Building the CoPogy 18

[AJZimm]

Got the first bulkhead, Bulkhead D at the aft end of the cabin, set up on the strongback.
Woo–hoo!

[2dogsnight]

Looks great. Fitting in the shop too.

[Dave Lesser]

The completed strongback moves about the shop floor with just a touch of the fingertip now. We’ll see how well it does when it’s loaded down. I’ll have to figure out some way of holding it steady when I don’t want it to move.

Looking good, Alex. You might just use a long lever to raise it up slightly, then slip blocks next to the wheels that just barely keep the wheels off the ground. That works for my heavy lathe.

[AJZimm]

Looking good, Alex. You might just use a long lever to raise it up slightly, then slip blocks next to the wheels that just barely keep the wheels off the ground. That works for my heavy lathe.

Thanks Dave, good tip.

[AJZimm]

Looks great. Fitting in the shop too.

Just barely! I'll see how much room I have once I get the other bulkheads mounted. I think the ability to move it about on the casters will be key.

[Rich Jones]

Just barely! I'll see how much room I have once I get the other bulkheads mounted. I think the ability to move it about on the casters will be key.

The casters are the key for sure. My shop is a little wider then yours, but not by much. Being able to move my Jericho Bay Lobster skiff around while I'm working on one side or the other is a blessing.

[KenStocker]

Not to pile on here, but I agree with Rich. I started my build, my first unlike Rich, on a strongback that didn't lock. Every time I went to either plane off a plank, or try to plane the gains, it made it very difficult. When the castors finally started to come loose, I replaced the lot and caved in to put on locking castors, it made all the difference. With all due respect, save yourself some trouble and either replace at least a couple of castors that lock, or find a way to "chock" those castors so they don't roll. I have been guilty of trying to "use what I have on hand" way too many times(and probably will again)so I get the temptation, but it will cost you in the long run and bite you in the proverbial hind quarters. Just my two cents worth.

[AJZimm]

Re: keeping the strongback from moving when I don't want to. I found some shallow wedges that I had made for some other purpose (don't now recall what), and they work fine when jammed under the casters at the corners.

[Yeadon]

Looks good. I built Haverchuck on a roll-around strongback. I blocked a wheel or two with chocks when needed. Worked great. Floor wasn't level. Didn't really matter. What garage floor is level? Strongback held up fine. Boat still floats fine. It's really nice to be able to roll your build in and out of the shop, if only to get a change of venue and a bit of fresh air. I'm probably going to build a crabbing skiff soon to replace my ancient aluminum Lund skiff. (Anybody need a Lund?) I plan to stick with the roll-around strongback from here on out.

[rgthom]

I made a building jig with one of these mobile base kits: https://www.rockler.com/power-tool-mobile-base-hardware
It sits on wheels at the back and leveling feet at the front, but there is a foot operated front caster for rolling around.

[AJZimm]

Work to erect the remaining bulkheads on the strongback is chugging along. I got 5 of the 7 put up:


and then stopped to add the edge backing to the transom, because the forward end of the strongback was handy as a work surface.

These all-plywood boats, with no keel or backbone structure, are kind of like egg crates. Lots of strength for not much weight. But, it does present a challenge when trying to figure out how to locate the support the transom in a spot off the end of the strongback, 3½ feet in the air. To locate it, I came up with this jig, where everything is referenced to the DWL:


Here you can see how the jig was used to locate the transom:


And here is the rather elaborate support structure to hold it until the bottom and side strakes get glued to it. Overkill, perhaps, but I didn’t want it to move during the glue-up. And I wanted to be able to move it easily to fine tune it vertically and side-to side. In the end, I didn't need to adjust it much at all. The rough ply with the patches on is only temporary, to attach the transom to the 2x4 supports.


And finally, here is the transom in place:


A batten run across the bulkheads touches them all the same, at this point, with no high or low spots. That’s a good thing.

Next is building the stem, then setting it up along with the last 2 bulkheads.

[AJZimm]

Forgot to mention that when I got the 5 bulkheads up, I cross-checked their bottom centerlines with a straight-edge. Two of them were off – one by 12 mm and the other by 5 mm. Yet they appeared to be bang on when checked with the large drywall T-square that I had used to centre them in the first place.

What gives?

After a bunch of head-scratching and re-measuring, I tracked down the source of the error. Originally, I had spent a lot of time ensuring the strongback was square and straight, but I had been working from the ends only. Turns out that one of the 2x10s I used for the outside beams had a slight dip in way of the two bulkheads, to the tune of about 2 mm at one and 3-4 mm at the other. When that dip to one side was translated to the vertical by way of the T-square, 5 feet up, the error was magnified. I went back, set the strongback square and level again and this time used the vertical line on my laser level to determine verticality. Problem solved, at least within 1 mm, as checked with the straightedge.

Forgot to take pictures of the debacle so you’ll have to imagine it from the words.

[Rich Jones]

Ain't those little problems a pain? That's what the moaning chair is for.
When I made my strongback, I snapped a line on the 2x10's and cut an absolutely straight line to make sure there were no crowns, dips, whatever.
Looks like you're moving along just fine.
Good work with that transom support.

[2dogsnight]

I was just wondering how is everything goin there, and here it is: lots of lumber to hang the bulkheads in place, strongback wheels locked, workspace tight but workable........lot's of work done! You are doing great Alex! Thank you for sharing!

[Hugh MacD]

That's looking great Alex! I'll take that strongback lesson to heart!

[AJZimm]

Post #12
Half an hour after the sun supposedly rose this morning, on the shortest day of the year here on southern Vancouver Island. Streetlights still on. When I opened the blinds it sucked all the light out of the room, it felt like.


Pissing down rain all day with a possibility of wet snow, even at sea level. A good day to work in the warm dry shop.

[Hugh MacD]

What's a warm dry shop?!? Mine's a tin shed and if it's damp and the sun comes out I can watch the temp drop from the evaporative cooling...but at least is is dry...and big (so hard to heat). Love watching your progress. Thanks for posting, Alex.

[Yeadon]

Forgot to mention that when I got the 5 bulkheads up, I cross-checked their bottom centerlines with a straight-edge. Two of them were off – one by 12 mm and the other by 5 mm. Yet they appeared to be bang on when checked with the large drywall T-square that I had used to centre them in the first place.

What gives?

After a bunch of head-scratching and re-measuring, I tracked down the source of the error. Originally, I had spent a lot of time ensuring the strongback was square and straight, but I had been working from the ends only. Turns out that one of the 2x10s I used for the outside beams had a slight dip in way of the two bulkheads, to the tune of about 2 mm at one and 3-4 mm at the other. When that dip to one side was translated to the vertical by way of the T-square, 5 feet up, the error was magnified. I went back, set the strongback square and level again and this time used the vertical line on my laser level to determine verticality. Problem solved, at least within 1 mm, as checked with the straightedge.

Forgot to take pictures of the debacle so you’ll have to imagine it from the words.

I like to put a nail centerline on the forefoot and then take a string and run it from that nail back to waterline heights along the station molds, seeing if port and starboard WL's are similar lengths along the string. Eventually, something is revealed. You can move that nail forward and aft along the keel shoe to check from various positions, too.

[AJZimm]

I like to put a nail centerline on the forefoot and then take a string and run it from that nail back to waterline heights along the station molds, seeing if port and starboard WL's are similar lengths along the string. Eventually, something is revealed. You can move that nail forward and aft along the keel shoe to check from various positions, too.

Good tip. I did something similar with Fire-Drake.

In this case, there is no keel shoe. However, once I put the already-built bottom panel up on the bulkheads for a dry test fit, it should serve the same purpose and I can do some fine-tuning of the positions of the bulkheads at that point if I need to.

[AJZimm]

Post #12
Half an hour after the sun supposedly rose this morning, on the shortest day of the year here on southern Vancouver Island. Streetlights still on. When I opened the blinds it sucked all the light out of the room, it felt like.


Pissing down rain all day with a possibility of wet snow, even at sea level. A good day to work in the warm dry shop.

Later the same day - the forecast snow showed up. Big heavy wet flakes. We don't get snow here very often and we pretend that we don't get it all so most residents of the city don't own a snow shovel, wouldn't think of buying snow tires and have no idea how to drive in the snow. Fortunately not supposed to last long.


Made a jig and got the laminated stem glued up. Now waiting for the glue to set.

[Rich Jones]

^ somewhat less then the three feet we got a few days ago.
We do, however, own a snow shovel...

[Rich Jones]

I see that the frame for the transom stands a bit proud of the plywood transom itself. Is that so it can be beveled for the planking to lay correctly?

[AJZimm]

I see that the frame for the transom stands a bit proud of the plywood transom itself. Is that so it can be beveled for the planking to lay correctly?

Exactly


Sent from my iPhone using Tapatalk

[Russell Brown]

Funny, that was the exact weather we had today. Raining cats and dogs and then snowed buckets.
I like the design you are building and it's great that you are sharing the build.

[AJZimm]

I like the design you are building and it's great that you are sharing the build.

Thanks Russell. I think the boat will be a fine small solo/duo motorsailer. With the little raise deckhouse I am hoping to extend my comfortable cruising season beyond what I currently do with an open boat.

[AJZimm]

Is that pipe insulation there to protect you and/or the edges of the forms?

We got about 4" of mush and lost hydro for about 8 hours.

Yes, pipe insulation until I get the strakes on. With the tight space in the shop I kept scraping skin off as I moved past the edges. The router did a fine job of making crisp edges, but they are a little more crisp than I need them to be!

Lights flickered a few times here but we didn't lose power, fortunately.

[AJZimm]

What's a warm dry shop?!? Mine's a tin shed and if it's damp and the sun comes out I can watch the temp drop from the evaporative cooling...but at least is is dry...and big (so hard to heat). Love watching your progress. Thanks for posting, Alex.

Hugh, you could actually insulate your tin shed, without any serious building envelope consequences, I think. Normally insulating the inside of a steel building, when it’s a living space, is not a good idea, as the insulation brings the dew point inboard of the metal and the moisture will tend to condense on it, outside of the insulation – leading to possible mould and corrosion. However, with just one, or maybe two, people working in a boat shop, not that much moisture is being generated, and you’re not there all the time, so condensation is less of a risk.
When I turned my garage into a boat shop, it originally had the one-piece uninsulated metal garage door that came with the place, about 15 years old. I added insulation to the inside and had no difficulty over the 20 years it was there, until I replaced the door for other reasons.

[Hugh MacD]

Thanks Alex,
I am insulating bit-by bit, but the building is bloody huge (I'm not complaining and I can't reach much of the ceiling. The eaves are 14' tall and I'm extending a loft so I can reach more of it. All a work in progress, but slow progress. Too many projects!

[AJZimm]

I took several days off from boatbuilding over Christmas, but am back at it now.
I got bulkheads A & B set up on the strongback and re-used the jig from locating the transom to locate the stem:



I finished laminating up the stem. Tad’s design doesn’t actually call for a stem, just a stitch and tape connection where the strakes come together. However, I decided that it would be easier to have a smallish stem to land the strakes and bottom panel on. Since much of it will be cut away, I used some scraps of purpleheart that I had from a previous project to make a centreline lamination, and the outer lams are D Fir. You’re looking at the top end here, where the stem has a kink to tie to the raised topside strakes.


The other reason I wanted a bit of a stem structure was to make it easier to have a solid backing point for a U-Bolt that will serve as the lower attachment for the bobstay, and also as a towing eye.


In checking the angle of the cut-away stem with a batten to see if I have it correct for the strakes to land, the subtlety of Tad’s design becomes apparent. The half-angle of entry of the hull at the bottom, waterline, (not shown in this image) is 18 degrees, considered by many designers to be an ideal number. It flares to 34 degrees at the top of the stem, which is what this picture shows:



Next up is to makes some strips to reinforce the inner edges of the plywood bulkhead side webs. Tad had originally called for 5/8” ply but all that was available to me in that thickness was meranti. It is considerably heavier than okoume and would have added nearly 100 lbs to the hull. Tad suggested ½” with stiffeners. Each web, when glued to the strake, will them be like a mini I-beam. It will also give a more finished appearance to the webs. Pictures once I get a few done.

[AJZimm]

I wondering how the ends of the planks in way of the bow eye are going to be fitted. No need to explain it ahead of time, I'll just watch.

I'm wondering that too! I'll figure it out when I come to fastening that strake.

So, an entry angle of 18 degrees each side. I'll have to check what mine is. Perhaps 18 is optimum for some configurations and hull types but not others, yours being sailable and mine being engine driven only.

Yes, I should have been clear that 18 degrees is what I've read about sailboat bow entry angles. Don't know enough about displacement power boats to know whether the same applies.

[2dogsnight]

This build looks very complicated......maybe is the size of bulkheads, don't know.
Good job !

[Hugh MacD]

Looking really good Alex! You're making enviable progress.

[AJZimm]

This build looks very complicated......maybe is the size of bulkheads, don't know.
Good job !

Thanks. Appearances can be deceiving. It's probably all the support lumber needed to hold the bulkheads upside down several feet above the strongback. Once the hull is flipped and all that stuff is removed, it should appear simpler.

[AJZimm]

Looking really good Alex! You're making enviable progress.

Putting up the big bits makes it look like things are moving quickly. When I get to the point of doing the interior, there won't be nearly as much progress to show per hour of work, in my experience.

[Hugh MacD]

True 'nuff...but they you have the warm glow of knowing you're working inside ​the hull you've finished. Of course, working inside, you're scrambling back out every ten minutes for the tool that's sitting just out of reach on the end of the bench