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Building a finless spoon paipo board

 
This forum is locked: you cannot post, reply to, or edit topics.   This topic is locked: you cannot edit posts or make replies.    rodndtube.com's (OLD) MyPaipoBoards Forums. Reading but no posting on the OLD forums. Forum Index -> Paipo Board Design & Building
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PaipoJim
Director of CTU


Joined: 31 May 2004
Posts:
Location: Oregon

PostPosted: Fri Jul 14, 2006 3:00 am    Post subject: Building a finless spoon paipo board Reply with quote

I thought it might be of some general interest if I documented my current project as it goes along in fits and starts. I've been riding Paul Lindbergh's traditional Hawaii Paipo Designs boards for several years now:



I want to experiment with pushing the finless spoon concept in a couple of different directions and see how that works out. (Maybe not so well, but it will be fun trying and I'm sure I'll learn some stuff in the process.)

Spooned skegless paipos go back a long way. Here's one in among a pod of Oregon lamaroos circa 1915!



I've seen references to spoon boards in Hawaii as far back as the 1930's. This next is an early Hawaii'n example of a wide-tail spoon made out of laminated timber planks. Reminds me of a kicktail skateboard I made from a glued, planed, and sanded 8" wide x 1/2" thick (nominal) piece of Oak back in the day.



The classic "guitar pic" shape started taking form in Hawaii in the mid to late fifties. These examples are from Greg Noll (who went to high school on the West-side of Oahu)



...and from Val Valentine who lived at Sunset Beach.



According to Jamie Farfor, Val started making deeply spooned boards commercially outside his house in an earthen mold lined with cement mortar. He put in glued strips of wood veneer and then pressed everything together with sand bags placed on top. That Paipo Nui logo is very cool.



Jamie took one of Val's boards home to Australia in 1960 and built plywood boards, with a more shallow spoon than Val's, in a concrete mold using a 20-ton hydraulic-to-airbag press powered off the local water mains!



Val later built his paipos out of foam and glass as does Paul today.



More recent advances include this extremely innovative, modular flexible fiberglass laminate design by Dale Solomonson:



http://rodndtube.com/paipo/forum/viewtopic.php?t=22
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PaipoJim
Director of CTU


Joined: 31 May 2004
Posts:
Location: Oregon

PostPosted: Fri Jul 14, 2006 3:46 am    Post subject: Building a finless spoon paipo board. (Part 2) Reply with quote

Compared to my favorite HPD I'd would like a new board to have even more snap out of bottom turns and to weigh less.

More planing area would be good in smaller, mushier waves. A more defined rear corner might make for better tracking in turns on larger waves. Kale Keahi's board on the right seems like a good direction to head towards for that.



I layed out quite a few designs on my computer using the Draw module in the open source program NeoOffice. I was initially thinking wider than an HPD XL too, but after a recent surf I think that would be overkill, not to mention unwieldy. I ended up mapping out a board with a length of 46" inches and based on elementary geometric shapes that I hope will facilitate straightforward construction. I am not, alas, a master shaper of 40+ years experience like John Mel so I need to keep it relatively simple.



This design is a bit wider in the nose than my current boards and will have a more acute angle for the chine in the fore and aft direction so with the additional planing area it may be harder to turn. I want to try to include some flex in the rail and tail in order to overcome this.

I plan to vacuum bag a fiberglass and carbon skin over a very thin 1/4" foam core so I am going to shape a male plug on which to form the board to it's proper shape. To assist in this I will make templates out of 1/8" ply to act as guides when carving the plug out of a block of modeling foam.

Here are the raw materials for this tooling, including a 3 inch thick 24"x96" piece of 6 lb per cubic foot Last-a-Foam (the single most expensive piece in the entire build.) This could be a costly waste of material if I get the shape wrong but any dimensional design changes needed for a re-shape on the next go round would most likely involve the removal of foam, so I'm pretty certain I will be able to re-use this plug for a "Mark II" version.


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PaipoJim
Director of CTU


Joined: 31 May 2004
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Location: Oregon

PostPosted: Fri Jul 14, 2006 4:58 am    Post subject: Building a finless spoon paipo board. (Part 3) Reply with quote

Time to draw the computer design on the plywood. If I had a big enough printer I could print out the templates and then cut and trace them onto the plywood but I don't and would spend at least as much time taping them together from 8-1/2x11 sheets as it will take me to transfer the co-ordinates to the plywood.



The board will be around 30x46 so I needed to saw the Last-a-Foam in half and re-glue it in order to have enough room for the shape. I was going to use 3M High Strength 90 spray adhesive but was concerned about the sturdiness of the bond so instead I used Gorilla Glue. Polyurethane glue for polyurethane foam.

I spritzed the bonding surfaces with water prior to the application of the glue by spreader. The porous nature of the foam required me to use about 50% more glue than recommended on the label in order to fully cover the surface. Here it is drying (and bubbling out of the seam.) Note the lamentable absence of pipe clamps in this jig which was somewhat offset by judicious placement of a vacuum pump and 1000 rounds of .45 ACP.



I'm planning to use carbon stringers in the board so while the glue was drying I decided to build a 1/6 scale model out of printer paper, super glue, and .030" carbon rods.



The paper is way less stiff in relation to the rods than the carbon covered foam laminate will be in the full size version, but bending the scale prototype did produce some useful results as to the behavior of the stringers in two different configurations.

With a relatively short top outside rail stringer and a straight bottom one along the chine, flexing the model on the left side in a manner similar to actual waveriding revealed that the board wanted to fold down the middle of the left side parallel to the bottom stringers.

On the right hand side, the top stringer runs much further back and the end of the chine stringer is pre-loaded by following the outside bend of the rail. When flexed, the tail of the board tends to bend the bottom in a more perpendicular direction relative to the centerline. More of the flex is transferred to the nose of the board via the top rail. The tail also exhibited a sharper and more pronounced "snap" back into position when released than it does on the left side.
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PaipoJim
Director of CTU


Joined: 31 May 2004
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Location: Oregon

PostPosted: Sun Jul 16, 2006 12:09 pm    Post subject: Building a finless spoon paipo board. (Part 4) Reply with quote

A T-square would have eased the task of transferring the co-ordinates to the 1/8" plywood. The ply is fairly fragile and when I cut out the templates with a Roto-Zip saw I incurred some delaminations which will require filling/repair. I dressed it up with my trusty block plane, but in lieu of a table saw and router setup, I would have been better off cutting the boards by hand. I'm going to use a different material for my nose rocker/spoon template(s).



Glueing up the foam went well. The underside which was against a vinyl sheet came out nice and flat. The glue dissolved the foam a bit at some spots along the edge of the seam but I'll be filling the surface of the whole plug anyway when I'm done shaping it.


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PaipoJim
Director of CTU


Joined: 31 May 2004
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Location: Oregon

PostPosted: Wed Jul 19, 2006 11:11 pm    Post subject: Building a finless spoon paipo board. (Part 5) Reply with quote

I printed out the templates for the spoon/nose rocker sections on paper then cut them out with scissors and traced the outlines onto 3/64" rotary knife cutting board plastic that I'm going to use as backing later on when slicing the carbon fiber cloth. The plastic was in turn cut with scissors and reinforced with 1/4" spruce stringer strips attached with contact cement:



The larger of the 1/8" plywood templates was used along with a Sharpie to draw the overall outline of the plug on both sides of the glued Last-a-Foam:



I then made a rough cut of the plug by hand with the compass saw. This took about 30 minutes as I was continually switching from one side to the other on the big block of foam.



There is enough foam left over to make a form for a 48" skateboard.
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Solo
Dolphin Glider


Joined: 10 Jan 2004
Posts: 67
Location: Newport, Oregon

PostPosted: Sun Jul 23, 2006 5:56 pm    Post subject: Reply with quote

James,

Many thanks for sharing an exciting project and all the photos, old and new! I'm really looking forward to more!

You wrote... "Compared to my favorite HPD I'd would like a new board to have even more snap out of bottom turns and to weigh less. More planing area would be good in smaller, mushier waves. A more defined rear corner might make for better tracking in turns on larger waves."

More planing area can definitely be an advantage in smaller, mushier
waves... as is increased bouyancy, especially when duck-diving is not an issue. But to widen a finless pronecraft's operating range, it's often wiser to increase buoyancy for smaller waves, rather than add too much planing area for larger waves. Adding buoyancy rather than planing area will also help to keep weight to the minimum. One way to introduce variable bouyancy is by means of loosely attached, interchangeable deck pads, using soft and flexible closed cell foam... also effective in absorbing some of the shock from bumpy waves.

Sharply defined rear corners increase the rail line, as well as enhance long-line tracking in larger, more powerful waves. Narrow rear corners can be loosened up for more maneuverability in smaller waves by making them flexible, bending out of the way through hard turns.

Developing more snap out of bottom turns can be improved by making a prone design that is no larger/thicker than necessary, with fast bottom/ rail shape and surface texture, and not dragging any part of body, swim fins or leash. Slight concaves and reverse rocker can also increase drive and projection.

Beyond glide, inertia, and the centrifical force generated through turns, prone surfing has limitations... primarily because the rider is dead weight on the deck. There is no significant weighting and unweighting as is common with standing surfers and their equipment.

Thus, resilient flexiblity in prone craft is inhibited, and cannot be fully exploited... unless a flexible bottom planing area is allowed to respond independently of a firm deck panel (red lines) supporting the rider's weight. This is the same basic "false deck" idea employed by George Greenough on his flexible carbon sailboards (standing use) for over 20 years.

Toward that goal, the following quick sketch (it's close to scale) depicts an idea I've only partially explored...

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