小洞不堵沉大船

A small hole not plugged will sink a great ship.

small / tiny / few / young

cave / hole / zero (unambiguous spoken form when spelling out numbers) / CL:個|个[ge4]

no; not so / (bound form) not; un-

to block up (a road, pipe etc) / to stop up (a hole) / (fig.) (of a person) choked up with anxiety or stress / wall (literary) / (classifier for walls)

to submerge / to immerse / to sink / to keep down / to lower / to drop / deep / profound / heavy

see 大夫[dai4 fu5]

big; large; great / older (than another person) / eldest (as in 大姐[da4 jie3]) / greatly; freely; fully / (dialect) father / (dialect) uncle (father's brother)

variant of 船[chuan2]

boat / vessel / ship / CL:條|条[tiao2],艘[sou1],隻|只[zhi1]