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oak_pine_maple_ash t1_j3p29qa wrote

Reply to comment by Coomb in 2012 Olympic male athletes’ weight [OC] by highcharts

in rowing the boats are designed around athlete's weights. So my boat is designed for a 130lb person, and my bf's is designed for a 180lb person. It's both longer and wider. We end up sitting around the same height off the water.

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SomethingMoreToSay t1_j3qa7hh wrote

Yes, but his has more wetted surface because it's longer and wider, hence more drag.

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Korvensuu t1_j3qqt1w wrote

as a simple example, you and your bf now swap boats

the lw boat your bf is in will be deeper in the water than when you were in it >> more drag

his boat that you're in now sits higher in the water >> less drag

the boats are designed for different weights but thats not really what we're looking at here, we want to know how much water is displaced as that determines the amount of water-boat surface contact surface area and hence the drag.

A scull rated to a heavier weight does this by being wider and/or longer, increasing the water-shell contact area [which is the key thing as by spreading your bfs weight over a larger area the boat 'sinks' less and has the right water clearance] and increasing the drag

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Coomb t1_j3sac93 wrote

You sure do, or at least I believe that you do. That doesn't change the fact that in order for the boat not sink, it has to displace slightly more than the weight of water equivalent to the weight of the boat plus all of its occupants. For any given boat, if you put more weight in it, it must displace more water (or be able to provide additional dynamic lift, but that's irrelevant for rowing sculls). Your boat and your boyfriend's boat have approximately the same freeboard, but his boat absolutely must have additional volume displaced below the waterline, and that necessarily induces additional drag.

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