This paper discusses several in-hull RF propagation studies on board one decommissioned and several active naval ships in the 0.8 - 2.5 GHz range. During these tests, it was repeatedly demonstrated that radio signals propagate from one compartment to another even when the watertight doors (hatches) are shut and sealed. In fact, signals have been received across several bulkheads. Results indicate approximately 20 dB of attenuation is associated with transmission through a bulkhead/watertight door. It has also been found that the wireless channel aboard naval vessels does not show good correspondence with a Rician channel. Finite element modeling of a shipboard compartment has been performed and supports the hypothesis that rubber door gaskets and other non-conductive structures may be the source of bulkhead penetration/leakage. For comparison, ultra-wideband channel measurements within the hull of a ship have also been taken. These measurements are used to characterize the propagation within a single compartment as well as through a sealed bulkhead/watertight door.