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Clear lumber for gunnels?

funbun

Well-Known Member
Sep 11, 2007
214
1
Alabama
Is it necessary to have clear lumber for gunnels and hard chine logs? Is there a disadvantage to use simple 1x whiteboard found at Home Depot or Lowes?
 

Kayak Jack

Well-Known Member
Aug 26, 2003
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Okemos / East Lansing Michigan
I use wooden spaces about 1/2" thick every few inches, then glue on a strip of 1/8" plywood. I have it about 3" wide at the center of the boat, and taper off to a bit less than 2" wide near the stem ends. This is about the same weight as a solid board - maybe a teensy weensy bit lighter - and is stronger, allows draining the boat when leaned up on edge, and provides tie down holes for camp gear.

Also, I seem to have a lot of plywood.
 

funbun

Well-Known Member
Sep 11, 2007
214
1
Alabama
Kayak Jack said:
I use wooden spaces about 1/2" thick every few inches, then glue on a strip of 1/8" plywood. I have it about 3" wide at the center of the boat, and taper off to a bit less than 2" wide near the stem ends. This is about the same weight as a solid board - maybe a teensy weensy bit lighter - and is stronger, allows draining the boat when leaned up on edge, and provides tie down holes for camp gear.

Also, I seem to have a lot of plywood.
Is that for the interior gunnel only? Could it be use for the exterior gunnel?
 

beekeeper

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Mar 4, 2009
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funbun
I used clear for both (outside gunnels and chine logs). I did not want to take a chance on stress breaking one at a knot. It is my understanding the main function of the chine log is to connect (nail/glue) the sides to the bottom. A knot in a chine log may not matter (stress wise), if the board survives the stress of installation. The gunnels probably will receive additional stress depending on its design and use. A knot or splice would increase the chance of failure. How much and is it enough to matter? I don't know.
We probably need the chine log experts to answer this. Anybody know a couple of builders who build boats with this type of construction who might answer this?

beekeeper
 

beekeeper

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Mar 4, 2009
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This may muddy the water, but I think this question may fit here. If I made my gunnels (outside) out of glued strips (laminated like a beam) , which of these two configurations would be best. The gunnel will be .75"wide x 1.25"tall. Five strips .75" wide(horizontal) x .25" thick stacked on top of each, or three strips 1.25" tall (vertical) x .25" thick sandwiched together side by side. Second part of the question; If the strips have to be spliced to be long enough, which way to laminate?

beekeeper
 

beekeeper

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Mar 4, 2009
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funbun said:
Yeah, this leads me to ask can you laminate 5.2 mm Lauan plywood to serve as gunnels?
I would guess so. There would be a splice issue to deal with for plywood. I did make a test board of five strips stacked and glued. A splice failed when I applied bending pressure. Could have been inadequate glue. It was a scarf joint of sort, really a butt joint with 45 deg. ends.
An outside gunnel also serves as a rub or bump rail. Wouldn't solid wood offer more crush and wear resistance.

beekeeper
 

Kayak Jack

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Aug 26, 2003
13,976
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Okemos / East Lansing Michigan
A gunnel is serving as a beam, like a floor joist. Using the same amount of material, it will provide more strength being thinner and taller than shorter and fatter. IE: (3/8" thick X 3" high) is several times stronger than is (3/4" thick X 1 1/5" high).

Using material to thicken it will strengthen it only geometrically. (Twice as thick is twice as strong.) BUT, doubling the height will make it FOUR times stronger; it strengthens exponentially.

Adding spacers, and it makes more sense to do this inside than outside, lets it work as an I beam, and he "ventilated" gunnel will be serviceable for both draining and lashing.

But, when it's all said and done, we each have to make our boats the way we like them.
 

graybeard

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Dec 24, 2009
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Between keyboard and chair
Jimmy W said:
Home Depot sells molding that comes in long clear lengths. At least they did when I built my pirogue.

This is what I've been looking at - 1"x2" nominal, S4S (Surface 4 sides). It looks like pine, is pretty flexible, and it's easy to find true & clear pieces @ 10 ft.
 

oldsparkey

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Aug 25, 2003
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Central , Florida
www.southernpaddler.com
Jimmy W said:
Home Depot sells molding that comes in long clear lengths. At least they did when I built my pirogue.
Home Depot has the strips up to 18 feet at our local store and that is all I used on the boats I make. Nice solid pieces and are pine which conforms to the shape of the boats. They are 1/4 by 1 1/2 inches and 18 feet long.

Chuck.