SS vs. Brass vs. Bronze wood screws

[EKE]

Simple question:

Stainless steel vs. brass or bronze wood screws for fastening various frame and trim parts in a small wooden boat....why would I choose one over the other?

Structural strength?
Corrosion issues?
Other concerns?

[htom]

Brass is for bells and belt buckles; don't use it for fasteners for anything larger than a cigar humidor.

[Noah]

It really depends on what other metals you have used, and if the parts are under water, etc.

Generally Bronze screws are the best. They don't have problems being under water, and do fine with salt, etc.

SS is only stainless when it has oxygen. If it's in an anaerobic environment, it will get crevice corrosion, which will lead to problems.

Brass screws really don't have any place on a boat. They will corrode and vanish very quickly.

[John of Phoenix]

Brass is too soft to be of much good. Nice for cabinet hinges and the like, but not for strength. You'll twist lots heads off just getting them screwed in.

Stainless is strong and non corrosive as long as it's exposed to air, ie not submerged.

Silicon-bronze is the best combo of strength and durability, even below the waterline. Guess which is most expensive.

In a small boat you might want to splurge on the good stuff. It shouldn't cost too much more to go first class.

[Vincent Serio III]

A follow-up question: can you use stainless on a dry-sailed boat whose screw holes are "puttied", i.e with epoxy--I would assume that this would qualify as an anaerobic environment--or does it? Can enough air molecules get through the wood to start the chem reaction necessary to "coat" the steel?

Does it even matter such that the dry-sailed boat rarely sees enough water to get into the fastening hole, and therefore not corrode?

[Scott Rosen]

I think you could use stainless fasteners on a dry-sailed boat without worry.

Stainless is a lot less expensive, and is stronger than bronze.

[Gary E]

Originally posted by Vincent Serio III:
A follow-up question: can you use stainless on a dry-sailed boat whose screw holes are "puttied", i.e with epoxy--I would assume that this would qualify as an anaerobic environment--or does it? Can enough air molecules get through the wood to start the chem reaction necessary to "coat" the steel?

Does it even matter such that the dry-sailed boat rarely sees enough water to get into the fastening hole, and therefore not corrode?I can show you small sailboats that are put together with BRASS screws, puttied over with who knows what cuz that's all we had in the mid 1950's that are doing just fine. The typical treatment they got was tossed in the lake on Sat morn, put back on the rack on Sunday afternoon.... there still doing that... would I use brass today? maybe.. depends on my wallet and the use. If I have my druthers, I'd spring for the better material every time.

[Bruce Hooke]

If you can really count on the boat being dry sailed you could probably get away with using regular hardware store steel screws! I don't recommend it, but a dry-sailed boat does lead a pretty cushy life (if it is properly stored!). You may, however, want to consider that somewhere down the road the boat may get store outside and allowed to get water and such inside that is not cleaned out, at which point it is not really being dry-sailed...

I would probably make the decision in concert with other related decisions being made about the boat. For example, if everything in the boat is being glued together with epoxy (and maybe even coated with epoxy) then if some screws fail due to crevise corrosion it hardly matters. In addition, if the woods being used are not very rot resistant then the wood is likely to fail before the screws if water gets in next to the fastenings and sits there. If, on the other hand, the boat is going to be built using traditional materials and techniques that it would seem to me to be very false economy to save a few dollars on the screws when the rest of the boat is going to be built using materials that are designed to survive being wet for long periods of time and when screws are integral to the strength of the structure.

[Bruce Hooke]

By the way, in general I would avoid brass just because it is annoying how weak the stuff is! After you've twisted off your tenth screw and wasted lot of time extracting or otherwise dealing with the screw rememants left in the wood I think you will likely be cursing the day you went with brass.

[Jay Greer]

A guy I once knew argued that brass was more exonomical to use and so, fastened his hull with brass.
His boat sank at the dock. Reason, the brass fastenings disintegrated in one season! He then re-fasteded with bronze. He didn't save much there did he? He could have fastened whith bronze to begin with, left out the engine, bought a bigger spinnaker and had money left over for beer and prezels for several months of pleasant sailing instead of being layed up on the beach!

[Vincent Serio III]

Yeah, my grandfather used brass in his boat business. I'm refastening a few planks now on one of his old (1947) boats--the brass is in good shape, but I don't want to refasten it with brass.

I think as long as you leave it alone, the brass is fine on a dry sailed boat.

[Scott Rosen]

Vincent's post reminded me that a boat kept in fresh water will have much less of a problem with galvanic corrosion. In fresh water, brass could last a long time. Brass is about half the price of stainless and bronze.

If it were my boat, I'd use bronze. A boat you intend to dry sail today, may be kept in the water by another owner some years down the line.

[JimConlin]

Also, don't bring a copper alloy (brass or bronze) anywhere near aluminum. If fastening aluminum hardware or to an aluminum spar, use stainless.

[Tristan]

The amount of work one puts into building a boat does not warrent going with second rate materials. That said, I've used ordinary galvanized finishing nails to fasten strip planked boats with, knowing they would be sheathed in fiberglass inside and out.

[wyndham]

Bruce really hit it. Brass is just too damn soft. The screws will strip, they will twist off in the holes....why bother? If your going to dry sail it and it's going to be sheathed and the fasteners are going to be covered and never seen, go with galvanized drywall screws. They are cheap, strong, plentiful and will last. Use a good screw pilot to drill the proper depth countersunk holes.

[essaunders]

This conversation leaves me with two questions:
should I remove the (red?) brass tubing I have used in either end of my (cedar-strip) canoe (painter attachment points) and replace with something else? I only epoxied it in last night.... Mac (Featherweight boabuilding) suggested pvc pipe in the book but I didn't have anything handy so I purchased this brass tubing (it was smaller, and prettier)

What should I use to fasten the plastic inspection hatches to my bulkheads (there is a question of bedding material too, but I was saving that for when I get pictures taken...). I guess I had notionally thought about using brass bolts (though epoxy filled, then drilled holes)

[htom]

The brass/copper tubing as a lining for a hole is probably OK. Bronze bolts, or stainless, depending on appearance.

[Bruce Hooke]

Originally posted by essaunders:
This conversation leaves me with two questions:
should I remove the (red?) brass tubing I have used in either end of my (cedar-strip) canoe (painter attachment points) and replace with something else? I only epoxied it in last night.... Mac (Featherweight boabuilding) suggested pvc pipe in the book but I didn't have anything handy so I purchased this brass tubing (it was smaller, and prettier)If it were me I would leave the brass. A canoe is pretty much always dry sailed and furthermore, I am guessing (without seeing the actual installation) that in the unlikely event that the brass did start to fall apart it would be very obvious that something was going wrong long before the painter would pull out of the stem. I am guessing that the brass is there mostly to provide some abrasion resistance and to make a smooth hole so that it is easy to pass a line through the hole. The strength of the whole thing probably comes mostly from the wood that the rope and bushing would have to pull through to come loose. I would be careful that there are not sharp corners where the brass tube ends because sharp corners can wear through rope in a hurry. You want a nice gentle curve for the rope to bend around.



What should I use to fasten the plastic inspection hatches to my bulkheads (there is a question of bedding material too, but I was saving that for when I get pictures taken...). I guess I had notionally thought about using brass bolts (though epoxy filled, then drilled holes)Since these fasteners will be exposed to the air stainless steel would certainly be a fine choice. However, given that the canoe will presumably be dry sailed and given that these plates are on the interior of the boat and will therefore normally just get damp rather than staying soaking wet even when the canoe is in use, I think brass would also work just fine. Furthermore, the highest stress on these bolts is likely to be when you are removing the inspection hatch so if a failure does occur (which I think is VERY unlikely) it would most likely just be annoying rather than being dangerous.

It seems to me that brass has commonly been used on canoes, and that it seems to work fine, probably because most canoes are dry sailed and most canoes are used on fresh water...

[Gary E]

Your in NH, it's a canoe...
I am guessing that it will spend little time actually in the water which will be fresh water.
I would not change anything you have done, and in fact would stay away from pvc anything, in cold weather it will likely crack. As for the screws?.. the ones used in the mid 50's to make those little sailboats are still ok.. your call.

[essaunders]

Thanks. Brass stays in. Probably will do brass for the inspection hatches. They don't have to be tight. By my figuring, they mostly provide a (very) little shear and tension (doing and undoing the hatch while mostly keeping the hatch close to whatever bedding I use. I noticed that many canoe trim pieces are brass, padeyes, rubstrips etc.

and I'll watch carefully for sharp edges on the painter holes. Still have to cut those flush, so that'll be the step for that.

edited to add:
Any brass that corrodes on this boat will be easy to replace. Worst case, drill out (even painter holes.. I only used half inch OD brass there...) and replace.

[ 06-06-2005, 06:49 PM: Message edited by: essaunders ]

[Gary E]

Before you cut to much off you can probably take a hard socket head bolt and use the body of that to roll the edge of the tube to flare it out, much like a trumpet, practice on some spare first..

[Bruce Hooke]

Since you will be cutting the brass off flush with the surface you will not be able to round it over that much. I would try to round it as much as you can, and if you do I don't think you will have problems unless you plan to tow the canoe a lot behind another boat. It is always a good idea to check the painter occassionally to make sure it is still in good shape. If it shows signs of significant wear then don't trust it until you replace it. Realistically, however, it seems like most people I know pull their canoe up on shore anyway rather than trust to a painter when they are either on a big lake or a moving river where a loose canoe could quickly get carried away by wind or current.

[essaunders]

the bolt head idea sounds good. I'll see how it goes -- I'll epoxy another piece into a 2x4 and try flaring that... In reality I should have flared before epoxying in... but the best thing about building a first boat is I can fix all my mistakes next time....: )

[Gary E]

Take 2 board...hold them together in a vice... drill the hole using the joint as the centerline... then you hold the tube in without glueing while you flare.. if it slips a little,,sand some off of the joint..

[essaunders]

Ahh. Gary, now I see what you are proposing. However, The tubes are already epoxied in the hull. My experiment was to see how the tubes would flare when backed by epoxy and wood. My guess is not much (if at all) and I'll be resorting to just rounding the edges and smoothly as possible.

[Robert McNitt]

refer to chapter 2 in Don Danenbergs book volume 2 on fastener metals.

[Kim Whitmyre]

On my ply/glass/epoxy cat, the forward tramp is lashed onto white oak rails ss screwed and epoxied to the hulls(by the original builder). The screws were counter-bored and filled. Unfortunate! The ss screws are being eaten by the white oak, as can be seen where the filling is rust colored. I did some work on the sterns that required me to chisel off about 6" of similar material: the two ss screws encountered were half gone. The cat was built in 1996.