Author Topic: Race Board Volume - pro's and cons  (Read 7812 times)

ukgm

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Race Board Volume - pro's and cons
« on: July 09, 2016, 02:30:28 PM »
I'm looking at race board volume for a new purchase next season. I'm 94kg. What are the issues surrounding too low a volume (I assume increased drag/reduced glide) ? Are there any known ways to calculate what is appropriate ?

Pierre

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Re: Race Board Volume - pro's and cons
« Reply #1 on: July 09, 2016, 02:58:58 PM »
biggest mistake is the belief that higher volume makes board more stable, which is a cliché, reducing thickness under your feet adds stability while reducing volume...  this is some of examples. stability is obtained by waterline transverse moment of inertia/ immersed volume, basically integral(LxW^3/12)/V... plus some above water volume on sides (secondary"differential" stability...  basically on choppy water some total volume in L  2x your weight in Kg fits good, if that buoyancy reserve is enough on sides, bow and a bit on stern... and minimal under your feet.
 in other words, stability is mainly prportional to the cube of width, your weight and height...
\HF/- Hi-Fun Hydroworks / custom boards,BZH, since 1982  /  *Link Removed*

Pierre

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Re: Race Board Volume - pro's and cons
« Reply #2 on: July 09, 2016, 03:03:00 PM »
draw back to too low volume above nose is too much water on deck... we are not paddling on submarines! some ideas here if my langage is understandable:http://paddlespot.net/download/les_carenes_de_SUP_race.pdf ( i'm too lazy to translate from french, may be you can see few tables on chapter"stability")
\HF/- Hi-Fun Hydroworks / custom boards,BZH, since 1982  /  *Link Removed*

Kaihoe

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Re: Race Board Volume - pro's and cons
« Reply #3 on: July 09, 2016, 04:25:10 PM »
Hi gm,

  Being a similar weight I keep running into volume questions my self when trying to  find a fast narrow race board.  I don't have a good answer. 

  I was talking with Travis earlier this year about using high sided boards downwinders and the new dugout NSP downwinder and he said that the sides give 'reserve' volume. My interpretation is he is talking about having usable volume in the right place at the right time in rough conditions where there are differing volume of water at different parts of the board.

  Personally I found the 24" 2016 AllStar to be quite nice, even though it claims to be designed for a max weight on 90kg. Where as I found the 2014 23" ACE to be really corky and the 2102 27" ACE to be a barge with just way to much volume (90 litres more than the 25" of that year)

Area 10

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Re: Race Board Volume - pro's and cons
« Reply #4 on: July 09, 2016, 04:37:10 PM »
Of all the stats you can know about a board, volume is about the least informative IMO. I wouldn't recommend using at as a starting point for any purchasing decisions.

Most race boards will have enough volume for you since your weight is only about the 75%ile for weight for a US male.

Since you are already associated with Naish, maybe you'd consider a Javelin? They have quite a lot of volume throughout for their width.

Bigger guys often find they can get good trim on Barks: Joe Bark is a pretty big guy himself.

Larry Cain is doing well on a Starboard All Star and he's a pretty good sized unit. (And before that he went well on a Bark.)

But, really, you just have to try boards to know if they are right for you. There is no other way to know, I'm afraid: A SIC FX 14 has enough volume to float you three times over. Plenty! But could you balance a 25" wide board? Only you can judge.

ukgm

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Re: Race Board Volume - pro's and cons
« Reply #5 on: July 10, 2016, 04:47:34 AM »

Since you are already associated with Naish, maybe you'd consider a Javelin? They have quite a lot of volume throughout for their width.

Larry Cain is doing well on a Starboard All Star and he's a pretty good sized unit. (And before that he went well on a Bark.)


This was the starting point of this concern as a Javelin is 'only' 260l (for the 26 inch width I'd go for) which is a lot lower than the 270-290l boards I typically use. Yes, I'll float on half that but I was concerned that the reduced volume would reduce glide performance. Yes, I need to test but I wanted a greater understanding of this issue first.
« Last Edit: July 10, 2016, 04:58:17 AM by ukgm »

Pierre

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Re: Race Board Volume - pro's and cons
« Reply #6 on: July 10, 2016, 09:47:58 AM »

Since you are already associated with Naish, maybe you'd consider a Javelin? They have quite a lot of volume throughout for their width.

Larry Cain is doing well on a Starboard All Star and he's a pretty good sized unit. (And before that he went well on a Bark.)


This was the starting point of this concern as a Javelin is 'only' 260l (for the 26 inch width I'd go for) which is a lot lower than the 270-290l boards I typically use. Yes, I'll float on half that but I was concerned that the reduced volume would reduce glide performance. Yes, I need to test but I wanted a greater understanding of this issue first.

for your weight, a race Javelin volume is not an issue, it should even be more stable for you in case volume is less ( recessed deck under your feet, or better with same volume but differently distributed ( more near nose and tails, less under feet) the higher concern is width. for you weight ( and size?) it may be insufficient as nose is pointed and tail quite narrow.
\HF/- Hi-Fun Hydroworks / custom boards,BZH, since 1982  /  *Link Removed*

ukgm

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Re: Race Board Volume - pro's and cons
« Reply #7 on: July 10, 2016, 11:12:53 AM »

Since you are already associated with Naish, maybe you'd consider a Javelin? They have quite a lot of volume throughout for their width.

Larry Cain is doing well on a Starboard All Star and he's a pretty good sized unit. (And before that he went well on a Bark.)


This was the starting point of this concern as a Javelin is 'only' 260l (for the 26 inch width I'd go for) which is a lot lower than the 270-290l boards I typically use. Yes, I'll float on half that but I was concerned that the reduced volume would reduce glide performance. Yes, I need to test but I wanted a greater understanding of this issue first.

for your weight, a race Javelin volume is not an issue, it should even be more stable for you in case volume is less ( recessed deck under your feet, or better with same volume but differently distributed ( more near nose and tails, less under feet) the higher concern is width. for you weight ( and size?) it may be insufficient as nose is pointed and tail quite narrow.

Bearing in mind my current flat water board is a 2014 26 inch wide starboard sprint, this has got to be easier !

supuk

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Re: Race Board Volume - pro's and cons
« Reply #8 on: July 10, 2016, 02:12:02 PM »
Just a few things to take note on odviosly once you have enough volume to float everything else is out the water. Changing the rider weight but 20kg will only change the water line by a few mm (i forget the exact numbers But depending on size and shape you are only looking at maybe 8-10mm.) volume above the waterline is more about the shape and its effects  than buoyancy.

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Re: Race Board Volume - pro's and cons
« Reply #9 on: July 10, 2016, 02:15:47 PM »
ukgm - as I said before, volume tells you virtually nothing useful, and no-one can answer your original Q - we do not yet know enough about SUP design principles.

So I'd suggest you forget about volume and instead ask about trim. It's all about trim. Some boards trim better than others at certain weights. If you are a big powerful unit you'll often find that what works for a 150lb elite paddler will not trim well for you, once you start putting the power down. You may find the board bounces too much, or pitches too much, or introduces rail steer. These are complex things to understand and so you just have to try the boards for yourself. It is quite common for power paddlers to find that they are faster on wider boards. Quite a few people out there would be faster on wider boards. But vanity prevents them from using one.

ukgm

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Re: Race Board Volume - pro's and cons
« Reply #10 on: July 10, 2016, 03:04:34 PM »
Just a few things to take note on odviosly once you have enough volume to float everything else is out the water. Changing the rider weight but 20kg will only change the water line by a few mm (i forget the exact numbers But depending on size and shape you are only looking at maybe 8-10mm.) volume above the waterline is more about the shape and its effects  than buoyancy.

Although volume distribution must be important too. Too little at the tail for example could see it get dragged down at certain parts of your stroke ?

Area 10

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Re: Race Board Volume - pro's and cons
« Reply #11 on: July 10, 2016, 03:38:48 PM »
The tail and nose work together. So a tail dragging can be as much about the nose as the tail. I have tried a couple of boards with very high volume tails that have nevertheless dragged their tails very badly. Think about what happens to the nose when it is compressed under power, and then what happens when that pressure is released. The nose and tail have to work together to reduce pitching.

Eagle

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Re: Race Board Volume - pro's and cons
« Reply #12 on: July 10, 2016, 04:55:53 PM »
ukgm - Why not just try a Jav or 2016 AS instead of being concerned so much about volume?  Time yourself on flat and see which width fits your abilities the best.   :)
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Pierre

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Re: Race Board Volume - pro's and cons
« Reply #13 on: July 10, 2016, 09:19:14 PM »
Just a few things to take note on odviosly once you have enough volume to float everything else is out the water. Changing the rider weight but 20kg will only change the water line by a few mm (i forget the exact numbers But depending on size and shape you are only looking at maybe 8-10mm.) volume above the waterline is more about the shape and its effects  than buoyancy.
As a 14' average waterplane area is about 2 m2 20 kgs excess weight makes a board sinking by about 9 -10 mm, this is a lot... another reason why heavy paddlers should take wider, to avoid excess drag at tail and nose.
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ukgm

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Re: Race Board Volume - pro's and cons
« Reply #14 on: July 10, 2016, 11:36:13 PM »
ukgm - Why not just try a Jav or 2016 AS instead of being concerned so much about volume?  Time yourself on flat and see which width fits your abilities the best.   :)

Yes, I'll run my normal test protocols when I can access those boards. Javelins don't come up as demo's over very often.

 


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