Boat, Small Craft
noun
A small boat is a boat or small craft. If something is a "big boat" it's better to call it a "ship" I think, which is why this is just a boat.
こぶね
The readings are all ones you've seen before. 小 uses its こ reading, so just think of this like a "child boat." This makes sense because it's small. Watch out for the rendaku.
太平洋上には小舟がひしめきあっていた。
The Pacific Ocean was filled with little boats.