British Development Canoe challenge at Worlds

by Phil Robin on 21 Dec 2007
Whilst the Development Canoe remains at a trial stage, it is encouraging how much interest, and more importantly boat building, the concept has stimulated. After a number of years where there had been few new ICs being built around the world (though a steady AC build rate especially in the UK has continued) opening up the hull shape to development seems to have hit the ‘spot’.

There was some initial concern about certain detailed aspects of the new rule and whether it would lead to the emergence of ‘unsatisfactory’ hull types (e.g. very narrow boats with outriggers to support the shrouds) but with experience these have disappeared, as the practicalities from sailing the new boats have become apparent. Whilst the DC rules do allow the flexibility to develop radical ideas that look great in theory, the acid test is whether you can sail the boat round a course quickly!

There has been a wide range of approaches taken to design and with the majority of DCs built or under construction sailing against each other at the World championship to take place in Melbourne in January 2008; it will be interesting to see whose ideas prove best!

Below I set out below is some background on my DC - GBR 311

I took the plunge in January 2007 and commissioned Phil Morrison to design a DC, something he was delighted to do. I took the view that building any new boat takes a lot of time, effort and cash, and with my limited knowledge on hull shape design etc, it would be a good investment to involve someone who has done it before!

As most people in the UK will know, Phil Morrison cut his teeth designing National 12s and Merlin Rockets, followed by a series of International 14s and more recently boats like the RS400, RS800 and RS200 – probably the best RS boats produced. He has also designed various multihulls and yachts and has a reputation of producing good looking and well behaved boats that tend to be ‘middle of the road’ rather than ‘radical’.

When I briefed Phil, I explained that I wanted to concentrate on changes to the hull design, rather than the rig, foils and deck layout. I reasoned that the latter elements had been subject to constant development and refinement over the last 35 years and seemed to work pretty well, whereas the hull design had not altered, apart from becoming much stiffer through the use of carbon rather than wood. A contributory factor was the limited time I would have to sail the boat before the Worlds – if I kept the same rig, the learning curve should be that much less steep.

So the rig will be a Superspar 55mm diameter carbon mast with one or two tweaks, and I will continue to use Lester Noble sails, as they produce sufficient power for a sailor weighing 88kg, with the only change being to go for a decked stepped mast, to keep things lighter and simpler (no need for lowers).

The photos give an idea of the new hull shape – whilst it is not as radical as some of the new DC designs – it is a major change from the Nethercot. The Hull is much finer in the forward sections, and is ‘U’ shaped to maximise buoyancy and to promote early planning. There remains a reasonable amount of rocker and the stern sections have less buoyancy to encourage the bow to lift, although I have not gone down the pintail stern route.

The boat has the minimum 750mm waterline width but flares out to 880mm at deck level (cp 1060mm Nethercot) and has a higher freeboard. The reasons for this are to ensure the boat is wide enough at deck level to provide an adequate base for the shrouds to support the mast, to provide a wide enough dance floor to minimise falling over the side and in recognition that the boat would be more wave piercing than a Nethercot and it would be a good idea to keep the water out!

The height of the rear deck is the same as a Nethercot in the centre of the hull, to maintain a low Centre of Gravity when tacking and gybing with a scooped design to reflect the increased sheerline height. This also means that the seat carriage can be lower than a Nethercot.

Phil Morrison advised that the current sailplan was efficient, and that an increased mast height would be needed to take full advantage of a una rig. The mast and foils are positioned in a similar place to the most recent IC/ACs, with the mast being 2000mm back from the bow. Phil also advised against a ‘T’ foil (the issues with short skiffs are very different to a long thin hull) and had strong views that there is every advantage of having the rudder in the traditional position rather than transom hung – less cavitation, smaller blade and smaller turning circle.

Since March, Andy Paterson at Bloodaxe Boats on the Isle of Wight has been hard at work and as I write this (early September) the boat is about to be finished and will hit the water as sooner as I have rigged the mast and screwed/bolted on the fittings.

Andy came to the view that, with the fairly conservative design from one of the most respected designers, others might be tempted and therefore it would be worth investing in a female mould - it would make building further boats far less time consuming. So a plug was made, followed by the mould and finally the first hull!

Andy and Phil Morrison have put much thought into designing the structure of the boat to keep it as light as possible. It is built with 5mm foam between carbon inner and outer skins, with extra carbon reinforcement at the high stress points and on that part of the deck where I will be jumping around.

Unnecessary structure has been designed out – for example the sides of the boat (at deck level) are straight where the seat carriage tracks are located to enable the loads to be transferred directly to the hull rather through the decks first, and the main bulkhead under the mast is tied in with the rear edge of the deck along its entire length which is taken back as close as possible to the shrouds. The completed hull and deck (painted) should weigh 23kg so there is a reasonable chance I will achieve the 50kg minimum all-up weight.

Andy has also made the foils. The rudder is the same as everyone currently uses but the daggerboard is slightly narrower at 225mm and fits straight through a slot in the boat rather than having a cassette.

Rob Michael is building the sliding seat and carriage. This continues the theme of relying on tried and tested ideas – Rob has built a few in his time – but it also meant that the build programme would be shortened as Rob is building the seat in parallel with Andy building the boat – just hope they fit together!

I am pleased that the DC rules do not allow wings/trapezes etc as I find the seat so much more comfortable, especially in lighter winds. However they are labour intensive to make and heavy – I reckon the seat and carriage will increase the hull weight by 50%!! In a sense the weight is not such an issue as most of it is moveable ballast, but it makes achieving the new 50kg min weight quite a challenge.

If time had allowed, I would like to have developed a moulded seat and carriage built from carbon and foam. It could save some weight and be quicker to build. But it is a complicated mould and to spread ‘tooling’ costs, might be best taken forward as a consortium. A seat/carriage could be developed to be a fairly standard bit of kit and worldwide delivery is feasible – something to discuss at the owners meeting at the Worlds!

I am trying to simplify fittings to some extent, but I think the ability to let off the shrouds downwind is essential and the beneficial effects of raking the rig in stronger winds makes me reluctant to leave this off, so I guess there will still be a fair amount of rope about! With the high load attachments – shrouds, forestay and kicker, Andy has bonded them into the hull structure rather than rely on mechanical bolt fixing which makes sense.

To complete the lightweight theme, Rob