority of ship losses were initially due to some other cause, fire, explosion, navigational error, a lee shore, etc. He briefly mentions the loss of the St George and Defence, in December 1811 as from the latter cause, however it seems clear that the disaster was also initiated by the earlier loss of her rudder (to be replaced by a temporary Pakenham device) and her jury rig (which had replaced her normal, and much more substantial, one).
Regarding the ship's boats, these were not really considered as 'lifeboats' (this was a much later idea) but rather as workboats, and for conveying the ship's officers. In any case, from their number (I think the Victory for example carried seven boats, from the Admiral's barge down to the diminutive jolly boat) they could only have carried a fraction of the ship's crew. They could also not have been launched that easily (using tackles rigged from the main stay and the fore and main lower yardarms, all of which would have had to be manned.) This would, in extreme circumstances, probably have taken far too long, but would have depended on the situation at the time. Early davits were just coming in at that time (I think the two aft on the Victory for the two cutters, for example, were introduced in 1804, which may have made it easier to launch at least these two boats fairly quickly.) I would have imagined that in an emergency the men would, if possible, have been mustered in their divisions, on the upper deck, and each told to grab their rolled up hammock from it's place in the nettings, and which was tagged with the man's name. (I would think that each man would know where his hammock was stowed.) The nettings, of course, were placed around the upper deck as some protection from small arms fire. It is known that properly rolled hammocks could remain afloat for several hours, and thus could be used as life preservers. Once the men had jumped into the sea however, hypothermia would in most cases have set in quite quickly unless they were in very warm waters, and most of the deaths can probably be put down to this rather than straightforward drowning.
As another example of the other extreme, when the Pandora was wrecked on her quest to find the mutineers from the Bounty, I believe they had around 11 hours before the ship foundered, plenty of time in which to launch the boats and take other precautions. I believe they nearly all eventually made it to an island, although Captain Edwards left the so-called the 'mutineers' (of whom some were and some were not) chained in the 'Pandora's box' as it was called. I think many of these eventually escaped due to one of the ship's crew throwing them the keys.
I would imagine that the ship's divisional system had a part to play in maintaining discipline when a situation developed, and Lavery maintains that discipline would probably have governed the crew, so long as there was a chance that men thought they would be rescued. Very likely the mental strength of the officers had a large part to play too, but there was always the danger that pressed men would eventually resort to there own inclinations – one of which was to break into the spirit room.
As to the convention that the captain should be the last to leave his ship, I don't know if this is enshrined in law. It may be, but I think it is at least customary, and I would think that any captain worthy of the name would think it his duty to see that all were as safe as they could possibly be, before thinking of himself. Frankly, I find the notion of the captain 'going down with his ship', especially when he had the opportunity to save himself, a rather ridiculous one, and I wonder if this idea has not been spread about by the Titanic drama of 1912. I believe that Captain Smith was said to have swum away, when he saw that the lifeboats were full, and thus committed suicide. Thankfully there are plenty of instances where this did not happen, and the captain was able to resume command of the survivors!