Thruhull Replacement on John William 37VT68

Groco Tri-Flange Seacock

To remove the old thru hull out use a die grinder to cut the seaside of the 

I do not use backer blocks with the flanged thru hulls but I do grind the inside and outside smooth. I have replaced a lot of thru hulls with blocks of wood, fiberglass and aluminum and usually find them to be loose, split or rotten. I also use 5/16 flat head SS machine screws and countersink the heads. 

John Mackie
John William 37VT68