Stainless Running gear?

[danshat]

I am in the process of replacing the running gear. I plan on replacing the main and intermediate struts, shaft seals, rudders, rudder ports, shafts, and props. There is a guy local who says he can fabricate the struts, rudders and ports out of stainless. Is this a good idea? I know it brings some bonding issues in but other than that what are the pros and cons.

Thanks
Dan

 

[captddis]

I would much prefer the bronze if I had a choice. That said, most of the custom boats and many boats that have been repowered have custom stainless struts and rudders. I have seen numerous SS struts break at the welds. I am sure quality varies greatly and the proper welding rods need to be used. The SS rudders are usually fine. YMMV

 

[Boss Lady]

Silicon bronze is the material of choice for struts. Silicon bronze can be welded and fabricated the same way as stainless. Gas Tungsten Arc Welding can be used with direct current straight polarity (electrode negative) and Silicon Bronze filler metal RCuSi-A, if needed for sections thicker than about 3 mm (1/8"). Thoriated Tungsten electrode (EWTh-2) is used for best life and minimum tip maintenance. Shielding gas is usually argon.

Stainless can be used but it will have short service life compared to bronze. With the high cost of fabrication and materials, I would go the extra step and get the bronze fabricated vs the stainless. I have seen submerged stainless fail within a year. The iron is oxidized at the molecular level, the bronze is just about impervious, especially with zincs.

Show the technicals above to you fabricator if he is not familiar with welding SiBronze.

Just my $0.02

 

[yachtsmanbill]

As BL said, the bronze is probably the way to go... in salt water anyway. On the sweetwater seas, we use a lot of stainless tho... ws

 

[bostonhatteras]

i would find out exactly what stainless alloy he would intend to use and what welding rod is required with that particular alloy. 316 at a minimum. fyi 18/8 is an old designation for what is now known as 304, the higher the number the better the corrosion resistance, in the 300 series that is. without digging out Nigel Warrens(?) 'metal corrosion in boats' he speaks about oxygen deprivation of stainless and how this creates a highly corrosive environment for the metal, dirty water makes it worse. your shafts are stainless or monel because bronze shafting doesnt hold up to the speed and horsepowers common today. what is wrong with the old struts? wilcox crittendon makes cast bronze struts in various shapes.
good luck

 

[dsharp]

Check with Buck Algonquin. They probably made the original equipment. I would be cautious with stainless, the quality seems to be unpredictable in salt water.

 

[krush]

To say stainless steel is not enough information--and this is where most people get into problems. There are tons different alloys when it comes to SS and choosing the wrong one for the application is often catastrophic.

 

[danshat]

Thanks for all the input guys. Found another guy who says he can get the stuff from Buck Algonquin in bronze. appreciate the help as always!