Moccasin 12

[John Burritt]

ChrisObee - no disagreement w/ your comments.  I'm concerned that the boat be pulled into shape before all the seams are glued.  Otherwise it may not be fair.

[ChrisObee]

No I didn't take that as a criticism of me.  I just wanted to be clear that your comment being specific to the boat should probably have more weight than mine being general. 

[slaterturf]

I can't thank you both (and others) enough for taking interest in this project.  I have commented to my wife what an amazing process this boatbuilding/forum conversation is.  I am teaching myself to build a boat and through this forum I have the ability to effectively be in a classroom and ask questions anywhere along the process.  Even the designer chimes in offering guidance, I think that is fantastic. I have never built anything out of wood, but I am determine to learn as much as I can about building boats.  It is really fun and a great diversion from my regular, every day tasks of work etc.  I love my work, don't get me wrong, this is just a really fun diversion, and I am learning something productive at the same time.  The learning of building a boat for me includes gathering the right tools, reading and understanding the design, finding the space, buying the materials, understanding about epoxy, learning the language, and more.  I had not contemplated that there is a vocabulary and language to go along with boatbuilding, although it should not be surprising.  I just realize that is an area I lack in as well. 

So, John, in regards to your post about springing gunwales around the shear to bring the boat into shape.  How do I do this? Do I tie the boat up with more rope and wrap to develop the shape until the butt ends come together?  Do I cut the gunwales and install them ahead of taping and gluing the butt ends of the sides?  I can conceptualize what you are saying, but I am not clear yet as to how to go about it.

Thanks.

[ChrisObee]

I can't thank you both (and others) enough for taking interest in this project.  I have commented to my wife what an amazing process this boatbuilding/forum conversation is. 

At the moment all I am doing is sanding, participating in another build, however virtual, helps keep Mr Jones at bay. 

[John Burritt]

Cut the outside gunwales a bit long - quite a bit if you're not sure of the length.  Clamp the end of one gunwale just a wee bit past the bow, but not enough so that it will interfere w/ the other side - clamp it along the shear and let it run wild past the stern.  Do the opposite on the other side of the boat - just fits inside the first gunwale, clamp it along the other shear, and let it run past the bow.  This should pull the boat into a fair shape at the shear.  Check the beam dimension against the plans and compress/spread if necessary.  Use several clamps spread out do you don't create a hard spot in the shear.  I'd also cut the breast hooks as per the plans and fit (not glue) them into the bow and stern.  These also will help give the proper shape.  Now see how the mid-ship side joints are fitting.  If they aren't tight together, they should be real close w/ the ends parallel.  Adjust the ties on the bottom/side seams for a good fit.  Once everything looks good, you'll be ready to think about gluing.  (If you haven't already figured it out, its real hard to end up w/ too many clamps.)

[slaterturf]

Thanks John.  I got excited and went off in another direction.  I just glued and taped the sides using a rigging that seemed to work to hold the butt ends in place.  I took some photos, but I will post them tomorrow when I remove the setup and see the result of this effort.

What does a hard spot in the shear mean?  Is that a flat area, rather than a curved shear line?

Thanks.

[John Burritt]

Could be either a flat spot if you're squeezing, (or a bump if you're spreading) the shear to meet the design width.  Its a disruption of the fair curve.

[slaterturf]

I taped and glued the sides on Saturday.  The photo shows the plastic covered panels used to back the epoxy and tape on the side.  I did not have clamps with a deep enough throat to clamp down half way or more on the side.  I priced some but it looked to me that I was facing $50 to buy clamps to suit the job.  So I screwed some wood down on the work bench and use it to back up the bottom of the boat against the outside panel on both outsides.  For the inside, I clamped the tops of the panels and used two pieces of left over plywood to fit down into the bottom of the boat.  The bottom of the scrap plywood pushed into the inside panel to hold the bottom of the panel in position.  

[John Burritt]

Several issues - the grey (white?) areas in the glass tape show where there are air voids between the tape and the wood - no bond.  The marvels of gap-filling epoxy are marvelous only when you add thickener.  Gap-filling is like filleting - no thickener, the epoxy drains out when it gets warm curing.

The midship joints typically are joined by a plywood butt block glued to the inside.  The grain in the plywood should run across the joint and the block should run past the joint 8 times the thickness of the hull sides EACH way w/ the grain in the block running fore & aft.  You can cut the butt block to fit under the inwale.  Which brings up that the gunwales & inwales can be glued in place before that butt joint is installed.

Whatever wood you use for the gunwales needs to be clear - no knots - and as straight-grained as possible.  Poplar should work - I know pine will.  Clamp or screw a STRAIGHT fence to your wood as a guide for your saw.  If you don't have a long work bench, a 2" thick piece of foam board make a good sacrificial base for cutting and protects the saw blade (use the circular saw if you do this.)

Unless your board is longer than needed for the gunwales, you'll have to epoxy (thickened epoxy) two pieces together using an 8:1 scarf.  Be sure to keep the joints straight in both planes while you're gluing them.  Rough cut and glue up both your inwales and outwales at the same time.  When fitting them in the boat flip them so that the inside and outside joints are not opposite each other.

[ecgossett]

Try this tip for a using a circular saw.

http://www.ehow.com/how_2239068_convert-portable-circular-saw-table.html

I know Lowes sells Rip Fences that hook to the circular saw and allow you to cut straight lines very easily.

http://www.rd.com/how-to-use-a-circular-saw-to-make-long-cuts/article18171.html

Try this article as well.

[slaterturf]

Gap-filling is like filleting - no thickener, the epoxy drains out when it gets warm curing.

I can use a little education here:  as the epoxy cures, does it release heat?  I read in another thread somewhere about epoxy boiling.  I was not clear what they were talking about, unless there is a reaction that causes heat.

I have not figured out how to do the quotes properly, yet.

I have cut out some of the tape at the butt ends gap and will need to fill the gaps with thickened epoxy.  I have not mixed any epoxy with thickener yet.  Any suggestions on the ratio?  I would guess until it mixes like peanut butter.  I must of read that somewhere.  If I do that and paste it into place, does it spread out a little as it cures, thus filling in the tiny missed spaces?

Thanks.

[ChrisObee]

I can use a little education here:  as the epoxy cures, does it release heat?  I read in another thread somewhere about epoxy boiling.  I was not clear what they were talking about, unless there is a reaction that causes heat.

Yes as the epoxy cures it releases heat. 

You use straight epoxy to coat wooden parts.  You use fillers when glueing, filleting, filling gaps, etc.  For gluing wood together you use epoxy thickened to the consistency of catsup.  When filleting or filling gaps add fillers to the consistency of peanut butter.  The filler you use depends on what you trying to do.  wood flour is good for glue, silica makes a fillet hold its shape better, wood flour alone tends to sag.  microballoons are good for fairing.  I typically add two heaping tablespoons of wood flour to three oz of epoxy for glue.  For fillets I add another 2 or three heaping tablespoons of silica to the epoxy and wood flour.  for fairing I use quickfair. 

Your milage will vary and there are as many practices and formulae as there are boat builders. 

[John Burritt]

If you leave mixed epoxy in a cup too long it will get so hot it will start to smoke.  Something you should watch for when spreading unthickened epoxy is that if the consistency gets thicker and the cup gets warmer, stop using it.  It will be too far gone to spread properly.

Back to filling and regluing the gaps midship, I'd leave those until I had the gunwales on and the shear fair. 

When gluing on the butt blocks, pre-wet both surfaces w/ unthickened epoxy.  Then apply thickened epoxy to one surface in a thin, even coat.  Use enough that you get squeeze-out when you clamp it in place.  Clean up the excess while its still wet.  Then go back after a bit and check for more squeeze-out.  Clamping is a balance between tight enough to firmly seat the piece and being too tight and squeezing out all the epoxy.

[slaterturf]

Is there a fire hazard to this situation?  I mix the epoxy in the shop I have in the basement of my house, use it, and if there is any left over I just leave it to harden.  I guess I should take any left over mixed epoxy outdoors to leave it to harden.  I know old oil rags left in the corner are fire hazards, this epoxy is new to me. 

[John Burritt]

The epoxy isn't going to burst into flames, although it may give off smoky fumes.  Just set the cup on something non-flammible and wait for it to cool off.  A metal cup (juice can) won't melt, but could get hot enough to burn your fingers.  A plastic cup can melt, which can make a mess.  The up side of this is that as soon as the epoxy starts spreading out, it will cool down much more quickly.  If you're coating a surface and the cup starts getting warm, pour the epoxy out and spread it around.  Working time is greatly extended.  Using a slow hardener, there isn't much chance of heat buildup this time of year unless you mix a cup and set it aside and do something else.  In short, the bigger the surface the epoxy is on, the slower the heat buildup.  Fillets and glue-ups may get a little warm, but not hot.

[slaterturf]

Thanks John.  I have been using the epoxy and hardener I got from B&B.  It has worked great and I have not noticed heating.  I noticed that when my two units arrived the hardener had a stop installed on the pump.  The prescribed ratio was two to one, epoxy to hardener.  The stop allows me to use one full pump of epoxy and half a pump of the hardener due to the stop on the pump shaft.  My guess has been that B&B provided that extra bit of service by placing the stop on the pump shaft of the hardener, which I appreciate, because then I don't use as much epoxy as I might otherwise have done.  The epoxy is pretty cool.  I have never used it before, so it is cool in what it can do.  I have enjoyed learning to use it.  I have not even started with the thickening agent learning curve.  That will be next.

I cut my 10 foot, 1x6 poplar board with my jigsaw.  The cut line is a bit wobbly, but I will make it work.  I will scarf the gunwales and inwales together as you recommended at 8:1.  I am going to have to come up with a whole lot more clamps.  I think I know where some big PVC pipe is that i can turn into clamps.  It is raining a lot today, so maybe I can go the pipe now. 

My goal it to have as much done on the canoe by Thanksgiving as I can in order to show it off to the gathering family at that time. 

Thanks.

[John Burritt]

Cut a piece of pvc pipe at least an inch wide.  Then split one side of it.  See how hard it is to spread.  If its not fairly hard, its not wide enough.  The trick is to cut it so you can just spread it to fit over what you're clamping.  Be sure they close all the gaps when you're clamping.  Might want to use some c-clamps in critical places.

[slaterturf]

Here are some recent photos.  I have been delayed in my progress, but I got started again yesterday.  It was raining the other day so we cut up 65 three inch PVC pipe into clamps.  They have worked really well.  I cut and fit the gunwales.  Then I epoxied the gunwales and held them on with the 65 clamps and then some.  My epoxy had been setting up for me in about 18 hours.  When I took off the clamps the gunwale sprung off the bow.  So I have re-epoxied the gunwale, clamped, and will wait longer. 

[slaterturf]

Actually, the tip I am looking for is how to measure the 8 degree angle on the sides of the breasthooks.  I expect I will use a plane to shave the wood off.  Thanks.

[John Burritt]

Check the beam measurement midships.  Clamp or spread as necessary to match the plan dimension. Then check the fit of the breasthooks you've cut.  Use a bevel gauge to determine the actual angle for your boat.  Check it at both ends of the breasthook - could well vary a bit.  Use the bevel gauge to mark the cut angles at each end.  Rough in a cut line on the underside and plane to the line, checking your fit periodically until you're satisfied w/ the fit.  Don't count on the shapes/angles being the same from side to side or end to end.