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Builders input needed/laminted deck beam


Kudzu

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I have the new manuals in with information on now to do the laminated coaming beam.  Here is an example of what I am talking about.

 

VZo8whpl.jpg

 

There are two small plywood frames at the gunwale to the chine, then a laminated beam spans the gap under the coaming. It lowers the deck an coaming height while still keeping the same knee room (on some boats it will increase the space) and it makes for a much nicer looking deck line on the boat.

 

While making the beam is pretty simple it does require some woodworking skills that many clients do not have. I have been back and forth on if I should offer an all plywood version or not? If I keep the deck line the same, it is going to mean a smaller opening and  harder to enter boat, especially if  you have long legs.

 

The other option is I keep the existing design and offer both versions. I am not to keen on that idea, just more work for me to keep all the files straight and very easy to mess up an order.

 

One option I am considering is making and stockpiling beams for those that can't make them. Not sure the cost and it it is worth the effort. But that would solve my dilemma but it not ready to commit to that.

 

Just and FYI, Short Shot will be the first plans released. Just as soon as I settle this issue.  Vardo and Ravenswood are next. I am working on the changes on these right now.

 

 

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My vote:  Don't compromise. 

 

You are the only one offering SOF innovations like this.

 

Explain to customers (a) how much laminated beams will improve comfort and safety and (B) how easy they are to make.  No one will want to settle for less.

 

How do you think the new beams will work with the Shad?

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The curved "coaming beam" is identified as the "masik" in traditional Greenland kayak anatomy. There are a couple of good books on traditional Greenland kayak building by Chris Cunningham and Mark Starr. That method of construction uses steam bent frames rather than plywood. The masik can be made the old fashioned way (carved from a single piece of wood) or laminated.

 

My own preference, if I am building a fuselage frame boat rather than a more traditional one, is to use plywood for frames, stems, and coaming for simplicity and quick assembly. If I wanted to use more sophisticated techniques, I would build by traditional methods. Of course, I have no idea how many Kudzu Craft customers and potential customers share my opinion.

 

Fair winds, Andy

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Is it feasible to offer both options in one set of plans? Add a third sheet with the frames for the laminated beam option? That way maybe you could provide (sell?) that sheet to people that have purchased the plans, but not yet built - like myself.

 

Possible but not really practical and it just adds potential confusion.  Doesn't matter how well I document it, someone will end up mixing them up and coming to me to try to sort it out. So I really don't want to go down that path. 

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My own preference, if I am building a fuselage frame boat rather than a more traditional one, is to use plywood for frames, stems, and coaming for simplicity and quick assembly. If I wanted to use more sophisticated techniques, I would build by traditional methods.

 

Appreciate that input. Just to be clear it is is only the one frame, not all of them so it is no going to add much work.

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You don't describe the woodworking techniques that may concern you, but in building a standard kudzu boat you have to cut some awkward bevels on the ends of the stringers and laminate a coaming, if you go that route rather than ply, so perhaps the masiq could just be considered a warm up for those activities.

I think steamed rib boats are way easier to build, personally, having done both. But then, I've been making odd shaped things from wood and metal and paper for 30+ years.

The bottom line is, if it improves the boats, you should do it. Especially if it makes them prettier, because the most wonderful thing humans do is make beautiful things. I think, anyway...

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I would just make a how-to video pretty detailed and leave it at that.....explaining how it could be adapted to all the designes...

And as for laminating,I plan on laminating a cockpit ring using 1/8" baltic birch one of these days...

 

I did this once with 3mm Meranti.... no, okume.  Bad idea. Was very flexible! Solid wood laminated is /was much stronger so I will not use plywood again to laminate a coaming.

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There are applications where laminating plywood on a curve is a good idea.  In the case of the SoF cockpit combing having near half of the grain going the other direction means it would take a lot more material, (which for me anyway is unacceptable) to get enough going the proper direction to create the stiffness needed.   This is another fine example of how the kind of strength you are looking for (stiffness, resistance to flexing) can be obtained, to just say strength would mean little.  On the other hand, that Baltic Birch plywood is hard and stiff, that the grain in the plywood is in opposing directions, and that the layers are more numerous than conventional building plywood and that the standards for the integrity of each layer are higher makes it a great choice for frames.  Building SoF isn't rocket science, but some of it can be darn technical.  Some details are not intuitive.  You really have to research the why part to understand.  I find plywood one the most misunderstood materials because some things about it are not easily (intuitively) understood. 

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I guess I need an explanation of the laminated deck beam. How does it increase knee room or lower the deck height any more than a plywood cross section, with the lower part removed, would? I have doubled up my plywood cross section at the front of the cockpit and reduced the width of the remaining wood to get a little bit larger opening and still maintain strength.  

   I haven't seen a set of Jeff's plans, other than those in the book. But the book has instruction for both the plywood and the laminated coaming. Wouldn't including instruction for both types, the masik and the regular cross section, be no more confusing or difficult than that?   

   Not meaning to be critical of the idea at all. I know i must be missing something here. 

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  • 2 years later...
  • 2 months later...

Didn't see a response to my previous question so I'll post again:

Any reason you can't just cut the shape of this deck beam out of plywood? Not seeing a response I did this with Okumne. I haven't finished lashing but it seems plenty strong. Thoughts?

 

 

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If you are taller than 6ft then you will probably appreciate the extra clearance provided by a laminated deck beam. I didn't want three deck stringers so my interpretation of your plan is just a minor tweak from the design. I barely fit in my frame but I'm not sure how I would fit as originally designed. I have photos posted in my other threads.

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I'm not familiar with the strength characteristics of okoume ply so I don't know if your plan would work. Since that might be the most critical frame in the boat, I'd do a lot of destructive testing on similar beam sections. I'd also try bonding plywood sheets to get 1 to 1.5" of thickness longitudinally on the kayak. Laminated Maple is very durable. Just judging by the orientation of the short fibers in a narrow cut of plywood, the ply version would need to be built heavier to get the same strength. Can the beam support your weight plus the coaming and skin tension? I would also consider the outcomes of beam failure, from discarding the skin for beam replacement to getting trapped.

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