Bronze/ Stainless screws

[Bremner]

I have been replacing some of my fastners on the bottom of my 40 foot pacemaker with stainless steel screws . the original screws on the bottom were bronze. will this pose a problem in the future. I was speaking to a someone and they indicated that overtime the broze will fail because I have used stainless steel as well is this true? . Can someone shed some light on this .
Thanks Dave

[Robert Gainer]

Stainless is not a good choice for underwater use in wood. Without oxygen it is subject to crevice corrosion. Bronze is a better choice for this.
Robert Gainer

[Bremner]

The boat is located in fresh water if it maters?

[Robert Gainer]

Salt water is more corrosive then fresh water and warm water speeds up the process of corrosion because it’s a chemical reaction and like any chemical reaction it is heat dependent. But the problem with stainless happens with a lack of oxygen and in wet wood there is that lack of oxygen and you get crevice corrosion because of it. It happens in boats used in either fresh or salt water.
Robert Gainer

[Ari]

Stainless steel perform best in an environment that have air.In an environment where air is deprive like underwater,stainless steel tend to 'corrode'.If this happen on your boat bottom, the screw and the wood will loosen a bit.If you have a lot of this ss screw then that bit and bit plus will give a bigger effect. Bronze and ss will react if there is direct physical contact between the two material like having ss washer for bronze screw.Material wise bronze is a better choice for this job.

[gonzo]

The stainless screws will fail. I assume you used 18-8 (304) alloy. Bronze is a more noble metal. Also, below the waterline SS gets crevice corrosion because of lack of oxigen.

[longliner45]

hey can I ask? what about zink plated bolts and screws ?

[lewisboats]

Originally Posted by longliner45

hey can I ask? what about zink plated bolts and screws ?

Galvanized fasteners have been used for quite a while...but the quality of the coatings have declined in the last 40 years or so. It is also harder to find quality hot dipped galvanized hardware. Do not use electroplated as the coating is far too thin. You are still better off using bronze to replace the bronze.

Steve