Wood vs. Foam with regards to flexspoon construction

General Discussion
1

i’ve been considering trying to make a fish kneeboard in the style of a velo spoon, and was wondering if it would be possible to use some sort of wood instead of pour-foam for the rails. the idea being that i could increase strength and bouyancy without adding significant weight, and possibly get a better flex and return from wood than foam.

After watching Mark take the drop on a 10ft set at the Lane and snap his carbon spoon, i’m inclined to believe that there’s a better way for us to make spoons stronger, while maintaining the amazing flex associated with a tail and belly made of pure glass.

anyone have any experiences/ideas/etc on the subject? especially you compsand/HWS guys who have lots of experience building with timber, any advice would be much appreciated.

2

hey dudley

i have thought alot about spoons

would be interested to advise on a compsand version

i honestly cant see point of a poured foam rail other then for authenticity

and to emulate the feel of an original spoon

i was thinking along the lines of a carved eps and epoxy one

with a composite flex panel with a foam or balsa core

so you would do up the templates in aps or illustrator

hotwire cut one

glass the bottom and sides with handlayup

hollow out the deck

vac on the flex panel core(maybe corecell or airex r.63)

then glass over it by hand

i was thinking to use carbon fibre twill over the rails

to stiffen the rail w light weigh

even perimeter stringers could work sweet

3

hey sills thanks for the ideas

definitely seems like it could/should work, at least it’s certainly possible.

i want to read and digest the pdf articles here first, then we can come back to this topic.

I won’t be starting this project until the summer rolls around most likely, so plenty of time to get the design and construction sorted

Jamie

4

Strange you bring this up - I’ve been thinking along the same lines, but afraid of getting told to “build it traditional - don’t reinvent the wheel”

I think that the oval shape of glassed rails do not lend themselves to the kinds of bending stresses that are applied longitudinally in a spoon rail. Seem that wood might provide better break resistance because it can yield to the compressive forces. (Ever been to the top of a 30m (100ft tall tree)? Man those things move a whole lot considering the relatively skinny trunk.)

I’m interested in your ideas and progress, especially since I am tending towards an edge board, rather than a traditional spoon.

Red

5

Could wooden parabolic stringers be placed in such a fashion as to not only strengthen the rails but also serve as an edge along the bottom?

With spoons carved from standard blanks, the stringer gets removed almost entirely.

I’m pretty sure Ken at Segway could whip up the density, position the stringers, make the blank as thick as you need and rocker it to your specs as well.

http://www.segwaycomposites.com/ParabolicSystem.html

Just an idea.

6

just a great idea john.

i’d been thinking about parabolic stringers, and the method Bert Berger uses for his shortboards, and how it could be done to build a better spoon.

i hadn’t thought about it in the context of an edge board, but it seems like it would work.

i’ll contact the guys at segway, see what they have to say

7

there was a balsa railed spoon in a SB surfshop(thought to have been made by GG then verified to be so).how it worked i don’t know, but it seems to me that were wood and glass meet at certain stress points, it would crack or fail easier than if foam due to different flex characteristics of wood and foam…

8

There were some built by Paul Gross and George in the mid 70s that had vertical grain balsa wood , very strong stuff, but they bailed on this when they went to carbon fiber. I have a flextail with some of that balsa in it and its still good 30yrs later.

9

Hi Jamie,

Yes, it is possible to use wood in the rails of spoons. The lightest and highest compression resistance is end grain balsa. Bear in mind that quality and weight of balsa varies quite a bit, plus it’s not inexpensive. I used end grain balsa in rails of my spoons 25+ years ago, cut into short sections, fit one at a time into the rails and bonded in place with resin and microspheres. This process is effective, but very labor intensive.

Later on I began using 2 part structural polyurethane pour

foam, about 10 to 12 lb. density. Using this foam was much easier and quicker to work with, resulting in a very light yet dense, perfectly conforming bond with consistent density and adequate compression resistance. I never worked with anything else that was superior.

There are a number of factors involved in creating a strong, light, properly flexible spoon. Laminate, resin and materials, shape of flexible structure, quality of construction, post-construction tuning, etc. For example, the core shape and thickness of a spoon rail has direct influence on how much laminate/resin will be needed, e.g. accentuated compound curves increase stiffness without need of extra laminate/resin. Understanding and manipulating this will translate to a lighter, stronger, yet properly flexible structure.

In addition to knowledge and craftsmanship, frequent access to the necessary (and uncrowded) waves, excellent physical conditioning and surfing skills are all important to achieving success.

Spoons can be made out of solid glass, but they’re extremely heavy. Lighter spoons made with lower density surfboard blank foam (softer polyurethane, EPS, etc.) fatigue and develop point loading “hinges”, and eventually collapse (unless carefully repaired) from compression failure.

Flexible spoons are complex to actually explore. Everyone’s wants and needs in surfcraft are different. Those who choose to seriously experiment with spoons (or “shells” as they were once called in Oregon) face a long term commitment. Along with a great deal of pleasure and many new experiences, it’s realistic to anticipate much expense, labor, and frustration.

“Nothing ventured, nothing gained”

10

Hi Dale and Jamie -

Manowar’s broken spoon at Santa Cruz even with a carbon fiber deck is a case in point.

I completely agree that end grain balsa and pour foam have good compressive specs but most of the problems I’ve seen with broken spoons seemed to indicate that stress issues were more of a longitudinal(?) nature. By that I mean the rails weren’t compressed so much as snapped across the length. The end grain balsa sheet I’ve seen looks like it could be broken across fairly easily with your hands even though you could stand on it without crushing.

I realize that in cases of snappage, there is a “compression” and “tension” side to the skins of the overall sandwich but I’m talking more about increasing the breaking resistance of the core.

I’m not an engineer by any means and I don’t have any meaningful experience riding or building spoons so please bear with me. I’m just wondering if something like strategically placed stringers (lengthwise) along/inside the rails wouldn’t provide greater breaking resistance? Full thickness parabolic wood stringers, fishing rod blanks, or just strips of wood laid up in the deck glass might be tried as strengthening material. Maybe inside the pour foam? Dale, I seem to remember you mentioning fishing rod blanks once but I’m not sure what the application was.

In any case, the flex of the core must approximate the flex of the overall sandwich, including the skins, or buckling on the compression side of the skin and catastrophic failure will result. Obviously in the case of a spoon where flex is the ultimate goal, there is a fine line between adequate breakage resistance and flexibility.

I know I’ve seen a lot of fractured spoon rails over the years.

11

hey beardman just some thoughts (a lot could be wrong and are just my opinions/plans/you cant stop me!)

pour foam too heavy, wood too heavy

not interested in spoons over 6.5 lbs

trying new lam schedule

shaped it already, just an old 2.5 lb eps, and left the blank raw thickness on deck, but 4 inches in from each rail basically finished the typical spoon deck rail foil, but rippin off dvs style full tubular rails with edge more drastic than black beauty style but less than greeno psychoticness, full velo has too narrow an operating range for the 438th time

butcher paper tape off both deck and bottom as if doing a cutlap, leaving the foam exposed for the apex (thickest part) of the deck rail, wrapping around to about about 3 inches in on the bottom

glass 3 layers of 4 oz carbon around each rail (7/8 length of board, going all the way out tail) , trim as if double cutlap, glass 2 full layers with laps 4 oz s-glass bottom.

grind deck.

top lam schedule: 2 layers 4 oz s-glass just where pure knee section will be, overlapping the inner part of already done rail laps a half inch or something

maybe one 3/4 length (all the way out the tail) 4 oz s-glass

maybe some roving to blend the foam to pure lam

for sure 2 full layers with laps 4 oz carbon on deck to encapsulate and blendify it all

hopefully 6 pounds with rigid flex rails and super twist knee lam part,

the difficult part is flowing the strength to minimize stress risers

edit - more possibly wrong ramblings, but it will be fun to break it in a turn

also john the perimeter stringers are great ideas dont need much maybe just like 3/32" thick balsa long grain following the horseshoe perimeter an inch in from the outside each foam rail

i once horrifically/possibly maniacally embedded 1/8 inch balsa stringers in the rear 2/3s of 8 lb pour foam, center of rail (thickest part) and it broke up front of it, board was 6.5 lbs and too stiff in the rail portions that contained the embedded stringers

the labor required would be difficult to muster the motivation to do it right tho, and they must go nose to tail to keep forces flowing, as we all know abrupt endage (or changeage) of carbon or stringas is gonna be the weakness

good luck beardman and remember the only thing that can actually quantify and explain the complexity of spoons and mats is the intro to norma jeans face:face!, or possibly the song nirvana by tom waits or ‘floater’ by every time i die, good luck

12

If I remember correctly, George Greenough said that none of his latter carbon/epoxy edge spoons ever broke. So all the compression fatigue problems associated with his earlier spoon kneeboards were finally eliminated.

His edge boards were made with special high temp cured epoxy, vacuum bagged laminate, high density pour PU foam rail cores. The early spoons were built with hand-laminated polyester resin and fiberglass, low density PU foam rail cores.

13

Hi run… the finished weight of high density/compression PU pour foam in rail cores is only about 10 oz. or less.

Greenough eventually resolved all his former spoons’ fatigue problems, and significantly reduced weight, e.g. improved strength to weight ratio through special blend of epoxy resin, carbon laminate, high density PU rail core… followed by vacuum bagging, high temp cure, post-construction tuning.