Vertical seams

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The Gutt Clan
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Vertical seams

Post by The Gutt Clan » Tue Jan 25, 2005 11:27 am

I need to plumb the pool of wisdom that this forum provides...

I had an idea for a feature strip that would run vertically. I was figuring on doing something to increase the strength of the joint, such as use a finger joint to increase the gluing surface. I'm not really interested in doing an in-lay as half of the reason I am considering the vertical stripe is a mechanism for dealing with shorter boards. The longest boad I can get locally is 16ft and I am planning on building a 17' Freedom.

Does anyone have experience with stacking multiple vertical seams in a canoe and the results on structural integrity? If it makes any difference, I am planning an angled stripe near the front of the canoe.

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mtpocket
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Post by mtpocket » Tue Jan 25, 2005 11:40 am

Is this the same idea you asked about titled "strip pattern idea", dated Nov.1,2004?
The Gutt Clan wrote:I had an idea for using shorter planks to build a longer boat. I was thinking that I could start at the front stem with a short WRC strip. Then insert a EWC strip then finish the strip with WRC. On the next strip 'down', make the first WRC strip a little longer. Maintain the length of the EWC then finish out with the WRC again.

The final effect would in essence be a slanting band of lighter wood from the front to the back from the gunwale to the water line (or below). The band would probably be about 2 ft in width.

I am a little worried about strength but figure that with 1-6 or 1-8 scarfs I should get a good gluing surface. I am more worried that it would look silly having a racing stripe on a canoe.

What do you think? Have you seen any other canoes with strips or patterns that progress from the gunwales down?
Last edited by mtpocket on Tue Jan 25, 2005 1:28 pm, edited 1 time in total.

The Gutt Clan
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Post by The Gutt Clan » Tue Jan 25, 2005 12:32 pm

Yup... I was hoping that perhaps people might have more time to answer now since I did not get any replies to my last posting... At least I now know someone read it... :smile

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Patricks Dad
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Post by Patricks Dad » Tue Jan 25, 2005 12:37 pm

Not sure if this is too helpful but my son and I are building a Redbird that includes a feature involving a couple of butt joints (one above the other) in a few places. This feature is near the shearline in the middle of each side of the canoe (station 0). A picture taken during construction is shown here:
Image

I was worried/paranoid about these joints holding up so we added a 1/16" biscuit in each joint to strengthen them. We have just about finished sanding the outside and haven't uncovered a biscuit yet but that is certainly a concern.

I would think that if you are doing an angle stripe near the end of the canoe, the stress on your joints might be less making a simple butt joint work fine. Also, if it's a simple strip, you might be able to cut the strips at an angle (in both dimensions) to increase the surface area for the joints.

Hope this helps.
Randy Pfeifer
(847) 341-0618
Randy.Pfeifer1@gmail.com

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mtpocket
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Post by mtpocket » Tue Jan 25, 2005 1:07 pm

I did read the last posting but did not feel qualified to answer. A vertical stripe from the gunwale down to the waterline is something I had never considered. If I understand you correctly, a vertival strip isn't necessarily what you mean. It sounds like you are saying that you will have the scarf joints in a straight line and not staggered. Is this correct? A vertical strip or vertical stripe? Hopefully someone with more boatbuilding experience can help you out. I am interested in their answers.

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Todd Bradshaw
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Post by Todd Bradshaw » Tue Jan 25, 2005 7:11 pm

On first glance, I think most of us tend to ponder the idea of vertical strips as if the likely outcome might be the boat breaking in half and the bow floating away while we sit dumbfounded in the stern. In reality, it may not actually be the case or anything to get overly concerned about. To a pretty large extent, the strips in a canoe form a non-compressable core with reasonably good sheer strength to hold the laminations of fiberglass to that core. They function as a part of a sandwich, yet when it comes to holding the boat together, they aren't the major player - the skins are. Lengthwise stripping can certainly add some rigidity to the hull (I wouldn't say strength though, since it's a pretty vague term) but anything which holds the inner and outer skins apart and which the skins will stay attached to will work and it doesn't have to be directional in nature.

You can build a fine canoe with fiberglass on either side of a foam core with seams in the coring going any direction. The fact that our wood strip cores are generally denser, less compressable and usually have higher sheer strength in the bonds between the core and skins - along with whatever stiffness we gain from the strip pattern, allows us to go lighter on the glass skins, or have greater durability if using the same glass layup.

I think the key questions here are #1 - Can you still build a fair shape with a non-lengthwise strip pattern? and #2 - Does the layup you're planning to use have enough beef to make up for whatever you might lose in lengthwise core stiffness? I would imagine that you would want the layup to be in the "sturdy" part of the regular spectrum. I doubt you would need to go overboard, but wouldn't suggest one of those ultralight, one layer of four ounce cloth layups, either. Also, the inside layup should be at least as heavy as the outside layup. If this boat breaks, it will almost certainly break inwardly and the inside glass has to be heavy enough to prevent this from happening. For a typical canoe, a full layer of six ounce cloth with an extra layer over the bottom, inside and out, would probably work. If there are indeed vertical joints in the stripping which cross large portions of the hull, I might also be tempted to add an additional narrow strip to the inside glass layup, like a cross rib, bridging the joint.

So having never tried it, I can't say for sure, but suspect it could be done and work fine. On the other hand, I certainly wouldn't suggest trying it on your first boat. There are enough serious issues to address there without adding experimental complications to the mix.

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Erik, Belgium
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Post by Erik, Belgium » Wed Jan 26, 2005 7:48 am

IMHO, the gluelines are stronger then the wood (WRC) itself.
I don't see any reason why a vertical stripe wouldn't be allright.

Erik, Belgium

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hoz
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contrasting strip designs

Post by hoz » Wed Jan 26, 2005 8:40 am

The fellows over at http://www.kayakforum.com/cgi-bin/Building/index.cgi

Build some radical strip kayaks using contrasting strips. Vertical, angled, horizontal, it doesn't matter to them. They occasionally post pics of their work too!

I saw one canoe with a DNA molecule (double helix) in the bottom. The trick is to glue the hull up as usual, cut the design part out and then glue in the contrasting strips. Seems pretty simple, just a lot of fiddly work.

Todd is right, it doesn't matter where the wood joins are or even if the edges are mitered, scarfed, biscuited, or butted. If the finished hull is epoxy and glass laminated the joint is as strong or stronger than the uncut material.
someday I'll fly, someday I'll soar

The Gutt Clan
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Post by The Gutt Clan » Wed Jan 26, 2005 12:03 pm

Thanks everyone... I didn't think it would be too big of an issue, but hey... I've never built a canoe before so what do I know.

I still haven't decided if I am going to do it or not, but I have a few months before I start my planking to decide.

Thanks again,

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Glen Smith
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Post by Glen Smith » Wed Jan 26, 2005 12:24 pm

This is the hull of Ross Leidy's kayak RL-1: Image
Last edited by Glen Smith on Thu Jan 19, 2006 1:05 pm, edited 1 time in total.

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Bryan Hansel
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Post by Bryan Hansel » Wed Jan 26, 2005 12:31 pm

You could always build the canoe as normal and then inlay the design. Check out this site, he does inlays on kayaks and they are outstanding.

http://www.cedar-strip.com

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hoz
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No fair Glen

Post by hoz » Wed Jan 26, 2005 3:25 pm

Leidy is an Artist...
someday I'll fly, someday I'll soar

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