Author Topic: What makes someone easy or hard to draft?  (Read 1186 times)

FloridaWindSUP

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What makes someone easy or hard to draft?
« on: February 05, 2017, 08:48:57 PM »
My coach / rival is very hard to draft on his 14x21.5" Hovie Comet GT, which has a flat bottom and sharp-railed square tail. It seems to have just the right amount of volume and tail rocker to release really evenly at the tail and not make any wake off the tail that I can see or feel. He's lighter and shorter than me but he's really buff and he has this way of plunging his paddle in and making big depth-charge like swirls in his wake, so it's like you're paddling over potholes when you're trying to keep up.

Besides speed, obviously, what makes someone easier or harder to draft? Are there some situations where even though it's flatwater you're better off not trying to draft? Does the "side wake" work when the back wake doesn't? Does riding the second or third wave back work when the position directly behind doesn't? Thanks.
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TallDude

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Re: What makes someone easy or hard to draft?
« Reply #1 on: February 05, 2017, 10:28:48 PM »
Wow! What a game!   ..... Oh, wrong thread ::)

I'm a big guy, so I'm good to draft off of. The problem is I can rarely draft off one guy, because they just aren't creating enough pull. I can draft off two or more guys. Then I can feel the pull. If you're old enough to remember driving a VW bug. It was not the safest thing to do, but if you got close enough behind a Semi truck, you could put the bug into neutral and it would pull you along. When racing you want you be right on their tail, almost touching it. Try to trade strokes, zig with their zig, and zag with their zag. I've notice if the train is 5 or 6 people, I can be almost a board length behind and still feel some pull.
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ukgm

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Re: What makes someone easy or hard to draft?
« Reply #2 on: February 06, 2017, 12:40:46 AM »
Wow! What a game!   ..... Oh, wrong thread ::)

I'm a big guy, so I'm good to draft off of. The problem is I can rarely draft off one guy, because they just aren't creating enough pull. I can draft off two or more guys. Then I can feel the pull. If you're old enough to remember driving a VW bug. It was not the safest thing to do, but if you got close enough behind a Semi truck, you could put the bug into neutral and it would pull you along. When racing you want you be right on their tail, almost touching it. Try to trade strokes, zig with their zig, and zag with their zag. I've notice if the train is 5 or 6 people, I can be almost a board length behind and still feel some pull.

I know what you mean but its not the same effect as with air. With air (think two bikes), you'll get a pressure hole and a circling air flow off the rear and that's what allows you to slipstream and get towed alone outdoors. You don't get that on water (on the road we can have more bikes in a line and get a better overall CdA but on boards having more in a line makes no difference to the overall net performance). I probably haven't explained this very well !

All you need to do is look for the best, heavy paddler on the start line. In addition, consider drafting off the beam on either side. Its cuts down your overtake distance (and power duration required) and (if is the same as open water swimming) will be just as low in drag - you're just using a different part of (either) their bow or stern wave to get pushed along.
« Last Edit: February 06, 2017, 12:43:29 AM by ukgm »
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yugi

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Re: What makes someone easy or hard to draft?
« Reply #3 on: February 06, 2017, 02:26:16 AM »
Ö
I know what you mean but its not the same effect as with air. With air (think two bikes), you'll get a pressure hole and a circling air flow off the rear and that's what allows you to slipstream and get towed alone outdoors. You don't get that on water (on the road we can have more bikes in a line and get a better overall CdA but on boards having more in a line makes no difference to the overall net performance). I probably haven't explained this very well !
Ö

Itís clear.

I have heard [here] that SUP drafting as likewise quicker for both tower and drafter. I, like you, doubt that. I wonder if it isn't someone in SUP just applying what they know from biking.

I even wonder if having someone drafting you behind isnít slowing the tower down. If the wave off the transom gets pressured does it not affect the leading craft?

Sure feels like it, but it may be purely psychological pressure.

ukgm

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Re: What makes someone easy or hard to draft?
« Reply #4 on: February 06, 2017, 03:27:41 AM »
Ö
I know what you mean but its not the same effect as with air. With air (think two bikes), you'll get a pressure hole and a circling air flow off the rear and that's what allows you to slipstream and get towed alone outdoors. You don't get that on water (on the road we can have more bikes in a line and get a better overall CdA but on boards having more in a line makes no difference to the overall net performance). I probably haven't explained this very well !
Ö

Itís clear.

I have heard [here] that SUP drafting as likewise quicker for both tower and drafter. I, like you, doubt that. I wonder if it isn't someone in SUP just applying what they know from biking.

I even wonder if having someone drafting you behind isnít slowing the tower down. If the wave off the transom gets pressured does it not affect the leading craft?

Sure feels like it, but it may be purely psychological pressure.

The simplest way I can put it is that in cycling, having a rider behind can make the rider in front go faster. However, when SUP paddling, having a paddler drafting you will make little to no difference to your own forward speed. If people are saying the effect should be the same, it won't be (as the density differences and things such as reynolds numbers make it incomparable at the slow speeds of paddling). Its more likely that any impact in that scenario is psychological. Ponobill or Luc could probably explain it better.
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Area 10

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Re: What makes someone easy or hard to draft?
« Reply #5 on: February 06, 2017, 04:05:23 AM »
Yet another way in which the heavier paddler is at a disadvantage in a racing situation.

PonoBill

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Re: What makes someone easy or hard to draft?
« Reply #6 on: February 06, 2017, 07:10:45 AM »
It depends on how you're being drafted. On some occassion when you have another paddler drafting very close, who stays in position without a lot of drama, observe your bow wave as he moves slightly closer and further away. Drafting makes the bow wave change. With a paddler slightly to the side or very close to the stern, the bow wave either moves forward, or disappears. Either change is good for the lead paddler and it's why drafting trains with good paddlers move ahead of singles in a race. If the bow wave moves forward and the nose drops a little, the person drafting has pulled their nose close enough to create a longer waterline. and they are submerging the stern wave. You can think of it as if they pushed the stern wave down, dropping the bow, but that's not what I think is happening. I think it's that the waterline length has increased, and so has the hull's wave period,  so the nose is no longer climbing the bow wave as much because it's moving faster and it's flatter.

In other words, if the drafter is good, and stays close without bumping, he helps the draftee. If he's all over the place then he's a handicap. The nose of the drafter's board matters too. If it's pure displacement, canoe style, then the waterline effect is heightened. If it's got some rocker then it's less.

I notice that when a paddler is drafting to the side that the bow wave seems to disappear. I think that's either an interference pattern or that the bow wave is forced to stay in contact on the side, as it generally does with an unlimited when the ratio of length to width is greater than 10/1.

Heavy paddlers make the best draft. Twin fins with a fence screw everything up by making a disturbed surface ripple rather than a trough. Pin tails make a nice deep troght, but it's skinny, you have to be in just the right spot to make it work. Rounded pins are best, square tails seem to depend a lot on volume distribution. Floaty, chiseled square tails make a poorly defined stern trough. Wide, but not strong.

If you want to break a draft, look at the bow of your board and wait for the nose to lift. That means the drefter has moved out of your trough. Paddle like hell and turn slightly toward the side they've been favoring. Most racers turn away from the draft side--that's wrong. They can reconnect easily with a small course change. If you paddle into the side they've been favoring they have to scross your stern and will generally fall behind.
« Last Edit: February 06, 2017, 07:35:07 AM by PonoBill »
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Bean

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Re: What makes someone easy or hard to draft?
« Reply #7 on: February 06, 2017, 07:30:03 AM »
What's the current thinking about general energy savings for the draftee and draftor?

TallDude

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Re: What makes someone easy or hard to draft?
« Reply #8 on: February 06, 2017, 08:58:31 AM »
Ö
I know what you mean but its not the same effect as with air. With air (think two bikes), you'll get a pressure hole and a circling air flow off the rear and that's what allows you to slipstream and get towed alone outdoors. You don't get that on water (on the road we can have more bikes in a line and get a better overall CdA but on boards having more in a line makes no difference to the overall net performance). I probably haven't explained this very well !
Ö

Itís clear.

I have heard [here] that SUP drafting as likewise quicker for both tower and drafter. I, like you, doubt that. I wonder if it isn't someone in SUP just applying what they know from biking.

I even wonder if having someone drafting you behind isnít slowing the tower down. If the wave off the transom gets pressured does it not affect the leading craft?

Sure feels like it, but it may be purely psychological pressure.

The simplest way I can put it is that in cycling, having a rider behind can make the rider in front go faster. However, when SUP paddling, having a paddler drafting you will make little to no difference to your own forward speed. If people are saying the effect should be the same, it won't be (as the density differences and things such as reynolds numbers make it incomparable at the slow speeds of paddling). Its more likely that any impact in that scenario is psychological. Ponobill or Luc could probably explain it better.
Yes, I know air and water have different physical properties. I was just creating an simple analogy to explain the feel of what happens. I find most people are on a conceptual level. With stand up paddleboards the air does play a factor when drafting into the wind.
Here's some info I found years ago. It applies to SUP for the most part.
  http://www.huki.com/index.php?page=Drafting
It may be overhead to you, but it's waist high to me.

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PonoBill

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Re: What makes someone easy or hard to draft?
« Reply #9 on: February 06, 2017, 06:25:17 PM »
What's the current thinking about general energy savings for the draftee and draftor?

I think that's what I just covered--the person drafting gets to save energy whether or not they do a good job of drafting. the person in front gets a benefit if the drafter is good and stable, holding position with the nose either very close or overlapped. If they do that, they make a hull that's somewhere around 28 feet long being paddled by two people (more or less).
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Bean

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Re: What makes someone easy or hard to draft?
« Reply #10 on: February 06, 2017, 08:43:55 PM »
You did cover it conceptually PB, the bean-counter in me was just looking for numbers. 

I think I get it, there is zero reduction in work load, if you speed up to the new theoretical hull speed.

ukgm

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Re: What makes someone easy or hard to draft?
« Reply #11 on: February 07, 2017, 12:23:51 AM »
You did cover it conceptually PB, the bean-counter in me was just looking for numbers. 

I think I get it, there is zero reduction in work load, if you speed up to the new theoretical hull speed.

From a racing point of view though, the later the race goes on, the more I'd be inclined to shift to the side draft. Not only does it reduce your finishing sprint distance to overtake but the actual quality of draft can be just as high as one off the stern. Those from an open water or triathlon background will know this from swimming - swimming off someone else's hip can be very potent (the only issue is avoiding the suction effect you feel whereby you get dragged into the person next to you).
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ukgm

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Re: What makes someone easy or hard to draft?
« Reply #12 on: February 07, 2017, 03:28:11 AM »
Ö
I know what you mean but its not the same effect as with air. With air (think two bikes), you'll get a pressure hole and a circling air flow off the rear and that's what allows you to slipstream and get towed alone outdoors. You don't get that on water (on the road we can have more bikes in a line and get a better overall CdA but on boards having more in a line makes no difference to the overall net performance). I probably haven't explained this very well !
Ö

Itís clear.

I have heard [here] that SUP drafting as likewise quicker for both tower and drafter. I, like you, doubt that. I wonder if it isn't someone in SUP just applying what they know from biking.

I even wonder if having someone drafting you behind isnít slowing the tower down. If the wave off the transom gets pressured does it not affect the leading craft?

Sure feels like it, but it may be purely psychological pressure.

The simplest way I can put it is that in cycling, having a rider behind can make the rider in front go faster. However, when SUP paddling, having a paddler drafting you will make little to no difference to your own forward speed. If people are saying the effect should be the same, it won't be (as the density differences and things such as reynolds numbers make it incomparable at the slow speeds of paddling). Its more likely that any impact in that scenario is psychological. Ponobill or Luc could probably explain it better.
Yes, I know air and water have different physical properties. I was just creating an simple analogy to explain the feel of what happens. I find most people are on a conceptual level. With stand up paddleboards the air does play a factor when drafting into the wind.
Here's some info I found years ago. It applies to SUP for the most part.
  http://www.huki.com/index.php?page=Drafting

I enjoyed that article. Thanks for posting the link.
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Kaihoe

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Re: What makes someone easy or hard to draft?
« Reply #13 on: February 22, 2017, 04:57:31 PM »
You did cover it conceptually PB, the bean-counter in me was just looking for numbers. 

I think I get it, there is zero reduction in work load, if you speed up to the new theoretical hull speed.

We did some (unscientific) testing in messy upwind chop a few months ago on a 50 stroke run the 1st draftee was taking 35-37 strokes.  This is with experienced racers and drafters working near aerobic threshold

Further to Pono's awesome explanation can confirm that the extended waterline affect works. When it happens the leader gets a push equivalent to what you experience in motor-racing but waaay slower (think NASCAR draft trains)

 


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