7'0"balsasandwich riding impressions.

General Discussion
41

I want to change materials for sure, but dont quite have that much money to buy all these things right now, so I’ll have to wait for a litlle bit more to go exploring.

Good to hear your board went in small waves,but does the too much tucked rails have to do with the boatiness? I think it’s more the volume this time. But that’s cool now you can surf even smaller waves or?

Have never heard of Dynel so cant tell you anything about it.

but let us know if YOU use it.

totally agree with timber and buttjoint placement.

How long planks do you get in NZ? Here in japan I get 900mm long 80mm wide ones.

Jimmy yoshio shibata.

42
Quote:

sorry ben, forgot you asked me BEFORE.

They’re made of 9mm ply. Total of three layers of 4oz when finally on board, feels flexy which I like.

Think the wood of the ply is lauan and something else combined.

Jimmy yoshio shibata.

thanks mate

43

hey dudes

took the new board out again twice today

and it was a bigger about head high on the sets.

must say the board went well

it is squirty on take off. alot quicker so it was racing away from me and a bit wobly(part of the reason it felt boaty)

also the sweet spot was very narrow

heres a few pics

this is the most gutless waves i have ridden at this size

its a really fat wave and hard to get drive of the bottom.

so im pretty happy with how the board went

my wife watched

me for a while and said i was surfing faster and more effortlessly.and she remarked a noticible improvment.

she was very surpized that a board could make that much difference

i would say i have gained maybe 5 to 10 percent speed increase in this board.

anyway getting there

after that i went and surfed a bigger beach break that was like a slow closeout with a lot more power

and the board may be my new favourite

i think i wanna build a thinner rail one though

sorry for hijacking yoshio



44

SWEET!

I had a good feelin about where you were going with this one.

Honestly, having a lot of squirt in gutless phat waves on a shortie is a real good thing…I mean REALLY good thing. Think how the session would have gone with your previous “under” boards. Fast squirt feels great in small waves (if you mirror image your pics it would look exactly like FL on a fun winter day)…just seems to make it more exciting. Not a lot of power but with a real fast flighty board you can have heaps of fun. Basically, youve found YOUR optimal tool for the application.

As you get used to the added squirt, youll start doing things you want to do much easier. And btw, controlling a squirty board is very technique dependent…I like to use a real low “Curren-esque” deep knee bend approach to getting more control…low enough to drag my finger tips on the water.

As far as that wobbly sensitivity part, Id say look at your fin setup…could be too much toein or too tight a cluster…thats why I love fin systems…it allows you to fine tune the feel of the board. But I gotta admit, those fins look sweet!

Cheers

45

surfed it again this morning at the same place. but it was only one foot .and fat

about waist hight .

there was like a 11 year old gromet doing lip bashes and a few mals

but mostly everyone else was just sinking.

so as a 35 yearold 83 kg rider on a 6 2 board ,managed a few off the tops and and 1 reo.

although it feels kinda silly doing it in such widdle waves.

cant say it was all that inspiring but i managed a few giggles

i was gunna suggest to a grommet that perhaps he would be more suited to trampolining as a sport.

the way he was bouncing up and down .

little bugger called me off a wave after he made an impossible section.

so a thruster can work. and be faster or as fast as a fish in small waves.

and it dont have to be 3 inches thick either.

in fact i feel that a thinner rail with hard edges provide for a lot more drive of the rail.

Quote:

As far as that wobbly sensitivity part, Id say look at your fin setup…could be too much toein or too tight a cluster…thats why I love fin systems…it allows you to fine tune the feel of the board. But I gotta admit, those fins look sweet!

i really think the fins are right this time they dont feel draggy at all and the board has a nice balance to it in turning .

not to skatey but seems to release better witout bogging down

im pretty sure that its the fat rails im not used to.

and also they are more like 60/40

46

Thanks you guys (Jimmy/Dan/Silly)

we should all start a technical thread of what and where we’re riding and how it’s working pluses and minuses.

Just like this thread

That’s what we need here instead of the bantering and ego stroking.

This is the worlds greatest test lab.

Maybe we should agree on baseline specs to describe our equipment

I hope to get alot more water time down the road to really put mine to the test.

including different fin setups

I’m game.

I can even compare it to a PuPe relative by switching back and forth.

Of course it all subjective

What do you guys think?

47

yeh mate sounds good .

we could just keep this one going

can we have a balsando 30kb photosize rule cuz im still on dial up.

id like to ride some pu/pes as well i only ridden a new pupe board once .

and it was realy nice .

i wanna see you ride some in some hawaii juice

all i mostly ride is 2ft dribble so i cant really judge except for those conditions

Quote:

That’s what we need here instead of the bantering and ego stroking.

well it is sillycberspace

it best not to take things to seriously

feel free to stroke away bro :slight_smile:

my wife tells me im stroking to much lately :slight_smile:

honestly the epoxy versus debate is kinda fun

its more interesting then watching sport

and you have to be polite while your cutting someone down.

that makes it more challanging.

48
Quote:

Bert has described his boards as stiffer than most until they are put under load. There is no way that I would describe my stringerless board as stiffer than most. I’m learning that a stiff board is great until your actually on the wave (chip should love that line). Thinned out rails seem to allow the board to perform more hooky turns but they don’t store energy so you don’t project out of the turns as much. A stringer stores some of the energy from the flex and gives it back as the board straightens out. If the stringer is too strong it hinders the natural flex the thin rails gave you. This means that you should design the stringer to overpower the rails were you want the board stiffer and … you get the idea

thanx for that dan i finally understand

49

Hi Paul!

That’s some pretty interesting stuff! I love this :slight_smile:

So, anyone have any theories as to WHY binding the skin to the rails/perimiter-stringers so strongly impacts flexability?

I do, but I’d be really interrested to hear other thoughts first. I seem to have been doing a lot of yacking/theorising on here lately :smiley:

50

look doug im not quite sure

it was just real world tests that proved it to me .

i dont know the thoery behind it

i imagine the structure becomes monocoque. therefore more rigid

it a boat building principle.when you overlap skins on chines and keels.

but ive kinda gone back to roys stewarts concepts of even thickness.

which i believe is so the different curves arent fighting each other as well.

also meecrafty and hein alluded to changing the foils dramatically with this construction

its not "why do you go thinner "

its where!

if theres to much volume in the centre part of the foil not only do you have panel stiffness form being to thick.

but also the skins are working against each other becuase they are different curves.(this can be good to some extent)

the key is to control the relationship of the skins.

control flex with some ways is better than trying to control with other ways.

u need to control it in “predictable ways”

im shure i could use say 8mm deck skin and still achieve a nice flex.

as long as the foil is right and the core is not to thick.

and the structure is not to tied together at the rails.

i thought about nothching in the deck skin.

51
Quote:

A stringer stores some of the energy from the flex and gives it back as the board straightens out. If the stringer is too strong it hinders the natural flex the thin rails gave you. This means that you should design the stringer to overpower the rails were you want the board stiffer and … you get the idea

dan can you please elaborate on this thoery for a silly person

im not sure if your refering to the “perimeter stringer concept” or the horizontal stringer concept

52

Hi Paul!

Looks like just us two in here :smiley: And these kinds of thread have a really low “views” ratio compared to such cerebral topics as “Show us your surf tattoos” :}

I appreciate the real world investigation, probably more than you realise. But I am also a person that has a drive to know “why”. And to know with some certainty. So yeah, adhoc real-world tests are valuable. But more so if we know the reasons behind the results.

Yep, monocoque is what I attribute it to. But monocoque construction really came into it’s own (as a modern construction technique) with WW2 aircraft construction, as I understand it. Now it’s used in all kinds of advanced composite construction - body boards, bicycles, cars, boats, aircraft, space shuttles, etc…

There’s a monocoque introfor anyone who hasn’t come across the concept before. One of the points of monocoque is to bond together the curves we have been discussing. Monocoque itself easily provides for tension & sheer forces, and when we carefully sculpt our 3D curves it can almost completely counter the bend/flex forces involved (compared to traditional construction techniques). THIS IS WHY Bert has been saying that bonding everything together is bad. One continuous complex-curve monocoque composite surfcraft (skins overlapping rails on top and bottom) will be as resistant to flex as is possible with the materials/construction techniques in use. In that scenario a concave deck could be almost disastrous to flex :slight_smile:

Wondering why glassing extra over the rails stiffens up the board? :smiley:

Not sure what you mean about Roy’s concept, can’t remember seeing that. Do you mean skin thickness? Board thickness? Anyway, sudden changes in either could be disastrous :slight_smile: I think you can change either as long as it’s a gradual change… And don’t go thin/thick/thin too quickly. So I think it’s not just “why” and “where” you go thinner, but how. And yeah, the different curves of the skin can be a very good thing. But we have to understand them to capitalise on them.

And yeah “predictable flex control” is going to be quite important.

I reckon you could go thicker than 8mm deck skin and still get good deck flex. Just don’t overlap the rails AT ALL :slight_smile: Use the glass to hold it together and make it waterproof.

Not sure what you mean by notching the deck skin. I am now wondering about the validity of not bonding the deck skin to the rails at all :stuck_out_tongue_winking_eye: Future experimentation, I guess.

Food for thought!

53

Paul,

Here’s some info about Dynel from a couple of sites I use. I use it as mentioned here for paddle tips and boat ends for impact resistance. It does absorb large amounts of resin and gets heavy. It does not go clear like glass, but wouldn’t be an issue where you plan to use it. I don’t think you would get what you want out of it anyway. FYI, The sweetcomposites site also has a great page on fabric characteristics.

http://www.angstkayak.com/compexp.html

“Dynel Dynel has extremely good abrasion resistance. This is why it is commonly used for paddle tips. It’s main disadvantage is its cloth to resin ratio. The cloth holds a lot of resin making it heavy. Its tensile strength is low making it impractical for a layer in a boat. This cloth however makes a super tough covering for outside seams and paddle tips.”

http://sweetcomposites.com/Polyester.html

Dynel fabric has very high abrasion resistance but swells in the resin such that it works better if vacuum bagged or pressure molded. The most common uses of dynel are for wear patches on boats, edgings on paddles, and the like. It has also been used as a deck covering on wooden sailboats. It seems to be a good choice anywhere that abrasion is a major issue. (This material is similar in its abrasion resistance to the original Dynel made by Union Carbide, which has been unavailable for many years, but it may be chemically different and have different properties in aspects other than abrasion.) Please note that it retains a milky appearance when saturated rather than turning clear in the resin like fiberglass. Hence it is not a good choice if one desires to see the underlying wood, as on a strip canoe. Style 90285 is a 30x30, 660 denier 2-ply twisted yarn, 5 oz plain weave.

54

thanks hafte for the link ill have a peek tonight,

my current understanding shows this.

doug what i mean by notching would be to take away some foam where

it joins the stringers, so the deck skin is the same hight as the top of the stringer,without overlapping at all .

allthough i imagine it would be difficult to get an accurate fit .]

so i guess sanding it off is the only practical way.

roys concept of even thickness through out the boards length.

im guessing he is basiaclly doing it becuase it gives a very predictable flex pattern.

because the curves are the same

its really hard to control flex once you go over 2 inches thick .small differences have huge effects.

so over 2 inches. foil really comes into play with regards to flex.

as you said if the curves arent smooth the curves arent in harmony

but if you keep the thickness at the lowest practical . it allows smoother curve relationship,\

as well as the basic thickness/stiffness ratio. (im assuming everyone understands this basic principle of composites)

so what you end up with is board that is basically too flexible .

as meecraty is discovering ands yoshio and myself.

i stiffend one up by addding more glass but it was hardly desirable way of doing it

you get the desirable “flex return” from the wood.

so build “not monocoque” with thinner foils .

result. have a flexible panel

add “stiffnes and flex return” in a predictable way with

ie. timber density in the skins , top hat or springer .

remember when yoshio made the hemp board and it was too flexible .

bert said to do a skin patch under the front foot.

see what i mean .

its kind of like building in reverse.

Quote:

Wondering why glassing extra over the rails stiffens up the board? :smiley:

look. it does and it doesnt .

i put about twenty once of glass on the tail rail to stop it from blowing out

cuz of futures fin boxes being too rigid .

and the board really came alive becuase i stiffend the rail

but it added a lot of weight

at the end of the day i think my rail glass experiments have been a dead horse

i could glass them 20 ounce and still get a flexible board.i think

no .its more about foil/thickness and the relationship of the skins from the monocoque construction theory

and response from the nature of the skin material…

(okay okay, and the springer,but theres no point in me trying it unless i know how it works right)

55

Hey Paul,

OK, gotcha re notching. What about just making the board up as plus thinner and then putting on the rails? That’s really going to minimise the skin/rail bond and increase flexibility :slight_smile: FWIW I am not sure we really need to completely remove the deck skin/rail bond. We do want soem flex resistance, to improve recovery, don’t we? Also, I think we can feather out the join to provide some control over this.

Understand re Roy’s idea, too.

Yeah, thicker you get the more your 3D curves are “magnified” in monocoque construction. If we reduce the monocoque nature it should be somewhat easier.

as you said if the curves arent smooth the curves arent in harmony

Yep. And wherever we have “single structure” we need to be extremely careful about how we marry our curves. A difference 0.25mm would probably be very noticable to a talented surfer.

but if you keep the thickness at the lowest practical it allows smoother curve relationship,

as well as the basic thickness/stiffness ratio. (im assuming everyone understands this basic principle of composites)

so what you end up with is board that is basically too flexible .

as meecraty is discovering ands yoshio and myself.

U-huh. BUT, if you don’t bond the skin to the rail at all you are forced to COMPLETELY rely on other factors to control flex and return. That’s OK, I guess… And probably IS more predictable. But it means you need to address flex AND energy/force diffusion locally in all areas. See, another feature of monocoque structures is the even distribution of force. I think that’s something that IS desirable in the boards we are making. My personal opinion is that we need to find a tradeoff. We need just enough of a monocoque structure atthe rails to harvest the benefits of even stress diffusion, with tension and sheer handling. But not so much that it becomes too stiff and flex suffers.

Yes, putting glass on the rails is more of a “patch approach”. But, again, WHY does it work? I think this is important! Additional layers of glass move the overall structure towards a more monocoquial structure! So imagine adding subsequent layers of a theoretical 1/10th oz glass to the rails. The whole structure becomes progressively more monocoquial. Hence the increased stiffness AND flex resistance.

Relying solely on a monocoquial structure on the rails is undesirable for reasons we have already discussed. But I think doing the absolute opposite (i.e., not utilising it at all) might not be the best answer. Ignore me if you like, I may be completely wrong :slight_smile:

…snip…

remember when yoshio made the hemp board and it was too flexible .

bert said to do a skin patch under the front foot.

see what i mean .

its kind of like building in reverse.

Yep. Selectively thickened. But if that one of Bert’s big secrets, would he have shared it so openly? In his situation I wouldn’t. And I don’t think that’s the best way anyway. But building in reverse encourages “componentised thinking” and I think that’s important with compsand boards.

…snip…

at the end of the day i think my rail glass experiments have been a dead horse

i could glass them 20 ounce and still get a flexible board.i think

U-huh. Yep, you could. But it’d depend on how the whole thing was built :slight_smile: If you have wrapped the rails then glassing over them increases the monocoquial join by a percent. And if you haven’t wrapped the rails at all you are putting in place an insignificant amount of monocoquial join. Even with the latter, tho, there’d be some increase in thickness, etc. It just wouldn’t be very noticable at all :slight_smile: I was referring to a board where at least one of the skins is wrapped over the rail to some extant.

no .its more about foil/thickness and the relationship of the skins from the monocoque construction theory

and response from the nature of the skin material…

(okay okay, and the springer,but theres no point in me trying it unless i know how it works right)

Foil plus thickness plus CURVES (in three dimensions). All of which, in collaboration with how it’s constructed, give it’s monocoquial profile. The “response from the nature of the skin material” statement is interesting :slight_smile: we are starting to touch on where infusion and other areas of pre-treatment come into this. A VERY interesting area in it’s own right.

Ah yes… the dear old springer :smiley:

Cheers!

56

Quote:

OK, gotcha re notching. What about just making the board up as plus thinner and then putting on the rails? That’s really going to minimise the skin/rail bond and increase flexibility :slight_smile: FWIW I am not sure we really need to completely remove the deck skin/rail bond. We do want soem flex resistance, to improve recovery, don’t we? Also, I think we can feather out the join to provide some control over this.

duh im so stupid

but feathering the joint is hardly what id call predictable flex control,

it could end up completely different every board.

we need to really address this unpredictable variable

Quote:

A difference 0.25mm would probably be very noticable to a talented surfer.

yeah man.now your talking

ill be looking very carefully at the deck foil from this point on.

Quote:

another feature of monocoque structures is the even distribution of force. I think that’s something that IS desirable in the boards we are making. My personal opinion is that we need to find a tradeoff. We need just enough of a monocoque structure atthe rails to harvest the benefits of even stress diffusion, with tension and sheer handling. But not so much that it becomes too stiff and flex suffers.

drat. back to the beggining of the problem.

Quote:

Yes, putting glass on the rails is more of a “patch approach”. But, again, WHY does it work? I think this is important! Additional layers of glass move the overall structure towards a more monocoquial structure! So imagine adding subsequent layers of a theoretical 1/10th oz glass to the rails. The whole structure becomes progressively more monocoquial. Hence the increased stiffness AND flex resistance.

Relying solely on a monocoquial structure on the rails is undesirable for reasons we have already discussed. But I think doing the absolute opposite (i.e., not utilising it at all) might not be the best answer.

right, so monocoquial structure stifffness of the wood is better than stiffening from glass cuz the wood has better

flex return. as opposed to glass.

spruce could do it well.

i really dont think berts hiding all that much actually

maybe manufacturing processes and such

also a 3000 board understaning of what works

Quote:

Foil plus thickness plus CURVES (in three dimensions). All of which, in collaboration with how it’s constructed, give it’s monocoquial profile.

mwhaa haaa haa

you got a compsand rule there methinks

important to have a clear uderstanding

if you add to this principle

“response from the nature of the skin material” statement is interesting :slight_smile: we are starting to touch on where infusion and other areas of pre-treatment come into this. A VERY interesting area in it’s own right.

okay lets get into it some more

Quote:

57

Doug: “HELLO…”

Echo: Hello… hello… ello… llo… lo… oooo…

but feathering the joint is hardly what id call predictable flex control,

it could end up completely different every board.

we need to really address this unpredictable variable/

Urm… Maybe freehand feathering is unpredictable… Actaully “Feathering” probably isn’t quite the right word. I have some ideas I’d rather not air publically right now. I am sure the various clever people on here can also think up something. PM me if you want to hear more offline.

ill be looking very carefully at the deck foil from this point on.

Sorry. Can’t help myself here :slight_smile: Do you mean deck foil as in whole thickness. Or as in deck skin thickness… I can think of lots of relevant things here :wink: Devli’s advocate ;D

drat. back to the beggining of the problem.

U-huh. But, like I said above, I am not that sure that it’s that big an issue. Will just take alittle lateral thinking… And lots of board-builds :wink:

right, so monocoquial structure stifffness of the wood is better than stiffening from glass cuz the wood has better

flex return. as opposed to glass.

spruce could do it well.

Absolutely spot on IMHO. In both cases (I have mentioned spruce on here before for this very reason).

i really dont think berts hiding all that much actually

maybe manufacturing processes and such

also a 3000 board understaning of what works

True. ESPECIALLY the latter. But I still think there are some things he is keeping relatively quite. At least in public. The 3,000+ board builds is his really big advantage, I think. I believe that he subconsouiously knows solutions to problems that we haven’t even run up against yet.

mwhaa haaa haa

you got a compsand rule there methinks

important to have a clear uderstanding

Never thought aouot it that way. Maybe.

The problem I have with “response from the nature of the skin material” is that it isn’t really separate. My understanding is that monocoquial construction considers skin (and skin area) properties an integral part of construction. I think it figures in somewhere, but don’t know for sure yet.

okay lets get into it some more

Oh by all means!

Any takers? Anyone?

58

ah im tired tonight

it has been quiet though

maybe everyone else has it figured.

ate shingle again at the rivermouth

i landed that blue board so many times into the sand and it still doesnt have a ding.

who could think a 2 ft wave could be so heavy

i will pm you soon re.joints

ll be looking very carefully at the deck foil from this point on.

Sorry. Can’t help myself here :slight_smile: Do you mean deck foil as in whole thickness. Or as in deck skin thickness… I can think of lots of relevant things here :wink: Devli’s advocate ;D

as in whole distribution of thickness. but in the skins as well maybe as ive been experimenting a bit with that as well

yeah man spruce has always been on my mind

my first post ever was about quarter sawn spruce.

quarter sawn has really favourable characteristics for wooden monocoque.

fir or oregon is prolly what id end up with though

as far as nature of skin materials

let start with (assuming we have strength to weight sorted )

density . grain orientation. and joints.

desirable and undisireable characteristics

59

ah im tired tonight

You have no idea. Beeped by work at 1am :frowning:

it has been quiet though

Accidentally knocked a pin off the table and was deafened by the resultant din.

maybe everyone else has it figured.

Oh god. I hope not. Wont surprise me at all.

ate shingle again at the rivermouth

i landed that blue board so many times into the sand and it still doesnt have a ding.

who could think a 2 ft wave could be so heavy

hehe! Lucky you! Yeah, there’s an aweful lot of water and energy in a 2 footer. Imagine something bigger!

i will pm you soon re.joints

Cool.

as in whole distribution of thickness. but in the skins as well maybe as ive been experimenting a bit with that as well

I mention because I think both are gonna be important.

yeah man spruce has always been on my mind

my first post ever was about quarter sawn spruce.

quarter sawn has really favourable characteristics for wooden monocoque.

fir or oregon is prolly what id end up with though

Spruce a remarkable timber.

as far as nature of skin materials

let start with (assuming we have strength to weight sorted )

density . grain orientation. and joints.

desirable and undisireable characteristics

With timber it’s never going to be quite as simple as that. Even two peices of timber from side-by-side in the same tree will have different characteristics. But it’s a start. Density and grain orientation are akways going to be biggies, I think.

yawn

Later.

60

man you guys are on drugs or something…

that was one hell of a conversation…

talk about bouncing ideas off the wall…

brainstorming el manifico!