Ripping stock for bird mouth mast

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Locutus
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Ripping stock for bird mouth mast

Post by Locutus »

I'm planning to build a bird mouth mast for my Skipjack. I'm wondering which type of board I should buy for ripping the staves. (I think that's what they're called.) I'd like to use Sitka Spruce, but it probably isn't available so will likely end up using Douglas-fir. Anyway, I drew up a quickie diagram showing four different board cross sections. The regular vertical lines indicate the rip cuts. Which type of cross sectional grain would be best for a bird mouth mast, which should I avoid, and why? Thanks in advance for your feedback.

Image

Mark Shank

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Lowka53
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Re: Ripping stock for bird mouth mast

Post by Lowka53 »

The top one you do not want 8)
ideal cut.jpg
ideal cut.jpg (14.22 KiB) Viewed 3375 times
the circled one is what you want :wink:
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Locutus
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Re: Ripping stock for bird mouth mast

Post by Locutus »

Lowka53 wrote:The top one you do not want 8)
ideal cut.jpg
the circled one is what you want :wink:

Really?
I would have thought the best one would be the first sketch. I've revised it below, showing the resulting stave cross section next to each one. Do you still have the same opinion?

Image

Mark Shank

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Lowka53
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Re: Ripping stock for bird mouth mast

Post by Lowka53 »

8) I stand by my statement quarter sawed lumber has the less shrinkage and warp-age I am a carpenter/cabinet maker with over 40 year experience with a degree in wood working. GD carpenter will probably tell you the same I think we both are about the same lvl of wood workers he maybe better than me even. The attachment show what the warpage is in lumber as it drys what you show would cup and warp very baldly
Don't be afraid to attempt anything. You might surprise your self in the attempt.
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Bon Voyage-"Wild Flower" 40' house boat being built
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32' Supper Huck-in design

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Re: Ripping stock for bird mouth mast

Post by gdcarpenter »

Perhaps this diagram may help appreciate quarter sawn and how it's cut. True quarter sawn logs are first 'quartered' then sawn so the grain is perpendicular to the board edge. With this method up to half the log is 'wasted', ergo it's expensive. It is however very stable as been mentioned earlier.

The video link may further help you follow where we are coming from.

http://woodtreks.com/why-sawyers-plane- ... umber/315/
Attachments
image.jpg
This is my first, last and only boat build.

http://www.gdzipbuild.blogspot.com

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Locutus
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Re: Ripping stock for bird mouth mast

Post by Locutus »

gdcarpenter, thanks for the diagram. Very informative.

Rod,
So here's what I think you're saying is the best way to cut the staves and assemble them. (Image copied from duckworksmagazine.com and then I added the woodgrain by hand.) Curve of grain cross section maybe a bit exaggerated but shows that you'd end up with a grain cross sectional pattern in the finished mast that closely resembles an actual tree.

Image

Mark Shank

gdcarpenter
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Re: Ripping stock for bird mouth mast

Post by gdcarpenter »

Do you want 'pretty like a tree' or do you want something strong with the least tendency to warp, split or check? I suggest you go buy a 1X12 white pine board that has grain running wide side to wide side like you have shown in your last diagram. Leave it outside for a week, or less if it rains, and see how badly it warps. There is a reason quarter sawn is valued despite it's expense - it is very stable!

It is your boat and you can build in any way you want, but Lowka53 and I are offering our advise towards your inquiry with years of woodworking experience. All the best with your build.
This is my first, last and only boat build.

http://www.gdzipbuild.blogspot.com

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Locutus
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Re: Ripping stock for bird mouth mast

Post by Locutus »

Well, now I'm confused. I thought you were both saying I should cut the staves such that the grain would end up like my last diagram. If I take a quarter sawn 2x12 board (actual 1 1/2 x 11 1/2) and rip a number of staves measuring 3/4 x 1 1/2, would they not look like the ones in my last diagram? Would the board not look like the second from top in my first and second diagrams? Or would they look more like the third from the top of my first and second diagrams? I'm not trying to contradict you, just trying to understand.

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Lowka53
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Re: Ripping stock for bird mouth mast

Post by Lowka53 »

:lol: One last try on how it should be sorry about the quick drawing
quarter sawn mast0001.JPG
I hope this answers your question
Don't be afraid to attempt anything. You might surprise your self in the attempt.
http://www.facebook.com/Home.Made.Boat.Building
Bon Voyage-"Wild Flower" 40' house boat being built
14' Mr John-being built
32' Supper Huck-in design

Rod H

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Locutus
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Re: Ripping stock for bird mouth mast

Post by Locutus »

Thanks. That makes it clear.

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