Design evolution - part 1

What works and what doesn't. Share design ideas, references and contacts for paipo board builders.
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bgreen
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Design evolution - part 1

Unread post by bgreen » Thu Mar 23, 2017 6:59 am

In 2011 I got the first of 5 boards based on the designs of Larry Goddard.

Board number 2 is: 4' 5 3/4" x 21 3/8" x 1 7/8". This board is the fastest board I've ridden. From the moment of take-off it takes off. It can be ridden finless and handles a steep wave, though isn't great as a tube-rider. If there is some turbulence or a section collapses, that's the end of it. Flat bottom .
MM2_profile.jpg
MM2b.jpg
MM2_deck.jpg
The next board was thinner & narrower. It was a bit too much hard work for me and I sold it to a friend who likes low volume boards.

Board 4 was a compromise board, more volume, not as fast but I've had some nice tubes on it. Same dimensions but the rails weren't as hard in the tail. It also has a handle. It is a good all round board. I mostly have ridden this board finned. Fins allow night tight arcs.
MM4_profile_w600.jpg
MM4_tail.jpg
MM4_tail.jpg (99.09 KiB) Viewed 2969 times
Last edited by bgreen on Thu Mar 23, 2017 7:23 am, edited 1 time in total.

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Re: Design evolution - part 2

Unread post by bgreen » Thu Mar 23, 2017 7:10 am

Another view of board # 4
MM4_bottom.jpg
MM4_bottom.jpg (85.46 KiB) Viewed 2968 times

Board # 5 is narrower - 4' 5 3/4" 21 " 1 7/8" , and notably has a rocker based on a surfboard, rather than Larry's bellyboard rocker. The other notable features are the deck dish and wings. This board, because of reduced volume, duckdives well but makes for later take-offs. The notable feature of this board is that it is a great tuber rider. However, faced with turbulence or whitewater it lacks stability or rather the ability to plough through. A lot of fun ridden finless. Boards 5 & 5 also have a narrower tail than earlier boards.
MM5-profile-bottom-S.jpg
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MM5_deckup.jpg
MM5_deckup.jpg (79.76 KiB) Viewed 2968 times
MM5Bottom-S.jpg
Last edited by bgreen on Thu Mar 23, 2017 3:40 pm, edited 2 times in total.

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Re: Design evolution - part 3

Unread post by bgreen » Thu Mar 23, 2017 7:22 am

The deck dish of board #5
MM5Deck2-S.jpg
Board # 6, was meant to be slightly thicker, but the shaper decided to add some drive, after I showed photos/footage of the board caught in whitewater as well as deep in a tube. The dimensions are the same as bard # 5,
MM6-Tail2.jpg
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MM6-foil2b.jpg
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MM6-bottom1.jpg
This board can get a noticeable burst of acceleration in a hollow section. This also ahs a surfboard style rocker. I've ridden it finless and finned - I want to experiment with fins a bit more (I've tried bonzer fins, a small keel and a small straight fin. All under 4"0. I haven't really fully tested this design.

I was going to not get another board for a while, but am somewhat tempted to try a hybrid of boards 5 and 6. Keep 5's wings and dish, but go a bit thicker, for stability.

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Re: Design evolution - part 1

Unread post by CHRISPI » Thu Mar 23, 2017 2:11 pm

That looks very nice , all it needs is to finish all the release points or were the water leaves the board with a taper

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Re: Design evolution - part 1

Unread post by bgreen » Thu Mar 23, 2017 3:42 pm

Chrispi,

Do you want to expand on what you mean by finishing with a taper?

Bob

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Re: Design evolution - part 1

Unread post by 1handclapping » Thu Mar 23, 2017 5:19 pm

Hi Bob good info.
I am just about to start a new board similar to the last but with 6" more length.
I will need to join the blank which should not pose a problem using epoxy.
I will keep the bottom flat with very little nose rocker soft rails leading into hard for the last 1/3 of the board.
My last board had very little volume which mad if hard to paddle into fat waves so I am hoping the extra length will help with this.
I will use a twin setup as I have used a set of keels,and happy with the performance.
We have been getting good waves although the water is a bit murky good banks have been formed on back beach.
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Re: Design evolution - part 1

Unread post by bgreen » Fri Mar 24, 2017 6:13 am

Hello Lewis,

Good to hear from you.

From memory you could go a bit longer (.75 of your height is one rule of thumb though I'm sure there are plenty of exceptions).

If you are around at Easter and there are northerlies I'd be very tempted to head down your way. I have a low rocker board you could try if you like. I posted photos of it on the mini-Simmons thread.

Are you still riding the bellybogger?

Bob

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Re: Design evolution - part 1

Unread post by 1handclapping » Fri Mar 24, 2017 10:55 am

Bellybogger,I loved that board unfortunately I snapped the tail.
I cut it down and rode it a few times it never performed like the full length board.
Some of the best sessions at the point was had on that board.
I am enjoying playing around with making my own.
Be great to catchup we don't get many paipo surfers round here.

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Re: Design evolution - part 1

Unread post by CHRISPI » Fri Mar 24, 2017 1:04 pm

Hi Bob
I seam s as if most people on this forum know how fins or foils work and how they must taper to work properly. But don’t put that same science in to the main lifting body? And no disrespect meant it just seems so clear in my head?!? I think we should open a post on design philosophy and how we make these decisions when shaping boards

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Re: Design evolution - part 1

Unread post by bgreen » Sun Mar 26, 2017 7:41 am

Hello Chrispi,

I'd be interested to see a photo or drawing of what you mean by tapered properly.

Hello Lewis,

I'll see what I can do. I try to avoid the real busy days. I'll be in spot X from Thursday to Thursday.

Bob

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Re: Design evolution - part 1

Unread post by CHRISPI » Mon Mar 27, 2017 1:45 pm

Hi Bob
Like I see it as clear as day in my head?? The last 1/3 of the rail must flow water like a fin. You can take any fin example you want from nature or engineering but they all have knife shaped release points, most square shaped prone boards have round, oval almost squarish release points wanting to cause cavitation and slow it down, I think that’s why the ply wood paipos have that fast darting path, because they are so thin but if slightly off pitch they lose lift quickly, that’s my theory??
Last edited by CHRISPI on Mon Mar 27, 2017 2:00 pm, edited 1 time in total.

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Re: Design evolution - part 1

Unread post by CHRISPI » Mon Mar 27, 2017 1:59 pm

I get most of my best perspectives from under water shots of board tracks there are lots you have to surf the net a lot find them

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Re: Design evolution - part 1

Unread post by nomastomas » Mon Mar 27, 2017 10:55 pm

Unlike a fin in water or a wing in the air or water, "flow" on a prone board is confined to only one surface, and that is the surface in the water, i.e. the bottom or hull. Yes, for proper release (of water) there needs to be an edge at the point that the water leaves the bottom. Water is actually sticky stuff, and will cling to surfaces until gravity pulls it away or until it encounters an edge. Hold a piece of PVC pipe or any round object under a faucet and notice how the water attaches to, and flows around the pipe until gravity finally pulls it off the bottom. Likewise, hold any object with a hard edge under a faucet and notice how the water falls away as soon as it encounters the edge. There is turbulence at the release point, as the laminar flow along the bottom is disrupted by the edge. (I wouldn't call this cavitation, which involves the vaporization of water due to excessively low pressure such as that produced by the rear-facing surface of a propeller blade at a high rate of spinning.) But this turbulence doesn't impact the speed of the hull, which has already moved past it. So, those bubbles that you see in underwater photos coming of the tail of a surfboard is the turbulence caused by a disruption in the laminar flow along the bottom created by the edge of the tail/rail. Now, if the release point is round, water will wrap around it and this will cause drag. "Squarish" release points are good, rounded release points are bad as far as preventing drag is concerned.
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Re: Design evolution - part 1

Unread post by bgreen » Tue Mar 28, 2017 5:50 am

Chrispi,

I went looking through your posts to see if I can find what you meant by tapered. Your latest description was more about the rail shape than the boards foil, which is what I thought you were talking about.

Here are two photos of yours that I thought may show what you were talking about - thicker up front to a thinner tail.
ChrispiFoil.JPG
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Chrispi.JPG
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Regarding hard rails, the first board of mine # 2 had rails so hard that when the board was washing around my feet on the shore, it superficially cut my foot. The rails have over time become rounder. Finless probably compensates for somewhat more drag as described by Nomastomas. I like the S decks and don't feel any great performance loss compared to the other boards that had a different foil.
Bob

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Re: Design evolution - part 1

Unread post by nomastomas » Tue Mar 28, 2017 10:48 am

Yes! Without fins, you need something to hold the rail into the wave face. Round edges hold better than sharp edges because they don't release water as well. The tucked-edge rail is a brilliant combination of round and hard. It allows water to wrap around (providing hold) but only until it encounters the bottom edge where it is released to (promote speed). I agree with S-shape foil (distribution of foam nose to tail) being ideal for prone boards. Over time I have moved the center of mass on my shapes more toward the mid-point of the board. It allows for a more level take-off position, and keeps the majority of the foam under the mid-section of my body.
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Re: Design evolution - part 1

Unread post by bgreen » Tue Mar 28, 2017 3:18 pm

Nomastomas,

I probably should have posted the full sequence. I've retained the S deck but have gone a lot thinner than Larry's original.The attached are Board #1 from the sequence. A fun board but it wasn't so easy to duckdive hence the move to a sleeker model which was faster.
MM1-foil.jpg
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MM1-foil2.jpg
MM1-foil2.jpg (81.29 KiB) Viewed 2478 times
MM1-foil3.jpg
MM1-foil3.jpg (76.18 KiB) Viewed 2478 times
MM1-deck.jpg
MM1-bottom.jpg
Bob

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Re: Design evolution - part 1

Unread post by bgreen » Tue Mar 28, 2017 3:30 pm

Here is board 3 from the series, I wanted to see if I could go thinner and narrower and retain the speed of # 2. It wasn't as fast as I wanted & harder work. It would be interesting to ride it again and see what I think but it has gone south. Note the hard rails on the tail.

Board 1 dimensions 4' 5 3/4" x 21 3/8" x 2 13/16"
Board 2 dimensions 4' 5 3/4" x 21 3/8" x 1 7/8"
Board 3 dimensions 4' 5 3/4" x 20 0/0 " x 1 5/8"
Board 4 dimensions 4' 5 3/4" x 21 3/8" x 1 7/8"
Board 5 dimensions 4' 5 3/4" x 21 0/0" x 1 7/8"
Board 6 dimensions 4' 5 3/4" x 21 0/0" x 1 7/8"


Board 3
MM3-foil.jpg
MM3-foil2.jpg
MM3-foil2.jpg (75.36 KiB) Viewed 2478 times
MM3-deck.jpg
MM3-deck2.jpg

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Re: Design evolution - part 1

Unread post by nomastomas » Tue Mar 28, 2017 3:54 pm

Yes, at a certain point, depending upon rider mass, low volume interferes with the shapes ability to plane effectively. I found the same thing as you when I dropped vol from 22L to 21L.
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Re: Design evolution - part 1

Unread post by Papa Paepo o » Wed Mar 29, 2017 1:14 am

Very nice boards with some groovy channels and tail drops. Can these boards do spinners?

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Re: Design evolution - part 1

Unread post by Papa Paepo o » Wed Mar 29, 2017 1:17 am

nomastomas wrote:Yes, at a certain point, depending upon rider mass, low volume interferes with the shapes ability to plane effectively. I found the same thing as you when I dropped vol from 22L to 21L.
Aloha, do you have video of you charging big suf ? What kind of do you ride? Is skeg or skegless?

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