Steel Screws in 70's Greenwoods

[steve bennett]

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From: Wood Canvas Jewels: The Canoes of Bill Greenwood February 9, 2012 by Mike Elliott

"The one drawback in many Greenwood canoes built in the early 1970’s is the fact that he used steel screws to attach the mahogany outwales. Apparently, Bill was feuding with one of his suppliers. He wanted 1.5” (37 mm) #8 brass wood screws in lots of 1,000 while the supplier insisted on selling in lots of 10,000. Bill ordered steel screws from another supplier in lots of 1,000. I have had to cut that beautiful mahogany into hundreds of tiny pieces because the steel screws had corroded to the point of being fused into the wood. I’m sure Bill thought he had won the war with his supplier, but it has made the restorer’s job much more difficult 40 years later."​

My Greenwood is in great original shape. I checked a gunwale screw and sure enough it was ungalvanized steel. Fortunately it came our pretty well. Gonna replace them all if I can. Question is, should I replace them with brass or stainless? What do I re-putty the holes with?

Thank you,
Steve

 

[Dan Miller]

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Question is, should I replace them with brass or stainless? What do I re-putty the holes with?

Neither. Use silicon bronze screws. I've not seen puttied gunwale screws. Usually they are just countersunk to just below the surface.

 

[steve bennett]

Thanks again Dan,

I imagine it was necessary to putty (or plug) to prevent them from rusting or bleeding.

 

[steve bennett]

Would one generally use silicon bronze to replace brass screws as well? Would there be an authenticity issue?

 

[steve bennett]

Another question for Greenwood owners: Do your canoes have puttied gunwale screw holes in any but the early 70's models? Are your early 70's models puttied? Maybe mine was retro-puttied, but I think not.

By the way, all the gunwale screws on this model are screwed are from the outwale.

 

[davelanthier]

Every Greenwood I have restored had ferious outwale Robertson screws. They were all filled with pink auto body filler as a putty. When I restore them I use brass Robertson's wthout the putty. If someone wants to be correct it is easy enough to instal the putty at a later date and the brass won't be seen.

 

[Dan Miller]

Would one generally use silicon bronze to replace brass screws as well? Would there be an authenticity issue?

Bronze is a whole lot stronger than brass, and old bronze is stronger than modern day stuff, for the most part (old brass, if you can get it as NOS (new-old stock) is much better, too). My preference is to use, and replace with, bronze, unless there is a reason to do otherwise - e.g. I use brass for stem bands for the color match.

If you are going to putty the holes (are they deep enough to bung them?), you could use stainless, as they won't show. Stainless otherwise looks way out of place on boats like this.

 

[steve bennett]

Upon closer examination, I found that the steel screws that I removed from the Greenwood had a narrower throats than their threads and had a different thread angle than the standard # 8’s that I looked at for replacements. The counterman at Tacoma Screw said that they were tapping screws, and that there were no standards for tapping screws, and likely couldn’t be matched.
I was able to find # 8 1-1/2” silicon bronze screws with full throat in square drive, but not in Phillips. These seem as good a replacements as I am going to find, but the square drive is hardly traditional and Dan preferred bronze over stainless for tradition. There is a product called Frearson, (see product description below) which has the Phillips type head, but a different design which I didn’t understand. What’s the best choice?

Steve

“#8 Silicon Bronze Frearson Flat Head wood screws appear similar to the Phillips head but the Frearson has a more pointed 75° V shape. The Frearson tool recess is a perfect cross which minimizes cam out, unlike the Phillips head, which is designed to cam out.
Traditional boatbuilders love these Silicon Bronze wood screws because they have cut threads and the full-bodied diameter shank. Unlike rolled thread screws with their reduced shank--these screws have a shank diameter that is the same size as the outside of the threads. This completely fills the clearance hole normally drilled for the shank thus creating a waterproof seal.”

 

[davelanthier]

I'm curious. Since you are going to such indepth screw detail why would you use an American Phillips screw on a Canadian canoe? The Canadian canoe builders used either slotted or Robertson [ square head ] screws.

 

[steve bennett]

Dave,

The simple answer is that I am ignorant. I'm happy to discover that I can replace the potentially damaging screws with something that will last. I figure that I want to fill the old holes as closely as they were before. I'm not looking for in-depth detail. I think the gunwale holes that once were plugged can be left open now. Am looking for what is the best choice for the canoe. And I appreciate your interest and question.

Steve

 

[steve bennett]

Dave,
In addition to being ignorant, I'm a little slow on the uptake. Yeah. I can get the silicon-bronze #8's with flat, slotted heads. And will do. Thanks for the guidance.

Steve