Opinions on fasteners(stainless vs bronze)

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Tim R.

Tim R.

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May 27, 2004
3,626
Caliber 40 Long Range Cruiser Portland, Maine
I need to mount my new winches and thought silicon bronze machine screws would be the best choice. Then I started thinking about it.

The old winches were mounted with stainless(not sure which type, didn't have a magnet around) and showed no signs of corrosion after 24 years. The winch bases were bronze.

The new winch bases are also bronze. While it makes sense to go with silicon bronze, SS is a bit stronger.

I would probably be fine with either material but I would like to hear what the experts have to say.
 
kloudie1

kloudie1

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Nov 6, 2006
10,217
Hunter 34 Mandeville Louisiana
Tim.. I would go with stainless for the extra strength, but do use an anti-sieze paste on the nut threads when they are installed. Bed them well (as teh old ones were) to keep water from corroding them. Bronze is probably fine too but I think the norm for that application is SS .. either 304 or 316 is fine, 316 is the more common for fasteners,304 is slightly stronger. Note: sometimes forming the nuts and bolts and cutting threads makes 300 series SS mildly magnetic.. Takes a soft magnet, compared to steel ..
 
sailingdog

sailingdog

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Oct 22, 2008
3,502
- Telstar 28 Buzzards Bay
I would recommend going with the stainless steel screws as well. However, be sure that the stainless steel screws are 316, not 304, since 304 is subject to chloride ion stress cracking in a salt water environment and far more susceptible to crevice corrosion, and not as corrosion resistant in any case.

Use TefGel, LanoCote or some other compound to galvanically isolate the screws from the bronze base.
 
Bob S

Bob S

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Sep 27, 2007
1,813
Beneteau 393 New Bedford, MA
I agree with stainless fasteners. Has anyone heard of 18-8 stainless. Any metallurgist out there can tell me the difference between 18-8 and 300 series stainless?
 
Tim R.

Tim R.

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May 27, 2004
3,626
Caliber 40 Long Range Cruiser Portland, Maine
I am not expert but I believe 18-8 is very simlar to the 304 content.
 
sailingdog

sailingdog

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Oct 22, 2008
3,502
- Telstar 28 Buzzards Bay
18/8 stainless steel has nominally 18% chromium, 8% nickel, and the remainder iron typically, and includes 301, 302, and 304 stainless steels. 316 stainless steel has molybdenum (up to 3%) added for increased corrosion resistance.[SIZE=-1][/SIZE]
 
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