Fish Box Thru hull

[mackbm]

I recently bought a 23'cc and absolutely love it. One issue I have is the amount of water in the bilge after taking her out. Granted two of the times I went out it was in a steady rain and yesterday 2-3 foot chop with a lot of spray. I have been looking through this website for quite awhile and have read some post on the thru hull in the fish box being a source for water in the bilge. What is the easiest way to determine if this is the cause?