This pdf is 28 pages long, 1 page front cover, 1 page editorial/SRD,2 pages of advertisement, leaving 24 pages of content, so let's check this out!

Intended as supplemental material for the naval combat material by Paizo, this sourcebook kicks off by providing 5 new types of ship: The Baochuán are giant 9-masted treasure ships, while catamarans, of course, should be a known type of smaller vessel and the two-masted, hard-to-ground coastal pirate dhows also get their own stats. Sailors from Osirion or similar Egyptian-themed lands may now sail forth on Khemetic Barques and finally, if you're into steampunk/playing on the verge of an industrial revolution or just want to feature an insane gnomish ship, you're in luck - the steamboat also makes an appearance here.

Now if that didn't provide a clue: There are also new propulsion methods in here. To be precise, a steam engine and power by elemental fury: Each of the 4 traditional elements provides a unique advantage and disadvantage to a ship powered by them. Propulsion mechanisms are also included: Elemental fonts, screws, stern paddlewheels and midwheeels. After these new ways to outfit a vessel, we're in for ship-templates:

A total of 10 different ship templates are provided and they are applied much like you'd expect them to be applied. Cargo-barges, heavily-armed bomb ketches, agile corvettes, dwarf-and elf-crafted vessels, cruisers, frigates and galleon merchant-ships can be created thus. If you want, you can also make your ship ironclad or even a luxury vessel.

If you want to, you can also modify your vessel with an adamantine bowsprit, brand it by the elements, include a bilge pump, weather-influencing sails, an improved armory, sickbays etc. and even make it (slightly)kraken-proof with spikes below (but I don't get why they don't make it easier to run aground...).
Specialized harpoons and the option to enchant cannonballs are also covered. 5 "piratey" traits are also included, though they felt not too exciting for me. 15 new feats are also part of the deal that range from lame bonuses to social skills when interacting with convicts (and penalties when dealing with agents of the law) and some birthright-feats available only at first level. These are sometimes a bit strange: One e.g. grants you knowledge whether one has killed via Sense Motive and whether the target is an assassin/executioner or has been sentenced to death. Weird and oddly specific. There's also a feat that helps you when ramming foes with your ship and I would have much preferred more "captain's"-feats like that to the other ones presented herein.

4 new diseases (including scurvy) seek to claim the lives of naval characters and about 3 pages are devoted to providing a glossary of nautical terms. There also are some mundane pieces of equipment including a price-list.
The pdf closes with a special ship-sheet.

Conclusion:
Editing and formatting are unfortunately not the strongest suits of this pdf - I noticed both formatting glitches and quite a few editing glitches - another pass would have helped there. Layout adheres to a mostly printer-friendly two-column standard and artwork is stock. The pdf has no bookmarks, which is very unfortunate for a rules-supplement like this.

This supplement, at least for me, has a hard heritage - my frame of reference will be Mongoose Publishing's "Seas of Blood" and take into account the fact that this pdf is, of course, intended as a smaller supplement. I really enjoyed the new ships, propulsion methods and ship supplements. The non-naval supplements like feats and traits, at least for me, didn't keep up with this usefulness and feel rather like filler, as did the glossary of naval terms. Even after a vast amount of careful deliberation, I'm not entirely sure about my stance on the ship templates - several of them felt rather like ship types than templates to me and I think, I would have preferred more ships to the amount of templates. I was also rather astonished how cheap e.g. the luxury vessel template comes and e.g. with the Kraken spikes I also felt that the repercussions of some of the modifications have not been entirely taken into account. That being said, the pdf still provides some valuable pieces of crunch, even though not all of it is an absolute hit. For the amount of content provided, the pdf is not exactly cheap and especially when compared to the caravan handbook, feels a bit less imaginative. In the end, due to the glitches and aforementioned reasons, I'll settle for a final verdict of 3.5 stars, rounded down to 3 for the purpose of this platform.

Endzeitgeist out.