Monday, June 23, 2008

Emergency Plugs for Thru-hulls (Small Boats)

Every boat that has thru-hulls or seacocks should have safety plugs on board. In the event of a seacock or hose failure, the plug is driven into the opening, keeping the water out.
Make the plugs of softwood, such as cedar or pine, oak, mahogany or ash are too hard and may crack the seacock housing. Easy to make, you'll need a hand plane or sharp knife, saw of some kind, rasp, 80-grit sandpaper and oil sealer.
Two sizes of plugs fit all thru-hulls on board. For large plugs (1 1/2"ID), use 1 1/2" stock cut into 5" lengths. Taper plugs from 1 1/2" to 3/4", cutting into an octagon shape with the help of an electric or hand saw. Place in a vise and continue tapering with a jigsaw and finish with a rasp. Alternatively, try whittling with a sharp knife or block plane. Finish off with sandpaper and round the ends to prevent splintering. For smaller seacocks (3/4"), use 1" cedar or pine, cut 4" long and taper to 3/4". Drill a small hole in the larger end for the lanyard. Dip each plug in oil, hang to dry, attach a lanyard of 1/8" polyester cord, and tie around the base of the thru-hull.
Make a few spares for every size of seacock and stow them in your tool kit. If you ever need need them (hopefully never), just tap the plug into place. The lanyard wraps securely around the seacock base to keep water pressure from forcing the plug out. Every year, inspect the plugs for rot and cracking and oil when necessary.