Most river and lake boats are not designed for 6 feet or larger waves

 So, in a storm on lakes or on the sea often these boats will capsize because the waves go over the stern or bow or side of a boat. This mistake usually occurs when people not familiar with waves trying to navigate things that their boat cannot do without capsizing.

It's a similar thing with weekend pilots in planes where they overload their planes weight wise and then take off as steep as when they are flying along then their wing stalls and they often crash at takeoff with their family and friends and their luggage aboard.

So, if pilots aren't used to the extra weight of family, friends and luggage they often crash on takeoff when they overload their private planes.

In other words in smaller planes unless you basically weigh everyone and their luggage and then compare it to what safely can be flown on that particular model of plane crashing often happens at takeoff.

Also, the higher the altitude you are taking off or landing at can cause problems too because they air is much thinner at higher altitudes and won't support the plane as well in the air.

In order to be safer at sea or on a lake or river in bad weather you need a boat or ship that is designed for the open ocean where even if waves come over the side of the boat or stern or bow they don't fill with water and capsize that easily. For example in many larger sailboats you can close the parts of the ship where you sleep downstairs off from the water so it doesn't fill with water and swamp the boat or sink.

A whole lot of thought needs to go into being on water or in the air when the weather is bad or the plane is overloaded.