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!

C2 compared with Duet

I’ve compared the new C2 with The Darkness C1 because that was the starting point for the design however, to get a proper C2 perspective, I should compare it with The darkness Duet C2.

So I laid them side by side and took some pictures and measurements.

Duet and new C2 – 1.

The Duet conforms to a continuous arc from bow to stern, whereas the C2 has a long section of parallel width. The Duet was designed by a Naval Architect using CAD tools and fluid dynamic algorithms, The C2 was pretty much guessed at.

Key dimensions are:

Max width at the gunwales: Duet – 68 cms, C2 – 56 cms
Boat depth from hull to central thwart: Duet – 27 cms, C2 – 28 cms
Boat depth at rear of cockpit: Duet – 26 cms, C2 – 29 cms
Boat depth at front of cockpit: Duet – 34 cms, C2 – 29 cms
Seat height: Duet – 20 cms, C2 – 15 cms.

Weight: Duet – 21 kgs, C2 – 18 kgs.

Duet v new C2 – 2

The weight comparison is a bit of a red herring as the C2 has the additional seat adjustment rails but would benefit from some additional stiffness within the laminate, but 18 kgs would seem about right.

This particular Duet is not really representative either as it’s based on two layers of carbon, hence the additional stiffening across the hull. Without the now standard internal layer of Kevlar it is more vulnerable to damage. A more realistic weight with the Kevlar would be about 23 kgs. This boat also has some seat rails because as the demo boat, it needs to be more adjustable. Adjustments for the rear paddler is serviced by moving the footrest.

Duet v new C2 – hulls

As both boats are ICF compliant, the only difference in the hulls is the cross section profile. The C2 is much slimmer but water resistance is usually measured by the wetted area. The Duet will support a heavier payload and is massively stable, but it would be interesting to measure the wetted area when paddled by two racing snakes.

Duet v new C2 – cockpits

The C2 cockpit has less open space but at 310 cms, it is still greater than the ICF 280 cm minimum spec. I’ve positioned the seats closer together to take advantage of the central buoyancy. As the boat tracks so well, it isn’t necessary to have the rear paddler way back towards the stern. Also, we don’t need to leave the central area available for camping kit and the like.

I’ve set the seat height for the C2 at 15 cms. This is 5 cms lower than the Duet because I’m expecting it to be less stable.

Duet v new C2 – front and rear decks

The front deck has lost the steep gradient and the ridge. This should make it more comfortable for portaging, but there may be more water coming across the deck in rough water.

Notice also the lack of a name, what on earth I am going to call it? Dual, Duo, Double, Dunno!

Duet v new C2 – bow and stern

The C2 is closest to the camera and it shows that the Duet has less height in both the bow and stern areas. It will be interesting to observe the freeboard, and how much will be sticking out of the water (and likely to catch the wind). I’ll also test the curved bow.

Tomorrow I get to test it, and the day after a Duet crew has agreed to give it a go.

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.

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!

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.
It’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.

C2 mold is complete

The mold is now ready, hurrah!

The plug was highly polished in preparation for making the mold. The red coating was sanded, rubbed and polished to the point where the black under layer started to appear. This was a clever way (for which I take no credit) to avoid rubbing too much in the same place and distorting the shape. (Dreadful phone picture)

Polished plug

The mold is made in two sections, joined down the centre with a wide flange to support vacuuming.

Mold joined down the centre

The boat seems narrower in the mold, this appearance may be caused by the join line though.

Rear deck

The combined weight of the plug and the mold is substantial.

Front deck

The cockpit rim will be made at the same time. I’m glad I’m not the one who has to release it from the mold.

Cockpit rim

The plug will now remain in the mold for a further ten days to ensure that the fibre glass has completely gone off thus reducing the risk of distortion.

It’s like waiting for Christmas, but hopefully we’ll get the boat wet by mid-November.

Devizes to Westminster – first female C1 competitors

The Devizes to Westminster (DW) International Canoe Race is arguably the hardest canoe race in the world. 125 miles non-stop from Devizes in Wiltshire to Westminster Bridge in London. In a double kayak (K2) or double Canadian boat (C2)

A kayak is powered using a double ended paddle and has a rudder.  A Canadian or open boat, is paddled using a single blade and a rudder is not allowed.

The DW was first raced in 1948, 66 years ago and the first female competitor completed the race in 1971 in a K2. The DW four day singles event started 29 years ago in 1985 and since then over 1,000 paddlers have completed the race in a single boat including the 2013 event but only 15 of those were in a single canoe (C1).

In the history of the DW, there is no record of a lady paddler ever having completed the event in a C1 and the same can be said about the Waterside Canoe race series which is four races on the DW course leading up to the main event.

Why?

Well first reason on the list is clearly because it is “quite hard”. It is THE most challenging vessel to paddle of all race categories and to do it for 125 miles over four days not forgetting the 77 portages where the boat has to be carried around locks and weirs,  is not for the faint hearted.

Another possible reason is the availability of a suitable boat. The current choice is somewhat restricted to traditional family, wilderness and touring crafts which tend to be large, robust and heavy, to the sprint, high-kneelers which are “somewhat” unstable. There are also American boats but they are few and far between in the UK and prohibitively expensive.

That is about to change.

Over the last three years I have developed a lightweight racing C1 which:

• Weighs 8kgs fully configured
• Is made of carbon fibre
• Conforms to the International Canoe Federation (ICF) specification for racing
• Is paddled sitting down using a sit&switch technique
• Has a mid-range stability rate of about 4 – 5
• And looks absolutely stunning!

For the 2014 Waterside series and DW, two of these canoes known as ”The Darkness” will be paddled by two lady competitors who will attempt to make history.

This blog documents the story of this venture and the progress from when I hand over the boats to the athletes to when they arrive at Westminster Bridge on Easter Monday 21^st April 2014.

I hope you find it of interest.