I would consider arging that the hovercraft caused this and thus it may be considered a result of combat-related activities. This is from an Army site on Combat-Related Special Compensation, but the law pertains to all services. IF you can get a finding on this, you benefits will be tax free and you may qualify for CRSC.
Definitions of combat-related:
In the performance of duty under conditions Simulating War (exercises, field training)
In general, this covers disabilities resulting from military training, such as war games, practice alerts, tactical exercises, airborne operations, leadership reaction courses, grenade and live fire weapons practice, bayonet training, hand-to-hand combat training, rapelling and negotiation of combat confidence and obstacle courses. It does not include physical training activities such as calisthenics and jogging or formation running and supervised sport activities.
While engaged in Hazardous Service(e.g., flight, diving, parachute duty)
Such service includes, but is not limited to, aerial flight, parachute duty, demolition duty, experimental stress duty, and diving duty. A finding that a disability is the result of such hazardous service requires that the injury or disease be the direct result of actions taken in the performance of such service. Travel to and from such service, or actions incidental to a normal duty status not considered hazardous are not included.
Through an Instrumentality of War (combat vehicles, weapons, Agent Orange, etc.)
Incurrence during actual period of war is not required. However, there must be a direct causal relationship between instrumentality of war and disability. The disability must be incurred incident to a hazard or risk of the service.
An instrumentality of war is a vehicle, vessel, or device designated primarily for Military Service and intended for use in such Service at the time of the occurrence or injury. It may include such instrumentalities not designated primarily for Military Service if use of, or occurrence involving, such instrumentality subjects the individual to a hazard peculiar to Military Service. Such use or occurrence differs from the use or occurrence under similar circumstances in civilian pursuits.
A determination that a disability is the result of an instrumentality of war may be made if the disability was incurred in any period of service as a result of such diverse causes as wounds caused by a military weapon, accidents involving military combat vehicle, injury or sickness caused by fumes, gases, or explosion or military ordinance, vehicles, or material.
As direct result of Armed Conflict
The disability is a disease or injury incurred in the line of duty as a direct result of armed conflict. The fact that a member incurred the disability during a period of war or an area of armed conflict or while participating in combat operations is not sufficient to support a combat-related determination. There must be a definite causal relationship between the armed conflict and the resulting disability.
Armed Conflict includes war, expedition, occupation of an area or territory, battle, skirmish, raid, invasion, rebellion, insurrection, guerilla action, riot or any other action in which service members are engaged with a hostile or belligerent nation, faction, force, or terrorists.
Armed Conflict may also include such situations as incidents involving a member while interned as a prisoner of war, or while detained against his or her will in custody of a hostile or belligerent force, or while escaping or attempting to escape from such confinement, prisoner of war, or detained status.