Boat hooks were originally based on the pike that was used by land soldiers and was used by crewmen as far back as Roman times, if you study old paintings you will see sailors using them, the land pikes were too tall for use on board ship, ( Up to 15' in length ) and were cut down to a more manageable length for ship fighting. These then were used as boarding hooks and stabbing spears, when these became redundant they were shortened more as well as the hook and spear head. The head was blunted and in some cases the Hook became a ceremonial thing, ( You can see pictures of them being used on Admirals launches etc ) all the pictures I have seen seem to show the sailor holding it upright with the butt on the deck and the hook appears to be approx; 12" above his head. I have taken this info from 'Ferrington's book of 1912 'Weapons of the navy', now sadly out of print, I would say that this would appear to make the hook about 7' in length, of course as already stated, it was probably shortened to suit the user.... Harry