Standup Zone Forum
Stand Up Paddle => Downwind and Racing => Topic started by: refthimos on November 01, 2010, 03:56:56 PM
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So I was reading a post on here from a manufacturer claiming that its heavier board was actually faster in straight line flatwater conditions than a similarly shaped board half the weight. The claim was that momentum is greater with the heavier board and thus the glide is better.
There were also other claims, such as increased stability and tracking from the increased weight, with it being tougher for chop and wind to push the nose of the board around. These claims I believe, so I'll leave them alone, but the weight claim gives me pause.
I come from a road cycling background and have heard scores of similar debates regarding what makes a fast bike. There are those that would argue that one a flat course, a heavier bike will actually carry momentum better than a light bike. But no pro rides a heavy bike; they all ride bikes that are at or near the UCI weight limit of ~16 pounds.
Now, there is very little debate that on a road bike, aerodynamic resistance is by far the most important factor in a "fast" bike... Followed my rolling resistance (more weight increases this) as well as mechanical resistance (e.g. friction in the drivetrain, bearings, etc). Now while rolling resistance may not play as large a role as wind resistance, it still plays a significant factor. Imagine pedaling a 300 pound bike. Not only would it be a bear to get up to speed, but do you really think it's easier to keep that 300 pound bike moving as it would be the 16 pound bike? No way.
I think SUPs are similar. Primary determinant of speed is hull design. Length, width and shape. Piercing nose vs. displacement nose. All the stuff shapers are playing with and figuring out. Aerodynamic resistance doesn't account for much because we're not going that fast and there is only so much you can do with body position on the board while still maintaining an effective position for paddling. So it's really just the resistance against the water.
I think a heavier board may be more stable than a lighter board, and stability is speed, but only to a point... There is no doubt in my mind that given the same paddle stroke, less weight (both rider and board) means more speed... think of a board weighing only 10 pounds, no rider and a magic "Harry Potter" style paddle moving it along... that board would glide so easily on top of the water that it would just fly... Now imagine the same board, now with a rider, 300 lbs total... There is no question that with the same paddling power, you are going to go a LOT slower... you have all that weight to push through the water.
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No question that a heavier board is slower. If you have any doubts just put fifty pounds in the center of your board and have at it. Or borrow my "world's heaviest F18". It's not terrible now, but it's a lot slower than it was when it was light.
Heavier = more wetted surface=more friction. It also takes more energy to accelerate the board--in both directions. We've discussed this before.
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My brother lives in London, and he said when he used to go to the race track there, every time he put 50 pounds on a horse it always went really slow.
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What happened to your F18 Bill? We are just dicussing the weight of the naish 17 on the breeze. I loved the boards shape but sold mine cos of the weight. Apparently they are around 16 kg which i think is about 35 lbs. I just found that a bit of a pain to lug around for a regular DW board on off roof etc
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There are several new plastic SUP designs being released on the market and was i wondering the same thing. The plastic models range from 15 to 25 pounds heavier than the traditional SUPs designs that I'm interested in. It has already been mentioned that it takes longer to get the heavier plastic design up to speed, but I'm wondering about the energy it takes to keep the plastic models at cruising speed compared to a lighter model of the same hull design. The benefits of the heavier plastic models is lower cost, vastly increased durability and more storage space (kayak design storage).
Is it really that much more of an energy expenditure to keep a board that is up to 25 pounds heavier up to speed, compared to a SUP that is around 25 pounds lighter? Assuming the boards are the same length and similar design of course.
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IMO the 'cruising speed' thing is a little bit of a myth, I find that my speed frequently varies when I'm doing distance. A gust of wind hits you head on-you slow down, you get distracted - you slow down, water state varies or another craft goes past - you slow down. So even a cruising paddle involves re-accelerating the board many many times.
For me the 'feel' of a light board is so much nicer, that surge forward with each paddle stroke is such a great feeling as opposed to the 'leaden' feeling of trying to get a heavy board up to speed, I know it's subtle but I think important.
The heavy plastic moulded boards do make sense from the storage and durability perspective though - would be pretty tough getting a big plastic board on and off high racks on your own. I mainly paddle on a full carbon Starboard Surf Race 14 and I actually get get a buzz out of lifting it on and off the racks so easily, just love a light board!
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If you think the Naish 17 is heavy, you gotta heft Bill's F18. I carried it something like 50 yards after a Maliko run and I'm thinking "damn that run tired me out more than I thought!" Nope, just turns out that a 50 pound board is really tough to carry.
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Personally I think the whole light weight board thing is a bit overrated.. Except the part where you're lifting it on and off the roof of the car.. Fast boards.. Light boards.. You still have to paddle them and they all start to feel the same except that one is a smidge faster.. If you're not in a race it doesn't matter that much.. I don't like super heavy and I'm also not a big fan of super light.. There is a nice medium and that's what most boards are.
DJ
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What happened to your F18 Bill? We are just dicussing the weight of the naish 17 on the breeze. I loved the boards shape but sold mine cos of the weight. Apparently they are around 16 kg which i think is about 35 lbs. I just found that a bit of a pain to lug around for a regular DW board on off roof etc
The F18 I have in Maui is waterlogged. The one I have in Hood River was a very lightweight one that Mark built to win at the BOP. The glass was super light--probably just 1 oz veil. I got tired of punching holes in it every time I looked at it and reglassed it myself--one layer of 6 oz and one of 4 top and bottom. It wasn't so bad at first, but my hotcoat didn't kick and I had to scrape it off and redo it. By the time I was done butchering the poor thing it probably north of 50 pounds. I'm scared to weigh it.
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Geeze Bill, thats a bummer. Your right DJ, not a problem on the water. Its on and off the roof and carrying it long distance is when its noticable.
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For me the 'feel' of a light board is so much nicer, that surge forward with each paddle stroke is such a great feeling as opposed to the 'leaden' feeling of trying to get a heavy board up to speed, I know it's subtle but I think important.
(http://i275.photobucket.com/albums/jj308/risley47/nail-head1.jpg)
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The guys in Oz & South Africa are always arguing this on the surfski board. The controversy surrounds spending a lot of extra cash on a lighter layup (the manufacturers always seem to make the skis in poly resin and a carbon version, and sometimes two different carbon versions: non-bagged and vacuum bagged).
The argument in favor of the heavier/less expensive boat is that you could lose 5 kg/11 pounds and get the same performance as spending an extra grand (or whatever).
For me its a no-brainer. It is so easy to tell the performance difference in the lighter boat. Its the dead weight that is unmistakable when trying to push the boat over the precipice of a bump.
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I had an interesting discussion with one of Australias most respected OC1 paddlers.
Anyway we were talking about weights in OC1's. He said that not so long ago boats were around 15kgs. He said at that time smaller guys never won races....... This got me thinking. Heavier boat, heavier paddler but still always winning.
His reason was that the heavier boats simply took more strength to get moving, off the line, upwind, to re-accelerate etc etc. The smaller guys were on the same boats but did not have the strength to pull them.
Now at around 10kgs for an OC1 smaller and younger guys are doing very well in comparison to before. Kind of like at 15kgs Kai Bartlett would have smashed Danny Ching were as now the odds are more a little the other way.
Is heavy or light better? Lighter the better!
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For me the 'feel' of a light board is so much nicer, that surge forward with each paddle stroke is such a great feeling as opposed to the 'leaden' feeling of trying to get a heavy board up to speed, I know it's subtle but I think important.
Good point--the feel of the board (due to being lighter) shouldn't be underestimated--same goes for the paddle.
In swimming, every swimmer shaves down before key competitions. It does make a difference in speed, and in swimming a tiny time savings can be crucial. But a big part of the whole thing is the ritual, and the feeling. You feel like you're slipping through the water effortlessly, and like you can feel every molecule of water. Some swimmers even rough up their hands and forearms with a loofah* to enhance the sensation. Shaving makes a difference far out of proportion to what science says the drag reduction should be.
It surprises me a bit that I haven't heard of people using heavier boards or paddles in training, then switching to lighter ones for competition. There's the argument that that could throw off your timing, balance, etc. but that's certainly just as true or more so with swimming, and no swimmer ever shaves down until right before their meet.
*There's some chance Michael Phelps got this advice wrong, and instead of using a loofah he used a hookah.
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The answer to this question depends on the intended use. There are indeed situations where a heavier board will be 'faster'. Also, let's be clear that there are two definitions of 'fast"... instantaneous speed, and average speed. The key to answering the question depends on whether the board is being operated at an instantaneous speed that is close to its theoretical wave making resistance speed.
http://en.wikipedia.org/wiki/Wave_making_resistance (http://en.wikipedia.org/wiki/Wave_making_resistance)
For those who like to race and go fast, a lighter hull is faster because board is constantly being pushed to the limits of it's displacement speed ability, beyond which point, resistance increases exponentially. For a 14' board, this speed is calculated at 5.01 knots. So racers, who operate in this range of speed, will be able to briefly accelerate their board to a faster *instantaneous* speed with a lighter board vs. a heavier board. Each stroke allows them to accelerate to a speed greater than five knots for a brief moment, before the wave-making resistance drags them right back down again. The net result of some time being spent at a faster instantaneous speed is to also have a faster average speed.
For everyone else, cruising speeds are much lower and the benefit of quicker acceleration is much diminished. For these people, the weight of the board doesn't really matter for overall speed. However a heavier board will provide excellent glide because it carries its momentum better. It is harder to accelerate, but over a long paddle, it *may* be faster on an average speed basis depending on the sea conditions and the paddler's ability to maintain a constant speed. Definitely, a heavy board will pierce through chop and rough conditions better than a lighter one. Most of the time however, the weight of board will make no difference in average speed.
Off the water, it's a different story. Lighter boards are much easier to handle and throw around. However they are also fragile. Heavier boards are the opposite, and in particular plastic SUPs are significantly heavier but also practically indestructible. Plastic boards are also significantly cheaper, about 50%, compared to fiberglass/foam, because the labor costs are much less... in fact so much less that it's actually cheaper to make them in the USA vs. China.
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Doesn't really work like that. This would require a really long post, I guess I'll write it as a Ke Nalu article. The core of the reason is that while displacement limits (the point where the hull starts to push over the bow wave) do mount rapidly as the hull speed is reached, drag also rises pretty quickly with speed. The curve is more hyperbolic than hockey stick. More weight, more hull in the water, more drag. The relationship of weight to hull speed is well known, especially in the scull and kayak worlds where folks have done lots of hydro testing.
One more addition to the long list of articles I've promised myself to write.
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Bill,
What doesn't exactly work like what? Please explain. I'm pretty sure that I disagree with you... LOL :)
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What doesn't work is the idea that at cruising speeds the weight doesn't matter. The Residual Resistance issues are less important at lower speed but the Frictional Resistance remains important. that's a function of wetted area, velocity squared and some coefficients that don't much matter. Wetted area increases with weight. I wish it wasn't so, but it does. Plus paddling is always a matter of accelerating the full mass of the vessel and it's load. Friction slows the craft, paddling applies force to accelerate the craft enough to regain speed lost between strokes. F=MA. If you think through the physics you realize that there IS no such thing as paddling to maintain speed.
Also, in race conditions the ability to accelerate above hull speed is not tied to weight to any great degree, other than higher frictional resistance at higher velocity. The Residual Resistance factors have a lot more to do with displacement to length ratio, the beam, the distribution of volume along the hull and the shape of bow and stern than they do weight. and of course the amount of power the paddler can apply. More weight makes it harder to accelerate, of course.
Really, way too long. I started to reply in detail but it's going to take hours to put it all together. I'll do an article and then you can disagree.
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Have to agree with Bill here. The idea that there is really a "cruising speed" at which a heavier board is faster than a lighter board doesn't work for me.
SUP and uphill cycling (climbing) are similar in my mind in that while there are a number of factors involved in determining speed (e.g. aero drag, road resistance and dragging weight uphill for climbing, aero drag and hydro drag for SUP), there is one factor for each that really determines speed: for climbing it is how much weight you are dragging uphill, and for SUP how much hydro drag you are encountering).
Intuitively, you know that if you are riding a bike uphill, it is going to be a LOT tougher if someone sticks a 50 pound weight on the bike. You aren't just "cruising" along when climbing on a bike, each pedal stroke is a mini-acceleration and in between a mini-deceleration. You are constantly changing speeds, even if imperceptibly. Power meter and cyclometer data consistently bear this out.
Well SUP is similar, in that you are not just "cruising" at a constant speed... You are accelerating your board every time you take a stroke... if you think you are just "maintaining" speed, you're fooling yourself, because if you simply "maintained" speed during your stroke, you would eventually slow to a stop, because you're board is ever so slightly decellerating in between every stroke (and really, probably towards the end of the stroke as well, depending on how efficient your stroke is). So a lighter board is going to be a lot easier to accelerate, and pull forward through the water, in order to "maintain" speed.
Now if you think that the added momentum of a heavier board is going to help you during the "glide" while your paddle is out of the water, I have a pretty good feeling that is not the case. I can't say I have empirical evidence to back it up, but I would be shocked if the additional hydro drag created by the heavier board did not more than offset any momentum advantage.
Continuing with the cycling analogy, it is well accepted that the combined weight of bike and rider are really what matters when determining power to weight ratios... In other words, a light bike will make climbing easier, but taking 10 pounds off your bodyweight (while maintaining the same power output) will have approximately the same effect as losing 10 pounds from the bike (and probably a lot cheaper!). The point is that you have to consider total moving weight. Same thing with SUP. Do you really feel that you would be faster if you strapped a 30 lb weight to the center of your board? I sure as heck don't.
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I remember reading an article about golf balls. Seriously! :D It said that golfers who said they "had to" have softer balls ( :D) actually couldn't perceive differences in hardness when the logo on the ball was hidden and they were wearing earplugs.
They were judging the "softness" of the ball by what they were hearing.
I have a feeling the same is happening with SUP race boards. We hear the board donging like a bell weirdly and it just doesn't sound "good". The more solid sound of a heavier board makes the board "feel" better.
But as mentioned, I think while we're "feeling" better, we're also working harder and going slower.
More weight, whether it's in your butt or built into the board, displaces more water. And more board under water means more drag. And the drag is on top of the added weight you're pulling to begin with. So adding weight to a SUP rider or board is like adding weight AND going up a steeper hill with a bike.
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... Can't wait for Pono Bill's article. Dunno if I'll understand it, but still...Can't wait! ;D
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To be perfectly clear, let me re-state my opinions.
1. At racing speeds, lighter boards are faster than heavier boards, all else being equal. I think everyone agrees with this.
2. At cruising speeds, and all else being equal, a heavier board *may* be faster depending on the conditions and the paddler.
Why might it be faster? The answer is the same as your argument that a lighter board will be faster:
You are accelerating your board every time you take a stroke... if you think you are just "maintaining" speed, you're fooling yourself, because if you simply "maintained" speed during your stroke, you would eventually slow to a stop, because you're board is ever so slightly decellerating in between every stroke (and really, probably towards the end of the stroke as well, depending on how efficient your stroke is). So a lighter board is going to be a lot easier to accelerate, and pull forward through the water, in order to "maintain" speed.
I agree that boards are constantly accelerating and decelerating throughout the paddle stroke and recovery. But you're fooling yourself too if you don't think momentum also is a factor. Consider the extreme case of a board/paddler that has no weight whatsoever. It would decelerate to a complete stop extremely fast the moment the paddle left the water because of friction. So would a heavier board be more resistant to frictional deceleration because of its greater momentum? Would a heavier board hold it's speed better after the paddle leaves the water?
Imagine a situation where you are paddling directly into a small wind chop. Every wave slows you down. Would extra momentum from a heavier board help you paddle through chop more efficiently? I think perhaps it might, but we really should test it on the water. I think there is a good chance that under cruising conditions without chop, the extra momentum may be a benefit as well in certain situations. Again, this should be tested... we're only talking theory here.
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Wetted area is related to weight so this would argue for lighter being faster. Acceleration is worse for heavier boards, whether that is a change in speed or height (climbing a hill).
I can see only one argument for the efficiency of a heavier board, probably only valid for relatively flat water and displacement boards. Unlike bicycling, a board slows between strokes, and each stroke brings it back up to speed. A lighter board does slow down more. I think that the turbulence created by the paddle is related to the speed of the paddle relative to the water, so paddling wastes the most energy to turbulence when the board is going its slowest. If the light board drops speed more between strokes, loss to turbulence in paddling will be greater.
I don't know if this argument really holds any water, but it is the only one that makes any sense to me.
Robert
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I'm on a 44 lb SUP now. And so far have not had much trouble keeping up with other paddlers (in flat water).
I know that when talking about weight with on a hydrofoil (SkySki or AirChair), many riders think they need the lightest possible ski out there. But what many of them need is high performance... and durable. I imagine this comes into play with a SUP too. As long as the performance is high enough to be acceptable, and the thing is tough as nails, then a certain amount of weight is acceptable.
I've already made one repair in my epoxy board, which undoubtedly would have taken on water had I not fixed it right away.
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I did a quick calculation on the increase of wetted surface area from a fiberglass to a plastic SUP. Let's assume it's a 14' x 30" SUP, and that the glass board weighs 25lbs and the plastic board weighs 50 lbs. The extra weight causes a 1% increase in wetted surface area (~0.35 square feet increase). Since drag is linearly proportional to wetted surface area, the increase in drag is 1%. Seriously folks... how many people would notice that? I'm sure that racers would notice it, and enthusiasts that like to paddle hard, but the average paddler, it's probably a non-issue compared to everything else.
For casual touring, perhaps a plastic board that weighs 25 lbs extra won't affect performance in any measurable way. I've done a lot of multi-day touring in plastic sea kayaks that weigh 65lbs vs. 45 lbs for fiberglass, and it doesn't make the kayak slower in any appreciable way at touring speeds.
I like Airjunky's comments. A little extra weight might be worth it if it also comes with increased durability. It depends on your use.
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First of all, I love these kind of discussions. This is a relatively new sport, and I am relative newcomer to it at that, but it's cool to be involved in these kinds of debates when SUP design and theory is still in its relative infancy. And some of us agree with others but everyone in a respectful manner. Very cool.
With that said, I have no way to verify your calculation that adding 25 lbs of weight increases drag only 1%, but it just "feels" like that is not accurate. If I go from my current weight of 195 to 220, and am unable to increase paddling strength, it just "feels" like I am not going to go only 1% slower. Similarly, if I stick a 50 lb weight on my board, am I really going to be slowed only 2%? 100 lbs, 4%? OK at some point we are going to sink this board! Haha.
I don't disagree that the engine is BY FAR the most important thing in the equation. I used to race against guys that could ride away from me on a 40 lb bike, my 16 lb carbon fiber rig be damned. Same would go with SUPs. And I could see where a hypothetical "weightless" board+ rider would not be as fast as a board+rider with "some" weight, but I still think the correct thing to consider is not board along, but board+ rider, and even a 100 lb female is putting enough weight on the board to avoid the "weightless" situation described.
I have two roto-molded sea kayaks, and I chose them based on durability and price. And selection, which is largely a result of the first two variables (manufacturers make many more roto-molded yaks than they do fiberglass or kevlar because that is what the (almost entirely recreational) market is looking for). But I don't think they are as fast as a lighter kevlar boat. Agreed that the difference is not so significant that a novice will paddle like a pro losing 20 pounds from the yak, but yes there would be a difference.
Heavier SUPs can be the right choice because they are cheaper, offer a greater selection, are more durable, can be repaired, etc., but not because they are faster. I think.
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I think this is a great topic, too. PonoBill mentioned that this has been discussed before--probably referring to this recent thread:
http://www.standupzone.com/forum/index.php?topic=9003.0 (http://www.standupzone.com/forum/index.php?topic=9003.0)
Anyone who hasn't read it should, because there were a lot of interesting points made on it, too.
Maybe the subject needs a whole book, rather than just an article. The book could make the NY Times Bestseller List for both Friction and Non-Friction.
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Heavier = more wetted surface=more friction.
I've heard that same equation before, but expressed slightly differently: "The more cushion, the more pushin' ".
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One thing i am trying to find out is if there is a BALANCE of the weight where you will have an optimal momentum with the least amount of pulling effort.
The reason i say these sort of things dont necessarily apply to outrigger and surfski and other styles of paddling is because they are using boats that are WAY more efficient in the water and already have amazing glide and extra weight would only make you pull harder.
But in our case stand up boards are these big flat things (to a certain extent) that sit in the water and are affected greatly by the water, or more so than the very fluid dynamic shaped outrigger boats.
Now you say that a heavier board is more board in the water thats just the way it is. But what if one board is double the weight but has a design that lets it be 2 times as buoyant? Im not sure if this is possible but wouldnt that give it the same amount of wetted area but a possibility of greater momentum.
What i am trying to see is if newtons law applies to aid us in the fact that "something in motion wants to stay in motion" and over time saves us more energy than having to deal with "something at rest wants to stay at rest" if that makes sense...
Who knows. I wanna read the article and try to come up with some calculations for myself and post them and see if people could throw things that i did not take into account at me and see if we can all come up with a definitive answer to "is lighter ALWAYS better?"
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Heavier = more wetted surface=more friction.
I've heard that same equation before, but expressed slightly differently: "The more cushion, the more pushin' ".
LOL - pdxmike, you are a comedian!
My first unlimited board was a 18' Bark that I bought used from my friend Herbie Titcomb who did not like it because he thought it was too heavy. It weighs 44 pounds and is a bear to move around but I kind of like the way it feels in the water (but not the way my back feels getting it into and out of the water). It takes more power to get it going but once it moves, the momentum keeps it gliding, think of a heavy flywheel. A lighter board will accelerate faster and easier but also decelerates faster. A heavier board can also be an advantage in windy/ bumpy conditions, where a super light board can be harder to control. In the right conditions, the Bark is a fast, competitive raceboard despite the weight and I did well with it in many races. I used it in the 2009 Molokai race, see picture, and finished in 6:15.
I have to agree with the others though, that most of the time, lighter is better. Using the example used before, think of two boards that are exactly the same size and shape, but one is twice as heavy. If you put them in the water, without standing on them, the boards will displace as much water as they weigh. The metric system works well here because 1 liter water weighs 1 kg. If a board weighs 10 kg it will displace 10 liters of water to float. If it weighs 20 kg, it will displace 20 liters. So, the lighter boards will float higher in the water, displacing less water= less resistance through the water. You can't make the heavier board "more bouyant" without increasing the wetted surface, thats just basic physics.
That said, spending big bucks to save a few pounds is probably not worth it for most paddlers. The paddle is a different story as you have to lift it up out of the water hundreds of times and even a few ounces will make a noticeable difference.
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I did a quick calculation on the increase of wetted surface area from a fiberglass to a plastic SUP. Let's assume it's a 14' x 30" SUP, and that the glass board weighs 25lbs and the plastic board weighs 50 lbs. The extra weight causes a 1% increase in wetted surface area (~0.35 square feet increase). Since drag is linearly proportional to wetted surface area, the increase in drag is 1%. Seriously folks... how many people would notice that?
As others have suggested, this is very easy to test.
Tape some weights to your board. Ten pounds will be plenty.
Use a GPS if you have one, but it really isn't necessary.
In my opinion, this subject is too complex for math.
Reduce the variables by using the same board, conditions, paddler and percieved effort.
Paddle hard, paddle easy - it matters not - average speed will be lower.
Seat of the pants testing will convice you. I'm sure of it.
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Continuing with the cycling analogy, it is well accepted that the combined weight of bike and rider are really what matters when determining power to weight ratios... In other words, a light bike will make climbing easier, but taking 10 pounds off your bodyweight (while maintaining the same power output) will have approximately the same effect as losing 10 pounds from the bike (and probably a lot cheaper!). The point is that you have to consider total moving weight. Same thing with SUP. Do you really feel that you would be faster if you strapped a 30 lb weight to the center of your board? I sure as heck don't.
Excellent points ref. My ass-o-meter tells me that climbing and paddling are very similar - countless little accelerations.
Back to your climbing analogy. As you are aware, (but failed to mention probably for brevity) racers modify their bikes for climbing stages. They use fragile, light weight wheels and add more weight to the frame (16# limit).
Wheels move more than the frame does. Removing weight from the outer edge of a wheel is 4X as efficient as removing weight from the frame. Reducing the wheels' angular momentum is the key to those countless little accelerations. Wheels and boards - the most dynamic part of the puzzle
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Putting weight on top of the board will not feel the same as having the weight distributed evenly inside the board and will also make it more unstable.
I agree that using a lighter board is noticeably faster, which is why I don't use that heavy Bark anymore.
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For some reason i still feel that there is "to light" of a board and there must be that perfect weight.
I understand now that the more weight is more wetted area and that buoyancy is relative to mass and weight is also relative to mass so yeah my bad LOL.
And adding 10 lb thing to your board does not "feel" the same as using a 10 lb heavier board.
I just wanna make it clear that im not disagreeing necessarily that lighter is faster but i think there is a point where lighter becomes not as effective.
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This turned into a really informative thread. The "wetted" area comparison makes sense as does friction. I have noticed a couple of analogies that I don't really agree with. Putting a ten pound weight on a board or whatever is not the best analogy as it doesn't represent the weight of a heavier SUP being distributed throughout the entire board, and not just in one spot. I have 10 pounds of gear with me on almost every paddle and when I don't, the difference isn't noticeable. What about buoyancy?
I noticed one example stating that a lighter SUP decelerates faster, which makes sense to me. This could bolster the momentum argument once a board is up to speed. Not completely sold on this though. There is a good reason it takes a loaded semi truck much longer to slow down than an unloaded one, or a typical passenger vehicle. The larger, heavier truck carries it's momentum longer than lighter vehicles. I'm not saying this carries right over into the SUP discussion but some of the variables make sense.
I have also read more than once now that a heavier SUP handles better on rough water and wind, thus making it easier to keep tracking straight. Flat water will be a little bit slower to get to speed, and a bit slower overall.
It really seems that unless your a racer, the biggest draw back is just getting the heavier board to the water from your vehicle. In the future I hope to have a range of boards including heavier plastic roto moulded designs and traditional designs. I am wondering how boards that are significantly heavier feel in both traditional and plastic designs. Is that walking on water feeling still there, or does it seem you are paddling a boat?
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What i am trying to see is if newtons law applies to aid us in the fact that "something in motion wants to stay in motion" and over time saves us more energy than having to deal with "something at rest wants to stay at rest" if that makes sense...
I will defer to the physicists in the crowd here, but I think there is this "fallacy of momentum" that in moving an object on level ground (in this case, water), heavier is better. As someone else stated, we see in just about every other sporting discipline out there (running, cycling, skiiing) that absent going downhill, lighter is faster.
If this "momentum advantage" were really true, wouldn't we see, all things being equal, heavier cars getting better freeway MPG? Put this another way: drive your favorite "wide-open" 100 mile route by yourself, then drive it with three passengers and a trunk full of luggage. If there were really a momentum advantage, wouldn't you find yourself faster over that same route with your car weighed down? You won't. There will be an increase in rolling resistance (the SUP is similarly affected by more hydro resistance), but more importantly, it takes more work to move more weight over time. Same as a wheelbarrow. Is it easier to push when empty or when loaded up with 100 pounds of bricks? That "momentum advantage" isn't doing you much good there. More weight, more work.
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I'm not seeing momentum so much as an advantage, but rather the ease of keeping at a good cruising speed once you get the heavier SUP going from a stand still. Does momentum help with punching through the chop and pushing through a headwind? Some of these examples are getting a little extreme now. Putting a weight right in the middle of the board, which doesn't accurately reflect weight distribution at all. A filled wheel barrow? Momentum in the terms we are referencing is in regards to once the SUP is moving and slowing down. A loaded car doesn't reflect this well at all imo until it is slowing down, which you would see the loaded car take longer to stop than the same model that is unloaded. I realize that a loaded car takes more work to move, but it is still an example with unbalanced weight distribution. An SUP is long and narrow. A car is short, compact, with a weight bias in the engine and then a huge amount of weight from several occupants distributed over a very small area. An SUP's weight is distributed through out it's length and it is much more streamlined.
How much work does it take to move a heavier SUP over time? Is it like moving a filled wheel barrow vs an unloaded one, or is it more akin to burning an extra 25 calories over a few hours of paddling? I don't think there is much of an argument here regarding a heavier SUP being less efficient over the long haul. It's how much less that is interesting to me and it seems pretty small. The momentum argument is interesting though and it seems that most who have paddled significantly heavier SUPs, state that once up to speed, the energy expenditure is not huge.
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Interesting. I do think the car example is a good one. It is well proven that a lighter car gets better milage.
For plastic boards you also need to consider the stiffness. Touring kayaks are an example. A stiff board (or kayak or boat) will glide through the water much better. The flex is using up energy. If you could make a rotomolded boat that was as stiff as glass and not too hard to load onto a roof rack, then you would have something.
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The roto-molded boards could help answer this whole question. You could test one, then fill it with sand or water and test it again. That would take away the argument that putting weights on top isn't convincing because the weight isn't distributed evenly. The board would also be exactly the same otherwise, except for the weight, so the other variables would be gone, too.
Another idea along those same lines would be to take an extremely light F18, ride it to become familiar with it, then smear layer after layer of fiberglass over it until you had doubled or tripled its weight, then see how it felt then compared to before. Not that anyone would ever do that.
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With that said, I have no way to verify your calculation that adding 25 lbs of weight increases drag only 1%, but it just "feels" like that is not accurate. If I go from my current weight of 195 to 220, and am unable to increase paddling strength, it just "feels" like I am not going to go only 1% slower. Similarly, if I stick a 50 lb weight on my board, am I really going to be slowed only 2%? 100 lbs, 4%? OK at some point we are going to sink this board! Haha.
In the interest of being clear... I calculate that DRAG increases by 1% with a 25 lb increase in weight at non-racing speeds, because wetted-surface area increases by 1% for a standard 14' SUP shape.
All else being equal, more drag equals slower board. But in the real-world, a heavier board has a minor negative effect on speed for the average person, and may actually be beneficial in rough water conditions.
Regarding the car/bike analogy given here. I can easily think of a situation where a heavier vehicle is faster than a lighter one. Instead of a smooth surface, put big bumps on the road, and make the heavier car due to the addition of larger wheels and bigger shocks. :)
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As others have suggested, this is very easy to test.
Tape some weights to your board. Ten pounds will be plenty.
Use a GPS if you have one, but it really isn't necessary.
In my opinion, this subject is too complex for math.
Reduce the variables by using the same board, conditions, paddler and percieved effort.
Paddle hard, paddle easy - it matters not - average speed will be lower.
Seat of the pants testing will convice you. I'm sure of it.
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LaPerouse,
I have been thinking about this subject a bunch and will do the real world experiment you proposed tomorrow morning but not seat of the pants, more like a science project. I know putting weights on top is different but it should result in something to work with.
I'm attaching a a picture of the setup:
12'6 Amundson board- I chose this one because it is stable enough to handle 30 extra pounds. It weighs about 30 lbs, so adding 30 lbs will double the weight and should make a measurable difference in speed. GPS and Go Pro cam taped to board: I'm planning to record the speed on the GPS with the camera to see how the weight affects acceleration/ deceleration and top speed.
I will post the results here shortly and am planning to write a more detailed review on my blog.
The plan is to paddle the board first without, then with weights on a timed half mile course and a 400 ft sprint (flat water with light wind predicted for the morning)
I figure the difference will be more noticeable on the sprint as fast acceleration is key and plays a bigger role. On the half mile course slower acceleration will play a smaller role.
If results are inconclusive, I will do several rounds of testing over several days.
Any suggestions or predictions?
Place your bets:
How much slower do you think the board is with 30 pounds dead weight on top? (in percent- sprint vs. half mile)
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blueplanetsurf--wow, that's initiative! My first thought was that you're going to eliminate all the fun of arguing about this topic, but then I figured we'll all argue over what the results mean and whether they're valid anyway.
I say 15% slower for the distance, and 20% slower for the sprint.
Next you can do an experiment to answer the question of the balance bracelet, and after that the "what's the best thing to eat or drink for performance" question. Then the 14' vs. 12'-6" question, then the long vs. short paddle question, then the Kialoa vs. Quickblade, then the Surftech Bark vs. custom Bark, then the this fin vs. that fin...
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pdxmike, wow that was fast.
All good ideas but one thing at a time :)
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I did a video test, the speed on the GPS should be easy to read.
Board weight/ speed test setup video test (http://www.youtube.com/watch?v=Bb2-KVnjgk4#)
Anyone other predictions?
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Good test. I'd start with the weight at the center of balance and then check it in the water to make sure it's not affecting trim. If it's tilting the board front or back, slide it until it doesn't. Shouldn't take much. the center of balance is not necessarily the same location as the center of buoyancy
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Thanks for the suggestions, Bill.
I'm getting ready to head into the water, meeting my friend at 6:15 am.
Still dark in Honolulu.
What's your prediction?
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This test more accurately represents the difference there will be with putting a heavy bag of gear right in the middle of your board than the true differences of a heavier SUP represents. The weight distribution just isn't there. It is still a good test. I'm thinking the biggest differences will be in getting up to top speed in the sprint and a slower top speed while cruising.
It would be interesting to know the results if you spaced out the weights on the board. One weight in the middle, one in the back, and one up front. This would come closer to representing the weight distribution of a heavier SUP.
Some gliding tests would be really neat to know as well. How long does it take for the SUP to come to a complete stop with and without the weights? I guess this could be measured by hitting a peak speed and then stop paddling. It wouldn't be the easiest test to do as water conditions and wind could greatly skew the results. Momentum/glide has been a big part of this debate, so this would be a good test.
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Very cool work! Looking forward to your results. Good choice to use a large board that can handle extra weight. If the weights cause enough sinking to submerge the deck, then that would dramatically increase wetted surface area and not be a true test.
I agree with Bill that it's important that you don't change the trim of the board by putting weights off the center of buoyancy.
Also, can you see the GPS speed while you are paddling? Probably best to do it blind, or possibly conduct the test by keeping speed constant and reporting your subjective effort level.
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Wow. This is great stuff! Can't wait to hear the results.
Thanks, BluePlanetSurf! And, BTW, Congrats on your win at the Halloween HK-Kaimana race!
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Ok, I just got out of the water with conclusive results. Will post them after my shower and protein power smoothie. BTW, Bill, the trim was slighly off with the weights but instead of moving the weights I just moved my feet back about 1-2 inches from my regular flat water trim position.
Sill no guesses other than pdxmike? Come on, let's hear some guesses.
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...While we're waiting, Pono Bill brings up a point which I meant to earlier but forgot:
Do shapers design boards so that the "trim" it has while unweighted and floating is the intended "ideal" trim with a rider aboard? Or does floating the board alone simply find the flattest part of the rocker and put it horizontal? Either makes sense and I guess it's a chicken-or-egg thing, so doesn't really matter.
I've heard some folks say that to find the ideal position on a race board, you should check a board's trim sans rider first, then try to match that when you get on (like Pono Bill's mentioning to do that with the weights in this test).
While "talking" here, I'm starting to see the answer already: Gotta get a gps and figure out the best position scientifically - measure! But I guess the "float" method will give you a really good starting point.
Another great conversation with myself... :-[
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Ok. I'll go out on a limb and say.... You went slower with the added weight. ;D
Ok ok. I'll guess, by doubling the weight of the board, plus your weight, you will now have that board very near it's intended load limit. And, as mentioned, you will be dramatically increasing wetted surface because of that.
So how much time/speed lost? By my exact calculations...
I have no farging idea. ;D
Ok...I'll guess losing 25% on distance speed, but I'll venture LESS on sprints because you're hella strong and might be able to put that thing more up on plane when sprinting.
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Being present when the tests (at least the short sprints) were conducted I conclude the following: Robert paddles fast.
But more appropriately, the difference in the added weight was most notable at the start of the sprint. Without the extra weight, the off the line acceleration was obviously faster. But the times indicate that the board was moving faster the whole distance, not just the start (the slower start does not account for 4 seconds different).
I think its pretty clear lighter is faster, but each person needs to make the assessment of whether its worth the extra money to get that lighter board.
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Scott, I did not know you are 1paddle2paddle, your secret is out!
I don't know if you saw the new thread I started but am already planning to do the sprint test again, as the video did not come out. Want to got again tomorrow morning?