Fasteners

I have been told by multiple realiable sources that stainless steel fasteners don't belong below the waterline where they will be completely submerged all the time. The rational behind that statement is always that stainless steel requires an oxygen environment to maintain its high resistance to corrosion. I have found no evidence that this is true and was actually quite surprised to hear this because I am a structural engineer and specify stainless in many applications. Anyway, I am about to purchase two-thousand silicon-bronze fasteners to begin refastening my 1964 37-foot Egg Harbor with and just thought it would be a good idea to do one final search for information. So if anyone out there knows about the do's and don'ts of stainless steel please let me know. Thank you.

[sailvayu]

What you have heard about SS is 100% correct. Use the bronze and life will be good If you use SS you will be refastning by this time next year if not sooner.
If you want to learn more read "Metal Corrosion in Boats" by Nigel Warren. This is one of the best books on this subject I have come across. Also note there are many typs of SS the type you may be used to may be not be what is used in the marine enviroment.

[Timm]

I agree - stick with the silicon bronze. Most of the SS on the market these days seems to be of varying quality, most lousy. I am always amazed when I see large custom boats being fitted with SS struts and rudders. The added cost of having these parts cast in Manganese Bronze is small compared to the cost of the entire boat.

[sailvayu]

The differance with the rudders and struts is that these parts are bonded and the larger mass of these parts makes them less of a problem with galvnic corrsion. It goes with out saying that to bond the screws would not be practical. Also most off the shelf SS screws are of 314 SS and most cast parts are 316 which is a better grade. Zincs are also fitted to the larger parts further aiding against attack. So not all SS under the waterline is bad and like most materials you must use them wisely
Also never use Manganese bronze, it is silicone bronze you want to use