Bronze vs Other Metals?

What kind, options, etc.

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Benj269
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Bronze vs Other Metals?

Post by Benj269 » Wed Oct 08, 2014 12:00 pm

This doesn't really fit perfectly into one of the forum categories, but I am planning on building a Crackerbox, so I am going to ask here.

The closest salt water is 1000 miles away from me, so my boat will be used exclusively on freshwater lakes. I am at the "excel spreadsheet-adding up the sticker shock" portion of the planning. I am researching hardware and see that for bolts there are at least two options. Bronze and hot-dipped galvanized steel. Everyone here probably knows the difference in price of these two options. For exhaust ports and shaft logs, the choices are chrome plated bronze or polished aluminum. If I'm going to stay away from salt, is there any reason to not go with HD gal steel and Al? I do realize the difference between polished Al and chrome and their respective upkeep needs.

Benjamin

John K
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Re: Bronze vs Other Metals?

Post by John K » Wed Oct 08, 2014 1:02 pm

You can also use stainless steel. Some SS can be use also in salt water. I used all SS on my flying saucer every where I could.

sands35
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Re: Bronze vs Other Metals?

Post by sands35 » Wed Oct 08, 2014 1:54 pm

Yes, stainless if OK. If possible, use 316 with matching 316 grade fasteners.

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Bill Edmundson
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Re: Bronze vs Other Metals?

Post by Bill Edmundson » Wed Oct 08, 2014 3:19 pm

I'm in salt/brackish water. Bronze and 316 SS are the order of the day. 316 SS doesn't pit as bad as other grades. Other grades are ok. But, don't look good as long. Chrome pits.

Chrome will work in fresh water with some wax to protect it. SS that is completely sealed will corrode. It's called Inter Granular Corrosion Stress Cracking. SS needs air. But, it probably won't get you. I'm not real proud of how I know this. :lol:

I guess it may depend on how long you want the boat to last.

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
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jcallends
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Re: Bronze vs Other Metals?

Post by jcallends » Thu Oct 09, 2014 5:55 am

Some wise soul previously stated in this blog that "stainless" is just as the name is implies, less corrosion but certainly not corrosion free.

Benj269
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Re: Bronze vs Other Metals?

Post by Benj269 » Thu Oct 09, 2014 6:03 am

I think I'm going to go with HD galvanized. For all the carriage bolts, nuts, and washers I would need, galvanized would be about $10. SS would be about $200, and bronze would be $600.

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hoodman
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Re: Bronze vs Other Metals?

Post by hoodman » Thu Oct 09, 2014 8:01 am

There must be a lot more bolts in the crackerbox than in my build. I only needed 6 bolts so I went with bronze. It was over $40 for the set but just a small percentage over the cost of the entire build.
Matt

Building a Geronimo......!
viewtopic.php?f=2&t=25139

Benj269
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Re: Bronze vs Other Metals?

Post by Benj269 » Thu Oct 09, 2014 8:22 am

hoodman wrote:There must be a lot more bolts in the crackerbox than in my build. I only needed 6 bolts so I went with bronze. It was over $40 for the set but just a small percentage over the cost of the entire build.
Qty 48 - 1/4" carriage bolts for motor stringer to frame reinforcement blocks. Assuming 2" motor stringers, 1" frames, and 1.5" blocks, I would need twenty four 3" and twenty four 4" bolts.

Image

Also there are two 5/16" bolts for the keel to stem connection.

Curiously, I don't see them in Fergal's build. I'll have to ask him about that.

Benjamin

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hoodman
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Re: Bronze vs Other Metals?

Post by hoodman » Thu Oct 09, 2014 8:33 am

If they are in the motor stringers you might have access to them to replace them if they ever went bad. The stem to keel connection will be embedded under epoxy I would think about springing for bronze for those maybe since you only need two.
Matt

Building a Geronimo......!
viewtopic.php?f=2&t=25139

John K
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Re: Bronze vs Other Metals?

Post by John K » Thu Oct 09, 2014 12:17 pm

316 SS is the only stainless that resists corrosion from salt. We used it all the time for our food processing equipment that was exposed to salt.

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jprice
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Re: Bronze vs Other Metals?

Post by jprice » Fri Oct 10, 2014 6:44 am

For the screws I went with bronze, but for all the bolts I also went the galvanized route.
In addition to them being galvanized, they're also covered with some epoxy and several coats of bilge paint.
My boat will only see freshwater as well.
I'm not worried.

cusoak
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Re: Bronze vs Other Metals?

Post by cusoak » Fri Oct 10, 2014 6:56 am

Where about's do you live that the price of Hd and SS or Bronze are that much differIent it price.
The other thing that I have found is that HD bolts don't seem to be as strong as regular steel bolts. I would stick with SS bolts as I also don't think they are harder than bronze. I used all SS in my Zip build.
Jeff

Benj269
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Re: Bronze vs Other Metals?

Post by Benj269 » Fri Oct 10, 2014 1:34 pm

My initial price estimates were based upon assuming all carriage bolts to be 4 inches. There is quite a price difference between 3 and 4 inch bolts. I seemed to recall seeing $8-9 per bolt for SB and then assumed at those prices the washers and nut would add another dollar to the price. I did some quick shopping cart addition and came up with:

Silicon Bronze: $320 shipped from BoltDepot
HDG : $25 shipped from BoltDepot
316SS : $147 shipped from Fastenal

Not quite as expensive as I had thought, but still a 6X and 13X difference in price over HDG. I just can't see spending the extra money for something IF it really only benefits you in a saltwater environment. And, since they would still be somewhat accessible, they could be replaced in the future if need be.

I'm not aware of HDG screws, so I will have to go with SB for those.

Craig Aho
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Re: Bronze vs Other Metals?

Post by Craig Aho » Fri Oct 10, 2014 1:45 pm

As I have been building my Sea Knight I often felt like the cost for the bronze screws was as expensive as gold and silver. I often have felt guilty of not having any investments but now realize I have a healthy investment in bronze. So if your like me I say go with the Bronze baby. :lol:

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Bill Edmundson
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Re: Bronze vs Other Metals?

Post by Bill Edmundson » Fri Oct 10, 2014 2:31 pm

If you go galvanized, you want hot dip galvanized. Mechanically coated galvanized are just that coated. Hot dipped actually changes the surface of the metal. For you Hot dip should last a long time. I doubt that you get hot dipped screws.

Bill
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