5/16" diameter shroud anchor pin threads through the hole in the hull deck lip and into the shroud anchor bar or nut/plate. Hobie® factory replacement part for Hobie® 16, 17 or 18.
Shroud anchor pins have been through a few manufacturing generations. Early generations can be easy to spot and should be replaced. Some of the 1st anchor pins were threaded all the way to the top of the shaft and were much weaker than today version. The next generation had threading that was cut into the pin and thus weakened the pin, you can notice these by the fact that the threads are the exact width of the pin. These also were slightly suspect and tended to only last a few seasons. Now we have the latest generation which the threads stop short of the top of the pin and are pressed into the pin and because of this newer construction method the threads stick out from the original pin diameter a little. These pins are very strong and will last for quite some time. It is a good idea to check your shroud anchor pins periodically to make sure they aren't showing signs of wear and that they are tight, as loose pins are more likely to break.