[paulk]

It sounds like a fairly tight space, though there appears to be no speed restriction. It also sounds like the powerboats don't care. You could try trailing some lines. Maybe some long, floating ones. You could figure that they at least wouldn't pass too close astern if you did that. Doing that, and working to the edge of the channel so they don't dare pass ahead of you, might work wonders. Sounding your horn (how many blasts for a boat on starboard? How many for port?) might confuse them enough to get them to slow down too.

 

[jzk]

That would be dangerous. What if they don't see the line, and they wrap it on the shaft? What if the wrapping force pulls the vessels together and causes a collision? People have ripped saildrives out by catching a line.

It sounds like a fairly tight space, though there appears to be no speed restriction. It also sounds like the powerboats don't care. You could try trailing some lines. Maybe some long, floating ones. You could figure that they at least wouldn't pass too close astern if you did that. Doing that, and working to the edge of the channel so they don't dare pass ahead of you, might work wonders. Sounding your horn (how many blasts for a boat on starboard? How many for port?) might confuse them enough to get them to slow down too.