SS in lieu of Bronze Fasteners

[imported_Glenn]

I am a novice builder working on my first boat.

Can someone tell me if I could use Stainless Steel carriage bolts in lieu of Silicon Bronze bolts.

I am in need of 8 to 10 inch long bolts at 1/4 or 5/16" diameter to tie together my skeg, keel and stern knee on a Catspaw Dinghy.

The SS I can get local of the shelf and although I could work on other things for a few days, I'd rather keep myself going on the skeg and keel instead of waiting to order the bronze. Options are also good to know for future projects.

thanks for any feedback

[pjwalsh]

You can use ss if you want to. In a project this size the differences in material properties like strength and stiffness will not amount to much.

generally ss is stronger and stiffer but more brittle than bronze. both materials have excellent resistance to corrosion. Typically hardware store ss is 18-8 grade which is not really great for direct contact with water, but it is probabally just fine for this job.

But, I would go with bronze were it me. You can probably find what you need off the shelf at Hamilton Marine in Portland.

[ 03-07-2003, 10:02 AM: Message edited by: pjwalsh ]

[Ken Hutchins]

I would depend greatly on what wood you are using if you are using oak, the acid in the wood might attack the SS if it is not the proper grade. Also a lot of the SS bolts come from the far east, I wouldn't trust them for anything. Use the bronze.

[Bruce Hooke]

Stainless steel has a nasty habit of corroding if it's in a wet environment and sealed up inside a piece of wood. Could you temporarily fasten the parts in place with regular steel bolts, and then replace the bolts with bronze once the bronze bolts arrive?

[Ross Faneuf]

As mentioned, it's wise to use bronze below the waterline, or on anything which is going to be immersed in salt water.

Also, your hardware store stainless may be a grade suitable for decks and such, rather than a grade intended for marine use.

Jamestown Distributors is also a good source. I use Hamilton's myself, but they are only 1/2 hour away; don't know if they have a web site, as Jamestown does.

[JimD]

Glen, have you considered galvanized (zinc coated) steel bolts? Just keep them out of contact with other bronze fasteners or parts to prevent galvanic corrosion.

[Nicholas Carey]

Originally posted by Glenn:
Can someone tell me if I could use Stainless Steel carriage bolts in lieu of Silicon Bronze bolts.

I am in need of 8 to 10 inch long bolts at 1/4 or 5/16" diameter to tie together my skeg, keel and stern knee on a Catspaw Dinghy.I'd go with the silicone bronze myself. You might have a hard time finding 8-10 inch carriage bolts, too, and if you do, they'll be expensive.

It might be cheaper and easier to use silicon bronze rod instead. You should be able to get silicone bronze rod from any decent non-ferrous metal supplier, or from other sources (see below.)

We pay about $4-6 US each for 4- or 5-inch x 1/4-20 silicone bronze carriage bolts. Online Metals (http://www.onlinemetals.com/) will sell you 1/4-inch silicone bronze rod (http://www.onlinemetals.com/merchant.cfm?pid=7819&step=4&showunits=inches) for $0.35 per inch (custom cut) or $2.42 in a pre-cut 1-foot length.

Cut the rod to length, thread each end with an appropriate die, then bolt the assembly up with a thrust washer, lock washer and a nut on each end. If you want to make sure it never comes apart, peen the ends of the rod down on the nut.

[Mrleft8]

I'm in exactly the same stage of my catspaw.... I used Galvanized carriage bolts at the stem... Stainless at the keel/gripe... and galvanized again at the keel/skeg. If galvanized won't last, I'll find out soon enough, but I figure it'll last long enough for me to find another boat to build, and by then I'll find a decent source of bronze hardware. Where did you find #13x1 1/4" rivits?....