Thames Barges

A flotilla/fleet/armada of Thames Barges just off of Gravesend ..with Tilbury in the background on the far shore of the Thames.
I suspect the use of each particular collective noun has something to do with the number of barges ...hence this will probably be a flotilla :) and in any case armada is a Spanish/ Portuguese word , yet one which we are taught at a very early age in the UK.