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New washers and re-tightening the keel nuts

The new laser cut keel nut washers are finally in place. After we reinforced the bottom/floor of the bilge with 4 layers of 600g biaxial fiberglass, we were able to install the new washers and tighten the nuts. The new washers are A4 (316/316L) stainless steel, 65x65x6mm with a 21mm hole and fit perfectly.

Keel nut washers

I tightened the nuts with a 210Nm torque wrench I bought in the local hardware store only for this purpose. Theoretically the M20 A2-A4 fasteners in their new condition should be able to clear 273Nm when dry or 246Nm when lubricated, but I didn't want to get too close to the maximum values and risk damaging the threads or breaking the rods and also I used a small amount of Loctite on the threads to prevent them from loosening due to vibration or movement, so I considered 210Nm is enough.

Tightening them even to 210Nm was not an easy task due to the poor access. I had to use my whole weight and push the wrench with my legs, with my back supported. We had two extra nuts, which we put on the first and last bolt as an extra 'locking nut', also just to keep them as spares and not lose them. They might come handy if for some reason in the future the threaded rods would need to be extracted from the keel.