rs 800 centerboard

[john_hamilton]

now where can i find one of those without subsequent anger from mym parents

[phil_kirk]

I tried sand when making the trolley cradle for E-numbers. I lined the laminate in the mould with cling film and poured the sand in.
I agree with Phil A that it was less effective than I had expected.
The sand can also reduce the temperature of the cure because it absorbs a lot of heat.

I suggest clamping thin ply around each side and lining the edge of the ply with your trailing edge.  I would suggest covering the ply with parcel tape to ensure it dosen't stick.

If a screw is screwed into the foam at each end nearer the leading edge and the screws supported so the foam hangs training edge downwards you can consolidate the leading edge by pulling or firming the peal ply down each side of the foil over the wetted out carbon.  

[Tim Noyce]

now where can i find one of those without subsequent anger from mym parents

You got a mate whose parents have a fridge?! 

[daryl_wilkinson]

Fridge pump really does work, but be sure to blag a degassed one. If you dismember one you find on the street you will be putting CFCs in the air, which is fabulously bad for the environment and very illegal indeed. They do pull a good enough vacuum though.

 

and the carbon, epoxy, bread wrap, tacky tape, gloves, peel ply, foam core etc... etc... is OK then? 

[john_hamilton]

yep i paid for that but dont feel like taking my chances by nicking their fridge compressor

[Banshee Ambulance]

As I have read somewhere, possibly on this site: 'carbon fiber = carbon footprint'! Nice to hear you have a core made, post a photo. What section/taper etc? I was thinking of the RS section with a 0.4 ratio trapezioid taper.

[john_hamilton]

my first core is just made to fit cheese's existing stock so i am not entirely sure what section it is. it looks like a NACA 10% but im sure. 22cm chord, 120cm lengthe (about 35cm not actually in water) and the taper is pretty much to 10cm chord at bottom fom 1/3 of the way up. its all a bit "by eye" im afraid! ill add a picture later if possible. i have done one side completel and am 2/3 of the way down the other side doing the sanding so its a bit rough.

[john_hamilton]

i did the first carbon layer tonight and realiseed just how much of an arse it is to do. any tips on how to do the carbon bit of a foil?

[ross_burkin]

Do all the layup in one hit and with minium waste.

For laying up the cloth make stand for the foil core which holds it horizontally trailing edge down. Will, have you got any pics from when we made your board? Diagram later....

[Will_Lee]

Hi John,

Well done on finishing the blank. Can you describe how you did the first layer?

W

[Phil Alderson]

As said before, the blank should be held leading edge up, you may need to put a screw in somewhere at the tip of the blade so you can hold it steady, the hole can be filled later.

If it is foam it should be buttered and if it is wood then wet it out with resin, this helps the cloth to stick.

I would then get a big sheet of plastic and wet the carbon out on it using something like a credit card or the plastic packaging that you often get with blocks to spread the resin.
The wet carbon can then be lifted on to the blank and smoothed down, there is much less waisted resin doing this than trying to spread it out on a vertical surface where it will drip everywhere.

If the leading edge of your rudder is mostly straight you can wet all the layers for your rudder out on the table then lift the plastic with all your laminate up onto the rudder and fold it all in place, peel back the plastic and trim to suit.

Peel ply is your friend when you are trying to get the laminate stuck in place and smooth,
also you may need to change gloves at the end of your laminating session as the heat from your hands can make the resin on your gloves go sticky before the resin elsewhere and this makes it very difficult to push bits down, if you put two pairs on at the start it is easy to pull one glove off for a clean but protected hand.

[john_hamilton]

the glove bit i noticed. basically i suspended the core leading edge up from a blow torch cabinet and then wetted out the carbon and put it on. i obviously forgot to butter the core so thats a mistake i wont make next time. The dried piece looks alright but has a few buble where i didnt smooth the peel-ply down enough ill sand that down and do all the other layers in one hit then.

question: which way should the universal carbon strands be aligned?

[Phil Alderson]

The Uni's should go up and down the blade. If you are planning on having a layer that does not go the full length then you should cut the end on an angle to act as a taper.

The butter helps to keep the weight down but also to stick the carbon to the foam, helping with the bubbles.

It is hard to get right, and practice will help.

[phil_kirk]

Well done for having a go Jon.
practice does help and all the tips mentioned above do make it easier.
Before long you will be an expert like the rest of us.

generally laminates are stronger if all the resin cures at the same time. there is also a greater chance that the fibres of each layer will interlock as the laminated is consolidated forming even stronger bonds between the layers.  if each layer is done seperately you rely on the bond between cured resin and new resin.  you also end up using more resin.  You know now.

just shout if you need a practical demo and i'm sure we can put a sticky weekend together.  You are not alone making foils at present.

[Banshee Ambulance]

Here is my first attempt at this foam sandwich lark. Its the transom for Hardly Sluggish (will be launched as Thunderbird 4) Its not quite as stiff as I think it should be. I did not vac bag it and I mixed the epoxy by mass rather than by volume (it says to do it by volume). I will let it post cure for a while and see what happens. It may or may not end up on the boat. Its a small pannel so nothing much lost in terms of materials if it doesnt. It was laid up on parcel taped MDF boards which were clamped together.