>>18328411
Shipbuilders had been covering hulls with tar to make them airtight since ancient times

>>18328411
They also added powdered metal to paint like copper or zinc because it prevented shipworms

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>>18328411
Look up what a Bilge (and bilge water for that matter) is. Even modern ships have water in the lowest part for various reasons. And with proper care this is a largely a non-issue; even for the ships prior to the 19th century.

Vikings and others used overlapping planks, and shipbuilders caulked joints with “oakum” or other substances. Wet wood swells and closes the gaps. Look at all those wooden water towers on top of buildings in NYC and elsewhere.

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>>18328463
>overlapping planks
Called clinker built. Those were really popular in northern continental Europe up until the 15th century. Still this style of ship building never vanished as a whole and to this day smaller ships and boats are built in the clinker way. There were also some interesting transitional ships where both of those methods were combined - the carvel style usually being reserved for the lower parts of the hull with clinker style making up the rest.
The advantages of the clinker style were that those ships were fast to built, they tolerated extended periods of being out of the water better, they didn't need a frame and are thus lighter and the whole construction is rather flexible and thus can endure forces quite well.
However carvel style ships allowed for overall larger and broader constructions, impacting forces were diverted like in an arch, they allowed for more larger and more complex styles of rigging and the smooth surface is easier to clean.

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>we all know that wood can't be airtight

>>18329101
Litterally not air tight, how do you think wine ages?

>>18329131
its watertight, that's all that matters

They used pitch to make it watertight, it has similar properties to plastic, both are polymers, except pitch does not use modern chemistry to bind the particles together and is essentially a very heavy oil that drips very very slowly, or basically not at all if stuck to wood.