Originally posted by blankitosonic:

Nope its just RNG , with a 5% of spawn at night in a 64mx64m square at sea ( and a blockspawm of 1000 secs if not spawn in that square ) , so best you can do its sail in a longboat in their 3rd speed to pass each square faster
Remember 5% at normal night and another + 5% if its raining/storming