Possible water leaking on I/O boat

Question
How do I know how much water should be leaking into my boat hull after several hours on the water ?  I just purchased a 1988 VIP vision 18' bow rider with 3 litre mercruiser outdrive. After we were out in the boat for several hours
(it runs fine)  When I pulled the drain plug it looked as if about maybe 3 gallons of water or more came out .
would this be enough to suspect a leak at the bellows ?
No one entered the water or got wet in the boat. it was dry the whole time.  since I just got the boat I was wondering how much leakage is considered normal into the hull ?

Answer
Hi Jake....Thank you for selecting the undersigned to respond to your question.

There ought not to be any water leaking into the boat.

Check the bellows. If no tears, haul boat out and onto trailer and pull drain plug. After all water has drained, securely replace the drain plug. Using a hose, partilly fill the boat with water and observe the underside for the location of leaks. Mark the leak with a contrasting color of crayon so it can be readily identified and repaired.

Safe Boating
Ron