Intro – Shapes

Swift started the production of IDBF design Dragon Boats in 2007, after having our moulds approved by an inspection team from the IDBF.

In addition to the moulds, Swift also follows all IDBF rules regarding positioning and material of seats, foot rests, steering arm, buoyancy tanks, drummer seats, gunwale capping etc.

Swift provides multiple shapes of dragon boats:

10 man (Festival)

10 man (Race)

20 man (Standard)

What is the IDBF standard boat design?

It is a list of rules and a set of drawings and measurements, based on which moulds are built, from which the IDBF shape boats are then built.

Does that mean that all IDBF shape boats are the same?

Regarding the hull shape, the answer is effectively “yes”. However, there are “tolerances”. These are necessary for the manufacture of any product. These tolerances are quite small, and allow for very slight differences between boats from the same moulds, which naturally occur due to factors such as the difference between the ambient temperature and humidity in different seasons. See below for more about these tolerances.

Regarding the cockpit, the answer is “no”. The tolerances for the position of seats and footrests is much greater, and the potential to build in other features, such as posts under the seats, means that the cockpit of boats from different builders can be quite different.

Regarding stiffness, longevity etc, the answer is a big “no”.
There is no stipulation from the IDBF regards the materials or processes that builders must use, so there is quite a lot of difference between builders, although this mostly comes down to 2 groups of builders: those that use 2 part moulds, and those that do not. The 2 part mould process is more expensive, but makes a superior boat.

Can the tolerances affect a boat’s feel and performance?
(or "Can boat builders manipulate the tolerances to change the design?")

Regarding the overall shape of the boats, yes, but only very marginally.

For example, the tolerance for length is +/-100mm, which is less than +/-1% of the length of the 20 man boats.

The tolerance for side rail width” and “gunwale width” is +/-20mm, which seems more significant, until we consider that about half of this tolerance must be used to eliminate the “tumblehome” which is part of the IDBF design for the 20 man boats. This is something which must be done by all companies that build IDBF boats with composite materials ( ie. not wood).

(“Tumblehome” is the name given to the feature of a boat where the gunwale is narrower than the sides.) The reason is simply that if the sides of the boats (and therefore the mould), were wider than the gunwale, it would be impossible to lift a finished boat out of the mould!

Therefore the remaining tolerance for side rail width” and “gunwale width” is about +/-10mm, much of which needs to be kept as genuine tolerance, so is not available to make the boats narrower or wider.

Regarding the cockpit, the tolerances allow for significant variation in position of seats and foot rests, which can therefore feel significantly different, and lead to differing performance.

hull image

We noticed confusion in the minds of many paddlers, regards boat shapes in 2009 when we were the official supplier for the 2009 IDBF World Nations Championships in Prague, where 4 teams were swamped during the turns of the 2,000m races.

As explained above, Swift (and all IDBF registered companies) are obliged to build moulds to the designs given to them by the IDBF. Our moulds were checked and certified as correct by the IDBF.

So what other reasons could there be for the swampings?

1. Something peculiar with the course?

The Racice course was found to be shallow and uneven. According to the IDBF, it should have been at least 3m deep, but was found to be less than this, with significant variation across the lanes. The effect of this, which was clearly observed, was a massive wave being pulled along behind the boats. The trough (low point) of this wave would also explain why some heavyweight crews thought the boats were stern heavy. On a turn, the wave that a boat has pulled behind it will continue at the same speed, even as the boat slows and turns side on to that wave. This will happen in any conditions, but is much worse on a shallow course.

2. The IDBF design is not suitable?

Did you know that the design weight of the IDBF boats is 75kg per paddler? There seemed to be crews that averaged 100kg, which would mean they were 33% over the design weight. Crews are getting heavier, and since these swampings we have been lobbying the IDBF to allow builders to build safer boats. These could simply be exactly the same boats, but with higher sides. A boat with higher sides is of course less likely to swamp, which is not only ideal for big crews, but would also make it safer to use the boats in a wider range of water. The important point for fairness of racing is that the part of the boat that is in the water would be exactly the same as boats with the current design.

3.There was wind and chop.

There was very little wind and the course is sheltered, so there was no significant chop.