While working on the development of the Physic paddle I looked at an awful lot of video of top kayak paddlers, to help establish design parameters. (The internet has some useful stuff amongst the fake news etc). I’d been aware that sprint kayaks do a fair amount of bobbing and weaving under power (and the movement towards more ‘rockered’ boats to reduce wetted surface area has accentuated this), but was still surprised at just how much this was happening when viewed with the benefit of head-on (and rear-on!) ‘Slo-Mo’.
Having attended a lot more sprint events in recent years, I was noticing just how much ‘ballast’ was being added to some (presumably ‘marathon’) boats to make the sprint minimum weight limit. It got me wondering if people were making an ‘informed decision’ on where to place the ballast in the boat. (With an 8kg marathon boat being used for sprint, there’s a significant amount of extra mass to play with).
Having 4kg in the lowest part of the boat improves stability, and this might well be appreciated while waiting in the starting position immediately before the ‘off’. But putting 2kg or so at each of the extreme ends of the boat, while having a smaller benefit on stability (weight not as low in the boat), has a performance gain by reducing the boat ‘bobbing and weaving’ under power.
I suggested this performance gain to the GB Performance Department a couple of years ago, asking them if they were in a position to measure / calculate the performance gain (I certainly wasn’t!) They were not able to measure the performance gain directly, but did implement the suggested ‘modification’ on the basis of video evidence showing the ‘bobbing & weaving’ had been reduced (and hence one could infer the performance gain*).
Hence assuming a paddler is comfortable with their boat’s stability when racing in the ‘hurly-burly’ of marathons (with no ballast), they’re probably ‘comfortable’ about the starts at sprint regattas. So if you’ve a ‘marathon’ weight boat you may want to consider adding the extra weight to the stern (via the rudder hatch), and to the bow (using a thin rod braced against the footrest, to hold some flattened lead ‘flashing’ in the bow). Bear in mind if doing this you still need to trim the boat to the manufactures (or your coach’s) recommendation.
*A bit like having a clean boat. You can’t measure the performance gain (unless it was very dirty!), but you ‘know’ a clean boat is quicker.