best way to prevent breakage

General Discussion
1

So i was surfing fun little beach break yesterday on my buddies trifin performance longboard, super fun. Get in fast before it shelved out on the inside, little closeout barrels all day long. Pretty much the funnest kind of surf sometimes. But later in the day, it started really sucking out on the inside, which i LOVE…but the whole time i was just thinking about not breaking my buddies board. It kind of held me back a bit, which i HATE. Soooooo, my question is…

What would be the best way to set my mind at ease about snapping if i were to shape one for myself?

Triple stringer as opposed to single?

More glass?..Heavier

Hand shaped EPS/epoxy…thicker glassing schedule…heavier, but not as heavy. (i’m leaning towards this)…maybe 6x6x6 top, 6x6 bottom (or more) on some 2 lb eps?

thoughts?

I want to be able to charge thick shore/beach break without worrying if i’m going to break/buckle the board.

Thanks in advance.

2

Best response :

Don’t surf anything you’re going to worry about !

Or,don’t surf at all.

ps. They all break.

3
Quote:

Don’t surf anything you’re going to worry about !

Where’s the fun in that?

Or,don’t surf at all.

Great advice… =/

i know there is no one answer…i mean, is it as simple as beef up my glass a bit and cross my fingers?
4

Best Response :

If you’re going to worry about it …don’t do it !

If you’re going to do it…Don’t worry about it !

Or just pray like heck !

5

Ok fine…i choose this one:

If you’re going to do it…Don’t worry about it !
6

Yup,

It usually works out better that way.

Praying helps.

7

dont use a leash

8

In all sandwich structures, thickness is the ultimate stiffener. Going thicker

on the shape will increase the load bearing capability more than any other single

thing you can do. Multiple or heavier stringers aren’t really going to help much.

Clark always used to give the example of the early '60’s Phil Edwards models that

broke with regularity even though they had multiple t-band glue-ups. The boards

were very, very thin.

In a hand laminated board with a center stringer the I-beam formed by the stringer

and the glass around it carries most of the load. When this flexes far enough that

the deckside glass fails in compression, the glass buckles (usually out from the core),

and once that bond has failed it’s over. So if you can enhance the bond right around

the stringer on the deck, you can increase the load bearing capability.

One way to do this is to “gusset” the I-beam. Clark’s suggested method was to make a

1/2" deep jigsaw cut right along both sides of the stringer, then take 1" glass tape and

stuff half of it down each slot, folding the other half out from the stringer. Laminate normally

from there. This method was actually tested and affected strength much more than

wider stringers or more layers of deck glass. (more layers don’t enhance the bond a bit).

A slightly easier alternative is to just crush the foam alongside the length of the stringer

(using the stringer as an edge guide, the corner of a wood block does a good job) and then

lay in glass rope along each side of the stringer at the beginning of the lamination. Most

glassers need a helper, and some bribery, to do either one of these jobs.

In the water practical testing offers a few tips as well. Equalizing top and bottom lam

schedules seems to help, but our experience here on the east coast would indicate that,

for a given board weight, (hand laminated)EPS/EPX and PU/PE are about equal in break strength. I could

find people who would argue it both ways… Only objective testing would resolve this one,

but it’s very likely that any difference is miniscule.

Jalama is a great place to test!!! I have fond memories…

Mike

9

Hand shaped EPS/epoxy…thicker glassing schedule…heavier, but not as heavy. (i’m leaning towards this)…maybe 6x6x6 top, 6x6 bottom (or more) on some 2 lb eps?

EXACTLY.

10

I have a EPS 8’4" mini-log with that same glass scedule that has had some pretty brutal abuse and it hasn’t suffered any major damage. I did crunch the nose once when the board rammed the sand but it was easily repaired. The weight came out about the same as a standard PU board.

11

…all makes sense to me…

I can add that heavier glassing won’t increase the bond, as you said, but it will help reduce breakage by increasing compression strength on the deck.

12

i don’t know much, but in my most humble of opinions, i’d like to add that one thing that will greatly reduce the likelihood of turning one surfboard into two lamp-tables is to take care of the little things as soon as possible. when a board breaks, it breaks from the rail in toward the center. any time you get a fracture on the rail, take care of it sooner rather than later. i’d be willing to bet that more than 90% of big breaks all started with something pretty minor that was left un-fixed.

and never leash it on in dumpy shorepound. i’ve had some of the best sessions of my life about 15 feet off the beach, but when you lose it nose first, the board needs to be able to go end-over-end. (nose in the sand + you strapped onto the tail)^ wave in between = very broken board. [my apologies to the mathematically-challenged]

13
Quote:

…all makes sense to me…

I can add that heavier glassing won’t increase the bond, as you said, but it will help reduce breakage by increasing compression strength on the deck.

You’re correct, I just didn’t want to over-complicate things. The bond almost always fails BEFORE the glass fails,

so the increase in strength is not that great for an extra layer of glass. Once the bond is gone 10 layers of glass

won’t keep the structure from breaking.

Mike

14

Rail dings create focusing of the load and that’s why boards snap on those spots.

Soulstice is absolutely right about small problems becoming big ones. Any big repair,

rail or otherwise, does this to a board. Even the fins or fin boxes create a focus directly

in front of them, which is a common place for the boards of aerialists to snap.

But conventional center-stringered boards (whether PU or EPX)with undamaged rails,

when loaded to the point of failure, will almost always initiate that failure by the deck

bond failing as I have described. The deck glass then buckles, and the rails and bottom

go very quickly. Once the bond fails you don’t have a sandwich anymore. You can look

at “partially” broken boards to check this (or look in a textbook), a buckle or “crease”

around the deckside stringer will be the first thing you see (if the rail is clean, if there’s

a rail ding refer to above)

Other types of construction HAVE introduced the possibilities of different modes of failure.

It’s getting really interesting…

Mike

15

On pu or eps, bonds are usually way stronger than the foam’s tensile strength.

It looks like the bonds fail but upon closer inspection the foam seperates first.

As noted, the failure modes described herein are primarily a function of laminate stiffness…which is controlled via thickness or resin modulus. Three layers of 6 with good stiff epoxy resin will get most people 95% of the way there, or one can go compsand.

16

So which foam has the higher tensile strength, pu or eps?

And I’m not convinced that a compsand is going to have a higher

load bearing capability than a conventional hand laminated eps or

pu especially if the “conventional” is reinforced in the manner I described.

There are tales of broken compsands all over this site. The beachbreaks

bizgravy surfs can be tough on boards.

Mike

17

Mike Daniel and Craftee, you are getting it right.

But tensile/compression strength of the foam is not what’s important, because it’s the bond between the glass job and the underlying foam, as Mike noted first

Therefore realize that the major contributor to strength is going to be the shear strength of the bond

I put for the proposition, therefore, that EPS might have an advantage since with careful glassing, the epoxy resin can penetrate the foam to some unspecified depth and thus distribute the shear stress that is otherwise concentrated at the foam/glass interface. Trouble is that EPS is by itself so damn weak in the first place that this penetration may only bring it up to equality with PU foam.

But overall, good to see acceptance that shear failure is how boards snap. And that thickness is the major contributor to board strength.

18
Quote:

In all sandwich structures, thickness is the ultimate stiffener. Going thicker

on the shape will increase the load bearing capability more than any other single

thing you can do.

i think this statement is not accurate

when you say load bearing

yes stiffness is good in “a wall” to hold the load of a roof

but its got nothing to do with stresses on a surfboards

which is going to break first when bent

a 3 mm piece of rubber

or a 3mm piece of wood

stiffness doesnt improve a boards resistance to breaking

flex does

the trick is to get the balance right

the snapped composite boards youve seen (i cant recall one on the compsand builders site btw)

have been either too stiff

rail material to thin

thinned skinned

or the core is to stiff (high density)

in other words not very well built

i surf overhead knee deep heavy shorebreaks all the time

ive nosed dived my board frequently into the shingle

and do re entrys on to dry banks

my board doesnt dent or ding

and doesnt even look like snapping no matter what i do to it

or alternatively

berts built hundreds of composite longboards

and his snappage rate decreased by something crazy when shifting to composites

and even then they were his superlight competition boards

19
Quote:
So i was surfing fun little beach break yesterday on my buddies trifin performance longboard, super fun. Get in fast before it shelved out on the inside, little closeout barrels all day long. Pretty much the funnest kind of surf sometimes. But later in the day, it started really sucking out on the inside, which i LOVE.....but the whole time i was just thinking about not breaking my buddies board. It kind of held me back a bit, which i HATE. Soooooo, my question is.......

What would be the best way to set my mind at ease about snapping if i were to shape one for myself?

Triple stringer as opposed to single?

More glass?..Heavier

…

Every 1/8" thickness increase in the stringer will have a substantial impact on snappability.

Thickness is the largest determinant of snappage strength.

MikeDaniel’s 1st post is pretty spot on.

20
Quote:

And I’m not convinced that a compsand is going to have a higher

load bearing capability than a conventional hand laminated eps or

pu especially if the “conventional” is reinforced in the manner I described.

well thats just goes against basic materials engineering principles

of course sandwich construction is stronger

otherwise Americas cup boats would be made of PU/PE

Quote:

I put for the proposition, therefore, that EPS might have an advantage since with careful glassing, the epoxy resin can penetrate the foam to some unspecified depth and thus distribute the shear stress that is otherwise concentrated at the foam/glass interface. Trouble is that EPS is by itself so damn weak in the first place that this penetration may only bring it up to equality with PU foam.

But overall, good to see acceptance that shear failure is how boards snap. And that thickness is the major contributor to board strength.

charlie

resin in the core?

no way

who wants a stiff corky board :slight_smile:

again

its the lower density foams which make better internal cores in sandwich construction

the board can bend with out breaking

pu has bad qualitys for a surfboard

it feels great for 1 surf

then fatigues and goes floppy

it pales in comparison to eps in a sandwich board

1 pound eps doesnt fatigue readily

wood and pvc doesnt fatigue readily

this is just a simple test for you all to do

get 1 pound piece of eps ,

a 2 pound piece, and a 3 pound piece of PU

make then the same length, width and thickness

now bend them

see which one can bend the furtherest without breaking

okay so you got a bendy core

now use the stiffer foams where they belong

in the “skin”

this creates the balance

use materials that can bend

when you put them together, they get stiffer

but they can still bend

we are not building a “wall”

it a dynamic moving structure

in kung fu you develop a bridge

it is stone

and strong against another stone

but can be beaten easily by water and wind (water erodes it and wind goes around and through it)

so as you develop your skills

“bridge” become less important/permanent and more intuitive

you only have it when you need it

and the rest of the time you are flexible and moving