Cozy Boat

102,784

215

54

About: Tim Anderson is the author of the "Heirloom Technology" column in Make Magazine. He is co-founder of www.zcorp.com, manufacturers of "3D Printer" output devices. His detailed drawings of traditional Pacific...

A little boat like a floating papasan chair. Perfect to lay in and look at the sky.
Exactly big enough for two people to snuggle.
The supermodels in the boat are Arwen and Saul.
This boat is part umiak, part currach, part coracle, part papasan chair.
Here's how to make a tougher skin for it from truck tarp material.
The book "Umiak" by Skip Snaith will fill in any construction details that aren't clear here.

Now on Know How!



Check out episodes one, two, three, four, six, and
seven!

Step 1: Stems

The boat ended up being 9'6" long, 43" wide (measuring to the outside edges of the boat, and 18" deep in the middle (measured on the inside of the boat.)

The first step was making the stems.
I sketched them out freehand and cut them from 3/8" marine okoume plywood.

To beef up and widen the outer edge I glued on some more plywood using epoxy thickened with wood dust as seen here.
White flour works just as well, whole wheat flour doesn't. Don't use 5 minute epoxy for anything, it's not waterproof.

If I did it again I'd make the stems taller and not nearly as beefy.

Step 2: Set Up the Frame

Here it is with two main ribs, keel, gunwales, stems, and headboards lashed together with strips of bicycle innertube. At this point you have some control over the shape of the boat.
Fiddle around and change things now when it's easy.
The stem-headboard lashings are nylon string soaked with epoxy afterwards because I was confident those parts wouldn't need to change. It turns out this boat wants to turn around and go the other direction regardless of which direction it's going. So I'd make the next keel with less or no rocker. Water sometimes splashes over the bows, so I'd make the bows higher.
Put those two facts together and the stems will have to be taller too.

Step 3: Peel Some Ribs

I made the two main ribs by cutting the rim of a papasan chair in half.
It's rattan, which is strong light stuff.
The other ribs are much thinner, willow shoots 6 or 7 feet long cut from a thicket. If they grow in the dark they get tall before branching. Then I tied them as seen here and let them dry for a bit. Danielle Smith is peeling the bark off these ribs with a vegetable peeler. "PLUR" written on her hand stands for "peace, love, unity, respect". You'll have to ask her why. The veggie peeler is the best way to take the bark off. If you wait too long the bark will get hard. If you do it too soon and don't oil the ribs enough they'll crack, which isn't really a problem.

The other lumber came from a company that makes wine racks. The lumber bundles they buy come wrapped with same-species tropical wood 20 feet long. I grabbed a bunch of that, ripped it thinner with a tablesaw and a thin-kerf blade, and rounded the edges off with router, plane, rounding plane, spokeshave, sandpaper, basically every tool I had. Router with quarter-round bit followed by hand sanding was fastest. Splinters while hand sanding were a major hazard.

Step 4: Lash on the Ribs and Stringers

The thin ribs needed little blocks of wood shoved in next to them and lashed over because the main ribs are so thick.

16 ribs times 13 longitudinals equals 208 lashings. I should have used string instead of innertube. It takes a bit longer, but after it's soaked with epoxy it lasts longer too. There's nothing temporary or easy to change about 200 lashings.

Step 5: Frame Details

The stringers don't need to reach all the way to the stem. It's a lot easier if they don't and the shape goes into some compound curves there so it doesn't really need them for support. The last rib at each end is too sharp a vee to bend, so it's two sticks. It would be better to use curved sticks, putting a bit more volume in the bows. The willow ribs were irregular, but once lashed into a mesh with the stringers, the whole shape got nice and fair. Willow isn't the only species that works for ribs, and unless you're cutting when the leaves are out you probably won't know what species it is anyway.

Step 6: More Frame Details

The stick that goes inside the ribs is for the lacing that tightens the skin onto the boat.
It's also good to rest a seat on, if you wanted seats.

When the thing was all together I soaked it with linseed oil. I could have done that first and it would have been less work, but at the time it always seems like a pain in the neck.

Step 7: Closed-Cell Foam

I put an inch of soft closed-cell foam between the frame and the skin. It serves a number of functions. If you hit a rock the frame won't bite a hole in the skin. It makes the boat float pretty high even if it's swamped. If it gets punctured it's self-healing. This foam is what they shove between the girders of curtainwall buildings. I think it's urethane about 3lbs/cubic foot. It's similar to what they use for sleeping pads for camping. What this foam doesn't do is make you comfortable, since the ribs and stringers are between it and you. So I made a thicker closed-cell mattress to lay on the bottom and cushion the ribs.

I glued the closed-cell foam layer together using contact cement following the directions on the can. It's DAP Weldwood original earthwrecking contact cement. Fabulous stuff unless you're a brain cell.

Step 8: The Skin

From this point the construction is exactly like Skip Snaith's book "Umiak", which is really cute and you ought to have it. Buy it here and the author himself will answer the phone:
http://www.rockisland.com/~kyak/

I used an outer skin of denim, regular jeans material, painted with black rubber roof paint (Sun Roof Systems brand). I used an inner skin of red taffeta to protect the foam from heels etc. and to make the boat more festive.
Here I am fitting the denim skin. There's a seam over each stem and a hem around the edge with a piece of cord in it. The cloth stretches enough to fit tightly over this boat's shape without any other gussets or seams.
When lacing the skin tight over the frame, the lacing cord is just poked through holes punched through the hem. The cord in the hem keeps it from ripping out.

Step 9: On the Water

Saul and Arwen embarking on the Charles River to see some fireworks. The oars are Irish style "paint stick" currach oars. The oarlocks are called "tholes and bulls". The pivot boards on the oars are "bulls" and the pins are "tholes". These oars are bigger than they need to be for this boat, which will never go faster than three miles per hour with any oars.

The wheels at the stern are from a bicycle baby wagon. The wheels come off easily but it's no problem leaving them on. To move this boat by bicycle I shove the oar blades under a rib, tie them to the bow with an innertube, turn the boat over, lash an oar handle to my bike rack or seat post with innertubes, and ride away.

Step 10: And in the Water

How stable is it? About that stable.
Now floating nice and high with all that closed-cell foam, a little bailing and the boat is back bobbing on the water like before.

Share

    Recommendations

    • First Time Author

      First Time Author
    • Big and Small Contest

      Big and Small Contest
    • Puzzle Challenge

      Puzzle Challenge

    54 Discussions

    0
    None
    MustafaS24

    1 year ago

    Can you share line drawings of above boat , beside the diy , I loved the design so much. I really need line drawings. As you said , it is mixture of 4 different traditional boat, I loved how she looks very much. If you cant , please tell us a boat plan or advise other lines drawing, please. Thank you, Umut , Istanbul

    0
    None
    cantbuildmuchatall

    3 years ago

    Really impressive, thanks for putting this up. What quantity of roof paint did you use? It's pretty expensive here and I'd like to get the right amount the first time.

    Thanks!

    1
    None
    bridi

    5 years ago on Introduction

    Nice job, nice boat. One correction; 5 minute epoxy is waterproof, I've used it as an emergency repair on boats below the waterline and it's lasted fine.

    0
    None
    neil1701

    5 years ago on Step 10

    I quite liked your home made boat.I made one myself and entered it in i think it was summer watercraft challenge on instructables last year.I made a frame on skin idea but used upvc planks like used for making double glazing window frame,plastic sheeting on the outside for a skin and blocks of foam and plastic bottles stuffed inside it for bouyancy.Was about 5 ft 5 inches length by 4ft in middle-beam at widest point and drew about 5-6 inches.A few pictures attached....

    Dinghy-Pump-pond.JPGDIY-Dinghy-3.JPGDIY-Dinghy-12.JPG
    0
    None
    yanksguyLegutki

    Reply 8 years ago on Introduction

    The ARC, Goodwill, alleys, yardsales... Most folks are trying to get rid of them.

    0
    None
    J@50nLegutki

    Reply 9 years ago on Introduction

    pier1, world market, walmart (maybe), tons of places, all over the internet

    0
    None
    LucDaRocka1

    7 years ago on Introduction

    could i build a skeleton out of bamboo? i have a lot that grows right down the street on property where the people who own the land let me pick it. :)

    4 replies
    0
    None
    WazzupdocLucDaRocka1

    Reply 7 years ago on Introduction

    Wrap, bind and duct-tape the joints before you skin it. Bamboo is extremely sharp on split edges and "splinters" (Google "punjie sticks"). Also, check out the Gaelic skin boats, I think the spelling is "camragh". They are brush rings bound about in a doughnut fashion and then laid on a tarp (skin) and then pulled inside and ticked under the brush ring. Paddle away! I pray you can swim, or have rescuers around the pool with a line. Keep trying.

    0
    None
    LucDaRocka1Wazzupdoc

    Reply 7 years ago on Introduction

    well it was cold when we sank, we were in jeans and heavy coats...... and thanks for the tips

    0
    None
    McGyver2

    9 years ago on Step 9

    nice.... now if it could only fly....

    0
    None
    McGyver2

    9 years ago on Step 9

    So if there are wheels on the up side of it, does that mean that it can be flipped over and doubled up as a land vehicle too?

    1 reply