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Flex paipo
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Solo
Dolphin Glider


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

PostPosted: Fri Jan 16, 2004 1:52 am    Post subject: Flex paipo Reply with quote

Here`s a link to one of my old finless/flexible paipos. Approximately 42" long w/a 32" wide tail, about 2" deep spoon. It came out of a female mold, and is composed of fiberglass, epoxy and hand-poured, 10-12 lb. density polyurethane foam. As can be seen, it`s a triangular spoon shape with a removeable, closed cell flex foam "false deck", otherwise it barely floats itself. This paipo has some torque, and bends the most in rear corners, last 12" or so. Bottom is flat, w/no rocker, and rolled up thin, rounded rails. There`s also a thin carbon rubber strip that extends across the top of the rear edge for an extra margin of safety. This paipo has had repeated grinding and repairs.

It`s fairly heavy (about 9 pounds), worked well in smooth, powerful, hollow 4`to 10'+ waves. I experimented with a number of different paipo designs, nearly all having false decks and flextails.

http://digitalstar.com/dalesolomonson/OriginalImages/289296ORIG.JPG


Last edited by Solo on Mon Jan 19, 2004 3:27 pm; edited 1 time in total
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doc
Dolphin Glider


Joined: 09 Jan 2004
Posts: 171
Location: the Frozen Northeast aka New England

PostPosted: Sat Jan 17, 2004 12:31 am    Post subject: Reply with quote

Agh- I love it! It's downright lovely and if it ain't capable of mach 43 I'd be surprised. 32" seems wide but with no fins and with mucho flex it becomes necessary, no? And I want one!

Couple questions, naturally. (just a couple....righhht )

That started with ? layers of ? oz cloth? Vaccum bagged or no?

Hand poured foam 10-12 lb /ft^3 - like a two-part floatation foam? , into female molded epoxy/glass V-shaped unit that was then laminated to the body of the critter? Or a different method such as a temporary mold clamped to the body?

The foam pad, about 1" before bevelling? With those posts ( rubber? ) as more locating pins with a tight fit than locking in with a cross-pin? how about a really rugged velcro glued on as an alternative attachment method?
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Solo
Dolphin Glider


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

PostPosted: Sat Jan 17, 2004 5:44 am    Post subject: Reply with quote

doc,

In answer to your questions:

"That started with? layers of ? oz cloth? Vaccum bagged or no?"

A cheap male master/plug of styrofoam sealed with 2\" wide, best 3M masking tape, bondo and glass/resin, then female mold. Fiberglass was common "E" cloth, 4 oz. for higher glass to resin ratio, much better flexibility. I began with about 12 to 15 layers laminated into mold. For flexible structures, it`s better to have more initial laminations than needed, and then sand them down. The bond between original layers is superior to adding them later. All hand-laminated, low-tech process. Black coloring agent was powdered tempera.

"Hand poured foam 10-12 lb cu./ft- like a two-part floatation foam?"

Yes. High density PU to help prevent rail collapse from flex fatigue/point loading stress. I used to install end-grain balsa sections with microspheres and resin, but very labor-intensive. I bought the hand-pour PU from Hastings Plastics in Santa Monica, CA., but widely available these days. Very consistent hard density foam... I made a cardboard/masking tape dam to limit the area to which it expanded/bonded after critical pour. Fast cure, a joy to shape, especially when compared to end grain balsa.

"into female molded epoxy/glass V-shaped unit that was then laminated to the body of the critter? Or a different method such as a temporary mold clamped to the body?"

I always tried to schedule one unit assembly. After initial lamination, the dam was positioned, polyurethane foam mixed and poured. Immediately after PU foam had cured, I shaped the core/chine contours. About 3/4" thick PU core toward front, tapering to nothing near rear 12". I then glassed over the shaped chines/rails, about 12 to 15 layers of 4 oz. fiberglass/epoxy. Grinding/tuning to proper flex is a tedious, but totally worthwhile, process. Carbon graphite and epoxy would be a logical next step.

"The foam pad, about 1\" before bevelling?"

The finished false deck foam (similar to PE camping pad) thickness was closer to 1 1/2"- 1 3/4". Thicker or thinner depending on needs. Quite flexible. It was a laminate of sanded, denser 1/2\" (blue) polyethylene, 1" thick PE and lighter 1/4" (white) Volara. If I were to build this project now, I`d probably not use PE foam, and make the false deck inflatable for variable buoyancy. There`s an incredible advantage in having the freedom of variable buoyancy.

"With those posts ( rubber? ) as more locating pins with a tight fit than locking in with a cross-pin?"

The two false deck attachments are small, contoured foam pillars, laminated with 4 oz. tooling cloth and epoxy. They`re not essential, I just wanted to maintain a centered deck pad. The pad was tied to the underside pillars with 1/8" dia. parachute cord and epoxy fasteners, sort of like wide epoxy washers... real simple and quick. Other tie-downs would also work.

The basic idea was to allow the deck pad to be removeable, and flex freely with the tail, to reduce inhibition of action. Minimal, yet strong attachment. As I said before, now I`d go with an inflatable deck, because top and bottom surfaces move independently, ala surf mat. More sensitivity and resonance. Plus, there are other related ideas, having much more potential merit, that I have'nt had time to build yet.

"how about a really rugged velcro glued on as an alternative attachment method?"

Yes... I`ve used a lot of Velcro, and it worked fine... at least until the waves got larger and more powerful. Then the deck pad was often torn off. For our waves, I`ve found more solid mechanical connections were best overall.

I wanted the flex to be gradual, whipping like a fine fishing rod, increasing toward tail. The most bend was focused in two rear corners.

That`s all for tonight........ zzzzzzzzzzzzz
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doc
Dolphin Glider


Joined: 09 Jan 2004
Posts: 171
Location: the Frozen Northeast aka New England

PostPosted: Sat Jan 17, 2004 3:01 pm    Post subject: Reply with quote

Y'know, I was bouncing the molding process around in my head and came up with one of my nickel and dime brainstorms. Let me run it by you and see what you think.

Take a rudimentary shaped/hacked chunk of styrofoam or just about anything this side of bread dough, and then....wax the mutha. That is, pour on some paraffin wax ( not to be confused with the UK/Commonwealth version of kerosene ) . Build it up with several layers if need be, scoring lower layers with a coarse rasp or toothed scraper. Finish quick and easy with woodworking tools and put a shiny surface on it with a heat gun or lamp.

You might have to have slow batches of resin when making the female mold from it, so that the heat from the reaction didn't soften and distort the wax, but that'd be it. Want to change the shape? Add or subtract wax, shape, heat gun and you're ready to go. Should turn out a female mold that'd need minimal finishing. Dunno how well PVA or one of the traditional release agents would mix with the wax, but it might be no problem.

Also - inflatable deck pad, sounds like an idea. You're the expert on that technology, so would it be possible to make one with a good sized fabric edge ( maybe generic-sized inflatable pad section) such that you could cut it to shape and then stitch a bunch of velcro or maybe even an industrial-grade zipper to it and epoxy the other half of the zipper to the board?

Just playing with the isdeas some, y'know?
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Solo
Dolphin Glider


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

PostPosted: Sat Jan 17, 2004 3:55 pm    Post subject: Reply with quote

doc,

I found that male master/plugs were cheapest/easiest for experimenting with bottom surfaces. I`d often use common (cheap and readily available) 2" x 8'-0" EPS or styrofoam planks, and stack them to build core thickness and/or rocker, used water-based glue for the lamination. If in a hurry, commercial grade double-sided tape worked o.k., too.

Once the core was cured, I`d do most of the shaping with a grinder. After that, I`d usually seal the master with resin-resistant masking tape. For a mold release, just prior to laminating the female shell, I`d apply a quick car wax to the masking tape, and finally wipe on a light film of Vaseline. No need for other mold release agents. As a release barrier, I`ve also used heated and stretched polyethylene sheeting, polyolefin shrink wrap, and even Saran wrap over male plugs... but only if the design is simple enough.

After lamination, the cured female shell pops off, w/ the male master usually fit for re-use after minimum cleaning/detailing. Once a specific design has been tested and refined, then it makes more sense to build a heavy-duty female mold from a highly polished male plug. Obviously involving much more labor.

You`re right... a male plug made entirely of wax will also work. Common paraffin is what I`ve preferred as it`s cheap and fairly hard at room temp. The downsides are its vulnerability to damage and poor heat resistance. I`ve mostly used it for smaller projects.

I`ve attached inflatable decks different ways: Velcro strips, a net pocket or laced grommets tied to fiberglass shell, and via contact adhesive. Whichever method, it`s critical to prevent water from accumulating and being trapped/sucked around on deck, under and around deck pad. Also the deck pad must be easily removeable, not getting in the way of re-sanding/glassing of the board, or inhibiting the flex action.

I even built a few spoon kneeboards with inflatable decks... I`ve learned over and over that variable (in-the-water) buoyancy is an enormous, functional advantage, no matter what the surfcraft.
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doc
Dolphin Glider


Joined: 09 Jan 2004
Posts: 171
Location: the Frozen Northeast aka New England

PostPosted: Sat Jan 17, 2004 11:25 pm    Post subject: Reply with quote

Ok- I was thinking of a styrofoam or generic foam male plug with the fine tuning done with wax, as it'd be easier to work with than foam and tape, say, or foam and glass - call it a roughly 1/8" to 1/4" wax layer. You could do something very quick-and-dirty with the foam, even chines stuck together with bamboo skewers or what have you, as all it is is something to hold the wax.

Cheap, quick, easy - and easily tinkered with, though weight'd be an issue. May have to play with that some, much easier and faster than some of the other methods I had played with. And maybe it'd allow a very nice surface on the female mold with very little work beyond just taking it off and a light polish.

More I think about it, the more I like inflatable pads. So many of our paipo/kneeboard colleagues have very floaty boards and frankly, I've disliked the very floaty boards I've had - What do you like for fabrics and adhesives?
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Solo
Dolphin Glider


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

PostPosted: Mon Jan 19, 2004 2:41 am    Post subject: Reply with quote

doc,

You can have the both lower (neutral if you wish) and higher buoyancies. The advantages are significant.

>"What do you like for fabrics and adhesives?"

I have'nt used adhesives for constructing inflatables in over 22 years. Everything I build is thermal welded, w/ mil-spec quality materials. For your purposes I`d recommend non-permeable, 200 or 400 denier, polyurethane-coated nylon.

First... closer to your area, I`d contact (http://www.uretek.com/) and
(www.highlandindustries.com/). I`ve used a lot of their products, and they`re outstanding. I`d request prototype yardage on which to experiment. In the past, they`ve both been very generous.

If you wish to try a more traditional process, I`ve used a lot of smooth- finish Naugahyde w/cloth backing (www.naugahyde.com/) bonded with "VLP" PVC resin (http://www.tapplastics.com/shop/product.php?pid=288). There are different types of Naugahyde, some breathable, so make sure to request non-permeable. It`s very popular as an upholstery covering.

There are many non-permeable, synthetic and organic materials available in roll stock, and most have compatible bonding agents. Such materials are commonly available through upholstery, tarp... or sailcloth suppliers, such as Bainbridge (http://www.bainbridgeint.com/flash.asp).

Hope this helps!
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doc
Dolphin Glider


Joined: 09 Jan 2004
Posts: 171
Location: the Frozen Northeast aka New England

PostPosted: Mon Jan 19, 2004 8:13 am    Post subject: Reply with quote

Ah, thanks. The times when I've very much wanted neutral buoyancy.... such as when trying to push under an oncoming set!

Funny you should mention Naugahyde, as I had just stumbled across a yard or two in the cellar while moving things around to locate a couple of industrial sewing machines. Left over ftom another project some time ago, but the stuff isn't cracking or stiff.

Still, looked at the links and I'm interested in working with some other materials, plus I have been looking for an excuse to start playing with something like http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=41592 - do you use something similar? I got to tinker with one while a guy was putting down a seamless restaurant floor for a buddy of mine. I suspect a small airbrush-type compressor would be perfect with this - another item that just happens to be kicking around the cellar...

Again, thanks - this is kinda fun, as I'm sure you well know.
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Solo
Dolphin Glider


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

PostPosted: Mon Jan 19, 2004 12:11 pm    Post subject: Reply with quote

doc,

No, I`ve never used anything like that. Nice... a tool which would be easy to have around the shop!

How fortunate! If your Naugahyde is non-permeable, it`ll likely be useful no matter how old. Most upholstery shops I`ve visited were filled with a wide variety of odd-size remnants, often sold for pennies on the dollar. I have some around the loft that I `m sure is 25 years old and still in perfect condition... of course, it`s been kept loosely rolled and hidden from U.V.

>"Again, thanks - this is kinda fun, as I'm sure you well know."

Yes. But as engrossing as the process may be, successful end use is the real joy. If sufficiently devoted, nearly all of a person`s time, energy and finances can be focused on designing, building and in-the-water evaluation.
The process of discovery can lead in many unexpected directions!

With no apparent return on labor and expense, observers generally consider such efforts as having little, to no value, nothing more than foolish obsession. It`s a long journey where few others of like mind are encountered.

Curiousity can extract a great deal of sacrifice. Prior to getting married and having a family, my nicknames went from "Solo", to "Doc" and finally to "Monk"... thankfully, that one never stuck! Ha ha!
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doc
Dolphin Glider


Joined: 09 Jan 2004
Posts: 171
Location: the Frozen Northeast aka New England

PostPosted: Mon Jan 19, 2004 1:31 pm    Post subject: Reply with quote

Yeah, there's variants on those tools with a small compressor in a box that they come with and I have seen some that actually had a small blower built into the handle. I guess ( as I haven't snagged one yet) the heating element is strady state and you mess with the heat of the air stream by adjusting the airflow. The Harbor Freight illustration doesn't really show the wee channel/guide along the top that lets you feed in a rod so that what you have is analogous to a MIG setup, so you get a real weld, not just hot glue.

For just sticking a couple of things together - might be useful to have a couple strips of wood available, to act as a non-thermally-conductive mask, if that makes sense.

You've pretty well described how my bit of Naugahyde was stored, albeit cellar versus loft. Dunno about upholsterers, but those bits of cloth definitely get in the way in a sail loft.

My tinkering problem - lets just say that it's not all watercraft related. When you look around a room and see a MIG welder, an old Singer 107 series industrial zig-zag sail sewing machine, a Milwaukee half-sheet sander, two shop vacs, an Evinrude Aquanaut surface supply diving rig, a small rolling tool cabinet, a broad hatchet for hewing timber, a watertight camera box full of photo toys and a spray gun, that might give you the idea. Especially as that's only a few of the things in the living room. Lots more toys in the workshops......
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Solo
Dolphin Glider


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

PostPosted: Wed Jan 21, 2004 1:36 am    Post subject: Reply with quote

In the living room????
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doc
Dolphin Glider


Joined: 09 Jan 2004
Posts: 171
Location: the Frozen Northeast aka New England

PostPosted: Wed Jan 21, 2004 9:38 am    Post subject: Reply with quote

Solo wrote:
In the living room????


Yeah, it's one of those living room-dining room deals which also does duty as a library with three walls that are mostly bookshelves.

The canvas, plastic and upholstery workshop is downstairs, wood and metalworking out in what was the garage.
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Solo
Dolphin Glider


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

PostPosted: Wed Jan 21, 2004 4:39 pm    Post subject: Reply with quote

I love that!! You`re a fortunate man!
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doc
Dolphin Glider


Joined: 09 Jan 2004
Posts: 171
Location: the Frozen Northeast aka New England

PostPosted: Wed Jan 21, 2004 8:44 pm    Post subject: Reply with quote

Solo wrote:
I love that!! You`re a fortunate man!


Well, I just got talked into building a shed this spring for the amorphous mass of garden tools and bicycles and boat stuff that's been taking over the front yard and parts of the garage where I want to put the lathe and vertical mill next year.

Though a parade of exes could testify that they object to my ideas of home decor. While learning to do canvas work I went and covered all the living room furniture with boat canvas, which is not only cheap but the dog can't dig through it. And it goes well with the wrenches.........
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Birdie



Joined: 20 Jan 2004
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Location: so cal

PostPosted: Wed Jan 21, 2004 11:11 pm    Post subject: Reply with quote

Thanks you guys, you made my week!

Birdie
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