Ozbow

This isn't about archery or bows, but it's about appropriate qualities of various timber types and I know you guys have knowledge on this and also you appreciate well made hand crafted useful items.

I'm re-reading Chris Cunningham's book "Building the Greenland Kayak" and out of interest more than action (at this point in time) I'm looking into what locally available timbers would be good/best for the job. CC's book mentions North American timbers but obviously these are typically not readily available here or would be cost prohibitive.

There are two main structural components to a GK. First are the gunwales which are approx' 75 x 19/22 at 4.8m to 5.1m long. These need to be straight grained and form the backbone of the GK (sounds similar to a bow right?). These are then forced into shape with deck beams. Second is the ribs which are morticed into the gunwales and steam bent into shape to form the hull basic shape. A keelson and chine runners are added on the outside of these to form the keel and chines. CC in his book uses 22mm wide by 9mm thick timbers which are thinned slightly (by 1/16th of an inch or 1.5mm) to allow it to bend more readily where needed. I am guessing max' length you would need for the ribs is around 30".

So I think you will see the two different main components need different properties. Both want to be lightweight but strong enough to do the job.

Gunwales.
Pawlonia has been used but has negative feedback as it breaks a bit too easily. Western Red Cedar is an alternative, only negative I have is it is very soft. American Ash and European Beech has been suggested but getting it in the size required could be challenging and expensive. I suppose it could be scarfed but not my preference.

Ribs.
I know Peter Ingram-Jones of Lampshades and Canoes has used bamboo lamellas from Bamboo Oz for ribs but this stuff is only 5mm thick. I've spoken to Shane from Bamboo Oz about their flooring but he was concerned the glues used would let go when steamed and forced into shape. Bamboo does sound like a good option but need to get it in the right format and dimensions.

I've thought King Billy Pine and Celery Top could work but doubt they are feasible. So, interested to get some input from you guys on what timbers you think would do the job.

Thanks in advance, Brad.

Hi Indie,

Watts Woods at Salisbury have an extensive range of timbers and are easy to deal with.

http://www.wattswood.com.au/list-timbers/

If you click on the timber species it will bring up the stock sizes.

Building one would be an interesting and rewarding project. Are you going to use the construction method as shown in the photograph?
Laminating the ribs and shaping them around an adjustable peg and board form may be easier and/or more accurate than steaming.

We are indeed fortunate to have a number of specialist timber merchants in the area.

Daryl.

Hi Daryl, yes essentially that's the structure I will be using. The method described in the book includes cutting all of the ribs to length, steaming and then shaping over a form. So as long as the form is accurate it should work out okay. The steaming method sounds like it does not include too much work and I was thinking that laminating etc would be more time and money consuming. I could be wrong about that. I'll go back to the book and read in more detail the whole steam/bending process and see what I think. If you were to laminate what glue would you use?

My main form of kayaking is offshore where I fish. I come from a sea kayaking start and also go camping out of my kayak on the now rare occasions I get the chance. There are several ways to make a kayak but I don't think any come close to the beauty of a well made skin on frame (SOF) kayak. They have their down sides and aren't really suitable for my offshore fishing but totally suitable for other things. The time taken to build the SOF is also a lot less than other methods. Also supposed to be fairly economical, depending on how much you pay for the timber. Apart from all of that you are right, and I do find it interesting.

Just been looking at Watts Woods website. That's a great link, thanks. I'll give them a call to see what costs are and if they have any suggestions. I would so love to build it out of Huon Pine but.....

Brad.

So I've read the section re' bending the ribs in detail. The ribs are pre-prepared including being cut to length and thinning and then steamed a few at a time. The end of the steamed rib is then put in a jig and bent more to break the grain than to a definite shape. While it is still hot the ends are pushed into the mortices on the gunwales. Sometimes the shape needs to be manipulated and pushed down in the middle. The ribs at the bow have a more pronounced arch in the centre to help form the hull shape.

So I gather that the shape of the ribs is manipulated during the installation process. As such I don't think pre-laminating may work as you'd be looking to achieve a definite shape during the gluing stage and this shape is different for every rib along the length of the kayak. Interested to hear your thoughts on it though.

Brad,

Before committing to a build plan are you wanting to build a flexible or rigid hull?

If using heat for bending the ribs dry heat may be easier than wet.

I believe any of the glues/epoxies used in the boat building industry should be suitable for laminating ribs.

Daryl.

Hey Daryl, the frame, therefore the hull, should be rigid. No doubt there'll be a bit of localised flex but on the whole the more rigid the better. I would have thought that dry heating would just make the timber harder?

I spoke to Michael from Watt's Woods today, very helpful bloke. Seems like there's some good choices at reasonable prices. Surian Cedar was pretty cheap and supposedly frequently used in boats. Oregon was the cheapest and is looking like a real option at this point. Price was $8.31/m for a 75 x 25 piece. Something that got my interest though was Huon Pine at $17.03/m and I will really consider that maybe after the first frame is done. Only thing is how well it will glue as it is a very oily timber but some of the marine epoxies such as Bote Cote should handle it. Note prices are exclusive of GST. I got a price for Sitka Spruce which would be the ducks guts but at $42/m it's a bit off the planet.

Note that not all those timbers are readily available in 75 x 25 and you have to see what's in stock at the time, so the above is only a price comparison for the same section of timber.

Hey Indie,

I can't help with the timber questions but you are already talking with Daryl and he is very knowledgable.

But I did remember seeing a Greenland type kayak that is built in Oz and wondered if you might be able to get some info from them on timbers used.

The detail of the 0 Six Hundred Kayak is here. . .

http://www.osixhundred.com

Hopefully it helps.

Enjoy the journey, I'm sure it will be very rewarding whichever road you take.