| Subject: Re: A few questions: |
Author:
cameron
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Date Posted: 17:20:52 03/11/02 Mon
In reply to:
Becks
's message, "Re: A few questions:" on 06:59:24 03/11/02 Mon
The flexing of a hull does affect things when going for the nth degree of speed. A very small amount of energy is lost when the hull flexes as the boat is paddled. More damage is done to speed with the hull flexing out of the designed 'optimum' shape. Nick Burnett's last incredibly stiff carbon boat was by a number of people's opinion the fastest Flame (in not all) in the country as the hull did not flex. When Nick was paddling an experimental layup which turned out to be very flexible, he rated my very stiff boat as faster even thought it was over 2kg heavier.
A light boat helps acceleration and agility, but has no effect on top speed, hull shape (and a stiff hull sticking to the hull shape) and paddler input are the two main factors.
As for finish, coming from a sailing background, we used to wet & dry out boat hulls down to about 400 grit. The theory was that the wet & dried surface would hold a layer of water and that water slipping past water has less friction. It certainly boosted performance to my dinghy when I did this. Wax is certainly smoother than a standard finish and it also fills in small pinholes (nth degree speed again), but Becks might be able to comment on whether it is legal to have a removable coating on your boat. The multitude of scratches and damage to the bottom of the boat would affect performance far more than waxing or sanding, though sanding has the bonus of smoothing out some scratches.
And as for duct tape on the front who cares!! If you are sprinting your bow is out of the water anyway. You should look much more closely at the shaping of your rear bumper as that is the last part of the boat in the water and where the most speed sapping turbulence occurs.
Hope that helps
cam
>>Has anyone actually done any testing regarding
>>different boat finishes and what kinda speed they
>>produce, like will paint on the underside slow me down
>>compared with straight resin?? and will waxing the
>>bottom of my boat do much and also how much does duct
>>tape slow you when it is holding on a bumper at the
>>front?? cheers
>
>Interesting questions, I think many of us have
>pondered these on the odd occaision. Although I don't
>think specific testing has been done
>e.g do you really need to drive your car over your
>head to know it will hurt?
>If anyone has done this sort of testing in NZ its
>probably Martin Bell (?) (specific testing of speed
>reducing effects that is, not driving over his own
>head).
>
>I'll give my opinions on your qs.
>hull finishes: surely the basic notion of friction
>applys here? I don't know the exct significance, but
>I'm guessing that the smoother the better? I think
>you'd have to use one of those water tanks used for
>testing boat hull designs. But assuming the aim seems
>to be to figure out how to go faster, surely the other
>more significant factors (such as paddler ability and
>style) should be focussed on.
>Also, what about hull distortion? (eg when you paddle
>real fast and you can hear/feel the hull of your
>supalite kayak flexing and bouncing around like crazy)
>Cam Butler of
>Virtuosity
>did his 4th year B.Tech project on a polo kayak, so it
>would be interesting to hear his ideas.
>
>Re the ductape, again, no hard data. But If I'm
>reffing your game and I see your bumper flapping up
>and down, you wont be goin no where fast from the
>subbing area, aye?
>i.e. Don't be such a lazy (also inconsiderate!) buga.
>How much effort would it take to dry your boat and
>glue the bumper down?
>Although your bumber may be taped on, even a small
>amount of lifting can mean the solid part of your boat
>contacts with some other poor sods boat when you
>tackel them.
>
>I'd be interested to see what testing has been done
>though.
>:o)
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