Larger vessels require the skills of a
character with shipbuilding proficiency,
an AREA outside the province of underground exploration.

The time period required to build a boat depends on its size.
As a general guide, the boat requires one week of construction time per foot of length.
Two characters with boatwright proficiency cut this time in half; three reduce it to one third, etc.
A max. of one boatwright per five-foot length of the boat can work on the vessel simultaneously.

The basic boat includes the hull, masts, deck, and benches as
required. Additional features such as a cabin or sealed hold add
about a week apiece to the construction time. Characters without
boatwright proficiency can aid the boatwright in construction, but
it takes two such characters to equal the time savings that one
additional skilled boatwright would provide.

Boatwright, Equipment: The boatwright needs to make a major investment
in tools or facilities, and needs to choose his loc. with
care. With the exception of kayaks, canoes, and small rowboats, <make entry for kayak & canoe in the PH equipment lists>
boats must be built close enough to a body of water that they can
easily be launched.
The amount of space a boatwright needs is roughly equal to the size of the boat being built, plus 10 feet in all directions.
The tools of the boatwright include all carpentry tools plus pitch || tar.
Cost: 1,000 gp (The cost of raw materials is 11-20%(1d10 + 10)of the value of the finished work.)
Space: 50' x 120'