solid balsa rails -- what's your technique?

General Discussion
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{reply}The questions is what has more floatation? Air or foam?{/reply}

Air. Also as you reduce weight you have displacement with less weight and thus will feel like it is more buoyant (corky).

Maybe I’m wrong, but floatation is directly related to the amount of water displaced. You’re splitting hairs here talking about the weight difference between a hollow and a foam cored board. I weigh ~ 150 lbs. Do you really think a lb of difference in the weight of the board will make any difference in the flotation of the board while in use? (Together we may weigh 154 rather than 155… big deal). Surface area is the key. Lighter boards will turn/respond faster and that’s where the value of lightness comes in.

yup your right it would should all be displacement vs weight…

The corky feeling that people refur to from surftechs is from the light core making the overall board lighter. The stiffness may also be contributing to the corky feeling.

Sure the difference between air vs 1 lb eps on a short board is not that significant, but as the board gets bigger and the and you compare higer density cores then it can play a factor. 2-5lb density core on a 10’ longboard and you have a fairly significant difference. But even 1 lb difference in the board itself will make a difference in responsiveness. Many people here are talking about trying to save a half pound. 1 lb could easily be 20% weight savings on a short board. Silly (I think) is in the 4lbs finished board range.

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No question, a pound would make a huge difference in the way the board rides. I snapped my 6’1" twice while I was in puerto the past summer and I can definitely feel the extra weight from the repairs in my turns. The board doesn’t float me worse because of it though. If you want to go hollow for the performance gains in weight, go for it – that’s a valid chase. Just don’t expect the board to float better because you’ve removed the foam core.

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Standard composite theory (Meecrafty’s diagram in earlier post) requires that the core be attached to the skins. Without an attached core, the strength to weight advantages would be lost.

I wonder how standard composite theory deal with a flexible inner core such as 1 lbs EPS. Surely this has an effect of the stiffness of the sandwich, in particular since the distance between the skins will probably change when it’s flexing…

regards,

Håvard

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nah my lightest board to date is 4.5 pounds

and my current is one is 6 ( double glass and fin systems .to take to Islands )

sabs has got them to 4 pounds

in my understanding eps foam has more air and is therefore more bouyant

a surftech of similar dimensions to a poly board would therefore have more float

if you go way back to berts early post you will notice that the advantages of this consruction cant be fully recognised unless you change the shapes.

in other words

go thinner… like maybe even 1.7 thick

this also obviously solves a lot of problems relating to stiffness.(check some data on composites )

if you want a bit more float go a touch wider instead of thicker as that will only make the board stiff.

if you want one thats tough ie (breakability)

use a thicker core on the deck upto 5 mm >they still flex nice with a thick cored deck.

all it takes is to build a alot of boards to know what works and building to extremes helps me relise the difference things make.

the variables all change when you change,

wave

weight of rider

style of rider

i cant comment on a springer cause i havent tried one

the reason why is because at this stage it is just another variable which would add to my confusion.

for example

paul puts in a springer it is x y dimensions

board is still a dog so i build another with a springer of xy dimensions

board is still a dog and so on until youve tried 100 different springer setups

only to relise at the end your rockers were wrong

or the board was to thick

or u used to much glass on the rails

etc etc etc

if a few guys doing this are claiming majic boards without the springer or product x

or this tool or this tech.

then heads up i say

why look further untilll u master the basics

and understand how and WHY they work

ive finished no5 and it looks okay it flexes nice and its a strong bugger

nothing added to confuse the matter (hell finsystems are hassle enough)

latter on when ive acheived a bitchin surfboard that improves my performance

I might delve into the mysteries of the springer and all other fibres foams resins etc

but probably not ,because i could spend ten years just getting a nice finish…

ps the balsa rails are just as much a water barrier as anything else (most likely place to get a ding)

i find gluing them on to a good way :slight_smile:

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Onr national sport is Hurling, which is a bit like Field Hockey it uses a 1" thick 1 piece solid Ash to hit a very hard ball big distances. Ash has excellent Flex & return for its size. When I finally get around to springers It will be 1" ash, leaf spring style. Now if you could in some way make the springers externally interchangeable you could have 1 board for all conditions.

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wow dan , i never realised i said all that in relation to the neutral axis in the past …

i havnt got time now to give some examples of how a flexing piece of timber behaves in regards to shear loads or no shear loads placed on it , maybe the only thing i can say that could help , would be comparing it to an internal combustion engine …

depending on how they are designed , some can put out way more power than others even tho the size is the same …

the bad ones waste energy internally because you have parts pushing against each other at the wrong times , making the engine work harder …

meecrafty , ive always found you to be one of the most analytical , you really ask solid questions to get a good grasp of something before you attempt it or except it…

i think that is a good way to go , on the other hand sometimes the amount of variables and possibilities just cant be calculated with certainty , so a gut feeling and a round about guess should get us close to the mark , based on our previous experience …

in regards to the neutral axis and basic engineering principals , where were ya when i needed ya last time ???

seriously now , would an engineering background be more benifical in helping to understand whats happening with a surfboard internally and how it functions , and then help one to design one closer to the mark ???

the reason i ask …

i was a board builder long before i picked up a text book , building boards in my early teens and not picking up a text book till my mid 20s , so i found in most cases that learning the maths behind what i was doing really highlighted exactly why some features or aspects of design were so good , but in other cases what was put forth as a design rule or engineering/physics formula by the text books , just didnt seem to match real life examples …

sometimes i would meet qualified engineers who knew there text books inside out , who would be absolutly positive about one thing being right and another being wrong because they knew the math …

so there education put them in a posistion to totally discount certain design or construction possibilities …

ive come to the conclusion that some of the text books are more of a hinderance to a quality understanding …

and even what we learn should always be cross examined against all other theories…

but that doesnt mean that the majority would always be right either …

i think it all comes at a cost whether you pour money into building your own ,learning the hard way , making mistakes and building a knowledge bank …

or buying heaps of different boards like oneula does …

in both cases we learn something , in both it cost something …

it shows we learn the most from getting out there and doing it , trying new stuff and rewriting(changing them a little) the text books …

i dont believe its vital to have an engineering degree to formulate theories or throw ideas around , but it would definatly help us out by not throwing ideas out there that are to extreme …

to ask whether we always need the next thing ???

thats a good question …

maraboutslim always seems to have a good answer for that one …

so much for keeping it short …

gota go …

regards

BERT

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meecrafty , ive always found you to be one of the most analytical , you really ask solid questions to get a good grasp of something before you attempt it or except it…

i think that is a good way to go , on the other hand sometimes the amount of variables and possibilities just cant be calculated with certainty , so a gut feeling and a round about guess should get us close to the mark , based on our previous experience …

my gut is telling me to ask lots of fundamental questions regarding the construction/ride relationship…

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Hi Paul

Good post I agree with all you have said.

I find that i am getting a little jaded with some of the other posts here and dare i say it even some of Berts

There seems to be a lot of words but not much actual usefull info.

I dont bother posting that often and sometimes wonder how others work along the evolutionary track or if they just race to each new idea as it comes along.

I have disasembled some of my boards then rebuilt them just to see what has been happening inside.

That way i know for sure what is going on.

Just as i also know that to get a light board you are very limited in what you can put in it as far as materials

My father who is a very clever man with a exellent understanding of boats,design and buildings, he was head of the Perth city town planing department and so worked with a lot of engineers over the years used to say this about some( i stress not all engineers) "WHY MAKE IT EASY WHEN YOU CAN MAKE IT DAMM NEAR IMPOSSIABLE "

So i would make this point, Sillys is on to it ,there is only so much that you can put inside a board before its weight has blown out, therefore dont make out how complex it is when in fact there is just not that much there to make complex.

Sorry the springer, a piece of wood horizontally imbeded in a plyable foam is just another way of adding substance to a overall shape, which can be achieved by several other methods all of which can have similar end effects.

I am just not convinced by some of the hype I am hearing, its good advertizing but I have to wonder about the worth of that advertizing and hype on the Swaylocks crew.

Mike

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to make solid progress requires thinking, making, thinking, making, etc.

To much of one without enough of the other will limit you. Thinking too much and not doing is usually worse than doing too much and not thinking, when it comes to evolving new designs. I know shapers who’ve done 20,000 boards and don’t understand rocker lines, and others who’ve done a dozen and understand its intricate details.

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There’s bound to be multiple truths, and just because someones experiences are different doesn’t make them right or wrong. All I’ve seen in this thread are people talking about what they’ve experienced and why they think its happened. If people are sounding definative I THINK its only because adding “I think” or “I believe” to every sentence would be insane. I DON"T THINK that we don’t have to all be going in the same direction in order to benifit from what others are doing (see what I mean about the I thinks :wink: ). I personally think that extreme lightness is overated, but then again I ride longboards that encounter different forces than shortboards. I want my boards to have a bit more structure to them. It doesn’t mean you should change the way you make boards, but why totally dismiss what my experiences add to the mix. However, I do find that the lightness of my current board really adds to the surfing experience.

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There seems to be a lot of words but not much actual usefull info.

What would you consider useful? The only thing that I didn’t find very useful so far is hearing how lame I am (I have loads of people in the real world to do that)

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Dan

i read everyones post with interest .that are doing this construction . and have learned things from everybody. your not lame mate youve got some good ideas .AS we all do

i remember my first post on swaylocks about quarter sawn spruce being a valid addition to decks as well as guitar type bracing. It was kinda lame cause id never built a board but now i relise it had a lot of merit.I think Bert thought i was Roy, because the concept was kinda out there.

i guess only those that are contributing can really follow these threads to a decent level of understanding. This is a good thing, because some ideas will,and do lead to confusion .(If people are confused and dont understand it might give them the drive to actually try and discover things for themselves.ie research!) Thats okay theres 2000 lurkers reading sandwhich posts and only a handful are actually posting . How many of those are proffessional board builders i wonder?.

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There seems to be a lot of words but not much actual usefull info.

thats okay as well

this is a forum .its all about words

some get bored going over the same ground .BUt often for some reason there can always be a fresh perspective.A good student teacher relationship enables both parties to learn something.

A discerning mine can glean the useful stuff or the stuff he/she likes and leave out the stuff they cant afford ,understand ,or just simply couldnt be bothered with.

my wife is is gunna kill me for spending so much time here

gotta go

enjoy all

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Hi Dan

Interesting you should comment,my statment was not made to any one in particular just a general comment,I would never criticize any one on this website who has the voom to get up and make their own thing, whatever it is.There are many differing ways of building surfboards, just as there are many differing designs and types of surfboards.No one type of board or method of construction suits every body.However.

There is all ways a lot of speculating which is of not a great lot of use with out practical obsevations,it gets the original idea out there but after that I find fails to help

Comment.

Neutural axis is only neutural when nothing is happening,flexing the object will result in the neutral axis moving up or down unless the object is exactly the same shape and sandwich or layup both sides of the axis point -try an experiment and see

Comment

The only reason i went on the light road was to test the bounds of what was needed for the structure to have enough strength to do the job -then i could work back from there to make the structure bend and flex where i wanted it to with out unnessesary structure impeding these qualitys

I just get frustrated when things are made out to be far more complex than they really are.

Mike

ps I am having a absolutly crap day at work dealing with 65 boatbuilders who all seem to be equally having a crap day too!!

pps Did losos ever find the info he was looking for when he started this thread

If not please losos tell me to shut up so you can get the tread back on your track!

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Thanks sabs… found through experiment. Tried one way, wasn’t happy. Tried another, still not happy. Tried again and finally found a method that worked well for me. Still lots of room for improvement, but plenty good enough for where I stand at the moment.

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I am having a absolutly crap day at work dealing with 65 boatbuilders who all seem to be equally having a crap day too!!

Tell me about it!!! Its been a brutal couple weeks.

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I just get frustrated when things are made out to be far more complex than they really are.

You have a huge advantage over a lot of us with your boatbuilding background! What might seem simple because of your experience at times seems very complex to me. I’m new to composites (and for the matter board building) so each step forward has required many hours of thought.

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There is all ways a lot of speculating which is of not a great lot of use with out practical obsevations,it gets the original idea out there but after that I find fails to help

My next batch of boards are going to be the same basic board with subtle changes to them. Its why I’m slowing down my pace of building. Hopefully I will learn what works for me and what doesn’t (for instance, my next board will be hyper lite with the stringer on the neutral axis).

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Hi Dan

Yep thats what ive been doing,each time i build a new board i build two at the same time one has the extreme changes from what i have been doing while the other is allways more conservative

Both boards allways have matching rocker and plan shape,the rail shape and thickness and the overall board thickness are different

Ive found that I get better comparisons this way,I do however end up with way too many boards which my wife now just laughs at when I cant decide which one to ride

I also now do all my initall tests with one fin set that i know how they feel,other wise I find it too hard to spot differences.

Mike

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I do however end up with way too many boards which my wife now just laughs at when I cant decide

Mine just rolls her eyes now :slight_smile:

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the neutral axis is the point where nothing is shearing …

shearing takes energy …

the neutral axis can be at any point inside a flexing object , not having to be at the center with equal layers either side …

the arrangement of our skins will determine exactly where the neutral axis is and thus determines the best place for adding the flex limiting horisontal stringer …

sabs !!!

you are pushing the limits more than anyone , probably because of your experience with these materials …

yes you can get around the problem of overload leading to failure in other ways …

simpler ways yes …

but it all comes at a cost …

for me that cost cant be comprimised , and thats not willing to sacrifice performance …

i have left so much unsaid , and without a doubt , all the same problems i had are now causing grief among some of you guys …

i think i even made the comment once , something like …

it will make crew apprieciate exactly where im at …

because unless crew understand the difficulty and the effort it takes to grasp the concepts around designing performance boards using construction techniques like this …

then the boards i build have no value , if no one understands how hard it is to get good results …

i agree , commercialism has no place on swaylocks …

why have i toned down my own time on here???

to be honest , now that its going mainstream and all the commercial ugliness is leaving a mark …

i feel ive lost a certain freeness of speech knowing that what i say can now be interpreted as having a commercial interest …

now my words have gone from a helping hand to being viewed with suspicion coz i stand to make a buck from it …

so im cutting a fine line between being helpful and protecting some techniques and methods i feel i deserve to hold back on so i can make a buck from it …

a few years back when i first got on sways a lot of the stuff i said was viewed as cryptic ,2 people actually picked up on my comments and understood them , holly and greg …

now dan and others are rehashing 18 month old statements and finally putting sense to them …

appart from any potential commercial benifits , it feels great for me knowing that others are gaining an understanding of stuff that i couldnt even discuss with anybody in the past because they wernt even on the same page …

you have to believe me , as cryptic as some comments seem now , just like the 18 month old comments that are becoming clear now , so will these apparent cryptic clues become obvious …

you cant leave crumbs down a path youve never taken …

some will leave them for others to use to …

and some will try to pick them all up and own them …

waves come free…

knowledge can either be earned or payed for …

and no one would begrudge either way of getting it , its only fair that if you cant afford it , then earn it …

im out, regards

BERT

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Hey Bert,

As I mentioned at HB, you would have made a great teacher. You understand the difference between teaching and learning. In teaching you try to pour the information into peoples heads (implying a passive learner). In learning the teacher puts out ideas that are designed to motivate the leaner to think. This approach takes much more work, but the effects last a lifetime. I believe the crumbs left along the way will take us much further than providing direct information which we don’t recognize the significance of.

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Bert

the best thing that can happen from all this effort is that both you and Greg get your just desserts…

that is a successful acceptance of what you two have spent a lifetime trying to achieve against the unforgiving eyes of an industry stuck on itself and everything it believes it is… false as that is in reality.

I see the little train that could just starting to make it up over the big hill…

Greg’s resin now that more people have been exposed to it will start to find a home in many a board builder’s shop ( I can attest to this personally, building out the distribution network is the initial problem) and as custom EPS blanks perimeter stringered or not become more widely available, stronger lighter custom boards will become the norm not the exception. Performance will still be an issue because it the design problem that will still need to be addressed as the materials problem goes away… But people are smart they’ll figuyre it out like alot of amateurs are doing here.

Once you and Nev get throught he business end of getting your concept to market your stuff will also slowly but surely become a viable option for those that want to pursue something better versus something cheap. Just like Airframe, Aviso and others, the market will continue to expand.

My only caution is that the big money and the personal demands of big business changes everyone, it the pandora;s box of success, so there will be some definite pain and personal unhappiness sacrificed as things take off for both greg and you. How you handle the money and pressure will be difference as whether it becomes all worth it to you in the long run and whether or not you’ll eventually be accused of selling out when you choose down the road not to put your heart in it like you’ve done all these years…

Just a genie in the bottle giving you a crystal ball look as to what may come…

But it the end most of us living on the bleeding edge, can’t wait for that new horizon to appear…

All the best

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the neutral axis is the point where nothing is shearing …

shearing takes energy …

BERT

actually,

i believe the neutral axis is where longitudinal tension / compression stress’ converge to zero.

however, combined longitudinal and vert shear stress’ are at a maximum along the neutral axis.

in general, that’s why the core is selected based upon the anticipated shear loads.

i’m sure the core doesn’t absolutely need to absorb the shear loads (hollow boards).

but, if not the core, then somewhere else like rails and stringers.

-bill