UK-Cherub Forum
Cherub Chat => Tech Chat => Topic started by: Neil C. on May 05, 2011, 11:17:15 AM
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I now have foam core buttered with lightweight filler. How best to stick the glass weave to the foam? Do I wet it out on a big table covered with plastic sheet, or do I lay the dry glass weave on the foam and wet it out in situ? Anybody have an opinion on the various consolidating roller designs or plastic squeegee thing?
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Our method is doing it all in one hit.
make or find a flat surface.
Butter the foam
apply the layer(s) of glass/carbon cloth
wet out glass with a plastic spreader. You can apply a reasonable amount of pressure.
Apply layer of peal ply (use spreader again to consolidate.
if not vacum bagging add a protective layer of polyethene (cheap dust sheet material is ideal)
add a flat board and add lots of weight (bags of sand are quite cheap.
If doing both sides at once turn over when you have added the layer of polyethene and repeate early steps.
good luck
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Hi folks, I'm after some basic laminating tips again:
1. I've been wetting out the glass on the foam using a brush and stippling action, followed by fluted roller and hard rubber squeegee thing. Seems to work OK, but it's slow. Even using SP106 slow hardener, the resin is starting to go off by the time I've done even a modest sized panel. Looking at your post above again Phil it seems like maybe you just pour the resin on out of the mixing pot and then spread it around with the spreader. Would that be right?
2. I have been wetting out 2 layers of glass consecutively. Is that correct, or could you lay on the 2 layers of dry glass together and wet them both out at the same time?
3. Also, do you apply further resin to the peel ply to wet it out too, or do you just squeeze it down onto the laminate below to soak up excess resin?
Any advice gratefully received.
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Hi Neil,
Yes - high summer is not the season for laminating!
First you can pour the mixed epoxy into a wide flat tray. That way the heat from the chemical reaction isn't retained so much, so the resin warms up less, so the reaction goes slower, so less heat is made, etc etc. Also don't hold it in your warm hand. Also don't leave it in the sun. Also you might want to place it on a cool floor, in draft, etc etc Every little bit helps. Each 10 degs it is cooler doubles the time to harden (poss not working time, but it definitely lengthens it)
Second, if you are reasonably careful not to put too much on you can pour resin on and then spread it out.
Third, I would not recommend trying to wet out two layers at once with a wet layup. There is room for it to look ok but not be ok. However when the second layer goes on it will partially wet out from the resin in the layer beneath.
Good luck! I have never used ice-water and all that to keep mixed resin cool, but it may work.
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I believe there is an extra slow hardener for SP106, tho not in most shops...
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Looking at your post above again Phil it seems like maybe you just pour the resin on out of the mixing pot and then spread it around with the spreader. Would that be right?
If the resin is runny and you are putting it under some pressure when ti sets this works fine. If it is setting under gravity I'd pour over, spread out with a ClubCard and then the solidy roller thingy to check it is worked in.
I agree with Will about laying/wetting 1 layer at a time (although both can be wet at the same time).
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I tend to poar the resin onto the cloth so that it leaves a thread of epoxy in a zig-zag pattern evenly across the section I am laminating and then spread it out with a bit of hard plastic.
In general I do not wet-out the peelply, unless it is a complex area and it is difficult to get the peelply to stay in position.
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Thanks guys. I can see that the stippling brush technique has a place for doing awkward corners and fiddly bits, but I'm going to switch to a pour-on and spread technique for bigger flat areas. I can wallpaper a room at reasonably good speed, but brushing resin into bigger areas of cloth seems too slow to me.
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Depending on the job I generally wet out the cloth on a peace of plastic using the pour and spread technique. You know it is wetted out when it goes translucent. Wetted out cloth is also easier to lay onto a difficult area. For larger areas I would agree with wetting out dry cloth in position.
I use plastic spreaders made from ice cream containers. Spreaders push the resin into the cloth without moving the wet cloth. They are also free if you like ice cream.
Stippling with a brush can help to consolidate dry peal ply onto wetted out cloth. Mostly i use the same spreader. Sometimes i will add a little extra resin to help the peal ply to stay put. This is worth while to ensure edges of cloths remain in contact with the surface they are meant to be stuck to.
Good luck.
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Next basic question:
I'm about to add a thin layer of epoxy-based filler to the outside of my glassfibre laminate, for the purpose of sanding most of it off again and fairing the surface smooth. When I look at the photos of other people's work, the filler mostly looks white. My low density filler powder (West) is brown though. Is this the right stuff to add to the resin? What do most folks use for this?
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Sounds like what you have is microbaloons, which are small bubbles of phenolic resin.
The white stuff is glass bubbles
for fairing I don't find it makes much difference
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Hey Neil, if I recal correctly West supply blended fillers. What you have, may be their filleting blend which is microballons with about 10% coloidal silica. Are there any white blobs in the powder. The silica is high density and a ***** to sand.
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I bought some West 410 microlight filler a while back when I was desperate to get *something* in a hurry. Its a pale reddish brown, quite a bit paler than the colour I associate with plain microballoons and although it didn't say so (either way) I felt it was blended with something, not just microballoons... Their web site is silent on exactly what that filler is made of: it might be something different again. You're going to put so much effort ino the fairing that its well worth getting exactly the right filler...
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410 microlight is plastic bubbles. Lighter and easier to sand than either microballons or glass bubbles. Juat what you need for fairing. Very pale brown / cream coloured.
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Hey Neil, if I recal correctly West supply blended fillers. What you have, may be their filleting blend which is microballons with about 10% coloidal silica. Are there any white blobs in the powder. The silica is high density and a ***** to sand.
Hi Dave,
That's right. It was WEST 407 Low Density Filler, which is a microballoon based blend of stuff, although interestingly they don't say exactly what on the tub. Certainly was a child of dubious parentage when it came to sanding. I've replaced it with a tub of WEST 409 Microsphere Blend, which seems a lot better. I think the 410 Microlight would be better still, but Rob Storrar didn't have any in stock in his shop.
The target is to get Duncan's old boat fully fixed up and ready for Day 1 of next season, i.e. no later than 1st March. Have given up realistic hope of getting her floating this season. But then again it was always going to be a big job so perhaps aiming for 2012 isn't so bad. I seem to recall a rumour that you had a hand in the design of this ship. Would that be right?
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For fairing, I use a mix of glass bubbles ( = hard ) and West microlight 410 ( = soft ) - varying the proportion depending on what job.
The 410 added to the mix makes it smoother and creamier to apply, and it sticks better to the surface, and easier to sand when cured - but a warm post cure or a few days at room temp is needed before non-clog sanding.
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That would be just a rumor Niel. The Pasta Frenzy, Platypus and (as I chose to call it) Flying Sub were all designed and built at a similar time, to the same rule set and all three of us (Simon too) swapped notes a bit. Duncan consulted me for details of previous designs as a starting point. Also, had I not mentioned that there was lots of nomex in a skip opposite Guy Lewington's place of work he wouldn't have used nomex. That said, the three boats had subtly different design briefs and the design is all his. :)
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That would be just a rumor Niel. The Pasta Frenzy, Platypus and (as I chose to call it) Flying Sub were all designed and built at a similar time, to the same rule set and all three of us (Simon too) swapped notes a bit. Duncan consulted me for details of previous designs as a starting point. Also, had I not mentioned that there was lots of nomex in a skip opposite Guy Lewington's place of work he wouldn't have used nomex. That said, the three boats had subtly different design briefs and the design is all his. :)
Having owned Lost in Space for a while i can understand why you call it the Flying Sub.
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I think it is a reference to a likeness to this:
http://www.adammillertoyandbicycle.com/images/257_product_Flying%20Sub.jpg
http://www.youtube.com/watch?v=A2nzDyQEgoM
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Exactly so Will. The similarity with the upside-down shell was uncany.
This does remind me of something...
Has anyone ever moved the centreboard case on this boat? Duncan took some influence from I14 thinking of the time which was to move the centreboard forward to load the rudder aswell. He started from measurements of Norwegian Blue then moved the board forward. Unbeknown to him what was new to the I14's was old history to Cherubs, all my boats had loaded rudders. I suspect that may have something to do with the handling reputation the boat has earned.
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It did not looked like they were moved when I had it. It was not too badly balanced / set up when it had small sails on but when I put more sail area on the handling was a bit more interesting. This is not that surprising as I could not get much more area in the jib. I am not sure the foils were not original which may have made a difference.
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Looking at the structure, I'm almost certain the daggerboard case has never been moved. It does look a long way forward. The leading edge of the case is measuring 2030mm from the transom, virtually the same as my old Paterson 4 at 2035mm. Our Woof is the complete opposite with the case way back in the cockpit, but it's parked along at the sailing club at the moment so I can't give an exact figure.
One more thing - I seem to recall that Duncan originally rigged the boat with a rotating mast with diamonds. Do you remember Dave? I could be wrong. It's quite possible that I was hallucinating due to an excess of Wadworths 6X at the time.
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As a comparison the E5's typically have the leading edge of the centreboard between 270-300mm aft of the mast. This gives a balanced boat. The rig can then be raked back to load up the rudder more but with the advent of skinny rudders this makes for interesting sailing in light conditions.
obviously E5 dimension relies on the big jib in fornt of the mast to maintain the balance. If you have a smaller jib and big main the board would want to move back a bit.
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Where is the mast foot located on the E5 Phil? Do you have a measurement from the transom? I vaguely recall the mast being about 2m from the transom on the Slug, but I guess it's probably further back on the E5/6's.
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Yes the original setup Duncan used was a rotating mast stepped at gooseneck. It wasn't a wing mast though. It was an experiment that didn't even last to the end of the boat's first event. Not sure what Duncan was trying to achieve but he very soon changed his mind.
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From front of snout to front of mast i think 1.92 on atom and 1.95 on the e5s or on antidote anyway .
Snout to transom is 4m and mast is 55mm.
This is a little far forward than a theoretical optimal rig but i felt there are economic things to consider esp as we had already decided to go for an ordinary kicker rather than gnaw or temple vang.
Board position was 270mm behind mast and raked at 4 degs.
This was a pointy board though with a long root chord though.
I would not advise moving a case unless it is unsailable . Kevin calls from long ago suggest that the clr moves about a metre when you move the rudder by one degree! This explains why similar boats with boards miles apart seem to both sail ok.
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Thanks Will. If I am going to move the case, now would be the time to do it while the boat's stripped down. But it's big job which I'd rather avoid if possible.
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Kevin calls from long ago suggest that the clr moves about a metre when you move the rudder by one degree! This explains why similar boats with boards miles apart seem to both sail ok.
Don't you mean move the *mast* by one degree Will?
Dave's point about rudder loading is important to consider in that respect... For all some people on line (not here) seem to wibble on about the vital importance of getting the mast rake in the exact right place for weather and lee helm, it seems to me that most of what's going on when the mast rake is changed is to alter the balance of load between rudder and daggerboard.
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I agree Jim. It's very rare indeed (like never) that I've ever had to sail with the tiller actually angled to windward to counteract a lot of weather helm. When we started sailing the Woof we had far too much mast rake on with the big rig and the tiller extension did a great job of trying to pull my shoulder out of it's socket. But the rudder was still aligned with the longitudinal axis of the boat, it's just that the rudder blade was carrying rather a lot of the lateral resistance load.
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I think Will means turn the rudder by 1 degree.
If 1 degree equals 1m of CLR movement you can probably get quite a high load on the rudder without having to turn it more than half a degree so it appears that you are not turning it but are carrying a lot of load on the rudder.
A lot of it comes down to feel. I have sailed boats which are normally sailed with lightly loaded rudders. Because that feels right to me I sail better with a similar set up on the Cherub.
You get a lot of extra load or a reversal of the load if the boat is allowed to heel one way or another.