Tech Tip Tuesday

In the better interests of time and the sanity of both students' and the instructor's fragile faculties, I decided to forgo the sewing of the skins that was used to build the kayaks last year was not the best option for skinning the hulls in this class.

So, you ask - how are we doing this?

Staples. 

The sewing class that was going on upstairs was interested to see how we were sewing the skins on the kayak and were somewhat bewildered and disappointed to find us stapling the fabric to the hull.  This isn't that odd, really.  When canvasing a canoe, folks use either canoe tacks or staples to fasten the canvas to the hull.  We're doing pretty much the same.

Note that we're not using just any staples - we're using stainless steel staples 3/8" long.  The fabric for the skinning is 8oz polyester from Dyson Baidarka & Company in Bellingham, Washington.  I like the way this fabric works, frankly.

The procedure is pretty straightforward.  With the boat upside down (or right-side-up if you're doing a deck...) we draped the hull with fabric and get it centered and aligned before we tack it in place at the sheer with thumb tacks.  We then take the staple gun and start to make a closely spaced row of staples through the fabric about 1/8" away from the top edge of the sheer in the middle of the hull about a foot long, pulling towards bow and stern to keep fabric taut.  We then pull the fabric taut around the boat and staple at 1/8" away from the sheer at the other side.  By closely spaced, I'm talking about an inch apart - sometimes less.

When we get near the ends, we cut down the middle of the fabric from the end of the fabric toward the stem, aligned with the keel.  I then seal the cut ends with a small butane torch - a very quick pass is all that is required.  We'll give you an object lesson why later...  The fabric is then pulled around the stem, stapling from the keel towards the sheer.  Excess fabric is cut away at the far edge of the stem and sealed.  The process is repeated with the other side of the fabric at the stem and then repeated at the other end of the boat. 

When the sheer and the stems have been trimmed and sealed with the torch to prevent fraying, we put a little bit of thickened epoxy over the stems to help seal them and to smooth out any bumps and edges.  When done, the boat looks like this:

 

Stems look like this:

 

Because this boat is a kayak, we'll put the deck skin on at the next class.  We'll then steam-iron out any wrinkles in the fabric before draining the water and setting the sole temperature to 450°F (with a digital meat thermometer) to shrink it a bit.  At this point, the skinning would be done for a canoe and the boat ready for paint.  In this case, it is a kayak and will get a deck skin, too.

Oh - I mentioned that I'd talk about why a quick pass with the torch is all you need.  The torch is VERY hot and I usually just sort of wave it past the cut edge of the fabric to keep it from fraying.  The student was doing this and may have had a momentary distraction or bit of inattention.  He got a surprise:

The surprise was a pretty large hole over the sheer clamp.  As you can see, we added a few staples at the sheer and the edge of the hole and put a bit of the thickened epoxy on it.  Fortunately it is in an area that will be covered by a rub rail, so it won't be seen and is high enough so that water will not be an issue.  WHEW!

More on the deck skinning in a bit.

 

Tech Tip Tuesday

After yesterday's post, it's probably a good time to talk about the methods that you can use to build a strip canoe. I want to talk a bit about how the strips are actually applied. It is a topic which most books seem to gloss over, but is at the heart of the process.

When building a cedar strip boat, you need to hold the strips in place on the forms while the glue that holds the strips together cures. You also need to keep them from moving on the forms and changing the shape of the boat that you're trying to build. In my class, we recommend that beginners hold the strips on the forms using staples. This, however is not as straightforward as it may seem.

You need to understand the terminology of the staples. They have two legs and a crown. The dimension that you see when you purchase a staple is the leg length. The crown is the segment that connects the two legs. For our application, we're looking for 1/2" crown width (or there about) At the bottom of the legs are the points or teeth. Chisel point teeth that cut the wood rather than crush and bruise the wood give better results. The thickness of the staple material varies from "lightweight" to "heavyweight" I like to use "heavyweight" staples as they provide more holding power. I also prefer stainless steel or monel staples to avoid putting rust stains on the boat if it your are building in a damp environment, or it gets wet somehow. On top of this, you need to be sure to be getting the right type of staples so that they work with your stapler. Never would have thought that there was so much to staples, did you?

There are many different types of staplers. Some are manual, some are electric and some are pnuematic. All will work. Manual ones are easier to deal with as you don' t get tangled up in the cords or hoses. Of the manual ones there are light and heavyweight staplers. Personally, I prefer the kind of stapler made by Powershot - it applies the lever's force over where the staple comes out which makes it easier to use.

Now that you have your staples and the stapler, you need to keep from getting the stapler all clogged up with glue. To do this you simply put a strip of masking tape on the bottom of your stapler. Easy. But, you also don't want to drive the staples so deep that the crown of the staple leaves a dent in the hull. To prevent making these dents you build up a stack of masking tape strips just adjacent to where the staples come out of the stapler. It will require some experimentation to get the required thickness. When the depth of the staples is right, the crown of the staple is just above the surface of the strip so that they are easy to remove later.

Staple length is also critical. I use 9/16" long staples at the forms and where the the strips meet the stems. If I need to keep the strips together between the forms, I use 1/4" staples so that I don't break through the cedar strips. The reason for this is that if you break through the back of the strips, little chips come out and make small craters on the inside of the hull.

When you're putting the staples into the strips, you want to put them in neat rows on the forms and minimize their use between the forms. These neat rows don't draw the eye so much as irregularly placed staples. Also, put the strips in the middle of the strip. You don't want to straddle the joints between the strips as it will prevent the strips from following the contour of the forms.

Next week? Staple-less.

Pick a name, any name.

One of my students is a graphic artist and a closet wooden boat lover. When he heard that I was going to be offering a class in cedar strip canoe building, he was really excited.

While he was very passionate about wooden boats, he didn't have much woodworking experience and occasionally would be a bit nervous around the tools and would also be a bit discouraged with his progress. I thought that he did quite well, and came a long way with his woodworking skills as he built his canoe.

Staples are used to hold the strips in place while the glue cures. He used LOTS of them. There were jokes going around the class that he had so many staple holes in his canoe that it would never float. He had staples at the forms, between the forms and anywhere he felt that the strips might be lifting. And then, if he was in doubt, he added a few more staples. The canoe had so many staples, it was actually heavy to lift when moving back and forth to the barn before and after class. I think it took three of us the better part of a class period to remove all of the staples before fairing the hull.

We finally decided that the boat should be named The Arrow. Not because of the fact that it was going to be a fast boat, but because of these: