Inwale scarfs.

[ppine]

I am right at the point of replacing two pieces of inwale on the OT Guide 18. They are 1 x 3/4 inch pieces of stock that looks like ash. What ratio do you like for scarfs? I am thinking around 6:1, maybe 8:1.

 

[alsg]

If I recall correctly, 8:1 is the minimum recommended to ensure no loss of strength.

 

[Jim Dodd]

I use a 10-1 ratio. but many posts I've found state a 8-1 as sufficient.

I use mixed epoxy to saturate,joint, (both sides) and then add filler to the batch I just mixed. Coat at least one side, and clamp. I also wait several days before stressing the joint.

So far no fails !

 

[Boatman53]

I would do 10x1 but 8x1 would most likely be fine.
Jim

 

[ppine]

Okay., Thanks. There is no indication of the material used for the gunwales on the original build sheet. The boat has white cedar ribs and red cedar planks. The thwarts and seats are ash. The gunwales even with the patina filed off are hard to identify. Besides white ash, what other material did Old Town use in 1953 for gunwales?

 

[Glenn MacGrady]

Besides white ash, what other material did Old Town use in 1953 for gunwales?

The old catalogs and build sheets I've seen say that AA grade canoes had mahogany gunwales and CS grade canoes had spruce gunwales. You can get the build sheet for your canoe via its serial number from the WCHA, possibly by just posting in the Serial Number Search forum

 

[ppine]

Thanks Glenn. Mine is CS grade. As I mentioned above, I have the build sheet and the space is blank next to gunwales. It is easy to believe that the existing inwale is spruce and not white ash. Your comment is logical and helps a lot. I can find Sitka spruce on the West Coast much easier than white ash. It has been used a lot for airplane construction due to the high strength to weight ratio as in the Spruce Goose.

I found a Sitka spruce 2x4 that is 12 feet long. They want $135 for it.
White ash is only $40 for the same thing.
It would be much cheaper up in WA where they have a lifetime supply.

 

[ppine]

Since my rib ends are still in tact, and the planks are all in place it is somewhat difficult to remove the screws holding the inwales to the decks. It is really difficult to get inwale stock over about 12 feet, which means a scarf, or maybe two if sent through the mail. I am now considering scarfed in 7 footers made of white ash matching on each side. The mounting holes for the middle carrying yoke have shredded the inwales over the years. The new pieces would extend from in the front of the rear seat to about a foot beyond the middle thwart. Each would require a scarf on each end. Ash is easier to bend than softwoods like spruce from what I have read. It is stronger for this usage and less than one third the cost. I do not care about using two types of wood (spruce and ash) as long as the repair is done properly. This is not a restoration. This is my first wood canoe repair, so I am happy to hear ideas from people with a lot more experience.

 

[Iskweo]

We have done inwale scarfs on a couple of boats and when in doubt just go to the lumber store and pick through the construction grade studs ( SPF) until finding one with a close grain. We have also in the past used Douglas Fir which you should have in abundance. It is also a little better for rot resistance. I personally try to use the original woods when I can so spruce would be my pick. It is tough to get a decent scarf on small pieces of wood like inwales. Try a couple of test pieces first to see if you can get it close to what you want.

White Ash
42 lbs per cu ft
hardness rated 1320 ft lbs

Douglas Fir
32 lbs per cu ft
hardness rated 620 ft lbs

Sitka Spruce
27 Lbs per cu ft
hardness rated 510 ft lbs

White Spruce
27 lbs per cu ft
hardnesss rated 480 ft lbs

 

[PeteStaehling]

We have done inwale scarfs on a couple of boats and when in doubt just go to the lumber store and pick through the construction grade studs ( SPF) until finding one with a close grain. We have also in the past used Douglas Fir which you should have in abundance. It is also a little better for rot resistance. I personally try to use the original woods when I can so spruce would be my pick. It is tough to get a decent scarf on small pieces of wood like inwales. Try a couple of test pieces first to see if you can get it close to what you want.

Yeah, I always thought that finding wood with nice close grain and with not much runout is key. Close grain fairly well aligned with the length of the inwale is pretty critical in determining how strong the piece will be. If there is a ton of runout it will in essence be the equivalent of a too short scarf joint in the grain even before any joints. In that case long scarfs will be kind of futile since even shortish scarfs are likely to not be much worse than the grain in the inwale already is before you do any joints. Not that I am suggesting short scarfs in any case, just that wood selection is more key than anything else.

If you live somewhere that you have access to a cooperative lumber mill getting what you need is easier. When I was in Maryland I'd go to one of the mills in SE PA (usually Groffs and Groffs) and they'd be happy to fix me up with something that was exactly what I needed usually with no need for scarf joints. At times when I didn't have a well equipped shop they'd mill it into exact dimensions for a decent price. In other years I'd break it down myself.

BTW, how are you guys cutting your scarf joints? I haven't cut inwale scarfs in years but used a jig for a router when I did. It was kind of the same principle as the way they flatten slabs with a router.

I think if I were going to build a jig today it would use a hand plane on similar rails. It would remove material fast enough and be very precise.

 

[ppine]

I just got a call from Jerry Stelmok at Island Falls. He thinks the 7 foot white ash scarf idea is a good fix. This is a highlight in my wood canoe rebuilding career. That puts a bounce in my step. Thanks for all of the comments.