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Old 23-11-2021, 07:00   #16
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Re: Replacing Base of Wood Mast

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Fourlyons,

Let me rephrase that. If water gets into a hollow mast, it will rot from the inside out. Don't ask me how I know that. The mast I showed in the picture is a round hollow mast but because it has very few fasteners was able to survive 50 years with minimal maintenance. It literally had moss hanging from the spreaders. Blew me away.
Sure, that makes sense. But that is a poor design or poor maintenance issue, there is nothing inherent to hollow wood masts that gives them a 50 year lifespan. Indeed there are examples that are more than twice that age. But it sounds like you know this.
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Old 23-11-2021, 11:15   #17
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Re: Replacing Base of Wood Mast

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As you note, flat sawn is more prone to cupping and twisting which will stress the glue lines and want to distort the box in general. The consensus is actually that quarter sawn checks less, not more, than flat sawn lumber.
A flat sawn board 6 in wide has a great deal more movement than than a board one and a half inches thick, that is quarter sawn. The comparison is 6 in to one and a half inches, that is going to encourage checking. If you look at the typical residential wood deck closely, you will see this is the case. For the same reason wood decks on boats are always, ideally, spec'd for quarter sawn lumber.
Yes, It is an interesting discussion. For stiffness quartersawn is best (when oriented that way!) I have ordered several quartersawn guitar necks in the past. What I intended to point out was if quartersawn is used on the mast sides, then it doesn't add the fore/aft stiffness one would think would be desireable...? But I suppose it's mostly inconsequential in the scheme of things really.
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Old 24-11-2021, 03:16   #18
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Re: Replacing Base of Wood Mast

This is fantastic guys. Much appreciated. By all means, continue discussing!!!
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Old 24-11-2021, 21:38   #19
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Re: Replacing Base of Wood Mast

I built a few wooden masts for DN class iceboats back in the day. Directions called for quarter sawn Sitka spruce. It was a two piece lamination using resorcinol glue. They were very durable and loads were EXTREME.
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Old 25-11-2021, 01:54   #20
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Re: Replacing Base of Wood Mast

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Originally Posted by Cheechako View Post
Yes, It is an interesting discussion. For stiffness quartersawn is best (when oriented that way!) I have ordered several quartersawn guitar necks in the past. What I intended to point out was if quartersawn is used on the mast sides, then it doesn't add the fore/aft stiffness one would think would be desireable...? But I suppose it's mostly inconsequential in the scheme of things really.
I would ("wood?") think that quartersawn wood is spec'd to ensure continuous fibers along the length of the mast, or as close to it as possible. Similar to steaks and fiberglass - long continuous fibers are tough / stiff, short fibers are tender / flimsy.
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Old 26-11-2021, 19:41   #21
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Re: Replacing Base of Wood Mast

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Originally Posted by Cheechako View Post
Yes, It is an interesting discussion. For stiffness quartersawn is best (when oriented that way!) I have ordered several quartersawn guitar necks in the past. What I intended to point out was if quartersawn is used on the mast sides, then it doesn't add the fore/aft stiffness one would think would be desireable...? But I suppose it's mostly inconsequential in the scheme of things really.
Ok, I understand now. That's a good point. I suspect the other advantages of quartersawn may out weigh the stiffness advantage to be gained fore and aft. Or perhaps the lateral load of the mainsail is more of a concern than the fore and aft loads?

Good call on the sugar maple (I'm guessing?) guitar necks.
I was curious to look up the magnitude of difference we are discussing, in the Wood Handbook, Wood As An Engineering Material, I discovered a table for 40 US domestic species, 20 softwoods and 20 hardwoods. A rough average was that quarter sawn is twice as stiff. Interestingly, Redwood was the sole exception with a 1:1 ratio.

Just some wood trivia
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Old 26-11-2021, 19:50   #22
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Re: Replacing Base of Wood Mast

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I would ("wood?") think that quartersawn wood is spec'd to ensure continuous fibers along the length of the mast, or as close to it as possible. Similar to steaks and fiberglass - long continuous fibers are tough / stiff, short fibers are tender / flimsy.
Actually you can get long fibers from plainsawn, just not continuous. A standard I once read from a structural engineer, is that you want no more than 10 percent grain runout, whether quarter sawn or plain. I suppose that makes sense, in that a scarf ratio of between 8:1 and 12:1 is considered to equal a continuous board in strength.
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