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Stainless steel running gear
Can someone tell me the advantages/ disadvantages of stainless steel
running gear (prop, strut, shaft, and rudder). I remembered hearing that it was a no-no, but I have nothing to prove either way. A boat I test drove had this installed, and it does'nt make sense why someone would dump all this money into the running gear if it provides no additional structural, corrosion resistance, or performance enhancements. Thanks! |
#2
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Stainless steel running gear
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#3
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Stainless steel running gear
Either you're confused or I am. Old fogeys like me were brought up to
never use stainless below the waterline. Although this rule has been relaxed somewhat, broadly speaking, stainless is less satisfactory than bronze -- its advantage lies only in lower cost. Prop, strut, shaft, and rudder on inboard power boats under sixty feet or so(which I'm guessing is what we're talking about here) always used to be made of bronze. This gave good strength, excellent corrosion resistance, and long life. Bronze has, however, gotten more and more expensive and stainless has gotten relatively cheaper, so that now it is cheaper to use stainless than bronze. Bronze is still the more satisfactory material as it is much more corrosion resistant and is somewhat stronger, allowing for smaller shaft sizes. (I'm painting with a broad brush here, as there are many different bronze alloys, but almost all of them do better than 303/304 or 316 stainless.) The only time you might be happier with a stainless prop rather than bronze is after hitting something hard, as the stainless prop might be less chewed up. Even there, however, it could be debated, as it is easier and cheaper to rebuild a badly damaged bronze prop than a stainless one. As for no-nos, stainless is OK (not great) if you use all stainless. It's also OK if you use a bronze prop on a stainless shaft -- many sailboats do this now -- provided you put a shaft zinc on. You're less likely to want to do this on a powerboat shaft that will spinning much faster, but electro-chemically it's fine. Jim Woodward www.mvFintry.com (kim) wrote in message . com... Can someone tell me the advantages/ disadvantages of stainless steel running gear (prop, strut, shaft, and rudder). I remembered hearing that it was a no-no, but I have nothing to prove either way. A boat I test drove had this installed, and it does'nt make sense why someone would dump all this money into the running gear if it provides no additional structural, corrosion resistance, or performance enhancements. Thanks! |
#4
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Stainless steel running gear
Cannons used to be cast out of bronze too until we learned how to cast
steel. My sailboat has the original SS shaft in sal****er for 25 years and is doing fine. For a number of years now there have been a gazillion shafts and props made of SS and I don't recall a lot of problems with them. Ron |
#6
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Stainless steel running gear
kim wrote:
Can someone tell me the advantages/ disadvantages of stainless steel running gear (prop, strut, shaft, and rudder). I remembered hearing that it was a no-no, but I have nothing to prove either way. A boat I test drove had this installed, and it does'nt make sense why someone would dump all this money into the running gear if it provides no additional structural, corrosion resistance, or performance enhancements. Thanks! Jewelery? Sailing is a status sport? Except for the elite. Ask Eienstein. Replacement cost / lifetime = Cost effectiveness (more or less) Vanity is a sin. Your gavanism may vary. All metals underwater might best be all the same alloy. Fat chance. Measure millivolts between evey possible pair with bonding on and off. Decide on zinks / year later. Terry K - My email address is MY PROPERTY, and is protected by copyright legislation. Permission to reproduce it is specifically denied for mass mailing and unrequested solicitations. Reproduction or conveyance for any unauthorised purpose is THEFT and PLAGIARISM. Abuse is Invasion of privacy and harassment. Abusers may be prosecuted. -This notice footer released to public domain. Spamspoof salad by spamchock - SofDevCo rc |
#7
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Stainless steel running gear
Stainless steels require oxygen (to bind with chromium to form a protective
chromium oxide layer) to work well. And even then they are susceptible to chloride stress corrosion, crevice corrosion, and galvanic corrosion, especially in oxygen poor stagnant areas (like inside bearings etc. Bronze is better, monel or nickel-copper better yet, but all much pr icier. That said, stainless steel can work satisfactorily but you have to use alloys specific for the task. Don't use 302/304 series. The 316 series is better but less strong and have been known to suffer catastrophic failure due to corrosion. The best SS alloys are expensive and known by various trade names such as Nitronic 50 or Aquamet 22. Those are the only SS alloys I would consider for use below the waterline (but be prepared for sticker shock) JJ On Sat, 11 Oct 2003 12:15:24 -0400 (EDT), (Ron Thornton) wrote: Cannons used to be cast out of bronze too until we learned how to cast steel. My sailboat has the original SS shaft in sal****er for 25 years and is doing fine. For a number of years now there have been a gazillion shafts and props made of SS and I don't recall a lot of problems with them. Ron James Johnson remove the "dot" from after sail in email address to reply |
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