Board "speed"

General Discussion
41
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speed is always relative, doesnt matter whether its about surfboards, cars or spaceships…

The most logical would be to measure the speed of a surfboard relative to the water passing underneath the board…

Yes!!! This is how I see it – and I think this was the underlying gist in my original question.

The relativity of speed somehow, at least to my intuition, relates to how we perceive speed on a surfboard. Laird at Teahupoo that Oneula was referring to and the reality of standing waves (ie riversurfing, flowmaster) confirm that.

It seems to me, that relative to the speed of the water they are traveling on, the fastest speeds ever achieved on a surfboard have been on a shortboard.

And that statement in itself is relative. I’m not necessarily saying that shortboards are faster than longboards but rather that the fastest relative speeds achieved on a surfboard have been on a short board (ie less than 6’). It could still be that a longboard will someday travel faster than a shortboard.

So ultimately, my question, “which are faster, short or longboards” is completely moot. The answer would be, it’s relative.

42
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mmmm I seem to recall from an earlier discussion of pretty much this same thing, or a "What is the fastest board in the water?" thread, that I and others maintained the fastest board was a old-style wood paipo:

I totally agree… and I know other “surfboard design experts” that do too. I’ve watched guys on plywood paipos make sections that standup surfers couldn’t. Fastest (wavepowered) boards I’ve ever seen.

43

I think the term everyone is looking for is “hull speed” vs “land speed”; like air speed vs ground speed in and airplane.

Just go out to Rincon or other point break and watch for awhile. A longboard cruises to the end of the point in a straight line while a shortboard gets to the same point but is zig-zaging a much longer route. Both board’s land speeds are pretty much the same and are dictated more by the wave than the board/rider. The hull speed of the short board is much higher as evident by covering much more area (actually length) than the longboard.

44
Quote:

I think the term everyone is looking for is “hull speed” vs “land speed”; like air speed vs ground speed in and airplane.

Just go out to Rincon or other point break and watch for awhile. A longboard cruises to the end of the point in a straight line while a shortboard gets to the same point but is zig-zaging a much longer route. Both board’s land speeds are pretty much the same and are dictated more by the wave than the board/rider. The hull speed of the short board is much higher as evident by covering much more area (actually length) than the longboard.

Exactly!

Coque.

45

Hi Mike,

As mentioned many times on past speed threads, our good friends Bill Barnfield and Terry Hendricks have done tests which measure speed relative to the earth and AND speed through the water, they report that the results agree closely. . . . remember that speed relative to the earth’s surface as measured by gps is not just horizontal speed as is often assumed, it includes the vertical component as well.

Movement is of course always relative to something. . . . … which is what allows it to be measured!

:slight_smile:

46
Quote:

I think the term everyone is looking for is “hull speed” vs “land speed”; like air speed vs ground speed in and airplane.

Just go out to Rincon or other point break and watch for awhile. A longboard cruises to the end of the point in a straight line while a shortboard gets to the same point but is zig-zaging a much longer route. Both board’s land speeds are pretty much the same and are dictated more by the wave than the board/rider. The hull speed of the short board is much higher as evident by covering much more area (actually length) than the longboard.

In that case the longboard is moving more slowly, and this will show up in gps readings. . . . remember that gps also measures vertical movement, not just ‘ground speed’

:slight_smile:

47

LOL! Yeah, of course, the hydrofoils but these things really take planing to a new dimension… awesome shot btw…

on conventional hulls… long waterlines are fast…

whoo. that is an awesome picture…

48
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Quote:

The amount of energy available from pumping is less than 10% of the total energy available to drive board and rider.

How are you quantifying this?

Using Newtonian physics

An approximate figure can be put on the energy output of an adult male doing continuous squats, it’s about half a horsepower

The horsepower available due to gravitational potential energy can also be calculated For a 100kg board and rider, the maximum horsepower available is in a vertical drop, and is 12.8 hp

The same 100 kg board and rider, on a glide path which is 20 degrees below the horizontal, has 4.3 hp available ( note that these figures are irrespective of the size of the wave, i.e. the size of the wave does not increase the power due to gravity which is available to the rider )

Now if we add the horsepower available from rider input, we find that in a vertical drop the rider input is no more than 3.1% ( although it’s a bit hard to pump in a vertical drop lol) , and on a shallow glide path of 20 degrees the rider input is no more than 11.6 percent

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Quite frankly I don’t get the whole speed thing. If speed is what you want, put a sail on it, howz 40 knots sound?

The whole idea, as far as I know, with (longboard)surfing is aimed at staying in the most dynamic part of the wave, the pocket… trimming, running the nose, cutting back, bottom turns, stalling all aimed at keeping us in the pocket…

If you were to go and tell an olympic sprinter that he’s wasting his time because you can go faster in his car you would be using the same (stupid!) argument

Dave, if you are not interested in surfing speed then you should avoid this thread (each to their own )

This thread is about board speed

:slight_smile:

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But, a short waterline is faster.

That hyrofoil vessel is a good argument in favour of using immersed horizontal foils in order to decrease drag and increase speed ( which we do ). . … however it is NOT an argument for short waterline planing hulls ( i.e. shortboard surfboards with conventional fins)

Agreed ?

:0

50

Actually I think arguing about speed is pretty rediculous. Surfboards are tools. Different people have different prefrences about how they want their tools to work and what end result they get. Just like one artist might use a broad brush, primary colors and heavy texture to make his art and another finer and subtler. Neither is necessarily best. They are just what that person chose to use.

No the picture does not support a short waterline length arguement. But, it does illustrate that there are two different modes of sailing, displacement and planing. And, once planing any benifits you gain from length only become penalties. Once planing it’s power/displacement with in constant control. So, the smaller the planing surface for a given amount of power while maintaining control the faster you can go. That’s why ice boats are so frick’n fast.

You like trimming and gliding. I like maintaining control while manuevering in the pockets of most power. It’s just different horses for courses.

51

This thread is for those who wish to DISCUSS surfing speed, and it was started by Mike for that purpose ( I assume)

If you think that the thread is ridiculous then perhaps you shouldn’t visit it.

You say that the picture of the hydrofoil yacht illustrates that there are two different modes of sailing (displacement and planing ) and then try to (once again) use the hydrofoil picture to support a shorter planing length is faster thesis. . . . but in fact the picture has nothing to do with planing, it shows that there is a mode of sailing based on immersed foil based lift . . . NOT planing !

The picture is an example of lift based on immersed foils, we use immersed foil based lift to reduce dependency upon planing lift, with very good results

:slight_smile:

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Oh I’m sorry I’ve offended you once again!

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I’m not offended, I’m just suggesting that this is a thread for those who are interested in speed, and that your hydrofoil picture is not, (as you claim it to be) an example of planing

:slight_smile: (That’s a smiley )

54

Foils are made up of extremely small and effiencent planing surfaces. So, they are IMHO a perfect example. However, I could post pictures of the other top five contenders for the world speed sailing record. Unfortunately, their planing areas are even smaller than the trimaran foiler I posted. I thought that picure said more with less.

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Planing hulls are those which skim over the surface of the water, they are not the same as ‘hydrofoil’ boats which use lift from immersed foils

Your argument seems to be that shortboards are faster than longboards because they use less wetted planing surface area.

There are various ‘ifs buts and maybes’ which apply here:

Firstly, it hasn’t been shown that shortboards are necessarily faster than longboards

Secondly, planing is the least efficient of the three kinds of water based lift ( underwater foil based, displacement, and planing), so if the surfboard is depending entirely upon planing lift then it is less than ideal

Thirdly, it has not yet been established that the length of the board implies that it is always using more planing area. … . some longboards are designed to reduce planing area as speed increases, and some longboards are less dependent upon planing lift than shortboards.

Fourthly , there are a lot of waves which a longboard can ride but a short planing lift based board can’t even catch. . .and if you can’t ride the wave then your speed is limited to paddling speed ! In other words there are situations wher increasing your wetted surface area increases speed, and a longboard has a bigger range of available weted surface area. . . which it can apply when necessary and reduce when going faster.

Fifthly, it is clear that the 'longboards are slow due to greater wetted surface area" argument possibly applies to noseriding longboards, but not necessarily to tailriding longboards . . … and the vast majority of longboards out there are slow noseriders. . . . . that’s just a matter of poor design, the Swindler’s list legends just can’t cut it in the longboard design department ( how sad :wink: )

Sixthly , PROVE IT. . . … or at least have a go at measuring your speed. . . it’s fun and informative !

:slight_smile:

56

Mike’s original question was speed is it a relative measure. I believe LeeV came up with a very concise explanation for what Mike was asking:

" I think the term everyone is looking for is “hull speed” vs “land speed”; like air speed vs ground speed in and airplane.

Just go out to Rincon or other point break and watch for awhile. A longboard cruises to the end of the point in a straight line while a shortboard gets to the same point but is zig-zaging a much longer route. Both board’s land speeds are pretty much the same and are dictated more by the wave than the board/rider. The hull speed of the short board is much higher as evident by covering much more area (actually length) than the longboard. "

My answers were not surfboard specific. I answered pictorially because, like I have for the last several months, wanted to avoid being dragged into your longboards are superior to short boards arguement. Each key I type I regret, because I know you just like being argumentative. But, obviously that failed.

Now you say that there are three modes of moving across water and include foiling. I maintain that there are only two and that foiling is included in the family of planing. My example of a link between planing hulls and planing foils are stepped hulls and/or multihulls flying on a single hull. They are all just ways of reducing wetted surface area while still maintaining enough lift to propel the craft forward at speed.

Now, I also give you that longer hulls perform at higher averages over a broader spectrum of prollusionary force.

But, once you’ve got enough force to over come displacement mode smaller is more efficient (faster) with in a controllable range.

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Just go out to Rincon or other point break and watch for awhile. A longboard cruises to the end of the point in a straight line while a shortboard gets to the same point but is zig-zaging a much longer route. Both board’s land speeds are pretty much the same and are dictated more by the wave than the board/rider. The hull speed of the short board is much higher as evident by covering much more area (actually length) than the longboard. "

Sure, in that particular case the shortboard will have reached a higher peak speed, and a higher average speed. However this does not prove that shortboards are faster than longboards.

Please note also that a gps unit will measure the speed during the zig zag route of the shortboard, and thus measuring by gps is a valid way to compare the two styles of surfboard.

What I am saying is that no one using gps is out there measuring the horizontal component in isolation, because gps measures the vertical componet as well, I mention this because it still appears to be the case that some of you believe that gps measures the horizontal vector only which is a myth. . . it appears that you have decided to call this ‘ground speed’ . . … but in fact the gps is measuring in 3 dimensions using the surface of the earth as a reference surface.

Excluding current, the gps based speed will be almost identical to through the water speed. The spurious argument that gps only measures horizontal speed has been used often on speed threads to try and support the idea that gps cannot capture the true speed of the shortboard. . . . which is absolute nonsense, as the gps measures in three dimensions.

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Each key I type I regret, because I know you just like being argumentative.

No, I am not being argumentative, I am merely being careful and thorough I am sorting the truth from the myths, a dirty thankless job that not many are prepared to do.

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Now you say that there are three modes of moving across water and include foiling. I maintain that there are only two and that foiling is included in the family of planing.

Quite clearly there are significant differences between underwater foil based lift and planing based lift, one notable difference being that underwater foil based lift can be achieved at a better lift/drag ratio than planing lift.

I am obviously not the only person who sees differences between planing lift and foil based lift, the differences are common knowledge in the marine industry.

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Once you’ve got enough force to over come displacement mode smaller is more efficient (faster) with in a controllable range.

Smaller is not always more efficient

At any given speed, for a surfer and board of a given weight, there will be an optimum wetted surface area, and this will decrease as speed increases. … but going smaller than the optimum does not increase efficiency. . . which your statement implies.

A longer board is able to decrease it’s wetted surface area as speed increases, if designed to do so, didn’t you get that point yet?

You are equating length of board with wetted surface area, but the two are not directly related.

:slight_smile:

58

I think there are several articles, perhaps a video or 2 of Laird Hamilton and the guys that broke through with the tow in craze explaining that their finely tuned big wave guns were too big for the giant waves they were riding.

There was too much surface area, and that was a problem with the speed they reached riding the giant waves. I think they’ve proven that short boards can go faster than long boards, and that they are much more rideable or controllable at high speeds.

I’ve also heard that a windsurfer is fastest form of sailing vehicle. I don’t know if that is true, but I think that less surface area equals less drag equals greater speed.

Now if you want to argue about the ability to paddle into a wave is better with a longer board, I’d have to say yes that is true, but I would not want to be on a really big board in really big waves. I prefer being on the smallest possible board I can be on that can catch the waves. Shorter, narrower boards will ride way better in bigger faster waves than any longboard. Shorter, wider boards do the same in smaller waves.

59

So how does board width fit ino all this speed stuff?

Say a 7’0 by 24" wide board vs a 10’ by 21" wide?

What about width at 18" from the tail?

60

Are you asking for my opinion?

Happy to give it, just checking.

:slight_smile: