Ask SAIL: A Dented Hull
Mark Neinast of Plano, Texas, asks:
“I am restoring a 1970 Santana 21 and have noticed that the starboard side of the hull is indented around the trailer bunk. Can I jack up the boat, push out the hull (hoping it springs back into place), then strengthen the inside of the hull with epoxy?”
Don Casey replies:
You need to know if the hull is flexing or deformed. If the hull has inadequate stiffness or support where it presses against the trailer bunk, it should more or less regain its original shape, perhaps with a little push from the inside, when you lift the boat off the trailer.
However, if the boat has been sitting on its trailer for many years, odds are the hull has not simply flexed inward, but has remolded itself in the shape of the bunk. When fiberglass laminate deforms plastically like this, the new shape is permanent.
Both conditions can be corrected. If the hull returns to its original shape when lifted off the bunk board, you simply need to stiffen the hull in this area. Adding epoxy or even extra layers of glass laminate will not do the job. You need to install reinforcing stringers or ribs inside the hull.
You should likewise stiffen a permanently indented hull to arrest further deformation, then see about filling in the indentation. Depending on its depth, fill and fair it with either an epoxy paste or by adding extra glass laminate to reestablish the hull’s original shape. Because it is on the bottom of the boat, such a repair is relatively simple, as mismatched colors will be hidden beneath bottom paint.