Even more compsands

General Discussion
1

Couple more for you fellas,

First one is a 6’6" round pin thruster, deck 8 over 3mm balsa 2 under, bottom 4over 3mm balsa 2 under.

Flat bottom except a little vee into the fin area.

A tad over 2" thick and a very slight deck concave.

Second one is a 5’9" round pin, round nose kneeboard, same skin schedule over 11 kg/m3 eps.

Sorry for mixing imperial and metric, just the way that some of us do it over here!!

The kneeboard has a conventional domed deck, with rolled vee in nose, running to double concaves to spiral vee with the apex just forward of the front fins.

All my compsands to date have had 3mm balsa , I have kept that and the eps constant and have varied laminate weights and shapes to try and get the flex right.

My next one will feature a 1.5mm bottom with the tail area diagonally planked. With either a 3 or 5mm balsa deck, to go for maximum twang. also a concaved deck, to try for the morph bottom?

Anyone got any ideas or had any successes in this direction.

I have steered clear of horizontal stringers, to keep my weights down and to eliminate too many variables.

Anyone out there have any thoughts on how the different pressure exerted by a rider on their knees would alter the way you would build flex into the boards?

I would guess that the middle of the board under the knees would need to be stiffer to eliminate over flexing and even though pressure is exerted through the tops of the feet, that would be less than a standup can put through his/her back foot?

This would necessitate having a more flexy tail? Engineered through thinness and laminate/ skin combinations.

2

great work as usual mark

id be interested to know how the kneelo goes

3

Thanks Paul

Yeh it looks kinda strange with the rounded nose, like a skimming dish. Some of the UK guys have been getting great results with similar shapes in poopee, so it will be interesting to see.

BTW, you have tried out different skin thickness combos in the past, what would you say is your favorite?

Are you bagging your skins yet, or just wet layup?

4

gday mark

yeah ive tried 1.5 mm on bottom and 2mm on deck etc etc

but this next board im trying a very dense quarter sawn 3mm balsa bottom

with a 5mm deck also quarter sawn but not as dense on the deck(not by choice all i could get)

believe it or not the 3mm weighs more

i was trying to get dent proof booard by cloth and resin, but relise core density is far more important

so next board will be as per sabs glass schedual 3oz all over

no im not bagging outer lam as i cant see the point other than not as bumpy on the laps.

i can glass a 4 oz side with 120 to 150gms of resin so if i use a bag how much weight do i save,

20 grams ??

when a finsystem weighs so much i cant see any point saving weight by bagging

it would be more appropriate to carefully select my core material and use a lot less cloth and resin and balsa cored fins (glass on saves 200 grams easy)

i may try sabs top hat idea

no2 board was hell stiff. its not because of the balsa it was beacause of

  1. eps core too thick. maybe 2 1/3

  2. too much glass on the rails

3 bottom skin lapped stringers

mike rekons sealing also increase core density so i will seal the inside of balsa as well before i do the inner lam/bagging

flex return and dent proof is from the balsa core

or maybe im just tripping

ps my boards arnt nearly as nicely finished as yours mate

5
Quote:
i was trying to get dent proof booard

well having only procured everthing, but having not started work on my compsands yet this is not from experience…

but I would think if you wanting dent resistant, you should put the higher density wood on the deck, even if it is the 3mm. You deck sandwich won’t be strong since it will be thinner, but the more dense 3mm balsa should resist dents more than the softer 5mm wood.

If you have access to a thickness planner maybe just take the 5mm down to 3mm, and go 3mm on both the deck and bottom just with the softer wood on the bottom.

Just some thoughts.

BTW all you guys are building great looking compsand boards. I can’t wait to get the time to get started. Got a 8’x2’x2’ & a 2’x2’x2’ block of EPS in the guest bedroom and a dining table full of balsa. (My wife may be too understnding)

looking good

6

Looking Nice! Have you come to any conclussions in regards to this

Quote:

have varied laminate weights and shapes to try and get the flex right.

7

I love being part of this. Every time any of you guys posts a new board, it inspires me to make mine better too. Beautiful work.

I’m with you on the core strength & light glass. Even on longboards, I’ve found I don’t need more than a single layer of 4 oz anywhere.

8

Conclusions to date seem to concurr with what you guys are saying

My personal boards are glassed 4oz deck (outside) and 2oz bottom, oldest is 8 to 9 months old and has no pressure dings anywhere.

I only glass boards I have made for other people heavier because I don’t want them coming back, none of them have, so I may go lighter from now on.

I don’t have much of an opinion on the flex issue, the most noticeable thing about these boards is the weight(lack of) and different feel this gives in the water, much livelier than anything else I have surfed. I am trying to make them as light as I dare and as flexy as I can, by all the means that we all have tried.

I think part of the ding resistance of my boards to date is the density of the balsa I am using, my supplier sells me his standard density planks (each one is weighed and marked by him!) I think these are heavier than some of you are using, judging by the fact that my weights are around the 5.5 to 6lb mark on a 6ft ish board.

I am happy with this because I agree that the core density is of great importance (I always put the heavier planks on the deck).

I have been toying with lamming without vac, but it just seems easier for me because I do top and bottom in one go, laps are non existant and I can then do a complete lam plus hotcoats in a day at work, whereas if I did them by hand, the waiting time between bottom/ hotcoat/flip/top/hotcoat would fill my day too much.

I also like that I don’t have to bother with chasing the laps at the nose and tail!

I agree that the weight saving is minimal, but You definately get a tighter lam with the vacuum.

I tried a prefab on the bottom balsa of the kneeboard, laid 4oz glass on rocker table, wet out and covered with primed balsa. When I released it, at first glance it looked great, but on closer inspection each crossing of the fibres had a pinhole, it would have taken a lot of effort to sort out, so I scrapped it.

One thing that I have tried to good effect on some mountain board decks that I make, is to paint the mould surface (warmed), with warmed epoxy resin, and keep returning to it and brushing over the separations until the resin has nearly gelled and doesn’t separate anymore, I then lay the cloth in it and vacuum the whole laminate stack. This way, it acts very much like a clear gelcoat, you have a resin rich layer on the mould surface and it requires no finishing (no pinholes). This could be used to prefab the skins? and get a decent finish.

9
Quote:
I have been toying with lamming without vac, but it just seems easier for me because I do top and bottom in one go, laps are non existant and I can then do a complete lam plus hotcoats in a day at work, ...

can you expand on this? so your not lapping the rails? what are you doing about glass over the rails then?

10

I do lap the rails, keeping overlap to a minimum, to avoid overstiffening the board.

Lam bottom-flip-lam deck- consumables-into bag-vac.

11

By glassing the top and bottom of the board at the same time it makes the laps almost invisible. The two just blend together.

12
Quote:

I have been toying with lamming without vac, but it just seems easier for me because I do top and bottom in one go, laps are non existant and I can then do a complete lam plus hotcoats in a day at work, whereas if I did them by hand, the waiting time between bottom/ hotcoat/flip/top/hotcoat would fill my day too much.

I also like that I don’t have to bother with chasing the laps at the nose and tail!

hey mark

id be interested to know your exact process in bagging the outerlam

do you glass as usual then put it into the bag

or is the cloth prewet

how do you keep thing from creasing and such .

it sounds great doing in one batch with no no sanding

13

Paul

Do a search, I did a thread once called something like ‘bagging the skin in one hit’, pictures and all.

I just wet out as normal, with a roller and no squeegee, weigh out resin 1:1, quite often I look at it and think it looks too good to put in a bag!!!

I dont use a wet out table because I like to have my cloth nice and straight on the board and also, I throw enough polythene away at work as it is without adding to it, If I was doing multiple boards It would make sense but I only do singles at the moment.

Pull your release film tight and you shouldn’t have too many wrinkles, and like Bert sez, use a nice stretchy bag material.

14

cheers will do mark