ALL of my keel bolts have lock washers beneath the nuts. I believe this was Ericson's standard procedure. I've assumed the washer not only performs a "locking" function, but also acts as a spacer to keep the "corners" of the nut from cutting into the larger, flat washer (if the nut scapes the large washer, all torque settings become meaningless).
As to what to do? Goldenstate had some revealing photos from his keel drop:
View attachment 46855
The conservative, (or the "independently wealthy") approach would be to drop the keel and, likely, to have any damaged bolts drilled out and replaced.
The "wait and see" approach might be to just live with it, check frequently for water seepage from that bolt, and inspect the keel joint at each haulout.
The "in between" (or, the "only ask the question of you can bear the answer") approach might be to torque all your keel bolts (this is best done on-the-hard). Our 1" SS bolts are rated to 286ft-lb, but most recommend torquing to around +/- 200 lb. Torque the suspect bolt last:
- If that bolt is severely compromised, it might crack off during torquing. Or, that nut may have to be rotated significantly further than the other nuts (which might indicate stretching of a weakened bolt). But then you have your answer.
- If it holds the torque (maybe I'd only take it to 180lb) after several weeks/months of use, then it might be a reasonable assumption (lacking any other contrary evidence) that the bolt is okay.
-If, on the other hand, that bolt needs to be re-torqued after a few weeks/months, that might be an indication the bolt is corroded enough to have lost a significant degree of strength.
Also, if you have a skilled yard where you haul out, ask them their opinion and recommendations.