The best stanchion bases I've been involved with, on a small solid fibreglass offshore
(glass over ply deck), were some we made with heavy (5mm thick) stainless bases, which we had pressbraked so they wrapped over the side and had a couple of big screws horizontally into the solid timber "shelf".
The shelf was the longitudinal member
, glassed-in immediately inboard of the solid glass gunwhale, forming a landing for the deck
The horizontal foot of the plates went well inboard with two decent bolts into a backing plate under the deck
, just inboard of the shelf. This foot was braced back to the stanchion in the usual way with a twin-legged bail of 6mm stainless rod, plugging into thru-holes in the base and welded from beneath, and bent around the outboard
side of the stanchion and TIG welded to it a short distance up.
These are the only small-boat stanchions I've encountered which had the same solid feel you get on a big offshore
boat. They've never leaked a drop in twenty years.
I designed these after coming back from a trip where, in an out-of-the-way anchorage, we caught up with some friends in a 25' charter
sailboat, a production boat of some repute.
One of our friends had lost
their footing and fallen against a stanchion, as a result of which the base had torn a hole in the deck. Luckily we had suitable tools and repair materials with us to make it temporarily safe, otherwise they'd have had to cut their holiday short, in a place where it would have taken several days for the charter
company to get a replacement boat to them, even if one were available.
Could have been worse: they were close to some pretty challenging waters....