A 1/72 Ajax would be just under 8 foot long… if this is what you mean…its a bit of a size. 1/96 is another scale usually used for warships but even then it would be almost six feet long…
1/100 scale figure are available form suppliers that do "stuff" for architectural work, plain white polystyrene figures easily painted to look like sailors.
Trevore as you will have read on the D-Day thread made a corvette to approx 1/32 scale to suit ordinary 54mm soldiers and this was 6 foot 6 inches long. A destroyer would have been 8 foot and a cruiser would have bottomed on our pond!!
Ashley