Shaft strut bolts- not created equal

[jtm]

Previously there have been some posts regarding the shaft strut and replacing its bolt fittings.

A few years ago when I replaced the cutlass bearing I also pulled a strut bolt that had a very slight rust water tell tale in the h28.5 aft qtrberth pocket.

If you have no idea when/if these bolts were ever replaced you may want to check them on next haulout.

It was interesting to see how one 20 year old bolt was so compromised. I pulled all of them and found 3 or 4 in varied states of corrosion. A picture of the four follows.

 

[kloudie1]

Crevice Corrosion On Stainless

Classic crevice corrosion on 300 series stainless.. Happens when stagnant water stands around stainless in a close fitting hole.. Really important to seal bolts like that from the outside so water can’t get in there and stand around.. attached is a shot of a bottom rudder support strap bolt from a friend’s Tartan 37.. The undamaged shank is 9/16” but up under the head, the corrosion has reduced the diameter to 3/8”, a reduction of 50% of the load carrying capacity of the bolt.