Marina's can store 1 ship/level with a max of 20 ships/lvls.
I never thought or got the impression that Marina's are making it difficult to find worthy ships to plunder. I will concede that when one had fleets consisting of Mows and SOL's, one had to carry purses to cover the ransom and avoid getting stripped down in a few hours of not being logged in.
This resulted with available plunders of 200,000+ fairly frequently. When the big valuable ships become protected, the large purse is not needed, so overall, there is less plunder available. Really though, this don't affect the newer players hardly at all. These mega fleets that used to sail Avonmora were out of reach for most players anyhow.
I really enjoyed that aspect of the game but it gets to a point where you discover there is more money trading than plundering. The danger of being lit up and having to carry a big purse to cover ransom.
You will see this happen again with the new 'crop' of players coming aboard as they progress. I look forward to seeing them lit up and vulnerable to a multi-million gc plunder.
I'll also submit that the cost of a Marina is almost prohibitive enough that only 'Special" ships that have considerable wealth invested in them are stored.I'm saving mine to take away all the new Sol's that will start to appear in a couple months
Myself, have war fleets as usual on patrol but to plunder a pirate for 5-10k, sometimes in a retail strike but for fun...not worth the DP gained
So, all in all, Marina's have allowed players to carry less in their purse but I don't think they are responsible for the lack of big fleets lit up.
The pirates are scooting about in Sloops and SoW's but they are mostly restricted to unprotected trade fleets and as they have no real assets, they carrying small purses .
Allow also the in-purse gc needed to run a Gold Smith is substantial so anyone with a smelter running have no desire to add DP and risk a 200k+ plunder due to the size of their purse