Wednesday, 28 September 2016

Footbraces, backstrap and finishing the cockpit

Finishing the cockpit
Following on from the last post, the top and bottom of the cockpit are faired and then as shown below the top and bottom inside corners are well rounded with a spokeshave. This is to make sure that the fabric does not snag when being fitted to the cockpit, and also so that the paddler does not snag getting in and out of the boat.
Then a support was clamped in a workmate to take the drilling of the thread holes that will secure the fabric inside the cockpit. The holes are drilled and inch apart and a few millimetres below the edge of the rim.



You just see the small epoxy fillet I put round the base of the rim beforehand. The cockpit is then finished off with about two hours hand sanding starting with 60 grade, then 120 and then really fine. It will be coated with the skin.

This photo of the finished cockpit also shows how the back strap is held in place, more of this later.
Footbraces and backstrap
After the first fitting showed the thigh brace to be too far forward this was moved back and lashed and pinned in place after glueing on a couple of thin pads of wood to the ends. This was to fill out the slightly greater beam a couple of inches back.

My initial attempts to support the footbraces added to the growing pile of firewood in a corner. Until

eventually I realized that it was possible to make a support that was held on three sides - to the gunwale and the two deck beams on either side. The photo below shows them about to be epoxied
with glass tape on the outside of the rounded top edge. You can see in the further of the two, the filleted inside edge. Looking at the nearest of the two - to take the right footpeg; it's right edge adjoins the gunwale, to which it is lashed. The front edge butts against the deck beam in front of the feet, and the nearest edge is held under the next deck beam back. to the inner edge the footbrace is bolted, as shown below.
That done the heel supports of 1/4" Cedar were lashed to the two frames beneath the deck beams.
I was half way through fitting the right side one when this photo was taken. Finally the D rings to take the backstrap were lashed to the gunwales. First of I had tried to attach to the frame in front of where I ended up, but the backstrap hung too low to give proper support. Then the frame was "oiled"

with a water based oil that will not prevent adhesion of the epoxy to the wooden surfaces. It's dark colour enabled me to ensure all of the surface is wetted twice.

And so on to skinning in the next post.











Thursday, 22 September 2016

Steam Bending Cedar

Steaming with Cedar
The basic frame weighed 9 1/2 kg. As I wanted the completed boat to weigh 18kg or less then the weight of anything else added from now on needed to be kept to a  minimum - without sacrificing strength.
That's why I decided to make the cockpit of cedar which I had used to complete the flange (that holds the deck in place) on a hoop before. That bent to shape really well and I remained hopeful that a full cockpit hoop and flange would be equally simple.
As I normally use 3/8" thick oak to make the hoop I considered that 5/8" cedar would be as, if not more strong, and so prepared a couple of pieces just over 1 1/4" deep from my stock of Cornish Cedar.
That I do not have any more pictures of the process than my measuring rope on top of the steam box (fits round the mould and so measures the correct circumference - to which a foot tapered overlap is added at each end) says alot.

There is a great deal to do and get right in the minute or so in which the wood remains sufficiently pliable to bend after coming out of the steamer. Steam bending is something which is best practiced frequently but rarely done unless you are building a lot of boats with bent ribs.
Finding the right time in the steambox is also part art. Within the adage "1" thickness needs an hour of steaming"; there are variations for hardwoods like oak need longer than softwoods like cedar, and the drier the wood - the longer it needs. Thus the 25 minutes in the box for my first attempt with 5/8"
cedar was probably not enough, for although I eventually pulled it round the mould, I was not able to tightly clamp it all the way round and it came out mis-shapen (shown on top of the second successful attempt in it's mould).


I was successful in steam bending a series of thinner woodstock pieces which were glued with epoxy to give a laminated hoop - still light but stronger.

This was faired and sanded

 before the rim/flange was steamed and bent in place,

 removed and faired,
and then glued and clamped in place.


The blue bits on the photo are bits of discarded disposable gloves used to stop the wood buffers under the clamps from sticking to the piece - comes off eventually! The excess epoxy was pared away with a chisel before it set really hard.

 The whole top of the rim was faired with a plane, block plane and spokeshave before sanding smooth - next post.
When I have a moment I will use the remaining cedar stock, still soaking in an old drainpipe to make a spare cockpit. Steam bending is skill that needs to be kept alive with practice.

Thursday, 1 September 2016

If you have an idea - test it!

I am not very keen on the short greenland paddle as a spare - for reasons which will become apparent later in this post and I thought a single bladed might make a good alternative so I set out on Tuesday morning with an ordinary paddle, a greenland paddle, a short (storm) greenland paddle, and an open canoe paddle to see how they compared with each other.

Why a single bladed paddle could be a good idea
  •  Native paddlers use and used them, particularly in Alaska - the Kodiak, Pacific Eskimo, and the people of the Nunvick Island, Bristol Bay, Hooper Bay and King Island where they seemed to use either single or double blades, and the Aleut apparently carried single blades as a spare, although they used a double blade for normal paddling. And then there is the rest of the world...
  • Easier to stow than a double blade, they are shorter than a storm paddle and also available for immediate use. Would be short enough to fit on the rear deck.
  • They could be drier in use than a storm paddle
  • They should be easy to roll with
Testing the Paddles

I used the similar method to what I have used before, noting the speed and time over a fixed course at a constant heartbeat, only as I could not find my monitor I used a constant stroke rate and took my pulse on finishing each leg - number of beats in six seconds. I used the same pulse rate as I had done about five years when I last did this - 100 beats/min. My resting pulse has been about 60 for as long as I can remember.

The setting and conditions

I used a course set between Swanpool and Maenporth Beaches to the west of Falmouth of approx 0.45 nautical miles between two outcrops of rocks and parallel to the shore. I travelled westwards against a F3 breeze from the southwest, for the first leg, and then returned eastwards on the same course with the wind on the quarter for the second leg - two legs, back and forth for each type of paddle. Each leg was done on the same transit using the rocky outcrop as the foreground. The wind raised a steep chop of under 1 ft, parallel to the boat at times with the reflections of the rocks.

The kayak and paddles

I was also using the occasion to sea test one of my  Alacrity kayaks which I have been renovating, of note was the higher seat. The boat is 16'6'' x 22 1/4'' and is a greenland type kayak of an extreme swede form. 

The paddles used were a pair of obsolete marathon paddles, rather like the old Lendals cut down to 216cm, a greenland paddle 223cm, a short greenland paddle often referred to as a storm paddle and an open canoe paddle. 

Results

1. Lendals, going west Stroke rate 60/min finishing pulse approx 90-100, time 7min12 sec, noted on GPS as approx 4kn. Going back to the east, Stroke rate approx 58, same approx pulse rate on finishing , 6min 20sec, noted on gps as approx 4.2kn.

2. Greenland paddle, West 7min 49sec, stroke rate & pulse approx as before, couldn't observe a speed on GPS. east 6min 39 sec approx 4.3 kn at end. Didn't get stroke rate or finishing heartbeat due to tricky quartering chop.

3. Storm Paddle with sliding technique, Going East 7 min 50 sec, approx 3.5kn when noted on GPS, stroke rate approx 50/min, finishing heartbeat approx 100. East 6min 56sec, stroke 42/min, didn't catch heartbeat at end (occasionally as in this case I couldn't find my pulse in time)..

4. Single blade
Not tested but when practicing off Swanpool I was managing less than 3.5kn into the wind - more like 3.2kn. I did not feel sufficiently safe with the single blade to go parallel to the steep reflected chop, as I was having to do a J stroke under the hull to keep on course. I knew that if I went over my GPS would be suspended from the deck lines while I was trying to roll and I didn't want to lose it.

Discussion

The relative speed of the Lendals and Greenland paddle did not surprise me - it was broadly in line with what I had noted when testing before.
What did surprise me was how well the storm paddle performed. Although the stroke rate was slower, the catch was much better as the sliding grip gives a broader more powerful alignment rather like that of the Lendals. Similarly once I had got used to them again the control ( which is better with the GP than the Lendals)  was just as good as the full length greenland paddle. What didn't surprise me was how wet they are. As you are gripping the blade which has just emerged from the water, alot of water ends up on the deck - which of course seeps downwards.
I was disappointed with the performance of the canoe blade. I think it was too long and although I have done alot of open canoe paddling, this was the first time I had seriously tried to use the single blade in a sea kayak. Directional control will be a big issue, and of course stability.