The James Dory Page
 
Boatbuilding Page

 
The page will have two projects: a catamaran and a kayak or two. First will be the Catamaran which will have two parts: photos at launch, then photos of building her. Click here for the kayak. (When I get it on the page).

Project One: Kurt Hughes 30 Foot Cruising Catamaran.


New (as of 2011) collection of all my catamaran photos are located at this place:
Jim's Boat Photos - Flickr Set. This page you're on now still has more commentary and explanations.
  • Photo. Catalog cut sheet showing cat elevations. (184 kb)
  • Photo. Catalog page of cat's plan. (149 kb)

Click here to go to the boat building section.

Photos of her as finished as she got.

(Building time to this stage was 10 months).
  • Photo. The first photo is as the boat was launched. We (a partner I built it with) launched her before she was finished so we could take part in a month long crab fishery. We fished here for a few weeks with crab pots, and in subsequent photos you will see a small mast and boom which we used to hoist our crab pots. The intent was to then finish her after the fishing season.
    As it sits in the photo, she only has a primer, no portlights, unfinished interior, no front deck or transom hatches, and little gear.
  • Photo. Another view, more of the side:


At this point I must explain that she met a sad fate. As she was moored against a floating dock, a 250 foot barge broke loose of its moorings and, blown by the wind, raced across a small basin smashing broadside into the cat. She now sits in my yard awaiting extensive repair. She never sailed, except once when we rigged a blue tarp like a crude spinnaker. She was in the water for exactly one month.

Launch Day!

  • Photo. The boatshed is down, getting ready to transport.
  • Photo. On the truck.
  • Photo. Heading to the beach.
  • Photo. Down the road.
  • Photo. Finally in the water!
  • Photo. Putting up the crabpot lifting gear, an old wing strut and aluminum pole.
  • Photo. Landlubbers trying to tie a knot.
  • Photo. Enjoying the view, successful launch.
  • Photo. Checking out the cockpit, my building partner test firing the outboards (Tohatsu 15s).
  • Photo. Test cruise, heading out the river mouth to the sea.
I have slides of her loaded down with 40 crabpots out fishing in Norton Sound (Bering Sea) but don't have a way to scan them. When I can do that, I will add them to the page.
 

Building the Catamaran.

This was updated 4/28/98, more to follow.
A brief prelude: I used Kurt Hughes cylinder mold method. This uses a simple form which I used to construct the whole half side of each hull. (To picture this, imagine a large vertical sawblade slicing each hull in half longitudinally, or along the length of the hull. These pieces -minus the deck- are what are built in one fell swoop). The hull was built of luan mahogany, 3mm thick 4 ft. x 8 ft. sheets of plywood, epoxied in two layers on the mold. He has a great manual and video that explains it to any interested. Stringers and bulkheads are added after the hull is put together. The following photos will explain it better.

To learn more, check out Kurt's page by clicking here. His designs are adaptable to different building strategies.

This particular method was a bit nerve racking, at least for the first time. (I had never built a boat before, but had many carpentry skills). Would I do it again? Yes, definitely, but I would also consider foam construction to get away from needing stringers. I would consider it again for making a plug, too. One problem which I haven't talked to Kurt about lately is the scarcity of quality luan plywood. The stuff that bends well is getting way expensive. I paid $6.00US a sheet back in '91 for some good wood. Those were the good old days. I have plenty left over for repairs, and in fact have been using some scraps in building kayaks.

The steps I took were loosely as follows: (My shop was small so I had to plan my steps).
1. Scarf the plywood into 8 ft. x 8 ft. panels. You need a way to protect the scarf edges on the panels where they will join with adjacent panels.
2. Loft the flat surface paper (see photos following).
3. Build the mold. Pretty danged quick. A couple days because I didn't know what I was doing. Stations all are the same. Less then a day next time.
4. Build the hull panels, and cut them to shape/size.
5. Move them outside under tarps, dismantle mold and make stringers, sheer timbers, and deck formers.
6. Bring two hull panels back in and join them, pour keel, add stringers, some bulkheads, and basically do as much as possible like adding daggerboard case, covering with fiberglass, etc, before kicking it out and doing it all over again on the next one.
7. Build a temporary boatshed and set up the hulls for the connective bulkheads and decks.
8. Back in the shop, build the connective bulkheads, and stuff...
9. Back in the boatshed, join em all up and watch it take shape. At this point, lots of visitors begin offering their wisdom on how you should do things. (Before, they never could quite picture what it was you were up to.
10. Well, add decks, sand, fair, sand, sand, sand, paint, probably more sanding, hardware, and launch.
There, 10 easy steps to build a boat. (Use your imagination for the details.)

Step one, scarfing plywood.

  • Jig photo. Scarfing the plywood. I had a electric plane, a 9 inch Milwaukee sander/ginder, and a router and tried them all. Kurt likes the grinder method (at least several years ago did) but I had much difficulty controlling it...maybe because of the big size of mine. Too much dust. So I bought one of those plane attachments advertised in Wooden Boat and had the designer of it fit it for 1:12 slope scarfs. That worked pretty good, but I never mastered it. Also for stop scarfs, where a scarf ends somewhere before the end of the panel edge, it wouldn't work. My favorite turned out to be a simple jig I made for the router with a sloped base and 1-1/2in. flat bit as in the photo. Set it so it doesn't feather the scarf completely or else you'll lose the edge. Finish off the scarfs with a sanding from a long board, using fairly rough grit and a couple strokes.
     
  • Bagging photo. I then tried making cauls (long timbers) for clamping the scarfs. I spent a few days on this. I perfectly handplaned in cambers so pressure would be equal in the center as well as out on the edges where they would have clamps. On my dry runs I still had gaps, so would replane. Then I tried building some out of laminated plywood, for more uniformity. More wasted time. I finally vacuum bagged several sheets at once, much quicker.
     
  • Bagging photo. For the vacuum bag, I used 6 mil plastic sheet and joined it with storm window snap bead, which worked O.K. I kept polyurethane caulk and tape handy for leaks. Bubble pak, some garden hose, some ABS plastic pipe and fittings, a shop vac, and waxed paper between the plywood scarfs about took care of it. I found some bigger, manila rope than in the pic to help evacuate the air. Also, next time I might try some of that bleeder fabric to see if it helps absorb excess epoxy.
     
  • A word about my vacuum setup. I used a shop vac and kept another in reserve. I used the 2 in. plus flexible hose that comes with it from the vac to rigid plastic pipe. The first small piece of plastic pipe I drilled 4 quarter inch holes for ventilation purposes. (Shop vacs use airflow for cooling so you need some leaks). I had duct tape covering the holes when I first began pulling the vacuum. When all the air was out (the motor would start to strain) I would release the tape covering a couple vent holes until the vac ran cool enough. I also plumbed in a vac meter to make sure I still had enough vacuum, and always did. I also plumbed the shop vac so it was outside because they are so noisy. Cooler out there to. Shop vacs move a lot of air. I would like to buy or rig an industrial vacuum motor so I didn't have to listen to the shop vac and for higher pressure for when I thought I might need it. Anyway, never burned up a shop vac.

Step 2, The flat surface pattern.

  • Lofting photo. Here's where I get to look like a boatbuilder, lofting. Notice the wrinkles in the paper, which wouldn't go away but didn't seem to cause problems.
  • Lofting Photo. I had some nice batten clamps I screwed to floor here, but eventually just started using whatever weights I had about the shop, cans of lead paint, anvils, tool boxes, etc, for controlling the batten. Easier to adjust. In step 4 it will become clear what the flat surface paper is for.

Step 3, the mold.

  • Photo. Setting up the mold.
  • Photo. Most of the mold, minus the front lip to hold the plywood. Just plain old CDX or oriented strand board works fine. I used whatever I had laying around.
  • Photo. This pic. shows a bit of the mold, mostly covered with the vacuum bag (6 mil. polyethylene) but in its finished state. It was raining out and my shop was not big enough to store the finished panels, so I built a carrier to suspend the last panel above the mold while doing the next, rather than wait for the rain to quit so I could get the panel out and under tarps.

Step 4, The hull panels.

  • Photo1. Photo2. Here's two photos of the flat surface pattern in place on a full hull panel. The black dots are where I punched holes so I could spray paint on locations marking the stringers layout. A can of spray paint transfers the pattern to the panel.
    Next time I think I would leave off that topside, portlight area. This makes clamping on the stringers and deck-former clamps a breeze, and makes for less plywood waste. Add it later.
  • Photo 1 Photo 2 Cutting the panels. shows judicious use of a skillsaw. Also, you can see how I transfered from the flat surface pattern marks for the stitching wires, keel area. Already looks pretty fair, eh? In photo 2 I'm cutting out that topside area I would do without next time. (Kurt's video shows an example of other methods).

Step 5, stringers, sheer timbers, deck-former clamps.

  • Photo. Photo 2. This step is mostly about finding clamps. I borrowed every one in the neighborhood. It is also about turning short fat boards into long skinny ones. I ripped the spruce on a tablesaw to about size, then rough cut out the scarfs with a bandsaw. I finished up the scarfs with a router jig. A deck-former clamp lays on the floor. Photo 2 is just gluing up a few stringers at once.

Step 6, joining hulls, adding structure.

Unfortunately all of my photos are slides in the joining process. You'll have to use imagination. Basically, a pair of hull panels were brought in and (I had already glued the sheer timbers to them) I laid them on a side, supporting the top one in relative position, and began sewing them together with copper wire, at the keel. I began at about 3-4in. apart for the wires. Then I stood them up and began spreading them to the position needed for pouring the keel, which is wider than final position. At this point, the keel area had several wows and dips and I had to work them out. This was tough because you can't get inside the hulls. I began to despair. In the problem areas, I doubled the wire stitching, and with some fussing, it all just finally smoothed itself out. Whew! Lesson learned: more wire stitching than planned.
  • Photo. Here the hulls are joined and I have the deck-former clamps installed, and keel poured. There's some stringers laying on the floor.
  • Photo. A view inside. Laying out for bulkheads.
  • Photo. Building patterns for the bulkheads. Since this method of building is more 'organic' than the typical boat mold method, you let the hull foldup determine the shape of the bulkheads. Kurt has it pretty well figured out, but this boat did turn out a bit narrower than spec, which means it has few more inches draft. Here I have used scraps and an electric glue gun to form patterns.
  • Photo. Bulkheads/stringers in place. Bulkheads are running wild at the top. In the foreground are balsa spacers where the connective bulkheads will be dropped in.
  • Photo. Gluing on the transom balsa. I caulked the bag to the bottom plywood skin that I ran wild. Again, don't use silicone or latex but polyureathane caulk.
  • Photo. Getting ready to add the kickup rudder slot.
  • Photo. The rudder house. (I don't know what you call it..)
  • Photo. The dagger board case in place. I'll clean it up later. I have slides of its construction. Sides are plywood, and ends are fiberglass formed over ABS pipe.
  • Photo. The hull kicked out of the shop.
  • Photo. Different view, you can see where the connective bulkheads will go.
  • Photo. And looking up at it from under the sea, so to speak.

Step 7, Setting up hulls for joining.

OK, I only have one shot (gotta get a slide scanner..). I got practice building a boatshop as I was too cheap to do it right. The first two blew down in summer storms...winds to 70 mph.
  • Photo. Moving the second hull in, before building the endwall of the shed.

Step 8, building connectives.

Well, again I need to scan some slides. All I have is a couple shots for now.
  • Photo. Vacuum bagging balsa core onto the luan skin. The anvil helps keep things flat.
  • Photo. Out of the bag and now pulling off the scrim that holds the balsa core together before gluing. I hate this stuff. Apparently resins will dissolve the binders, but not epoxy. So for good adhesion, it must be removed. Surely there is enough demand that they can make it compatible with epoxy?!
  • Photo. A detail of the same, yuck!
  • Photo. Here's a mistake. That main bulkhead, that supports the mast, has a 'fairing' on its leading edge. The fairing consists of mini-bulkheads and a covering skin, which is being bagged on here. Well, you are supposed to put it together before installing the main bulkhead into the boat. Oops, I made the job harder by doing it afterward. Still not sure if I'm good enough to build it to fit, without it being on the boat, but I sure would try next time.

Step 9, putting it together

No prints, just slides again. It'll probably be awhile before I get them online.
  • Photo. By my buddy is by a little sign we placed in the boatshed for the visitors. It says: Warning! (giving us) advice costs (you) $1.00. Questions: 1. Launch date: (Answers cost)$5.00. 2. How are we moving it? $2.00, and 3. Where does the mast go? $.50. I'm up sanding or gluing something in the cockpit.

Step 10, finishing it off.

No photos yet.
 

More to follow when I get some slides scanned! Might be awhile.

 
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