Actually, lacking a smaller boating pond somewhere near, the very same question has kept me from trying out my "snipe" on Lake Constance, German/Swiss border, from here to the end of the lake at Bregenz, Austria, it's a mere 46km ...
Perhaps one should have larger boat around. Well, now that I have my sailing boat in the water, just come around and we try them both with my sailor as rescue ship... Kidding aside, I see an additional problem: have some wind on the water and I fear that small waves will pose another threat for these open hulls.
I would like to have a proper boating pond, like the fabulous one in the Gardins de Tuileries, Paris, France. But that's again a bit far away...
Tethering the boat is a possibility, but looks, ah, a bit odd. And do not underestimate the sheer weight of a normal, wet line while a fishing line might get entangled easily in the rudder/screw...
But perhaps I am simply a scaredy-cat.