Not all lakes have a glacier/icebergs in them or are connected to a waterway/creek large/deep enough to permit boat operation. Shakes lake is unique so lets consider this specific situation. The lake water comes from the glacier, there is one way current toward the Shakes slough and the Stikine river.The entrance to the lake is not very wide but icebergs cannot block it because they get stuck before they get close to the entrance.In another words if you have enough water in the Shakes slough you can always enter the lake and hit the brakes before you run into the icebergs. The photo #1 shows situation when there is plenty of room around the icebergs to proceed to the glacier.Lately there were so many icebergs piled up at this spot (wall to wall and about a mile deep) that you could not get past them=you could not go to the glacier.
Jetboats can live in a few inches of water if they are on step/plane but then you got to go wide open and cannot slow down or stop does not matter what. If you do you get stuck and in the wilderness with no traffic it is a BIG problem. So any good jetboat Captain will read the tension on the water surface ahead of the boat and if he detects too shallow area he simply will not go there.Another trick is to make a sharp 360 turn and to watch how the wave you created behaves ahead of you. If the shallow area is not too wide the momentum (in full speed) will carry you even over dry land or solid ice. The best of the best can cross a shallow area by going at the full speed and just before the shallows they engage the reverse.That will stop the boat and the action creates a good size wave in front of the boat.You must immediately accelerate to full power to get on the top of that wave and to surf over the troubled spot. Of course this trick requires a perfect timing.You can also jump over fallen trees if there is no other way to avoid the obstacle. If the jetboat gets stuck you cannot restart the engines because your pumps intakes are on the bottom of the hull and instead of water you will suck in mud,sand and gravel and plug everything.
I have been in two groundings, one of them in fog in full speed. I was the only one standing trying to calm the nervous cruise ship passengers so I got a bit banged up.It was like a car crash at 40mph but in a slow motion. We had to abandon the boat and walk the passengers in their Gucci shoes etc. thru sticky mud to a deeper spot where another boat could pick them up. Not a good day... Ivan.

Not all lakes have a glacier/icebergs in them or are connected to a waterway/creek large/deep enough to permit boat operation. Shakes lake is unique so lets consider this specific situation. The lake water comes from the glacier, there is one way current toward the Shakes slough and the Stikine river.The entrance to the lake is not very wide but icebergs cannot block it because they get stuck before they get close to the entrance.In another words if you have enough water in the Shakes slough you can always enter the lake and hit the brakes before you run into the icebergs. The photo #1 shows situation when there is plenty of room among the icebergs to proceed to the glacier.Lately there were so many icebergs piled up at this spot (wall to wall and about a mile deep) that you could not get past them=you could not go to the glacier.
Jetboats can live in a few inches of water if they are on step/plane but then you got to go wide open and cannot slow down or stop does not matter what. If you do you get stuck and in the wilderness with no traffic it is a BIG problem. So any good jetboat Captain will read the tension on the water surface ahead of the boat and if he detects too shallow area he simply will not go there.Another trick is to make a sharp 360 turn and to watch how the wave you created behaves ahead of you. If the shallow area is not too wide the momentum (in full speed) will carry you even over dry land or solid ice. The best of the best can cross a shallow area by going at the full speed and just before the shallows they engage the reverse.That will stop the boat and the action creates a good size wave in front of the boat.You must immediately accelerate to full power to get on the top of that wave and to surf over the troubled spot. Of course this trick requires a perfect timing.You can also jump over fallen trees if there is no other way to avoid the obstacle. If the jetboat gets stuck you cannot restart the engines because your pumps intakes are on the bottom of the hull and instead of water you will suck in mud,sand and gravel and plug everything.
I have been in two groundings, one of them in fog in full speed. I was the only one standing trying to calm the nervous cruise ship passengers so I got a bit banged up.It was like a car crash at 40mph but in a slow motion. We had to abandon the boat and walk the passengers in their Gucci shoes etc. thru sticky mud to a deeper spot where another boat could pick them up. Not a good day... Ivan.

Ivan I bet you could fill a book with your stories. You are almost as good a story teller as you are a photographer.