We recently hauled the older 100 ft motoryacht which I run. It has a shipwrights bowthruster installed in an 8" FRP tunnel. One of the two gratings was missing. It seems that nobody I can find sells screens/gratings for thruster tunnels. Do most bow thrusters have these or no? Does anyone have a recommendation where I can get one or is it safe to run without? We have presumably been running with a missing gratings for a while.