Any plans for a folding SOF available?

[brian.cunningham]

I've asked this before, and the answer was no.
I'm hoping the situation has changed.

I also want to build a boat that will fit into the back of the car.

[Leon Steyns]

Pardon my ignorance, but what's a SOF?

Greets, Leon Steyns.

[Hwyl]

I also wonder what an SOF is. I did build a cape cod frosty http://www.capecodfrosty.org/ that would fit easily in the back of a station wagon or minivan (in fact I used to crank the heat on the way to races to ensure that the epoxy from my "this weeks modification" had cured) you could also build a coracle (after all they were featured in Lord of the rings), There is information on how to build one in Robert Morris' book www.brewerycreek.ca (http://www.brewerycreek.ca)

[KenC]

Pardon my ignorance, but what's a SOF?
Skin On Frame - the folding, or take-apart ones (that I'm familiar with) are kayaks. Some can be broken down to fit in a rigid golf-bag case for travel.

[Steve Paskey]

Here's a possibility: plans for a 13-foot folding canvas-covered kayak. 40 lbs, fits in two bags, the longest being 7 feet.

http://www.clarkcraft.com/cgi-local/shop.pl?cart_id=d2be948f0cce019271f22e4c67a3c6d3&type=item&categ=014&item=934901066

[ 12-27-2003, 10:17 PM: Message edited by: Steve Paskey ]

[Aramas]

Percy Blandford's book Canoes and Canoeing (1961) with his designs from the 50's has plans for a folding sof kayak. I've paddled a 12 footer and it's too short - the stern gets sucked under at full steam. Other than that they're good boats - light, stable and easily paddled and handled - much lighter than Kleppers. Good directional stability. The plans are set up so that you can pretty much make it any length you want.

Blandfords plans for the 13' (12'6' x 27" x 40lbs) single and 17'(17' x 32" x 60lbs) double are available in the US from Clark Craft (http://www.clarkcraft.com/) - However, Blandford stated in his book that the reader is free to build boats "for his own or club use" but not for sale, without paying a fee - so I'd be a bit annoyed at having to pay for them.

There are some photos of other Blandford designs at the the Canvas Kayak Website (http://www.brunel.ac.uk/~acsrrrm/kayak/) and more folding kayak stuff at FoldingKayaks.org (http://www.foldingkayaks.org/)

[ 12-27-2003, 11:17 PM: Message edited by: Aramas ]

[brian.cunningham]

I found a real nice page about building folding boats.
http://foldingkayaks.org/build.html

I really like Tom Yost's designs,
http://www.rtpnet.org/robroy/baidarka/slideshow/slides/parts.jpeg
http://www.rtpnet.org/robroy/baidarka/slideshow/
but they're all in aluminum, and he's never made plans available :(

What I'd like to do is a bigger version of this boat.
http://foldingkayaks.org/eva3456.jpg
http://foldingkayaks.org/eva.html

[ 12-27-2003, 10:49 PM: Message edited by: brian.cunningham ]

[Aramas]

Here's a nice pic of the Marosk Greenlander:
http://www.rtpnet.org/robroy/baidarka/slideshow/slides/14.jpeg

ANd here's Volker Born's lovely greenlander:
http://www.pouchboats.com/pics/afbbc/volker_eski/frame_small.jpg

http://www.pouchboats.com/pics/afbbc/volker_eski/volker_small.jpg

And Peter Chopelas' 14 pounder:
http://www.pouchboats.com/pics/afbbc/peterchopelas01_small.jpg

http://www.pouchboats.com/pics/afbbc/peterchopelas02_small.jpg

All from PouchBoats.com (http://www.pouchboats.com/index.html) who also have an interesting folding boat builder's forum smile.gif

See you there tongue.gif

[ 12-27-2003, 11:41 PM: Message edited by: Aramas ]

[Aramas]

Here's the Ludens Nauticus from Chile:
http://www.qsl.net/xq2fod/Nauticus/kajak10.JPG

And an advanced case of livingroombuilderitus:
http://www.qsl.net/xq2fod/Nauticus/kajak7.JPG

The story is here. (http://www.qsl.net/xq2fod/Nauticus/Nauticus.html)

[ 12-27-2003, 11:54 PM: Message edited by: Aramas ]

[brian.cunningham]

Originally posted by Aramas:
All from PouchBoats.com (http://www.pouchboats.com/index.html) who also have an interesting folding boat builder's forum smile.gif

See you there tongue.gif http://www.pouchboats.com/pics/rz96/pacific01_small.jpg
:cool:

[brian.cunningham]

Originally posted by Aramas:
ANd here's Volker Born's lovely greenlander:
http://www.pouchboats.com/pics/afbbc/volker_eski/frame_small.jpg

http://www.pouchboats.com/pics/afbbc/volker_eski/volker_small.jpg
That's one, actually three smile.gif , nice boats!
http://www.pouchboats.com/volker_born.html

[Eric Sea Frog]

Your humble servant's last creation:

http://im1.shutterfly.com/procserv/47b3d706b3127cce8f4829da22360000002610

I have to add that the bow is at the right. Its lacking volume is a faulty feature, exaggerated by the wide angle of the lenses. The take-apart paddle is a special tendinitis alternative to the traditional greenlandic tool.

http://im1.shutterfly.com/procserv/47b3d706b3127cce8f4820d062a00000002610

Again, the bow stempiece should be higher.
The craft weighs about 15 kilogrammes. As a few kilometer's portaging in the heatwave left some painful souvenirs, the next maid should be twice as light.

Ash-tree is a heavy species. Carbon fiber rods are a rare and expensive possibility for stringers.
Rear view: the black velcro is showing.

http://im1.shutterfly.com/procserv/47b3d706b3127cce8f482240e3010000002610

[ 12-28-2003, 12:58 PM: Message edited by: Eric Sea Frog ]

[Aramas]

That's an interesting structure Eric - any chance of some close ups of the fittings?

[Eric Sea Frog]

Aramas, this is the rear stem. Smaller tubes slide into larger 3/4" tubes, and vice versa.

http://im1.shutterfly.com/procserv/47b3d706b3127cce8f482fe0a33f0000002610

Station 1. Okoumé ply fitted with instant nylon clamps that snap on tubes.

http://im1.shutterfly.com/procserv/47b3d706b3127cce8f48224ee30f0000002610

The two-part, 20" long coaming. A metal hinge is visible, but a nylon hinge fits he coaming halves to the deckbeam underneath the skin. (Aft boat part.)

http://im1.shutterfly.com/procserv/47b3d706b3127cce8f48224362320000002610

Forward lacing: there was not supposed to be any, but as the skin was tightly sewn before glueing, I had recourse to permanent caesarean surgery for easier sliding of the structure into the truck tarp.

http://im1.shutterfly.com/procserv/47b3d706b3127cce8f4820be62ce0000002610

The seat is a simple piece of tarp slung over the stringers. The coaming parts have screwheads that fit into grommets.

http://im1.shutterfly.com/procserv/47b3d706b3127cce8f48254c22a60000002610

More on the coaming fittings:

http://im1.shutterfly.com/procserv/47b3d706b3127cce8f4bdd59c32b0000001610

The little yellow buoy was beachcombed and would float my keys in case of capsizing.

PS. I must remark that the dimensions given to some of the projects referred to here can be a problem.
Very large beams (like 32") especially on singles, mean more wetted area, drag and are a hassle to paddle at the end of a trip, which reduces safety.
The sheer stringers would also come in the way of the paddle, which consequently should have a very long shaft which increases momentum and tiredness.
A single kayak should hardly exceed two feet.
And a kayak shorter than four feet isn't much more than a beach toy.

[ 12-28-2003, 06:27 PM: Message edited by: Eric Sea Frog ]

[Aramas]

There's a lot of good ideas in there Eric. How long did the whole project take? Is that your first? What did you base it on? It doesn't look like it has inflatable sponsons - how is the skin tensioned?

My ex- folding kayak is in my ex-house with my ex-girlfriend. She thinks it's worth something and won't let me have it. A few years ago her boyfriend tried to put it together and couldn't lol - I met him and if something couldn't be done by being loud and pushy then it would have been beyond him smile.gif

I liked the boat but it was too heavy and bulky. It was the Australian Special Forces model which was based on the Klepper 2 seater that it replaced, and the entire foam/carbon frame was hinged so it came apart in only 2 pieces. Elegant but bulky. Part of the spec was that it had to remain afloat with 2 fully equipped commandos after being machine gunned in the water, hence the bulky carbon/foam stringers and frames.

PS. I must remark that the dimensions given to some of the projects referred to here can be a problem.
Very large beams (like 32") especially on singles, mean more wetted area, drag and are a hassle to paddle at the end of a trip, which reduces safety.
The sheer stringers would also come in the way of the paddle, which consequently should have a very long shaft which increases momentum and tiredness.
The wide beam is pretty standard on the doubles, and since the maximum beam is close to the waterline and the edge is rounded and soft (inflated) it's not really a problem. The padle just kind of slides when it hits the gunwale, and doesn't do all the clacking and stuff like with a hard edge. They're also intended to sail so the extra stability is usefull.

They're also good load carriers - my gf and I spent 3 weeks paddling around Bathurst Harbour and Channel in SW Tasmania with around 150kg of gear at the start, and we managed just fine in some really strong wind - 50-60 kts (downwind only - lol). Still, towards the end when we'd almost finished the side of bacon, fruit cakes, shortbreads, water crackers, boxes of chocolates, whiskey, liqueur, pate and rounds of brie (I know how to look after a woman in the wilderness smile.gif )the thing felt like it was almost planing.

Imo the doubles are too bulky and heavy for use as a single, so I'd like to make a more streamlined 1.5 type - maybe a greenlander type, but the cockpit would take some thinking - the open type means wet legs.

I read that the Inuit commonly put their wife in the stern of their ulta narrow singles, and their child in the bow - lol. I've yet to meet a woman that would go along with that tongue.gif

[ 12-28-2003, 09:49 PM: Message edited by: Aramas ]

[brian.cunningham]

Eric, your the man!

After strolling around the local Home Depot I decided a hybrid frame, aluminum tubes with ply bulkheads is the way to go.

a couple of questions.

Where did get the "instant nylon clamps"? :confused:

What did you use for the skin?
I asked at the local kayak/ boat places for PVC skin, they were all stumped as to where to get it.

Will polytarp work? at least for a prototype.

[Aramas]

There's a lot of good info on the pouchboat forum - you can either use synthetic waterproof tarp material like Eric did (and get glue from the same place) or if you can get Hypalon in liquid form you can use it to coat any fabric when diluted with 80% turps. There are other 'old fashioed' ways of treating canvas over there too. I like the idea of ripstop nylon with a Hypalon coating (super light), but have no idea where I could get it here. There's also a 'heat stretching' method that turned out a very fine boat.

I'm also thinking of using an all wood frame with no metal fittings (except perhaps locating pegs). I need to find some closeups of the Nautiraid webbing attachment system.

[Eric Sea Frog]

Aramas,

Good boats and yaks only react to their master's voice (at least it's a theory that's been kicking around for quite a while), so expect more fun! :D I'm sorry for her!

Nautiraid also makes alu structures now, along with the old brass and ash-tree woodworks.
I talked to their boss last week at the Salon Nautique, they use polypro instead of polyethylene (PHDE) which has been Feathercaft's choice. He says it has less flex, but perhaps it doesn't snap on as easily?

Nautiraid fittings (http://www.brunel.ac.uk/~acsrrrm/kayak/nautiraid/photos.html)

Sponsons aren't necessary on a yak that has moderate beam and a reasonably strong structure.
Inuits wouldn't use them; they're fragile and take time to inflate. You may add inner floatation inside both ends of the hull.
This yak has a taut skin.

The kayak beam question is indeed debatable, but commercial builders have to make boats of their own: real yaks are tippy, especially for a first-time user. I know of XVIIth C. yaks that are 38.7 cms large, but Bumpkin Joe could shy away from such a contraption, however fast it is!
And do narrow yaks peel off like flamin'rockets Matey! Even with a 2 meter skinny paddle!

Nautiraid use some straps, but those won't keep firmly the two assembled pieces of wood at a permanent angle, so straps are used only as a complemental device on wood structures.

Instead of brass fittings that aren't so easy to make, you can use off-the-shelf steel fittings and coat them with varnish or paint. Crappy? Yes, but they're easy to come by for twopence if they rust. L-fittings can slide into u-shaped fittings, you may buy them flat and bend them over their perforations. The red spots are what they're supposed to be: christening liquid!

http://im1.shutterfly.com/procserv/47b3d923b3127cce8a18749b92150000001610

That's the way I built my previous take-apart yak.(The first was a funny Rathburn-Romaneck folding Scout kayak -not a real kayak actually).

http://im1.shutterfly.com/procserv/47b3d923b3127cce8a1991d673ce0000001610

The fittings were screwed into the ash stringers' wood thickness. Station 2 is missing.

Splash You Later, tongue.gif

Eric

[ 12-29-2003, 06:00 PM: Message edited by: Eric Sea Frog ]

[Eric Sea Frog]

Originally posted by brian.cunningham:
After strolling around the local Home Depot I decided a hybrid frame, aluminum tubes with ply bulkheads is the way to go.

Brian, the lobster claws-and-plywood assembly wouldn't be my better advice for a first take-apart yak. Don't do like I do...
The problem is those clamps can(t be screwed into the laminated side of plywood stations, which is too fragile. You have to trim special wood connecting blocks. Yet this won't be easy because they must have a slant face in order to make for the overall curve of the gunwales.
Nylon clamps indeed are too thin to be effectively beveled, even though you'd have to file their ends so that those won't protrude into the skin (that's also the reason why stations' sides are concave).
I made this choice nevertheless because I was going ultralight, and because of thick tubes the project would be too heavy. But it took me a whale of a time.
I just might, à la rigueur, screw clamps to fir or spruce moldings to make the stations.
THose nylon clamps are used (at least in EU) to hold electricity cables in basements. The (German) maker is Fischer. Comes in several sizes.
If you don't have this problem you'd better pick 1/2" thick HDPE or polyropylene panels.
That's what Feathercraft or Tom guru Yost use.

What did you use for the skin?
I asked at the local kayak/ boat places for PVC skin, they were all stumped as to where to get it.
Will polytarp work? at least for a prototype.I fear water could sneak into polytarp when it wears out, as it's a woven material. It could just be used as temporary sails or tarpaulins.
My advice is: look for a tarp maker in the yellow pages, and buy a can of glue.
For layout sizing, remember you'll need at least the length of your kayak for the bottom as you won't want any transverse seam.
It's not as necessary for the deck.
So perhaps you may save the corners to make the bridge. The material may come in various breadths anyway, you'll need at least the added widths of the bottom panels (better trim two of them even though you'll have a seam underwater) plus the sides plus the deck, plus an estimated 2" overlap margin.
A light color reflects heat very efficiently.
A big advantage of truck tarp is it won't strech, which is better for a t-a yak.
The glue is atrociously toxic.
Assemble outdoors preferably. Hypalon is even worse.
I fear such advice may look peremptory given all your boating experience...
My two € cts.
Now I'll be giving a look at your site.

Eric

[Leon Steyns]

Eric,

That is some really cool kayak-stuff you've got there! :cool: :cool:

I started (and finished) a take-apart-frame based on Igor Ravbar's 10' EVA, but I got stuck with the truck-tarp. It's difficult to handle and I can't figure out a good way to cut strips of it to glue/sow a tight-fitting 'sleeve'. Any suggestions?

Greets, Leon Steyns.

[Eric Sea Frog]

Hi Leon,

Glad to know you're in the middle of a construction.
Here's how I glued my last yak.
As it involves some sewing, you better have some extra spare time for the job.
First trim the deck and bottom panels. If the bottom or the deck are pointed, don't hesitate to cut two panels for each in lieu of one, else the skin would get all wrinkled.
(By the way, does your Ravbar adaptation retain that large floor ply panel, or have you reinforced it with an additional ash keelson or equivalent? It's an easy job to do, same thing for the gunwales).

Add an extra 1 or 2" margin for skin overlaps.
Fit the PVC panels in place to the wood stringers.
Use duct tape, pinches, clamps, whatever holds during the night (depending on the heat) so that you won't have to refit everything on the next morning.
Then start sewing the top to the bottom.
Sew into the overlaps, using strong thread, spacing at about 1", zigzagging up and down from one stem to the other.
From tome to time tweak and pull the thread, a bit like playing the harpsichord, to kill slack and keep up the tensioning.
(Your yak will actually show an interesting open grand piano aspect -enjoy, it won't last!)
When you're done with that song, trim the side panels. Retain a 1" safety margin type overlap.
Start baby-steps glueing. Lay the glues evenly on both sides, let dry 10 to 20 minutes depending on temperature, then clamp firmly.
I used Carmo PVC seal, made in Denmark
(Hojvangen 19, DK-3060 Espergaerde)
1 liter can.
Your hull is now fully closed, like a floatation compartment. The skin will be drumtight, to the point you'll experience trouble running the woodwork into it. One tip there is to cut out 5mm or 1/4" length from the rear of bow stem: it worked on mine! Just let the varnish dry before you assemble again.
I imagine you can shorten the process by skipping he sewing job, using duct tape in place of thread.
But non-folding s.-on-f. greenlandic replica-builders do sew.
Now cut out the coaming. Glue one or two additional layers of PVC cloth along the edges to strengthen before setting the grommits.
Cut the deck skin along from the aft coaming to the stern. Glue one or two layers as reinforcement. Fit grommits, at about a 4" spacing. Use the brass kind to avoid rusting.
Run 3 or 4 mm thick flat cord from stern to coaming. The round kind doesn't pull tight.
Fit screwheads into the coaming thickness so that they'll face grommets, marking the places with a pencil.

I think I'll sew my next ultralight yak, using polyester cloth then spraying it, or soaking it with a silicone and turpentine mix, à la Timo Noko. I don't know how it will hold the grommets. Sewing several layers of cloth for that purpose would be quite a long job. Look up Peter Chopelas' site on the subject, perhaps he has tips from building his retrieval yak.

One of these years I'll go to Hindeloopen or Brielle to see those recently restored 17th C. yaks.

Greets,

Eric

[ 12-31-2003, 09:17 AM: Message edited by: Eric Sea Frog ]

[Leon Steyns]

Hello Eric,

Thanks for the tips and instructions! I will study them and have a go at it. The extra spare time is going to be the biggest problem... :rolleyes: :rolleyes:

I built EVA without a keelson. The two bottom halves have "teeth" (two-and-a-half), so the centre frame bolts the bottom firmly together (I'll add a picture when it's daylight again... ;) ). Anyway, the frame is rigid enough as soon as all the stringers are in place. I'm thinking about building another one using your tube idea - very cool!

Greets, Leon Steyns.

[Edited] There are more Skin-On-Frame folding miracles at http://www.foldingkayaks.org/. Vewy coowl!!! :D :D :D

[ 01-01-2004, 04:11 PM: Message edited by: Leon Steyns ]

[brian.cunningham]

Tom Yost added a page for fitting skins on his WebSite
http://yostwerks.com/Skin1.html

[Leon Steyns]

Thanks for the link! Looks good at first sight, but I'll have to study it some more. I like the idea of sewing the seams and the velcro.

Here are some pictures of the frame I built:

http://www.imagestation.com/picture/sraid99/pa6075c33a325300c99194722904bbd71/f9f07991.jpg

http://www.imagestation.com/picture/sraid99/p20c31ec66f64201323054ce4dcd143ad/f9f07990.jpg

And the baseplate:

http://www.imagestation.com/picture/sraid99/pc1594cd8b8e67dc830d16ab912399ba6/f9f0798f.jpg

http://www.imagestation.com/picture/sraid99/p235f6167b74e4b76ffb7ccaedd6690ed/f9f0798e.jpg

Greets, Leon Steyns.

[Eric Sea Frog]

Leon,

Nice work, but structurally such an arrangement could make problems beyond a simple flat water use for a child.
The skin could touch the sides of the stations, those should be trimmed concave.
Same for the base plate. If you keep it, the edge should be beveled and rounded rods lining the edges should be glued and screwed along to avoid skin wear.
Ckeck the connection fittings of the stations to the stringers and gunwales.

The fitting of the amidship station to the floor looks questionable too.
Did you pick waterproof glued plywood? It's thick enough, but when the structure starts wearing and flexing at sea or on fresh water, the hinge will pull the vertical pindles in a dangerous manner as they come up thu the fragile, laminated side of the station plywod thickness.
Builders never screw into the lamination, only perpendicular.
You could cut out a rectangular panel from the baseplate at hinge level, and add a strong -about 1" thick- keelson running underneath the floor planking as a reinforcement.
Screw a transverse metal fitting across the stringer. Screw two L fittings to the bottom station, spaced so that they come right and left of the keeelson stringer, under it.
On the oher side of the station, screw a wood or metal wedge to the keelson to keep the station from sliding. Just slide the stations fittings under the keelson fitting, framing it.

There used to be some pics of horseshoe fittings there...Can't find the precise link.

web page (http://home.t-online.de/home/derpoly/home.html)

To assemble the two floor halves, it should be possible to make a couple of horseshoes from the arrangement you've built:

Don't forget varnish or epoxy, or paint.

It's a bit hurried and oversimplified, but I lack time.
Keep us posted.

[ 01-15-2004, 07:44 PM: Message edited by: Eric Sea Frog ]

[MarkC]

Brian - you could log onto ebay.de and have a look at the folder kyaks for offer here in Germany - well being the home of klepper, pouch, and some of the older DDR (communist) creations.

The older ones go for a couple of hundred, some without skin (differing states of repair). People find them in their garage roofs etc, and want to get rid of them. They would make a good restoration project (or dare I say a good template for self-build!!) I think all the clamps were/are bronze, Also, you can buy new skins and parts if you run out of steam.

Postage, hopefully, wont cost a leg. Email me if you want to write to them or send an email to them. Cant help you much about the low US dollar though...

[rbgarr]

Here's a set of 1943 SOF kayak plans for sale (not folding SOF though):

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2781786192&category=2883&sspagename=rvi:1:2