One of their safety issues relates to the protection of swimmers in the water. The Traversée internationale du lac St-Jean provides customized prop guards so swimmers cannot be cut by boat propellers.
These are especially important because the professional marathon swimmers who compete in the Traversée internationale du lac St-Jean and other professional races not only swim closely to one another, but the athletes' coaches also direct their boat drivers to get close to their athletes which means that boat propellers and swimmers can be dangerously close proximity.
In the heat of competition, a few coaches think only of their swimmer without regard to other swimmers in the race. Additionally, over a long marathon swim, anyone can get a bit inattentive and accidents can happen.
In order to prevent any potential problems and unintended accidents, the far forward looking organizers of the Traversée wisely installed prop guards many years ago.
Similarly, Tom Hecker, a renowned channel swimmer, has proposed use of the Prop Guard because of his own close calls with propellers during his swims.

These situations happen more often than most people realize, both in solo channel swims and relays and in races around the world. Tom asks, "Perhaps a Prop Guard at US$250 should be mandatory on all swimmer support vessels?"
We recommend the following when boaters and swimmers intersect on the open water:
When a boater is caught in a pack with swimmers all around (left, right, front, rear), do not panic. Take the boat out of gear, turn the motor off, wait until the swimmers are safely clear, and then resume operations. Because the prop may still turn with the boat our of gear and the motor off, consider putting the boat back in gear (with the motor off) to stop the prop.
There have been plenty of times when a boat loses steering control and has turned into a group of swimmers. Because of these situations, emergency actions should be reviewed in the Captains meeting. While constant vigilance is always the primary goal, there are moments and situations occur that are inevitable, such as when the sun's glare reduces a pilot's view, waves causes problems or there are mechanical difficulties.
When swimmers and boats are in close proximity to each other, getting the prop stopped and making the vessel safe should be the primary concern. While swimmers may swim into the vessel which can hurt, having them get hit by a spinning prop is disastrous.
Copyright © 2011 by World Open Water Swimming Association