Question regarding boat weight and paddling on the water

[bignevermo]

Hi all, I am asking if I might have a premise or two correct. First a little background. And I beg your patience.

I paddle on a Dragon Boat team. That is a 45' long canoe with 10 rows of two people for a total of 20 paddlers, plus a steers-person with an oar. The canoe with people weigh about 3.5 K pounds more or less.

We determine who gets on the boat to race by trial and we use an Outrigger canoe(OC) and we use an OC-2 for these trials There is a person who paddles(the trialer) and a person behind who steers so that steering poorly is not a factor in the trial.

Premise one: It has been told to me that a heavier person has an advantage. I posit that extra weight in and of itself is not and advantage but a liability.
That premise was based on the assertion that a heavier person will have more momentum.
I posit that that extra momentum will be offset by the extra friction created by the heavier boat.

Premise two: That a heavier person will have the advantage on the OC, because they will have to pull less of a % of their body weight in relation to lighter people. ie. the person being toted by the trialer weighs 140 pounds. The person trialing weighs 220 for a total of 360 pounds plus the boat.
another trialer weighs 165 for a total of 305 pounds.

Who if anyone has the advantage?
The wind is a factor and I have advocating the use of an anemometer but that idea has been dismissed.

Premise three: the wind is an advantage to the heavier person.
In my instance my body acts as a larger "sail" I am 6'4" so in a head wind i say it is no advantage at all, in fact more of a detriment.

Premise four: In light of the fact we need to move so much weight in the Dragon Boat, the people who can paddle with more weight should be used, even if heavier themselves.
examples of outcome of said trials, In 2:30 minutes:

Person 1. 157 pounds carried both people at 297 pounds to a distance of 377M
Person 2. 222 pounds carried both people at 362 pounds to a distance of 366M
Person 3. 200 pounds carried both people at 340 pounds to a distance of 373 M
all people so far with no wind.
Person 4. 222 pounds carried both people at 362 pounds a distance of 383M
with a head wind at an angle of 45 degrees. speed unknown approx. 5kph

Best distance was by Person 5. 203 pounds 343 pounds total to a distance of 400M no wind.
If the wind factor isn't specific enough you can ignore. :)

I appreciate any feedback on any of the premises... the main one being heavier is better... i posit that that can't be true. If I weighed 20 more pounds at 242 I would not go as far with the same strength.
I realize this is a weight to power ratio issue is it not?

The other variable would be paddling technique... which gets me to my next premise
Premise 5. a paddler with less weight to power ration can overcome this disadvantage with better technique.

There is also an ERG machine that is used to determine who should be on the boat.
That is a "rowing " machine with a paddle adapter. The results, with "raw" data and "adjusted"(for weight) with 165 as over under for adjustments.The distance, again in 2:30 minutes in Meters

Person 1. 492/497
Person 2.489/462
Person 3.539/522
Person 4. 506/481
Person 5. 523/5053

The machine does not take into account someones paddling technique.
Best paddlers to be in the Dragon Boat in order?

 

[sophiecentaur]

Interesting problem but I have no idea of the answer or if there actually is one. All sports try to bring Science in where they can - with varying degrees of success. A dragon boat is more or less a displacement boat, I assume, and its top speed is very dependent on waterline length. How near its top speed is it going when flat out? IS there any overhang that could be increasing waterline length when it's loaded? Does the actual displacement make a lot of difference to the speed? You could do some towing tests with various weights of occupants and see what speed a particular power boat could achieve by pulling through the water.
Windage could make a difference - but the only way to find that out would be by experiment. Likewise for most of the other parameters you are discussing.
I do know that top rowing crews tend to be pretty big, so that must be a factor - as long as the heavy crew is more than a 'pudding'. For a given weight of boat, a heavier crew with the same power/weight ratio as individuals, would produce a better power/weight ratio for the total crew plus boat. But is there any aspect of the boat design that makes it behave worse when it's low in the water? Does it take the sea differently, for instance? How important is manoeuvrability in a swell?
Paddling skill will be a very important factor. I know that tideway rowers can absolutely dump on high-performance smooth water rowers.
Basically, I reckon you will have to try all the combinations that you can, out on the water.
PS I suppose the Dragon Boat design is not open to being modified?

 

[bignevermo]

Thanks so much, the design is a standard design and not open to modification. In fact at a race the boats are supplied by the promoter so no individual modifications are permitted. We paddle at the Miami Rowing center and so I am familiar with the rowers and their craft.
I was more interested in the individual aspect of this sport, the time trials on the OC actually. One of my coaches said I have the advantage because I was heavy, which I don't believe is true. I use to weigh 240 pounds and now I am at 222 so I know that for the same person(me) I will paddle farther in the same conditions and time now that I am lighter. The USA coach said they did some studies where a ten pound decrease in weight led to an increase in distance. I was just wondering too the power to weight ratio and if any of you would be able to find that a lighter person would be a benefit or the heavier person would be a better fit. I am thinking that it may be a combo of the two as the seats in the boat are not all uniform and I (Person 4) would not fit in the first two or three rows. Those are for the smaller people.
Thanks for your input and have a nice day! :)

 

[CWatters]

It depends if any weight gain/loss is dead weight like fat or useful like muscle...

Any increase in weight implies a greater displacement (boat lower in the water). The greater wetted area causes more drag force. So in that respect lighter is clearly better.

However if the extra weight is in the form of muscle then the power to weight ratio, and hence the power to drag ratio, might improve. In that respect heavier should be better.

If all the extra weight is muscle and then I would expect the boat to be faster because the overheads (weight of the boat, paddles, bones) are constant.

 

[sophiecentaur]

I don't think there is a magic formula for this. Assuming all the contenders for inclusion in the crew are strong and skilled, there is the matter of ability to work together synchronously, as a team That's even more intangible and can only be determined by sea trials and a really good coach. I feel that Physics has to take a back seat, once the power/weight ratio for each crew member has been measured.

 

[bignevermo]

Thanks to all who are responding, I should habve made the questions a little more direct... I thank each and everyone for your input! :)
CWaters, yes i agree if it is added muscle, however the person said the advantage was to the heavier person... strictly speaking that isn't true. Thanks!
Sophie, thanks to you too as you sussed out the bottom line, being "in time" DB parlance, is very critical! :)

 

[Settlenow]

An OC2 time trial does favor the heavier paddler. It's not that the weight makes you faster in an OC2 you are paddling while the steerer sits there. It is that it does not slow you down enough. In a DB you need to move your weight plus 1/20th of the boat including steersperson and drummer. Your share is about 55#. In the OC2 you are hauling about 200# so your own body weight plays a smaller role in the outcome. All testing methods for DB have their limitations. That is a major one for OC2.

 

[Jacobdf]

Hi all, I am asking if I might have a premise or two correct. First a little background. And I beg your patience.

I paddle on a Dragon Boat team. That is a 45' long canoe with 10 rows of two people for a total of 20 paddlers, plus a steers-person with an oar. The canoe with people weigh about 3.5 K pounds more or less.

We determine who gets on the boat to race by trial and we use an Outrigger canoe(OC) and we use an OC-2 for these trials There is a person who paddles(the trialer) and a person behind who steers so that steering poorly is not a factor in the trial.

Premise one: It has been told to me that a heavier person has an advantage. I posit that extra weight in and of itself is not and advantage but a liability.
That premise was based on the assertion that a heavier person will have more momentum.
I posit that that extra momentum will be offset by the extra friction created by the heavier boat.

Premise two: That a heavier person will have the advantage on the OC, because they will have to pull less of a % of their body weight in relation to lighter people. ie. the person being toted by the trialer weighs 140 pounds. The person trialing weighs 220 for a total of 360 pounds plus the boat.
another trialer weighs 165 for a total of 305 pounds.

Who if anyone has the advantage?
The wind is a factor and I have advocating the use of an anemometer but that idea has been dismissed.

Premise three: the wind is an advantage to the heavier person.
In my instance my body acts as a larger "sail" I am 6'4" so in a head wind i say it is no advantage at all, in fact more of a detriment.

Premise four: In light of the fact we need to move so much weight in the Dragon Boat, the people who can paddle with more weight should be used, even if heavier themselves.
examples of outcome of said trials, In 2:30 minutes:

Person 1. 157 pounds carried both people at 297 pounds to a distance of 377M
Person 2. 222 pounds carried both people at 362 pounds to a distance of 366M
Person 3. 200 pounds carried both people at 340 pounds to a distance of 373 M
all people so far with no wind.
Person 4. 222 pounds carried both people at 362 pounds a distance of 383M
with a head wind at an angle of 45 degrees. speed unknown approx. 5kph

Best distance was by Person 5. 203 pounds 343 pounds total to a distance of 400M no wind.
If the wind factor isn't specific enough you can ignore. :)

I appreciate any feedback on any of the premises... the main one being heavier is better... i posit that that can't be true. If I weighed 20 more pounds at 242 I would not go as far with the same strength.
I realize this is a weight to power ratio issue is it not?

The other variable would be paddling technique... which gets me to my next premise
Premise 5. a paddler with less weight to power ration can overcome this disadvantage with better technique.

There is also an ERG machine that is used to determine who should be on the boat.
That is a "rowing " machine with a paddle adapter. The results, with "raw" data and "adjusted"(for weight) with 165 as over under for adjustments.The distance, again in 2:30 minutes in Meters

Person 1. 492/497
Person 2.489/462
Person 3.539/522
Person 4. 506/481
Person 5. 523/5053

The machine does not take into account someones paddling technique.
Best paddlers to be in the Dragon Boat in order?

 

[Jacobdf]

I suggest the following:
1) Carry additional weight on the OC2 so that all paddlers 'pull' the same weight.
2) Don't do the test when it is windy, but if there is light wind, just sit on the water for say 30sec and see how much you drift. Add/deduct this from the result.
The data will give you a more reliable ranking of paddler strength and remove argument about 'heavier is better'.

I recommend you download this spreadsheet
www.users.on.net/~malcolmandjane/HullCalc/HullCalc.xls
It is a very comprehensive set of calculations that can be used for modelling hulls, taking into account weight etc.
First model the OC2. You will find a table that gives kW vs Boat speed. So you can determine the calculated power of the paddler.
Now model a full sized boat. Determine the average power/paddler required to propel the boat at a certain speed. You can now add/subtract your test paddler power form the average which will give you a new speed. Then add/subtract the weight difference from average and see what impact this has on speed. This will give you the true impact of having paddler A vs Paddler B.
The absolute values may not be so accurate, but as you use the same calcs for both paddlers, the difference will be quite reliable.

Ergs are not so useful as poor paddling technique can still give a good erg score. However, you could use ergs to determine if a specific paddler is stronger or weaker than when first tested in the OC2 (assuming you also did an erg test at the time) when conditions are not suitable for on water testing.

Instead of measuring distance, it maybe more useful to measure time over a fixed distance. Pick a distance that gives an average time similar to your full crew 500m time so that the impact of paddler A vs B on the crew is likely to be 1/20 of the time difference.
I assume you also do the OC2 test with dragon boat paddles.
You may also want to encourage your paddlers to test at average stroke rates that are similar (say +/-5%) to the stroke rate you use with the full team.