normal water in the boat?

[MrHunters]

After my fiasco with the dealer forgetting to put two of the three drain plugs in I have been especially paranoid about water in the hull.

After a normal trip of about 5 hours and no waves over the bow or stern, I drain for about a a minute and a half or so on a relatively steep incline. Is this normal water or should i be looking for possible reasons for this?

There is a plate with slots mounted on the bottom of the hull near the stern.. any ideas what that is for??