Stainless steel bolts
Judging by the good condition of my '78 Cat 27 keel bolts, I would say that they are stainless. For a little technical info, stainless steel has a 300 series and 400 series, like 308, etc. The point here is that some stainless alloys are not magnetic, so the magnet test may not be conclusive. Great material for areas with magnetic mines.A mechanical/marine engineer could fill in details. Hope this helps.
