艦 is a Japanese kanji written with 21 strokes, listed here under the keyword “warship”. It is built from 監 (oversee) and 舟 (boat). In Remembering the Kanji by James W. Heisig it is frame 2020.
On KumiJi Glyph Explorer, open the parts search and type “oversee” + “boat”. 艦 is among the results, together with every other character containing the same shapes.
Open 艦 in the interactive kanji search
to expand every part down to its smallest pieces, add your own names and mnemonic stories,
or search for other characters by their parts.