Thread: looking at building a timber strip kayak, just a few questions

Howdy,

Most of these timbers are too heavy to build much of a kayak from.

The two best choices for the timber strips are
Western Red Cedar
Paulownia

Both of which help keep the weight down.

However many of the other timbers you mention would look nice as contrasting colour strips in a couple of places.

But you do need to choose timber that glues very reliably. I am not sure, but I think the beech has gluing issues and the American white Oak can have gluing issues too depending on the species.

Jarrah is heavy ... so you would not want to use more than a narrow strip.

The normal way of working out the right number of strips is to work out what size they are going to be when finished.

Most kayaks and canoes use 6mm thick strips.

The width usually depends on what is economical from the original stock. Common widths to aim for are around 22mm, though I have been supplied with as wide as 24mm and as narrow as 19mm.

These are normally "cusped and coved" ... one edge i routed convex and the other edge is routed concave.

Once you have worked out the effective width of the strip then run a tape right round the girth of the kayak. Take that measurement and divide by the strip width and you will have the strip number required. Generally you would want 4 or so extra strips.

Best wishes
Michael Storer

Chickroll

Have a look at a recent tread titled 'strip planking'. There is a post by Allan Newhouse showing kayaks made of a mixture of Paukownia and WRC that are beautifull.

thanks for the replies

just jotting down my brain here... if it helps anyone in the future then it's served a purpose

i was just having a look at the weights of timbers, as i don't really want to spend any money on the timber- those listed are what i have access to (and in large quantities)

came across this website giving kg/cubic metre (remembering water has 1000kg/cubic metre, anything below it will float, the lower the better buoyancy)
http://www.simetric.co.uk/si_wood.htm
pounds/cubic foot is the imperial
16.01846 is the conversion rate
pounds/cubic foot x 16.01846 = kg/cubic metre

(approximate weights)

North Queensland Mahogany ~ 995kg/cm
Western Australian Jarrah ~ 820kg/cm
European White Beech ~ 700kg/cm
American Cherry ~ 610kg/cm
Spanish Cedar ~ 416kg/cm
American Oak ~ 640kg/cm
Tasmanian Oak ~700kg/cm
Queensland Blackbean ~ 755kg/cm
New Guinee Rosewood ~ 650kg/cm
New Guinee Walnut ~ 550kg/cm
(unknown origin) Silver Ash ~ 650kg/cm

the 2 suggestions
Paulownia ~ 240kg/cm
Western Red Cedar ~ 380kg/cm


so how much is the average cost of Paulownia and western red cedar, unmilled and milled? (i have no issues milling it myself)

Chikoroll

Where do yo live? It has a significant bearing on whether it is practical to obtain a log to mill your own planks and strips.

Originally Posted by Chikoroll

the 2 suggestions
Paulownia ~ 240kg/cm
Western Red Cedar ~ 380kg/cm


so how much is the average cost of Paulownia and western red cedar, unmilled and milled? (i have no issues milling it myself)

Have a look at whitewood's website (he grows and sells paulownia) - as he says the freight will be the main issue, nit the cost of the timber itself.

brisbane, inala, 4077

A Guillemot has about 4.5 m2 of surface area. If you use 6mm strips, there would be 0.27 m3 of timber in the hull and deck.
If you use Paulownia that would weigh 6 or 7 kg
WRC would be about 10 kg
Tas Oak would be about 19 kg
Jarrah would be about 22 kg

You would need to add somewhere between 6 and 12 kg for the glass and resin as well as the coaming, footrests, seat etc.

So a Paulownia kayak would be between 12 and 19 kg finished weight.
A Jarrah one would be between 28 and 34 kg

I know which one I would prefer to lift up onto the roof rack on top of the car.

While it is possible to use 22mm strips, that is wider than most kayak builders use and you would need to rip some to half that width to get around the curve at the chine on most designs.

I used 19mm strips and that seems to be by far the most common width. I used 10 or 12mm wide strips on the tighter curves.

Not everyone uses bead and cove edged strips. I have built four and just beveled the edges where necessary. Bead and cove creates some extra problems where tapered strips need to be fitted.

This site:

http://oneoceankayaks.com/smallwin/stripcalc.htm

may help you work out how much timber you need.

It is one of several that have a wealth of information about strip built kayaks.

He's right you know!

Cheers for that anewhouse

Mik

big thanks for that anewhouse

is 10kilo's that much a difference when it's in the water? be about the same weight as a plastic one wouldn't it? - and wouldn't the design of the kayak also minimise the effects of this- such as making a longer lead in to deflect the water more efficiently

i will do a bit more researching before i commit, and then i will give whitewood a yell if i decide to go for paulownia, (or i might just use the spanish cedar- i have 5cubic metres in 4 metre lengths of this in 50x50 and 150x150)

Chikoroll

I don't want to enter into the debate over light versus heavy kayaks. However water craft that are built for speed are also built to be as light as practical. Having said that I live just over the Qld border near Murwillumbah. If you wanted a Paulownia log or 2 to mill your own timber I'm sure we could work out a deal. I have logs that have been in a stack for 2 years so the timber will air dry in days if cut into strips or a few weeks if it's 25 mm thick

John

Having always owned light kayaks and canoes, I would argue that 10kg makes an enormous difference.
I can easily lift mine onto the car and carry it to the water with one hand. Friends with heavy tupperware kayaks often need help to load and carry their kayaks.

Heavy kayaks that I have paddled often feel sluggish in the water. They may not actually be that much slower, but they feel unresponsive.

Modifying the design to have a long tapered bow doesn't completely eliminate the disadvantage of the extra weight. It doesn't help with acceleration and it means that the bow won't lift over waves as easily. That is partly because of the reduced volume in the bow and partly because there is more weight close to the ends of the kayak, so there is more inertia and the bow resists lifting.

A good solution to the choice of timber might be a mixture of your Spanish cedar, which is a reasonable weight and Paulownia. I am assuming the cedar is a bit like WRC, so it would contrast nicely with the very pale Paulownia.

Chikoroll
10 kg is an enormous amount of weight in terms of kayaks. You will notice the difference in handling more than speed and 10 kg could be the difference between a craft that is beautiful to paddle and one that is a dog.

The weight will also have a big impact on handling the kayak on land, I know one of my kayaks didn't get near as much use as it otherwise would purely due to the hassle of lifting it on and off the car. I ended up selling it even though I loved the way it handled rough conditions purely because of the weight factor.

A friend of mine built a cedar strip plank Cape Ann Expedition kayak to which he added extra layers of glass to beef it up. The end result was about the same weight as many commercial composite sea kayaks but since then he hasn't used it much as he prefers his other kayaks. Without the extra weight it would have been much more fun to paddle.

Do you have a vision of what you want your kayak to do? The conditions it will be used in, loads it will normally carry etc? Also speed vs maneuverability vs stability? Perhaps you could find some kayaks to test paddle in your area to help establish which criteria are important to you?

Sorry for rambling on for so long but I hate to see someone go to all the trouble of building and then see it sit in the shed instead of being used like it's meant to be.

Kelvin

I would agree with all the above. My feeling is that even 5 to 7 lbs over a strip cedar built boat is a big difference.

The only area I would add ... is that while an extra 5lbs is noticeable on the water it is probably about 5 times more noticeable when you have to lug the boat somewhere by yourself. Maybe car roof to the beach.

Under 50 lbs it is reasonably easy for one person - though lighter makes it simple. But by the time you get to 60, 65 or 70 it is starting to be quite a weight for one person.

The hull for my Beth sailing canoe was 70lbs originally and as a 30 something (age) I could put it on my shoulder and carry it down to the shore over a distance with some degree of discomfort - it was better with some help ... but at least I could do it by myself. I couldn't consider it now at the end of my 40 somethings - so would have to put trolley wheels at one end or launch on grass or sand where I can drag the boat.

But a 50 pounder makes it easy - no pain and discomfort when I was in my 30s but now almost 50 ... I am wanting every single pound removed from the boat that I possibly can.

If you look at a boat and think of carrying it and what you feel is "no worries" then you are going to use that boat a hell of a lot.

Best wishes
MIK