Gfrktyl

Would a ship made out of a single piece of wood have any advantages over a normal vessel?

Context:
A particularly clever/mad mage has discovered how to make a living ship by binding a dryad into a particular shape instead of an ordinary tree. Such a vessel is self repairing, and capable of directing it's own actions to a certain extent, though it has to follow orders from it's Captain.

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I am basically wondering if a hull made from a single piece of wood would be practical for a sailing vessel, or if the traditional ribbed/plank design is important for flexibility. In way the ship would be similar to a giant dugout canoe, except grown into shape rather than carved.

A lesser question would be about the practically of a hull that would be essentially green wood, rather than timber that has been dried and seasoned.

Trees make already a good job at resisting side loads, so I see no big advantages with respect to flexibility.

PRO:

One big advantage I see is that, having no junctions between adjacent planks, there are less to no risk of water infiltration. This means no need to caulk the junctions, no need to use pumps to remove the entered water, which makes for an easier maintenance.

CON:

One potential disadvantage is that, being a living creature, the ship will grow bigger. This means that over time you will need more crew to maneuver it, larger docks to harbor it, and so on and so forth. If you have a fleet of these ships, you risk that chasing their growth becomes your only purpose.

Another possible disadvantage is that your living ship will need room for the branches, leaves and roots to be able to thrive. This can make the usability of the ship quite a nightmare, as compared to dry wood ships.

Another disadvantage is that tree growth is rather slow. While skilled personnel can fix a crack in a dry wooden hull within few days, it can take several months or even years for a tree to achieve the same.

You need a mangrove - especially if this is a sea-going vessel

I quote from this article

What's a Mangrove? And How Does It Work?

"Mangroves are remarkably tough. Most live on muddy soil, but some
also grow on sand, peat, and coral rock. They live in water up to 100
times saltier than most other plants can tolerate. They thrive despite
twice-daily flooding by ocean tides; even if this water were fresh,
the flooding alone would drown most trees. Growing where land and
water meet, mangroves bear the brunt of ocean-borne storms and
hurricanes. How do mangroves survive under such hostile conditions? A
remarkable set of evolutionary adaptations makes it possible."

https://www.amnh.org/explore/science-bulletins/bio/documentaries/mangroves-the-roots-of-the-sea/what-s-a-mangrove-and-how-does-it-work

The article goes on to describe in considerable detail what makes a mangrove so tough, e.g.

Saltwater can kill plants, so mangroves must extract freshwater from
the seawater that surrounds them... [they can] ... hoard fresh water
... breathe in a variety of ways ... [have] Roots That Multitask..."

and finally

Mangroves are fast-growing trees

While the hull in itself, if grown appropriately, should be stronger than a planked hull. Repairs become a considerably more complex proposition.

Minor damage can be repaired by the ship, but major damage, where normally a few planks would be taken out and replaced would need to be healed over from the edges. Trees can heal, but it leaves significant scarring. Only one or two rounds of major damage might leave your tree almost unsailable.

Drying and seasoning you don't have to worry about. The principle there is that wood warps as it dries an can crack up, so you're working with it after the distortion which makes it a known quantity. That's not a problem if it remains green. Should your dryad die at sea you'll be in trouble though, your ship could crack up and sink.

I can picture a scene though. A busy harbour where the ships of the wealthy merchants and navies are green, clean and unscarred, but the dirty cargo haulers are scarred and dead with physical patches.

Assuming that the dryad would grow exactly like regular ships, so with beams, ribs and sections the ship should act like regular one. Main disadvantage would be need to accommodate all technology to dryads.

As you can see the trees are round while the planks are flat. It's easier to move cannons on flat surface, walk on it or store good. With a living ship you could face a problem when the ship capacity would change during travel to the point that you would have problems with removing goods from storage. Moving heavy loads inside the ship would leave it scarred creating either ruts or fresh wounds filled with sticky resin and syrup.

Using them as battleships would also change how you make naval battles. I assume setting the ship on fire would result in the ship trying to run away (it don't need to by hurt bad, just enough for the dryad to panic) or submerge in water to take out the fire. People on board? Why would the ship care for the people? The wood would also pop up on the surface and the dryad don't need people to go where it wants.

In story this could make a good backstory to old, not used free ships that roam the waters doing where they want. Flying Dutchman.