The Mermaid Queen says the ship is "North" but this is a very vague description.
There's a martial artist NPC in a field that says the ship left from Rippleport, but that's about it.
How is a first-time gamer with no guide supposed to properly find it?
Interesting detail--his appearance is not described in The Truth. Everyone's image of him is totally created in their imagination and outside sources.
He could be tall, short, thin, fat, black haired, red haired, bald, long haired...
Even his ethnicity isn't really described, other than maybe a little bit pale, since the red scar from the R on his forehead has to show.
William is even more generic than Moist.
His father gets more description than he does, and that's just a line about being tall and lanky (which is why the cover of The Truth looks so odd). William's appearance gets slightly more detail in later books from Vimes' brief perspective (it's not flattering) but that's it.
That means whatever your first answer was when you read the topic? Not from the The Truth. Funny how pop cultural absorption works.