I'm planning a Dungeons and Dragons 5E campaign for my friends where they're going to take on the role of divers who use magic to explore the ocean's depths in search of sunken treasure and they need a ship to take them from one dive site to another. While I could easily use a generic 'sailing ship', I thought this might be a fun educational opportunity for both me and my players.

You see, the campaign is going to take place in a fantasy version of renaissance Earth - all the land masses are the same, with the difference being the preponderance of magical monsters and phenomena (both on land and sea). 
Sailing in this world is much more dangerous due to the probability that some deep sea beastie is going to look up and see something big and decide to see if it's edible. As such, ships should be f a s t. 

To be guaranteed to outrun these monsters, they should be able to maintain a speed of 12 knots in most weather conditions. I know modern trimarans are capable of those sorts of speeds, but they also benefit from modern engineering and material technologies. And this ship needs to be big enough for ocean crossing with a crew of about 15-20 people (call it a displacement of about 50 tons, about what a caravel would be capable of). It should be able to remain on station in the middle of the ocean for days at a time. Can a wooden hulled triamaran achieve the desired performance? Or would there be a better alternative? 

The use of minor magic is allowed, for instance:

1. You can have a mage casting shape water at the bow in order to minimize the bow wave.
2. You can have people using Prestidigitation to clean the hull and keep it smooth.
3. Magical construction techniques can join wood planks and beams together into a single whole.
4. An immovable rod as an anchor.

Anachronistic technologies are also allowed as long as they can be manufactured with the approximate technologies available (ie: solid wing-sails, crank driven propellers instead of oars).