Victory Challenge IACC120 Design and build thread

Other America's Cup Boats
101

Have to excuse me then Anders about my igornace about vac bagging :indiffere

I was under the impression that when you wet the lamination, lay it in the mould and then bag it within the pot life of the epoxy, in other words the fibre is still wet “flexible” to vac around edges at the sheer line, even if it is at 90 degrees.

I had the impression that the epoxy went off first ! … before bagging (reason for stiff fibres)

Sorry Alan

102

Hi Anders,

I understand you are a little unhappy with the first hull, could you give some more details with some photo’s and will give you a diagnosis.

My only suggestion at this point in time is that if you have a lamination job that over runs a little, you should always heat the job up once the vacuum is applied as this will reverse the gelled resin (up to a point) and make it flow again…

Hope to hear from you soon, Jim

103

Vacuum layup: The short version.

  1. Layup the material (glass, CF, Kevlar, etc)
  2. Wet out material with resin
  3. Layup release cloth/film/material/plug, etc.
  4. Layup vacuum bag, or put all in a vacuum bag.
  5. Vacuum the air out.
  6. Let cure.
  7. Remove layers to get to final product.

If done properly, you get a product that has just enough resin to create a matrix between material weave.

Remember if pulling a 20" Hg vacuum, equals to ~ 10 psi. So for example, a 5"x12" fin in a vacuum bag would be like putting 600 lbs of weight on it during the cure.

104

Hi, will try to explain how I did it and what problems I encountered.

@ Alan. I think you are absolutely right, you are supposed to bag it before the resin goes off. But I can’t wet out and arrange the fibers in the mould fast enough. Maybe I have to look for a better method of wetting out the fibers. Currently I am applying the resin with a painting brush. Have thought about pouring out the resin over the fibers (plastic lay-up method), and then distribute the resin with the brush in stead of applying it with the brush…

Back to the hull and how the lay-up went…

I had all the fibers cut, according to a template generated from the CAD model so I had about 10-15 mm extra width of the fibers. This turned out okay.

Mould was waxed and polished 4 times.

Temperature during the lay-up was a little less than 20 degrees properly 17-18 degrees. The resin was stored at 24 degrees over night, but I guess that the temperature in the mixed resin batches goes down pretty quick, especially when distributed over the area of the fibers. This could be a source of some of the problems.

The outer 80 g/m2 glass layer and the first of the two 160 g/m2 carbon layer were wetted out and applied using the plastic method. But it almost went totally wrong with the carbon layer, so wetted out the last layer in the mould. It seemed the draping and arranging of the fibers was easier this way, but it is very difficult to be sure if the fibers are wetted out properly.

All fibers are arranged at 0 & 90 degrees, so the draping was a bit of a challenge. But from my previous tests, I found that this direction of the fibers gave the part the best characteristics.

Both fibers, peel-ply, perforated film and breather was cut according to the same template, so they where all the same size.

I struggled a bit with the peel-ply… properly spend 10-50 min making it drape. The roll of peel-ply that I’ve got is not wide enough to arrange it at 45 degrees, which could properly speed up that part of the process. Arranging the perforated film was pretty easy. The breather was also a bit tricky, especially in the bow, which is very narrow, but it was possible to squeeze it all in there.

I put the whole mould and lay-up in the vac. bag and made sure there was plenty of bag material inside the mould, so it wouldn’t have to stretch. The vacuum connection was placed approx. 5 cm out side the back end of the mould. As mentioned earlier, it was properly about 3 hrs from first epoxy batch was mixed to the vac. was applied.

Vacuum applied was aprox 0.55bar. The whole lot was moved to a room with a steady 24 degrees C. Vacuum applied for about 4 hrs.

My hypothesis:

I think the lay-up went okay actually. Maybe a little slow, but maybe the low temperature gave me longer pot life, but also thicker resin.

For my tests I used maximum 0.3 bars vacuum, but as I thought the first layers of resin had already gelled up, I applied 0.55. I think this is the main reason for the problems. It can also be seen from the pictures that the back-end, close to the vacuum connection is missing a lot of resin. I weighed the breather after taking off the mould and it had gained a good 100g, which also point in the direction that too much resin was vacuumed out of the lay-up.

The other big problem is the edges. I cannot figure out if this is actually caused by the breather material and vacuum bag messing with the fibers, or it is caused by the fibers not being able to bend around the sharp edges of the mould. My solution to this problem would be to trim the wet fibers in the mould before applying the film and breather. I am also not sure if the film and breather should be trimmed to fit the fibers or if it should overlap the fibers. Also I have to be more careful when arranging the bag around the edges, but I am not sure how to do it right.

Is it necessary to use the glass layer. It would save me some time, if this layer could be left out. Pin holes can be fixed by the r-g.de pinhole filler, and I plan to paint all my boats, so I don’t care so much about white pinhole filler spots.

I’m thinking if it would be an idea to order another perforated film before making the next attempt. The other available film has twice the distance between the holes, meaning 1/4th the numbers of holes this should give more fiber compression and not so much resin evacuation.

Have to stop writing now, as my fingers are bleeding from typing… :lol:

Regards Anders

105

Anders, I admire your patience and I feel frustrated for you at the same time :headache:… I would’ve spat my dummy out the cot by now :stuck_out_tongue:

I’m thinking the time taken for lamination seems to be the problem, the outer Fibreglass cloth looks like the epoxy has gone off before the wetted carbon cloth has had time to bond to FBG layer, temperature plays a big part, personally I don’t attempt any laminating below 25 C anymore and relative humidity is below 50, moisture can do funny things.

Personally, I don’t like using brushes as they can easily deform light weaves if you’re not careful, prefer to use plastic spatula with nice round each and float the epoxy into the weave.

For my two cents worth, I’d be tempted to lay-up the fibre glass in the mould “by hand” (forget the plastic) and then wet it out in the mould with generous amount of epoxy to help wet the next layer of 160 gsm carbon which hand lay-up by and wet-out in the mould also then, do the same for final layer, then roll-out with hand roller to help release any air bubbles and sponge up excessive epoxy. Trim any over-hang with long pair of very sharp scissors and slip it in the bag

But let’s see what Jim says, he’s the expert.

Cheers Alan

106

Hi Anders…

Righty-o I will do my best to bring some solutions to the table.
Looks like a combination of a few small errors are apparent, nothing that screams bad technical ability, just a bit of beginners bad luck.
First off, I have a comment on the time it took to laminate and bag up.
The laminating duration is dictated by the resin/hardener you are using at a given temperature. As I have no experience with this system, I’m unable to comment accurately if this indeed was too long and is a contributing factor but my gut feeling is that it did.
There are a couple of tools that will help you to speed up the process. First is a squeegee or plastic spatula if you like, and the second is a 100mm roller and a suitable paint tray. The roller head type is critical and I would only recommend the use of the ‘mohair’ type replaceable heads. These give no trouble unlike long hair emulsion rollers or foam.
When wetting out the cloth on the table I always use the spatula first, then followed by a good roller-ing out as well. this really evens up the resin through the cloth and if you have accidently over saturated a part, or missed a little bit, it is quickly dealt with by using the roller - nice!
You should be able to wet all the fibre in less than 5 mins with this system, no sweat!
On-to the results.
The outcome is a little weird and I think that there are several reasons for that.

  • There is a lot of air present at the sheerline along with trapped air both against the mould and between the 1st and 2nd layers.
    I am almost positive that the 1st & 2nd layers were gelled when the vac went on. The bag did some of the job of compressing the fibres, but the air could not escape once it reached the right angle of the sheeline. You think that too much vacuum was applied, but I feel that maybe not enough was used to really force out the trapped air.
    Another sign that the 1st layer had gelled is the air has lifted the glass away from the mould, as it was trapped in between and not able to pass through the weave due to the curing resin. It could not pass over the right angle of the sheer as this is like a ‘pinch point’. the hard edge acts a a seal.
    The ‘dryness’ in the fibre - On the vertical sections and in the aft end can be caused by the resin draining from the cloth itself thanks to gravity. I cannot see everything from the photos but I have a hunch that the glass & carbon near the point that was lowest in the mould looks nice and wet out and as you get progressively further away, the more pronounced the dryness is. You mentioned the Vac point is also placed in that area, only making things a bit worse. If possible hook up a second point to the bow as well. You will see if you look back at my construction that I am using a woven plastic mesh. This gives superior vacuum travel. If you are only using a very light breather a extra second or third layer around the perimeter of the hull mould will really help even up the vacuum, no pics so just guessing again on that point…
    On the drainage - this is something that I have experienced a lot, not only laying up my IACC boats but IOM’s as well as much, much bigger jobs ;-). You will find the 100mm mohair roller comes in very handy as you can soak up the drained resin and re-apply it to the dryer areas. Here the roller speeds up any adjustment and makes a good ‘consolidator’ as well by working the fibres down, removing more air and balancing the resin out. (This tool is used constantly though the layup to keep the resin in the vertical areas…FYI)
    I can see that the disposables (peel ply, perf,breather) were laid perfectly as there are no bridges or flaws in the hull that would point to that being the cause of your issues.
    You mentioned that the perf layer may have too many holes, could you take a snapshot showing the perf with a ruler against it for scale please? I will be able to tell you immediately if this the case.
    A little more attention to bagging up is needed over the sheerline. Its a good idea to get as much of the bag into the middle of the mould as the vac comes on, Once you have almost too much vac to move the bag ,then pull the bag back out over the sheerline so it becomes taut over the edge and you have minimum wrinkles. This will give you a neater finish at the sheerline. I’m guessing that you were quite relieved once the bag was finally on!
    Now - The fibres that have strayed over the edge… Im curious as to why this is a bad thing. I am able to trim 2 layers of cured RC200 easily with a sharp pair of scissors … the finished cut edge is quite nice and ‘crisp’. Have a go and see!
    If the moulded edge at the top is the true sheerline of the finished yacht, you have no choice really, but to over laminate a bit and then trim back.

I hope that gives you some food for thought…

Don’t forget the perf pic, thanks!

Ciao for now, Jim

107

Use the roller gently - as they embed air bubbles if you move the too fast over the surface. This is why most recommend “tipping off” a rolled epoxy surface with a long-haired brush - it breaks down the bubbles (possible voids/pinholes in the glass) and allows the epoxy to self-level. Bubbles tend to get worse as the epoxt starts to “go off” - as the roller deposits the epoxy and then has a tendency to lift the epoxy back off the surface when you roll over it. May want to thin (slightly) first and second coat to allow it to flow out. Note sure if recommended but I have used the process for a number of years - and even on furniture.

108

Just to add - If the roller is lifting the cloth due to the tacky resin - You should abort laminating and get the job in the bag!

Thinning the resin is not recommended, especially when vacuum is involved, however selecting a resin system that has a lower viscosity is the correct procedure.
You are able to thin resin for cosmetic results, but structurally speaking, generally not a sound practice.

Off to stick some more bits of carbon together now…

Ciao, Jim

109

Hi

Jim. Thanks for taking the time to write your suggested diagnostics, it all sounds reasonable… Will have another go at it this coming Friday, as temperatures will get above 20 degrees.

The perforated film is from r-g.de it is the P1 type that Iv’e got, P3 is the alternative.
P1: Distance between the holes: approx. 7 mm, hole-diameter: 0,045 mm
P3: Distance between the holes: 13 mm (No information on hole diameter)

I will take a picture when get home from work today.

I appreciate all your inputs, thanks guys…

Regards Anders

110

Attached a picture of the perforated film.

Also a sketh of the corners just to make sure that I was actually doing it correct in the corners, only have to pull the bag to make a smoth fit.

Regards Anders

111

Hi Anders,

Two points -

First - Is that the P1 or the P3?.. as it looks like that perf has far too many holes.

Second, I am guessing this is an omission, but there is no breather in your vac stack :wink:
Don’t forget to pull the bag from inside the mould onto the flange when you are smoothing out. This will prevent the Vac stack puckering up the laminate.
Other than that the technique is correct.
You seem to have a good bagging system that just needs a little fine tuning, thats all!

Cheers,

Jim

112

Hi Jim

It is the P1 film. I will have to order some P3 film, as mentioned before it has twice the distance between the holes.

Properly it is best to wait for this film before trying again. I have lots of other stuff I can progress with, and use my bad carbon hull for practice. :slight_smile:

Yes i forgot the breather in my sketch :graduate:

Thanks, Anders

113

Anders.

I make the top of the plug and mould about 5mm higher than needed. Then I grind a 45 degree fillet off between the topsides of the mould and the top flange. That way the fabric goes around the corner easier. I use scissors or tin snips to cut the excess off after curing.

It is important to have everything ready to go before mixing any resin. I usually have 2/3 layers of fabric, then the peel ply (much easier to install in 3 overlapping pieces, rather than 1 big piece), no plastic film, just the breather/absorbtion material and then the bag.

I find the easiest way is to wet out the mould first, then place the first fabric in place ( 2 persons and a rectangular shape of fabric make this easier), wet this cloth out, cut off excess fabric - I use a brush and flexible sqeegee - add more resin all over before placing next fabric, etc.

Most of the time consuming carefull work is wetting out the top sections - brush on extra resin if needed, and also sqeegee excess from centreline of hull towards to top. Final carefull sqeegee to remove spare resin (without the plastic film it can be hard to remove peel ply and absorbtion cloth from hull is it is soaked heavily in resin)

Next, peel ply in -( making sure it covers every bit of resin) - bleeder cloth ( sometimes taping it to the peel ply and mould sides to keep it in place) - place in bag and vacuum on - about 30 minutes solo (I use fast setting hardner too!)

To help with the top corner, try pulling some excess bag towards this corner so the fabric is still standing upwards ( you might need to shuffle vacuum on/off a bit to get it all the way around). A nice big bag helps.

Jon

114

Hi everyone

I had a go at making a finn this weekend.

All went well, except for the epoxy part (as usually).

I used two layers of uni carbon 125 g/m2 on each side. I used the vacuum system to compress the laminates. I didn’t use a perforated film, just a piece of vacuum bag, thought it would give a acceptable finish. Unfortunetly I placed a sheet of brether on each side, with the intention of distributing the presure from the vaccum. But it made the surface quite bumpy, so there is propperly some hours of filling and sanding waiting for me to fix that. Next time I have to do this, I think it is better to have the breather arround the fiin, then air boubles can also be spottet through the bag.

I also forgot to apply resin to the top of the last fiber layer to form the surface, so also have some problem areas due to that, but nothing that can’t be fixed. I must suffer from some sort of epoxy stress syndrom… I cannot think straight while working with thst stuff. 5 mins after I’m thinking “why why why”. But I gues I cann only continue and get some more experience.

The finished untrimmed fin, which is slightly longer than the final finn is 150g, and deflects 20mm under the load of 3kg.

I think it is an acceptable result, for a first try. Anyway it is good for now, and I can continue with the finn box.

Regards Anders

115

Anders,

The surface finish should be as good or better than the fabric you are using. To have it bumpier than that suggests unwanted resin.

Did you have anywhere for excess resin to “escape” to? From your second image where the fin is in the vacuum bag I would normally expect to see resin in the breather/absorption layer.

If you did use the perforated film, you should see resin showing in the breather/absorption layer at very perforation very soon after applying vacuum.

For very light layups inside a mould where I want the layup still to be “attached” to the mould after removing consumables (peel ply, breather/absorption etc) I have found using shade cloth (used around buildings to provide partial shade areas) very successful to absorb some resin and also to be able to delaminate the consumables from the layup without demoulding. See attached image.

There are many steps involved in this process and it is too easy to forget one. Keep persisting Anders!

116

I just want to make a little update of the thread. It has been a while since the last update. I have sadly been working way too much and haven’t had much time or energy for boatbuilding. Now thing are looking brighter, only the weather is getting cold, which is not good for epoxy work. :mad:

I have been doing some progress, but without posting it here.

Main sub-projects right now are finishing the Finn box-bulkhead assembly. I am trying out an alternative construction, than what I have been seeing in the build logs. As you might remember I’m having an extended cockpit, which doesn’t allow for the regular setup.

I have already made two carbon parts for the finn box.

I’ll be trying to make some molded carbon bulkheads. It’s a bit tricky. I start with a balsa plate which I sand to fit exactly inside the hull. Afterwards I cast the mould over the balsa part using regular hobby plaster. It actually makes some really fine moulds. The lamination is very difficult because of tight corners etc. The first attempt was not a complete success. I used 3 sheets of carbon and peelply on both sides, just to get a good bonding surface. It might not be necessary. On the attached picture I haven’t finched removing the peelply, so it looks a bit messy.

I almost abandoned the idea, but I think I will give it another go, using strips of carbon instead of each layer covering the whole mould. If this also fails, I have to use a wooden construction maybe in a carbon sandwich. But must admit that the full carbon solution seems more fun :slight_smile:

Other than that, I am also working on the mold for the cockpit, and the plug for the bulb.

Attached some pictures to make the words make sense…

Hope to be back with more news soon. (No promisses) :lol:

/Anders

117

Hi everyone!

I was reading the IACC120 rules, to find out what all the fuzz about the LWL was about, I didn’t find it, but something else caught my attantion.

I would like to hear your oppinions regarding my “extended” cockpit.

In the rules section D2.2 it says “behind the mast is required a cockpit” But my cockpit is also under and a little in front of the mast.Is that a problem??? :confused::confused:

I don’t think it is illigal, but maybe my interpretation is wrong, better be safe than sorry.

/Anders

118

Sorry…
Out of rule if you don’t mask it with something this “strange” hole, like in mine boat (like you’'ll see mine internet page ac120 http://www.progetto-urca.com/urca/)

119

As I understand it the cockpit should begin behind the mast…
The LwL conflict is on the English IACC forum and basically a stand off has been initiated by the Italians changing the rules to suit themselves.

Cheers, Jim

120

Claudio,
can I also add…
You may need to change the radius at the sheerline for your design. The new rules state a radius maximum of 5mm, and I believe the renderings of your designs are significantly bigger than that. Have you noticed the latest additions?

Cheers, Jim