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discussing_weight_effect_2015

Weight Effect on Boat Speed

Interesting reading…regarding light skis.
David Scherrer

07/16/15 #17712

Feedback?

Relax – a few extra pounds may be a good thing. In your surfski. - Surfski.info - News, Product Reviews and Interviews

There’s just nothing like the feel of taking your feather-weight 24lb (11kg) surfski off your car racks with one hand, carrying it to the water…

duncanhowat
07/16/15 #17713

Don't agree with this guy in most areas. If your twichy in a light 17“ ave weight then go a little wider and lighter. Having had a couple of various kinds and weights, I've found (at a old age) light (18.5-20 lbs stable gets you up and over some stuff I couldn't do before. Now on flat water light gets it done ,period. Besides, when you have a broken scapula, as some us do, two hips replaced,as some us do, rotator cuffs gone,as most of us do, knees replaced, and then you turn 80,carrying a 35# boat up the goat trail at the white salmon river take out can't be done, but a 19# boat can. See you all on the river. Wind blows all next week at the Gorge.

Reivers Dustin
07/17/15 #17714

couldn't have said it better. Or when the Big O was asked about this he said, “Lighta is Betta”. The boats weight is dead weight. Yes, it is cheaper to get rid of body weight, but this is live weight that can be used for balance or leverage. Even more important is the weight of paddle. You carry and move the paddle a whole bunch. I want all my competitors to have heavier paddles than mine.

Why else would a builder succesfully market those Ultra constructions. My demarcation line is at about 30 pounds. As the bankers say, “Substantial penalty” for anything over that.

rd

Michael Gregory

07/17/15 #17716

There are two instances where a very light ski is helpful; accelerating the ski and carrying the dang boat to your car after a work-out. For most of us the latter is probably more important than the former.

Steve Scoggins

07/17/15 #17717

I can't remember a time when I was wishing I had a few extra pounds in the boat.

Steve

John Rybczyk

07/17/15 #17718

I'm always wishing that your boat had a few extra pounds Scoggins!

Johnr

zach
07/19/15 #17723

I think light might not be THAT much faster. Here is a link to a nerdy page that does all kind of math to determine the effect of weight on the speed of rowing shells:

(Original link invalid - similar content )

FAQ: What is the Significance of Weight in Rowing?
At the bottom of the page the calculate the effect of dead weight on boat speed taking into account the increased displacement of water (wave generation). Their result is that every percent increase in boat+paddler weight will decrease speed by one sixth of one percent. In other words, a 170# paddler going from an ultra layup epic to a performance layup would increase total weight 3% and decrease boat speed by 0.5%. That is 18 seconds over the course of an hour.

In the bump I am not sure if weight has more or less effect. catching runs is more about acceleration than steady state speed, and acceleration is much more directly affected by weight. However, if the heavier boat still accelerates fast enough to catch every wave that the lighter boat can catch, then overall speed will be the same. If the lighter boat allows a few clutch moves to jump a wave, the lighter boat will be a few waves ahead. On the other hand, if the lighter boat is corkier and the paddler is less stable than maybe the light boat would be slower.

It gets awfully complicated to theorize about.

I guess I am in the camp that the main benefit of light boats is carrying them in and out of the garage.

Reivers Dustin
07/19/15 #17724

Before we got whatcompaddlers rolling (what a clunky name), I followed a yahoogroup with more of a worldwide sprint-boat membership. There were a few members of that group who were technically solid in nautical engineering. One in particular worked for the Navy - his job was modelling and testing boat properties. He took special interest in sprint boat speeds vs. surfski speeds. His superior qualifications didn't stop others from arguing with him - of course. This is a yahoogroup. That's the whole point.

Anyway, one of his big observations was that wave effects tend to swamp* certain predictions of modelling or lab testing boats. The guy had access to a full-on drag pool. My own observation is that the lightness of the boat mostly matters at the moment you try to pop onto a waveface. This might be due to my weak skill at timing the rides.

Enjoy the discussion. It might not be possible to totally conclude the truth for all purposes. I spoke with Mr. Findeissen (can't remember his first name) at one of the “San Juan Challenge” races years ago. He said he built a light boat and it was terrible. His attitude was that I was a dummy for taking a light-boat position. I suspect his life as a boat builder gave him a way different perspective. Especially because he was dealing with the materials at hand three decades ago or so.

*”Swamped“ used here as a mathematical expression for overpowering or making other factors negligable. Sort of a geeky pun in this case. forgive the punster.

rd

discussing_weight_effect_2015.txt · Last modified: 2020/09/16 21:49 (external edit)