Tag Archives: Canoe

Duet – new construction

It’s been an interesting few weeks building boats using epoxy resin and vacuum bagging, we’ve learnt a lot and the quality of the finished product is improving.

I still use a laminate stack of two layers of 200 gram carbon twill sandwiching a layer of 200 gram carbon/kevlar, but the vacuum bag is really forcing the layers together and squeezing out the excess resin. This produces a lighter boat but without the additional polyester resin from the wet layout process, some of the stiffness has been lost.

Rather than simply adding another fabric layer, I have implemented a frame structure within the hull to add strength and stiffness without adding much weight.

The initial design incorporated a gunwale shape which creates a strong rim around the cockpit. This is supported by the three tubular carbon thwarts across the width. Next is the flange which runs along the inside of the cockpit. This supports the cross braces for the seats and footrests. Addition longitudinal rigidity is gained from the carbon tape along the central join.

Duet geometry


Below the flange there is nothing. This was fine using polyester wet layup, but not with Epoxy vac-bag. We don’t want it too stiff because it will break if the boat is dropped or hits an object in the water, so some flexibility is required.

So I took a leaf out of the Wenonah design and implemented a series of ribs.

After a couple of trials on the demo boats, I decided that the optimum number of ribs is twelve, spaced at 300 mm intervals within the cockpit hull area. They are not required beneath the decks as they are stiffened through the design geometry, but they also retain enough flexibility to absorb impacts.

Rib material requirements


I cut out 50 mm strips of Sorix and 100 mm strips of uni-directional carbon fibre. Soric is a core material with hexagonal cells.

Soric core material


The cells do not absorb resin, but the outlines do. This creates a very strong and stiff framework. It really is amazing stuff and I now use it to thicken and stiffen the gunwales, on the seats, and for the ribs. I also use peel-ply to ensure a consistent surface finish.

Material preparation


The ends of the Soric strips finish just under the flange.

Soric measuring and positioning


The uni-directional strips extend beyond the flange, up the side of the hull, but the ends are tidily encapsulated within the flange support.

Uni-directional carbon measuring and positioning


The centre join is formed by a 50 mm strip of carbon/kevlar and a top strip of bi-directional carbon. The ribs are sandwiched between the two thus increasing the strength.

Ribs complete


Once the ribs have gone off, a platform is laid into the hull to support the installation of the flange materials. These comprise of:

Flange materials and design


This right angled flange bonded to the inside of the hull really improves the rigidity of the boat. It tidies up the ends of the ribs and of course supports the footrests and seats.

Flange construction


Coupled with the seat and footrest cross bars, the boat is truly ridged. There is still a little bit of flexibility between the ribs to help absorb impacts.

Cross bracing


The epoxy resin and vacuum bag construction method also improves the quality, but it is massively more expensive than a polyester wet layup.

I also use Soric along the gunwales to thicken, stiffen and strengthen. It doesn’t look as nice because the pattern of the Soric matrix comes through to the surface due to the vacuum pressure, but it is far more efficient and at the end of the day, it is a racing boat.

In summary then, I now have the boat construction I wanted. I believe it uses the best materials in the best way, but in the least quantities. It’s jolly expensive but we diggers are worth it!

First prototype

The first boat came out of the mold last week and I collected it from Devon. We’d had a number of discussions regarding the construction and I was adamant that the boat had to be light, and the prototype was the right time to take a risk. We agreed on a 200 gram carbon twill supplemented with a 200 gram Caron/Kevlar weave. We knew this would not be stiff enough so we implemented a series of uni-direction cross members. These in conjunction with the flanges, would form a sort of scaffolding……………..or at least that was the theory.

The boat came out of the mold weighing 12 kgs. This was crazily far too light for a C2. However the construction seemed to work, with the right kind of stiffness but with some flexibility to absorb knocks. However we hadn’t continued either the flanges or the cross bracing beyond the boundaries of the cockpit, so the deck and hull in the stern and bow areas are a tad flimsy. That will be rectified on further boats and may add another kilogram.

As the design is based on The Darkness C1, I immediately compared the two, yep, completely different! The front deck especially, has lost its sharp gradient and ridge. The gunwale edge remains which adds lateral rigidity and supports the full length spray deck.

The C2 (I must think of a name for it) has a constant cross beam at the gunwale of 55 cms, The C1 has a maximum width of 51 cms.

Comparing the C1 and the new C2 – decks


The hull seems to have more curvature than the C1.

Comparing hulls


The array of different materials is starting to grow on me but I’ve never been a fan of Kevlar. We do need it though to give the boat some strength.

The boat is actually quite deep. I added on 10 cms of deck height from the C1 to increase the freeboard. The boat will sit lower in the water and it will interesting to see what level of payload it can support.

Birds-eye and side views.


It took a couple of days to fit it out with seats, footrests, thwarts, portage handles and buoyancy.

Fit out complete.


I took advantage of the parallel flanges to mount the seats on rails. These enable a high degree of adjustment which will allow many people of different shapes and sizes to easily and quickly change the setup. These will be discarded for a racing setup as they add over 1.5 kgs to the weight and I do lose some rigidity across the width.

Cockpit arrangement.


I’ve added the usual grip tape the assist non-slip getting in and out. The thwarts are positioned to provide a stable hand hold during embarkation. I will be putting some cycle handlebar tape in the centre to improve grip and comfort.

Rear seat on sliders.


The seats are to my own design, similar to racing kayak seats but with a much bigger seat pan. This adds comfort and better stability. They are currently set at 15 cms high which is 5 cms lower than the Duet.

Front seat setup.


The footrests support the pull bars which have proven very successful in The Darkness Duet C2, and the footplates have grip tape on them.

Bow and stern.


The bow is more curved to help avoid picking up weed.

The handles are my own design and made of carbon. They are similar to the Marsport handles, but shorter, lower profile and have a deeper recess to support a torch. I’ve mounted plastic tubes wrapped with cycle handle bar tape for better grip, comfort and warmth in lieu of a torch.

So, it’s all over bar the paddling.

I’m looking forward to its maiden voyage and subsequent experimenting with the setup, and then I’m hoping a few crews will try it out.

Onward to Australia

So we have a box, now need to pack out the boat. I decided that the most secure way would be to pack it like an egg-in-an-egg-box.

Conscious of the strict import rules in Australia, I opted for polystyrene and scoured my garage to find all the bits of buoyancy I’d kept “just-in-case”. I use a profile tool to mark the canoe shape holes to support the boat along its length. I also supported the weight with blocks of foam insulation.
c1_packed_1
I then used all the spare bits and positioned them just proud of the top so that the lid would clamp the whole thing together when I screwed down the top.

So far, so good but now came the big challenge of how I was going to transport it to the shipping depot in Basildon. The shipping company offered to collect it for £175, but cost were already high so I decided take transport it myself.

The crate weighed in at 87 kgs, ten times the weight of the boat! I was convinced that with half a dozen blokes, we could put it on the roof rack of my estate car. OK it was on the limit in terms of weight and size, on the border of road legal but it should be fine.

My wife decided that it wasn’t fine and proceeded to describe all the potential things that could go wrong (she has a very vivid imagination!). The alternative was our camping van which has four roof rails and it somewhat longer. However it is 2.5 metres high, how the hell was I going to get it up there?

A call round the neighbours and a text to my cycling mates meant that seven blokes turned up to help. I lashed two ladders together as a ramp, and reduced the gradient by putting the base of the ladders on a patio table. I used a long rope to act as a brake and another to stop the crate crashing down when it reached the pivot point.

With a lot of huffing and puffing we inched the crate up the ladder ramp on to the top of the van. I dismissed the troops and lashed it down. There was much talk of beer owed!
c1_on_van_1
The next day I drove very gingerly to the shipping company depot in Basildon where the crate was unloaded by forklift in about 30 seconds.
c1_on_van_2It’s now out of my hands, as the shipping company are now responsible for getting it to Brisbane. If anyone is interested, the cost of shipping is £491.80.

Bon voyage to The Darkness.

Boat to Brissy

I follow a FaceBook site which was setup by the canoeists in Australia called Australian Canoe Racing https://www.facebook.com/groups/AustrlianCanoeRacing/. It is fascinating to see all the similar sort of things we do in the UK, being done on the other side of the world.

I did noticed some familiar looking boats and I realised that a guy called Frank Harrison developed a similar sort of boat design to The Darkness C1, but many years earlier. In fact it took a few posts to convince the Ausies that I didn’t pinch his ideas!

There are some differences as there are some national canoe design standards for Australian touring canoe racing, but the concepts are the same.

To cut a long story short, an Ausie digger has ordered one of my boats and I’m now in the process of shipping it to Brisbane.

So, what on earth do I know about exporting canoes to Australia? Well not much, but I’m learning fast.

I’ve found a shipping agent who is prepared to transport the boat, but first it has to be crated. No problem I thought, pop down to B&Q, buy a few sheets of plywood and knock a big box together. Not so fast! The timber has to be heat treated and certified for import to Australia. If you ever watch those fly-on-the-wall documentaries about Australian customs, you’ll know they are pretty strict about these sort of things.

So the shipping agent recommended a packing supplier in Eastleigh and I started a dialogue.

I estimated that the boat would easily fit in a crate measuring 5.5 metres long, 65 cms wide and 45 cms high and I was quoted £170 (inc VAT) for the timber. Blimey, one hundred and seventy quid for a plywood box! It wasn’t until I collected the timber that I realised why, I had a complete construction kit for a fork-lift ready, palletised crate.

Flat-pack crate.

Flat-pack crate.


The suppliers had given me some vague verbal instructions, plus I managed to take a few pictures of other crates in the warehouse. So I called my mate John in order that we could figure it out together.

The timber was cut to precise dimensions which should fit together in a specific way.

So, first off we constructed the base. (The picture shows the underside)

Underside of the base

Underside of the base


After that, we worked through the ends, sides and lid. It was only when we attempted to put the components together that we realised we’d made a few mistakes. Luckily we’d use screws so it was fairly easy to rectify it.

A BIG box.

A BIG box.


It was certainly a big box, but was it big enough? Only one way to find out.

The Darkness C1 fits with room to spare.

The Darkness C1 fits with room to spare.


Yep, plenty of room in there for loads of packing, should be nice and safe for the passage to Australia.

Seat development

I’ve now got quite a collection of racing kayak seats in my quest for a better canoe seat design. One thing that has struck me is that they are all pretty much the same size and shape. OK there are a few tiny differences but the manufacturers seem to assume that one size will fit all racing kayak paddler’s bottoms.

Once again, compare this to the cycling world where there are literally hundreds of saddle designs, shapes, sizes and materials, plus a whole host of different options for lady riders.

The discerning canoe racer however is more demanding, and much prefer a tractor seat type design, plus they are seated much higher.

Anyway, I set about modifying my original effort and recast it to have more volume at the back.

Increased surface area

Increased surface area


The picture shows the size compared with a “standard” racing K1 seat.

Next I needed something on which to mount it. I have made a number of seat supports using timber and fibre glass, but they take so long to shape them to support the seat pan.

As it happened, two new seats from Nelo had just arrived. These are a rather different and innovative design in that the seat is supported by a cast metal frame.

Nelo K1 racing seat

Nelo K1 racing seat


The seat pan is secured by five rivets. So I drilled off the rivets and separated the cast metal “spider”.

Nelo seat "spider" support

Nelo seat “spider” support


Together with some stainless steel bolts and some plastic spacers, I secured the new seat pan to the frame.

New seat pan secured

New seat pan secured


I had just got the Darkness Duet back for a few days, so I bolted it into the rear of the C2, and John and I took it out from Pewsey Wharf.

New seat in rear of Duet

New seat in rear of Duet


I’m showing it compared with a K1 racing seat. The marks around the edges are where I used pegs to hold the two layers of foam whilst the glue set. At this point I was reluctant to cut the seat runners down.

Well at first it felt weird because it was different to what I was used to. On the return from Wootton Rivers I’d forgotten about the new seat and was quite used to it after the hour.

I’ve now made a second one and secured both to square profile aluminium tubes ready for testing. I’ve also trimmed the runners.

New seats ready for testing

New seats ready for testing


I’ve mounted them on timber supports so they should sit on the flanges with just the timber drilled to math existing holes.

I now need to get them tested.

Does my bum look big on this?

So, just got back from an hour’s paddle on the Basingstoke canal using the wider seat. It was unexpectedly uncomfortable!

Having more bum area in contact with the seat actually felt more stable, especially in combination with the pull bar. Also having more area at the back of the seat enabled me to push back into it. But the pressure points seemed to be in the wrong place.

One factor compared with a C2 setup, is that the height of the seat is significantly lower in a C1 than a C2. In the C2 I have set the seat height to 20 cms, where as in the C1 it’s set at 12 cms. This may make quite a difference, which I can test once I get my boat back.

Those of a nervous disposition may wish to look away now, but I’ve taken some photographs to illustrate the point.

The first picture shows a standard British bottom on a standard K1 racing seat. Neither the back nor the sides are supported. However, this may be because there is so much movement due to the paddling action.

Standard K1 racing seat.

Standard K1 racing seat.

I wonder if it’s the same principle as in cycling, whereas novice cyclists are often convinced that their sore bums would benefit from a big, wide saddle, where in fact all racing cyclists tend to use narrow saddles which support the bits which matter most.

So-called cycling comfort saddle versus cycle racing saddle.

So-called cycling comfort saddle versus cycle racing saddle.


Now compare the area of support with my new wide seat design. Much more bum area is supported.
New wide seat design.

New wide seat design.


I do wonder whether the seat would benefit from sides in the same way as sports car seats are designed.

Yes I know they have sides to prevent slipping out of the seat due to the G-forces during turning, but are they more comfortable?

The seat I use at the moment is a bit of a compromise in that it doesn’t have hard edges and allows the “excess baggage” to overflow.

Current C1 seat.

Current C1 seat.


For DW, John and I used Zastera seats with two layers of foam. They seemed comfortable to us, even on the long pound to Wootton Rivers, but it’s the additional height which seems to make the most difference
Darkness Duet DW seats.

Darkness Duet DW seats.


I need to get some wide seat prototypes out to the Duet paddlers.

Bums on seats

One of my original design goals, and indeed a unique-selling-point of The Darkness, was the ability to use the seat design most suited to the paddler. This was delivered using a simple flat platform mounted on flanges on the inside of the boat. On this, I mounted a foam seat which was larger than the usual kayak racing seat, and theoretically much more comfortable over longer distances. If necessary, it could be changed quickly during a race as conditions dictated, for example a lower seat for more stability.

Unfortunately I wasn’t able to find someone who could make the foam insert in a single lump, and had to construct the shape from multi layers of foam matting. It worked, but didn’t look great.

Original seat concept.

Original seat concept.


At some time or other, I decided to use a kayak seat after all. I can’t remember when this was, but I experimented with a number of different designs.
Carbon seat fitted

Carbon seat fitted


I didn’t think any more about it and proceeded to use carbon kayak seats on the Duet.
As I was able to persuade a few people to start testing the Duet, one of the main subjects of feedback was how uncomfortable the seats were compared with the traditional tractor seat design used by Wenonah. So I set about designing a bigger seat.

I am somewhat restricted by the availability of tools, materials, experience and skill. I have good ideas, but translating them into something tangible doesn’t always work out in the way that I’d imagined it. So instead of starting from scratch, I used a K2 seat I had as a platform. I taped on an end-stop and filled the gaps with expanding foam. I didn’t realise quite how much this stuff expands!

K2 seat with expanding foam.

K2 seat with expanding foam.


Anyway as soon as it set, I cut it down with a saw.
Foam cut down tp shape.

Foam cut down tp shape.


And then applied some filler.
Filler applied and smoothed.

Filler applied and smoothed.


My plan was to use the shape to make a mold. I would then use the mold for testing and then to produce more seats. Unfortunately I didn’t have any chopped-strand-mat fibreglass which is best for making molds and had to use carbon fibre instead.

Carbon fibre isn’t as malleable as fibreglass. Plus I used too much resin. Anyway, I wetted out 4 layers of 200 grams carbon, covered it with peel-ply and cling film and popped it into one of those vacuum bags used for compressing clothing during packing.

Seat under vacuum.

Seat under vacuum.


I used this technique when I was making paddles and it’s quite effective (and cheap). Once it had gone off, I stripped off all the peel-ply and cut it to shape with my dremel.
Seat size comparisom.

Seat size comparisom.


Compared with the kayak seat, it is about 4 cms wider.
I then made a seat support, the same dimensions as the kayak seat so that it would be easily changeable in my existing boats, plus it could be used in a conventional racing kayak.
Seat with support and fixed to platform.

Seat with support and fixed to platform.


I mounted it on a plywood platform so I could fit it to my C1 for testing, and stuck on some cushioning.
Seat fitted with foam cushioning.

Seat fitted with foam cushioning.


I’m on the water tomorrow to see how it performs.