Date: 202109
Local time of day: 0601-1200
Flight conditions: Marginal
Weather elements / visibility: Fog; 0.25
Light: Daylight
Aircraft: Lake Aircraft Undifferentiated or Other Model
Operator: Personal
Operating under: Part 91
Flight plan: VFR
Mission: Personal
Flight phase: Cruise
Airspace: Class G ZZZ
ATC / advisory: Tower ZZZ
Reporter organization: Personal
Reporter function: Single Pilot
Reporter qualification: Flight Crew Sea
Human factors: Situational Awareness; Distraction
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter VFR In IMC; Inflight Event / Encounter Weather / Turbulence; Inflight Event / Encounter CFTT / CFIT
Detector: Person Flight Crew
When detected: In-flight
Result: Aircraft Aircraft Damaged; Flight Crew Regained Aircraft Control; General Maintenance Action
Contributing factors: Procedure; Weather; Human Factors
Primary problem: Weather

Narrative: I filed a VFR flight plan as a private Part 91 pilot in my Lake Amphibian aircraft between ZZZ and ZZZ1. I was given a cross border squawk code and was using it flying north towards my destination. My aircraft has a current IFR pitot static system certification and my instrument ticket is current. On a VFR flight in suddenly deteriorating ceiling and visibility; I was flying low over the water in a place noted on the chart as Name enroute to ZZZ1 in what is clearly class G airspace. I was under some pressure to arrive at XA45 in ZZZ1 due to customs wanting a landing within 15 minutes before or after the filed time of arrival. I have quite a bit of experience flying low over the water in class G airspace; able to land in low visibility ceiling conditions. At approximately XC15; flying low over the water I suddenly and completely unexpectedly hit the water. I had already configurated the plane to a flaps down; mixture full rich; prop pitch flat attitude; for a water landing were it necessary to do so. But; I did not anticipate the plane hitting the water and when it did so the let down on the water was extremely violent. The plane pitched up in the air and back down slamming onto the water extremely hard. The plane came to a stop and myself and my single passenger were in dense fog. I [climbed] out of the cockpit with the plane on the water and stood on top of the cabin and looked at as much of the airframe as I could see to ascertain if there was any damage in the place as detectable in that portion of it visible floating above the surface of the water and saw none.There being no visibility and ceiling sufficient to fly in we displacement taxied for some 20 minutes. Being on the surface of the water and too low to contact anyone by radio my passenger called [number] and informed them that we would report back airborne if we were able to find a ceilings and visibility adequate to fly in. After 20 minutes of displacement taxiing on the water we got airborne and arrived a short time later in ZZZ1. I [received priority] going into the pattern because we did not get an up and locked light on the gear and wondered if we would get a down and locked light before landing the plane on the runway back to ZZZ and do a grass landing adjacent to the runway gear up rather than do that on the water or suffer a gear collapse landing on the runway. Tower was helpful. When I cycled the gear down I got a down and locked signal on the panel and proceeded to land the plane on the runway without incident.I flew home later that day and have not been able at this point to find damage to the airframe. It may be the case at the time of annual when I pull up the floorboards I will discover some bent frames but that is to be determined when I perform the inspection. The take away lesson in all of this is that despite not liking to set the plane down in saltwater because of a several hour clean up to prevent corrosion it is obvious to me that I need to be willing to do so if encountering lowering ceilings and visibility as I did when the event occurred.




Synopsis: Pilot reported striking the water during low altitude flight caused by weather. After returning to the home airport; air frame damage was discovered.