thru hull backing plate

thingiverse

This allows you to put a 29mm thru-hull block (Harken brand) on the hull of a boat, and pass a rope through it. Inside the hull, the rope can travel through a 1.5-inch hose to another such device, allowing for a water-tight system. It's nice having an under-deck line that allows no water into the hull of the boat and no air to escape should the boat be taking on water. I designed it and later made corrections and improvements. The first 29 downloads have a slight mistake that can be fixed with filing; I've since corrected things. The thru-hull block is bought from Harken; a small line travels into the hull with the help of the block, and then in a switch-back fashion makes a secondary turn around the printed pulley and out the hose barb. I'm using 4 of them on my Slipper 17 traveler system - so far it works great and seems water-tight. The rope gets a little wet in the hose, so I am to add a T-fitting and drain to the hose soon. I use ceramic bearings in the block to prevent rust; 4 of them can be pressed into the pulley. The inner diameter of the pulley is 8mm diameter, and an 80mm-long 8mm bolt will do. Two number-10 by 24 bolts go through the Harken 29mm block into the hull; number-10 by 24 nuts go into the printed part to allow the part and the block to sandwich the hull.