Originally Posted by SloopJonB
People trash talk iron keels a lot. Undoubtedly lead is best but iron works well as long as the lower density is accounted for in the design. They can rust if not sealed in epoxy but if they ARE sealed, it isn't the maintenance nightmare some suggest.
Bill Garden figured iron was better for cruising boats that sometimes have to "feel" their way into anchorages because it bounces off any obstructions while lead, due to its softness, "forms" around the obstruction and transmits more impact into the hull.
I've seen iron keeled boats bounce off rocks and it looked exactly like he described.
One nice aspect of iron keels is that the bolts (studs actually) can be withdrawn and inspected as well as easily replaced - not so for lead.
Boats are not made to bounce on the rocks but if that happens a lead keel has advantages. While the all iron keel will deform very little transmitting to the hull attachment point (that is much weaker) all the force of the impact, a lead keel will deform under the impact absorbing in that deformation a lot of energy. The energy transmitted to the hull attachment point will be far less.
I had saw once a wauquiez that had hit rocks hard at speed: The lead keel was incredibly bent but not even a small fracture on the point the keel meet the hull. I was very impressed.