back your boat down the ramp when it's not busy and while still attached to trailer, but floating, check the carbon ring with your hand (boat not running). You'll know if the boot or seal is trashed if it's leaking.
If it's not leaking when sitting in water, then I'd take it for a run with a buddy and see if the seal is leaking with a load on it.
If that doesn't show signs of the leak, you could put the hose in the bilge with the boat on the trailer in the driveway and get under the boat and look for water dripping.
Some models were known to leak at the seams where the 2 halves where mated together.