There are two ships of equal size and strength. One is made of wood and the other of steel. Can you explain which one is heavier?
The wooden one. It's weighed differently from metal IIRC.
Right answer, wrong reason
It soaks up the water, making it heavier than the metal ship?
^--- Wouldn't make sense to build a ship out of wood then?
Wood is heavier. It's like with golf clubs.
The wood is thicker?
Trust basically has it.
The answer is: wood is weaker than steel, by mass, so if they are "equal strength" then the wood one has to use more wood and is heavier.
That's pretty much what Trust said, extended.
While I was typing this, Ergot posted another basically-right answer :)