The strongback

The strongback is the basis for building the boat. On this a skinning frame will be setup that will be used to get the shape of the skin right. This frame will not be part of the boat later on.
I build the strongback exactly as designed by Thomas and put some effort in making it straight and level. The strongback is of course re-usable and can be used for lots of other boats.

In stead of long bolts I used m10 stud that I shortened using the lathe.


Bolting the strongback together:
I try to get the kids, Yentl (6) and Levia (4), a little bit involved in these projects. Even when that sometimes means that you have to do things over again.....

Obtaining materials

The first major hurdle is obtaining materials. For some reasons it gets difficult when you want something that goes outside the scope off the do-it-yourself-shop. And living in the Netherlands I have to find other suppliers than supplied on the yostwerks site.

The design calls for:
Aluminium 6063 or 6061 tube in various telescoping english sizes
PVC coated fabric in 10 and 18 oz weight
HH-66 PVC glue
Folbot sponsons (air tubes for the commercially made Folbot folding kayaks)

First the tubing:
I will have to use metric tubing, with the disadvantage that they will not telescope properly. Metric sizes have a zero tolerance fit, wheras with english sizes you can end with 0.2 mm clearance. But as I do own a lathe I will turn down the inserts slightly, no big deal.
The only material I can get is 6060 T6. Not as strong nor as corrosion resistant as the required materials, but I am happy that I can get any proper material. I will use the folowing sizes:
Keel / stringers: 19x1.5 mm
Inserts: 16x1.5 mm
Sleeves: 22x1.5 mm
Coaming: 13x1.5 mm
Total material cost for tubing is approximately 130 euro.

Second the PVC:
Yost uses 18 oz fabric for the hull, and 10 oz fabric for the deck.
18 oz is approximately 640 gr/m2, and 10 oz is approximately 340 gr /m2.
Luckily I found a company nearby (Pro-seal zeilmakerij) that makes lots of products out of PVC coated fabric. They were willing to sell me some PVC. Regretfully the lightest material they have is 500 gr/m2. So I ended up buying 680 gr/m2 PVC in black for the hull, and the same material in yellow for the deck. I also got some quite supple 500 gr/m2 material in grey that I might use for the sponson sleeves and the coaming. I could use it for the deck as well, but the yellow is much more beautiful.

Then the glue:
HH-66 is only available in the USA and canada. I found a shop in the UK as well, but they refuse to sell overseas. I probably will use another glue, Helaplast. A German builder has used this and it should work identical to HH-66. Another possibility is Tarpo-S, from Planenwelt.

And the sponsons:
The sponsons are sold in the Folbot webshop. But shipping from the USA is quit expensive unless I use the non-trackable USPS that I hear mixed reports about. I decided to order from the German Folbot dealer: Outtrade. Four sponsons including shipping will set me back about 178 euro. If I make a second boat I will probably try to make the sponsons myself.

Building an inflatable kayak

The start of a new building blog. I just have to make things and as I love bicycles and kayaks it is not surprising that I want to build them. Last project was a bicycle made for two, shown at tandembuilder.blogspot.com. From the road to the water: the new project will be a boat.

For long I have been fascinated by collapsible boats. We own a Feathercraft K2, and although a bit on the heavy side it is a dream to be able to take a kayak on a plane. A couple of years I ago I wanted to build a single folding kayak, but insufficient attic space blocked the effort. Recently I stumbled on the internet over the magnificent site www.yostwerks.com, by Thomas Yost. Thomas has been designing and building folding kayaks for years and is sharing all his designs and knowledge on his site. His latest efforts have been the development of a series of seaworthy inflatable seakayaks called "Sonnet". Those kayaks are way beyond anything that is currently on the market. The traditional image of a folding kayak is that of the large, wide, overly stable double kayak. And then come the Yost Sonnet designs: sleek, narrow, rugged greenland-style kayaks, capable of handling rough water, and that in a package with a weight below 10 kg that you even can transport on the back of a motorcycle. Amazing.


Here an beautifull Sonnet 16 example build by David Long. (courtesy www.yostwerks.com)

I have a trip planned to Australia to visit my brother who happens to be living aboard a boat near Sydney. Actually, his boat is the larges sailing Proa in existence that he designed and build himself, but that is another story found at www.pacificproa.nl.

With this:


as my temporary home, a seakayak would be a treat for an avid seakayaker like me. So I am going to build a Sonnet 16 and take it on the Plane to down under.

In this blog I will try to document the building process and share my experiences. The design details can be found at the inflatable kayak builders manual. This build wil be mine, but all credits for the design and the technology are for Thomas Yost, of course.