quod erat demonstrandum means: 'that which was to be demonstrated'; quod = which, erat =was, demonstrandum is a gerundive, hence the to be demonstrated. This phrase is commonly used at the end of a mathematical proof. E.g. I prove the fundamental theorem of arithmetic, and end it with Q.E.D., standing for quod erat demonstrandum. The intended effect in the post was no doubt 'precisely my point'; a clever riposte, I appreciate it.
Reading through the previous posts, I've noticed the mentioning of the Bolivarian Armada of Venezuela - which begs the question - how is it in any way relevant to the discussion? Obviously numbers are not everything, but it has a total of 50 vessels (including submarines), most of which comprises patrol boats. It has four submarines, all from the seventies, and only seven operational 'large' surface combatants (in relative terms to other vessels in its arsenal), all of which come below the 3000 tons mark, and all but one of which dates back to the early eighties. Not bad compared to some other Latin American countries, but is way out of its league against the top 10 most powerful navies in the world.
I shall assume 'powerful' denotes the ranking of each navy in a head-to-head situation (note that while the comments only refer to the Navy immediately above, in fact I have compared and accounted for all possible pairings). Moreover, the rankings are based on the status quo and makes no provisions for the future.
1.United States Navy
2.Russian Navy - Obviously no match for the United States Navy - a number of vessels are nearing obsolescence, and poor maintenance of a number of vessels reduce their combat effectiveness.
3.Royal Navy - The two active Invincible class carriers compare disfavourably with the Admiral Kuznetsov Class - likewise, the principal surface combatants are slightly inferior. Technology is similar, and training perhaps slightly superior to that of the Russian Navy. Superior amphibious capability, and similar capabilities in submarine warfare. Overall numbers (of minimal significance) similar and only marginally smaller.
4.Japan Maritime Self-Defense Force - Second largest navy in Asia, extremely modern, and technology is at least on par with the Royal Navy. Vessels excellently maintained and professionally crewed. Marginally surface combatants compared to Royal Navy, inferior amphibious and submarine warfare capabilities. Helicopter carrier as opposed to a 'true' aircraft carrier.
5.French Navy - Nearly as modern as No.4, and boasts comparable levels of technology. Surface combatants slightly outclassed although powerful new vessels are being launched. Superior submarine capabilities, marginally inferior amphibious capabilities.