Monday, October 26, 2009

3. Taking shape

Being a week-end warrior does provide one the opportunity to plan, think and anticipate problems which, in most cases, do not really manifest themselves.
One of my big concerns during the week was; What adhesive/epoxy to use. A brief and productive visit to the friendly people at Advanced Material Technologies (AMT) quickly solved that problem.

I always enjoy visiting these industrial suppliers. They know that you, as a member of the public, won't place a massive order like their normal customers do but their service is always friendly and the advice sensible and informative as opposed to the salesmen of the normal hardware supplier on the corner of the street. (A few days ago, with reference to a certain electrical component, I had to explain to one of these saleswomen what the difference between "male" and "female" is.) I opted to use the AMT A032 clear epoxy for the cedar strips.
The quick-set epoxy is clear and with a tensile strength of 30 Mpa and with adequate penetration when clamped it is good enough for me.

The weather during the week-end was not really suitable for paddling and I managed to make some good progress. Having cut a few strips I joined them with splayed butt joint to the full length of 4m + but when I started gluing the first one in place, I soon realised that it's not going to work. It is extremely difficult to handle a 5mm x 20mm x 4m long strip - especially when using quick-set epoxy.
This may raise some eyebrows: My modus operandi now is to use shorter lengths ( 1.5 to 3m long) and butt-join them on the bulk-heads as I go along. This worked much easier especially when I started negotiating the rather sharp curves near the top of the bulk-heads. Progress slowed down considerably at this point because the edges of the strips need to be splayed carefully with small hand planer to ensure a tight fitting joint, particularly externally.
Had these curves on the bulk-heads been tighter, or the strips thinner and wider, I would not have been able to obtain a fair external curve in these areas afterwards without sanding the strips down to unacceptable thickness.

Having reached the curved section on the hull, the C-clamps had to be discarded (the C-clamps were now too small anyway) and replaced with home-made "clamps" made from rubber tubing that the spear fishermen use on their spear-guns.

I managed to fix six strips on the one side and just had to sand down a section to see how visible the joints between the strips are and whether a fair curve would be obtained without losing too much thickness in the wood.

I am fairly satisfied.
The decorative white strip is Ash which I bought for its excellent steam-bending properties and will be used for the external stems of the hull. It is intended to catch up with laying strips on the other side of the hull during the week to counter stresses that might distort the hull.

A quick word on Western Red Cedar:

We know that this tree is the largest living organism on the planet and with a density of only 340 kg/m3 is one of the lightest woods available for use in construction. In comparison, Beech is 750 kg/m3. (I hope to achieve a total weight of not more than 30kg after glassing.) We were astonished to count 50 growth rings in a 200mm wide strip.
this means that the diameter of these massive trees only increases by 40mm of a 50 year period (less than 1mm per year). I almost feel guilty using the wood but at least we are building a kayak and don't use the wood for making fires.
With the excellent tonal qualities of the wood, the kayak may produce pleasant sounds when paddling over choppy waters.

Total hours spent to date: 28

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