Guideboat planking question

[Lazy Jack]

Happy Holiday

I am planning to assemble an Adirondack Guideboat this summer and I have prefab'd all the laminated ribs, stems, seats, risers, everything that can be built without building

So the question is about planking. Historically, quatersawn white pine was used by the adirondack builders and the boats I studied at the Adirondack Museum all seemed to have quatersawn planking.

I don't know where to obtain this without considerable cost, but there is plenty of the rift sawn select white pine to be had locally. I would produce 3/32 inch planking stock from resawn 5/4 select stock and double plank the hull with the seams staggered the width of the traditional lap to circumvent the need to carve full thickness planks to the contours of the hull (requres much time and skill of which I have neither) Does quartersawn really matter on 3/16th softwood planking that is heavily fastened and epoxied to a boat that is only in the water while being rowed?

[Bob Smalser]

The difference in seasonal movement between quarter sawn and rift sawn is moot....and rift sawn has the advantage of taking fasteners better in traditional planking.

Rift sawn is still considered "vertical grain" and looks like this, tho, to be sure we are talking about the same thing:

http://pic3.picturetrail.com/VOL12/1104763/3223936/39972445.jpg

Personally, I'd look to using riftsawn cedar instead of pine for glued planking...it's cheaper than qsawn, lighter than pine and it moves less.

Given a 3' expanse of crossgrain planking in your hull, pine will move seasonally anywhere from .25 to.75 inch, depending on the degree of vertical as opposed to flat grain. Cedar, in contrast, will move a full third less than that, .17 to .40". Epoxy is flexible stuff, but pine in a trailer boat may push the limit of its flexibility in those crossgrain plank to frame glue joints.

[Lazy Jack]

Hey thats the stuff! Where could I get some? That would be perfect! Cedar has been used although Grant felt it too "spongy and puffy when thoroughly wet thereby destroying the symmetry of the vessel" [Durant: The Adirondack Guideboat] What do you suppose he meant by that?

You provided me information about the relative movements of cedar versus pine over changes in moisture content, (thanks for that by the way) but in reality, under several coats of paint or varnish and short term immersion, how much would the moisture content realisticly change? Hmm..calls for another shop experiment...

[Bob Smalser]

That's CVG Doug Fir in the truck from the local sawyer....namely, me. Find your local sawyer by talking to local arborists and loggers.

On a trailer boat in Vermont I'm guessing the seasonal swings will be 9 to 15%.

Coat the outside of a cedar hull with epoxy, and "spongy" is no longer much of an issue.

[ 12-29-2004, 11:40 AM: Message edited by: Bob Smalser ]

[Lazy Jack]

I just re-read your post, you spoke to SEASONAL changes which is a much longer equilibration period not to be prevented by a few coats of finish...and the beautiful examples at the ADK museum are of course in a stable environment...

I also mispoke when I refered to rift sawn, most of the stuff I can lay my hands on is cut mostly tangent to the annular rings (90 degrees from quarter sawn)ya know, the Home Depot cut. What kind of seasonal movement is there at that orientation? Is there enough compliance in each plank to accomodate the seasonal changes without compressive set and or splitting? I suppose I could construct a little shop experiment...

I'll look into the cedar thing

[Bob Smalser]

Given a 3' expanse of crossgrain planking in your hull, pine will move seasonally anywhere from .25 to.75 inch,depending on the degree of vertical as opposed to flat grain. Cedar, in contrast, will move a full third less than that, .17 to .40". Epoxy is flexible stuff, but pine in a trailer boat may push the limit of its flexibility in those crossgrain plank to frame glue joints. Flat grain = plain sawn = flat sawn = Home Depot cut.

[Lazy Jack]

Ah, gatcha
Thanks!