Turnbuckles are typically secured with with two cotter pins to prevent the turnbuckle from rotating and loosening the stay. The problem with cotter pins is the legs can get caught on lines and flesh of passer byes.
Some riggers will turn the legs around, bent so far that they point into the turnbuckle. This works well and when covered with rigging tape, provides a safe, snag-free, secured turnbuckle. The problem comes when you try to remove the cotter pin.
The legs have been bent so far that they are hard to bend back to remove the pin. Since the legs were bent so far, they are mangled and will not be easily reused. The excessive bending also runs the risk of breaking the legs, which would make the pins worthless.
The alternative to cotter pins on small day sailors is to use a single piece of stainless steel welding wire. The wire is bent to look like a "[". The horizontal parts slide through the turnbuckle screw holes and are then bent over to hold the wire in place.
This single welding wire will hold the turnbuckle in place, while offering no risk of snags. I don't cover the wire in rigging tape because I like to visually inspect the wire frequently. Since it is snag free, the tape is not required!
To remove the wire, simply straighten the legs and slide the wire out of the pins. It can easily be reused over and over. If the legs break from use, another piece of wire can be fabricated to replace it.