Victory Challenge IACC120 Design and build thread

Other America's Cup Boats
21

HI Anders
I took your picture an checked the CE position with the carton method and I found out that the CE is somewhat 70mm behind the mast back surface, see image below.
Clearly your Main is very big compared to the Jib. according to my extimate the jib is around 40% of the main
In principle good equilibrium is achieved with a jib surface around 50% of the main and even a little higher
Under this condition your mast may be 3.5 to 4 cm further toward the bow.
Cheers
ClaudioD

PS: I just picked up a sail plan drawing used for AC120 of 78dm² short mast of 1600mm against 1750mm allowed.
Please notice that the CE is at 36mm from mast back face.

22

Hi

So… I made a new sail plan.

Changes: Smaller main, shorter mast. Jib is now 50,3 % of main. CE is now 48,8 mm behind backside of mast, compared to 75,1 mm before.

On the previous picture the sails where actully shown with curvature, so they look a bit smaller. This time, it is the flat area displayed…

/Anders

P.S. Is this a better solution?

23

Hi again

I have a quick question about sail winch and blocks.

I want to order some blocks from cap-maquettes in france, but what series of blocks should i go for? What is the best for IACC120 boats. Im thinking about the 10mm “serie light roldanas” or “Serie race roldanas” anyone know the difference?

Regarding the whinch, is it the HITEC HS-785HB i need? If it is, i might as well order it allong with the blocks.

/Anders

24

For the winch, the HS785 is a drum winch and is robust but slow. For the same price and weight, the HS815 is an arm winch. Just as robust but a lot faster.It comes out of the box with 140 degrees of travel. In the IOM, we put on a 4 inch (10cm) arm with a block on the end. Run the line from the bulkhead, through the block, the out through the bulkhead to the deck. This doubles the line travel.

John

25

Hi Anders, I have changed from Cap-Maquettes to TD Model in Italy http://www.tdmodel.com/vela%20radiocomandata.htm only because Tiziano makes high quality components, less expensive and has more options available for AC 120 class … you can even order completely IACC 120 if you wish

When you look through his on-line catalogue click on “Listo” and you have down-loadable price list in Excel spreadsheet of all his parts (albeit it is in Italian)

Great guy, speaks English & ships anywhere around the world …ask for his specail recipe for “Spring Rolls” and he will know who put you onto him :stuck_out_tongue:

Cheers Alan

26

Hi folks

Have been drawing allot lately to get the details figured out. And i’m getting closer to a good solution. (I think)

I have made it so the mast can be moved 4% =40mm forward and 2%=20mm backwards. As i understand from previous threads, that should give plenty of room for “tuning” please correct me if i’m wrong.

Should the forestay attacment be able to move the same distance as the mast? In my case it will be arround 60mm.

I still think that the rig looks to be placed allot towards the front. I have checked and re-checked the CLR & CE, and it seems to be right. Everything is still as shown on the sail plan in post #22, so the jib is 50% of the main. I gues it is just because I have a big main sail?

I have also been working on the deck layout, not all finished yet.

I’m planning to buy the blocks and carbon masts from TD-models. Thanks for the tip Alan!

And last but not least, i have recieved the great news that after 4 years on a waiting list, I will get a garage/workshop in the building where I live. This means no more boat building in the livingroom! :lol: And hopefully allot more boat building. :lol:

/Anders

27

Gidday Anders,

Just to give you an idea of what adjustment I have on my boat, there are 3 points to take into consideration:

1.The Mast Step: Here I have 30 mm long slot for keel step arrangement. Within this 30 mm there is mast ram head (7mm) and round CF mast (10mm) this leaves 13 mm adjustment for mast stepping which I have 3 steps which are 4 mm apart in the mast heal block at bottom of the hull. I use only middle hole for light air and move mast forward in heavier air, fine tuning is done by changing the rake of the mast backward or forward to find ideal helm balance.

2. Jib Pivot Step: Here I have 3 steps which are 13 mm apart, but I only use the most forward point for all weather conditions. but it does not hurt to have all 3 for if you ever want to change to different sail plans in the future.

3. Sheeting Post: Here make sure you have a “telescopic sheeting post” for when you are raking the mast, as the main boom angle will change with mast raking, then you can adjust the sheeting post up and down, to be as close to the main boom as possible. Further just for extra adjustment possiblities there is 3 adjustable main sheet anchor point on the main boom, for when the mast is stepped backwards or forwards, not absoutely neccesary, but I like to have them.

Providing you have your CE as per the design plan in relation to CLR, these 3 adjustment points serve as rough position & then you can fine tune with mast raking etc. which work perfectly for all wind conditions on this boat.

Attached are pics for reference,hope it is helpful & looking forward to seeing SWE 96 finished, your drawing look great, well done !

Cheers Alan

28

Thanks Alan

It is quite helpfull actually. I will reduce mast movement to propperly 20mm forward and 10 backward, and make 3 jib steps, instead of the 7 I have now :).

Also I found out that on Claudio’s plans the rudder is more angled backwards than mine was, which actuallt caused the CLR to be 5mm behind mine, this is also corrcted.

I’m starting to think about materials for the boat. I think i will go for carbon fiber, but what kind of CF should i get g/m2 and how many layers should I use. My initial thoughts was 160 g/m2 and 3 layers, maybe only two. Looking at expected wheigts of the hull without deck, 2-layers will be 242g and 3-layers will be 353g. So im leaning towards 2 layers maybe with a thin layer of GF inbetween. I gues the wheight is a good guideline so what should my target whight be when using carbon? I gues its a little lower than GF?

/Anders

29

Hi Anders …it’s about personal preference but 20 mm mast step adjustment is more than enough, consider when you add mast raking (tilting mast backward & forwards) this will add another 20-25 mm of C.E adjustment range, you would be having easily add up to 40 mm C.E adjustment for fine tuning.

For my 2 cents worth on clothes & I’m no expert, but the cheaper 160 gsm CF has larger bigger weave, which means bigger gaps between the fibres to fill with unwanted excess weight epoxy.

When I built my first hull I used 4 layers of 80 gsm GF and I had problems with microscopic pin holes coming from tighter weaver 80 gsm cloth (see attcahed pics) then I had to add more filler twice, to plug microscopic pin holes, this means more weight again.

My next hulls will be 2 x layers of 80 gsm GF sandwiching 100 gsm CF to have same hull strength as 4 x 80 GF & reduce hull weight & I will be extra cautious with epoxy this time to ensure I have no pin holes using latex method, rather than the prevouis hand lay-up I did last time.

Jim is the expert in this area, hopefully he can offer some professional advice 1?

Cheers Alan

30

Hi Anders,
as said many times the lamination with carbon is not a must but if you so wish you can mix it with glass. The advantages resulting with carbon are essentially the lower weight obtainables, but after some calculations you may discover very little gain overall.

According to my personal experience, the quantity of composite needed is basically responding to a weight range for this size of boat varying from 6.0 g/dm² up to 7.5 g/dm².
Secondly is much better to use 4 layers of 80g/m² than 2 layers of 162g/m² because is less porous once laminated and produce more rigidity.
Example : for a rather strong hull of 34.5 dm² hull surface, starting from the external surface :

2 layers of glass of 80g/m²
1 layer of carbon of 93g/m²
1 layer of glass of 105g/m²

Calculations of g /dm²

2 x 0.8/dm² + 1 x 0.93g/dm² + 1 x 1.0 g/dm² = 3.53g/dm² of tissus that need to be mixed with the same quantity of epoxy resin therefore 3.53 x 2 = 7.06g/dm²
The projected hull weight will be :
7.06g/dm² x 34.5dm² = 243.5g

consecuently 4 layers of glass of 80g/m² are more then adeguate and will produce an hull of 4 x 0.8g/m² = 3.2g/m² x 2 = 6.4g x 34.5dm² = 217g
similarly, but expensive and fragile, 3 layers of carbon twill of 93g/m² will produce an hull of : 3 x 0.93 = 2.79g/m² x 2 = 5.58g/m² x 34.5 = 192g strongher then the above with glass and little lighter.
As a personal experience and because of the carbon laminate fragility, my Class M Studio2 are made with 2 layers of carbon of 93g/m² and one layer, between the two carbon, of kevlar 73g/m² for an hull of 178g
Kevlar is required in sandwich to procure strenght against shocks. NEVER use kevlar outside , impossible to work with, it do not accept any sort of abrasion and difficult to cut.
Hope this explanation is sufficient for you leaving others to tell their points of view.
Cheer
ClaudioD

31

Aaa yes, the CF pin hole nightmare. As Claudio said the key is fiberglass. Specifically, put the glass on the “outsides” of the laminate. Personally I have found that one layer of .75oz/yd^2 to 1.5oz/yd^2 is all that is needed on the side that contacts water/air. The trick is to really wet out the glass, to the point of looking like it is swimming in epoxy, then lay down the CF.

The fine weave of the light fiberglass will hold the epoxy and make a non-porous film and make a smooth surface.

Don’t get me started on Kevlar/Amrid, I hate the stuff. But it has it’s uses. There is a trick of cutting the stuff with scissors, get a really cheap set, then grind the cutting edges to 90° to shear the material. If you have to cut/sand it after it’s laid up, wet the edge with CA, then cut/sand. When it frays, re-wet with CA, repeating till done.

32

Thanks Guys

There is a little bit to think about… I think maybe i wanted to go for carbon, just to avoid ending up one day thinking “I wish I would have built it from CF in stead of GF”
On the other hand I could crash it one day where the carbon breaks and GF would have flexed instead of breaking, and then would be thinking the other way around.

But if I have to dig in to the bone, my initial thaughts where to build two similar boats, and lean to sail and trim the boats. Also I was planing to host small match-racing events for my friends, so hopefully others would get interested and I would have somebody to sail with.

As I sit here, I can see that it all points in the direction of two GF boats. Then If I feel like it (propperly will) I can make a Race Maschine, and incoorporate whatever I have lerned from the two prototypes into that one. No need to go crazy with CF for the first ones, as long as they are similar, so they can be compared when tuning and testing.

Only problem would be the extra time to build a race machine, still planing to go to Italy for the cup. But when the moulds are made, it might be quite fast to build a new CF hull…

Thanks guys, you gave me the small push needed to realize which way I have to go. :D:D

/Anders

P.S. Alan, do you have a link to a place where this latex method is described?

33

Just wish to pick-up on this point Claudio has made which is perfectly right. The question I asked myself was “Why when the calculations are right for weight saving, that you finally discover there was very little gain made when the hull is finished ?”

From my experience making my first two hulls, both were spot on with laminations target weight, if anything, I was little under weight due to not using enough epoxy to flood the fibre, hence the pins holes (Thanks for the tip GUZZ) The killer was finishing the hull with filler, primer and then paint and you can easily add another 200-250 grams here, if you are not careful !

This is the reason I’m trying the Latex approach this time around, is to elimante the filler, primer and base colour paint weight which in my eyes, unnessary hull weight.

I should point out that I’m using a male mould, my plan is add epoxy colourant to the outter hull layers of FG and by stretching the latex over the wet laminations, my hope is to flood the fibre to prevent pin holes and have a smooth finish that does not require filler, primer or final base colour paint.

Anders I have no links to show you sorry …but I will take some pictures over the weekend and post of the male mould preperation I that I think is required to use Latex method successfully, it takes some changes to the male mould mounting board

Naturally with a female mould you would have the same result & using vacuum bagging is even better again. If the Latex approach is not successful I would have saved time making female mould. If it fails I can always fall back of preparing my male mould to make a female mould.

Anders, I will catch up with you seperately about the idea of starting up Central European regatta for IACC 120 class, there are few builds being completed now & I think we will have a minimum of 10 boats ready this Summer, and it would be great if we can find a place to meet in Central Europe and have some fun together …maybe some Italians will come and join us too !

Cheers Alan

34

Hi Anders,
I just wanted to add my findings on the topic of hull AC 120 lamination. As you have gathered by now, there are many ways to build these hulls.
Everyone has their own techniques and it has everything to do with the particular skill set they have and the tools and equipment at their disposal.
I naturally understand you when you mentioned the potential room for regret if you build the yacht initially from glass then having second thoughts later.
I would then suggest a glass/carbon hybrid as this will give the best combination of weight & strength.
Aramid is another option, but use the carbon/aramid woven type (we call it ‘Squashed wasp’ cloth)
Moving on to the weight of cloth needed to complete the hull skin.
I have built 2 hulls. the 1st was 1 layer of a 300gsm carbon fabric called ‘Double Bias’. The result was very stiff and I was surprised at how good it was considering that it is just a 1 layer job.
The 2nd was 98gsm ‘Uni directional’ and 100gsm ‘plain woven’. This was almost too light and was a really an exercise in technical ability.
So from my experience a final target for the overall weight of hull lamination for a stiff/light hull can be around 300-350 gsm.
You will get a stiffer structure from using more layers to obtain a desired thickness, especially when you change the orientation of the cloth during the layup process.
Just be aware that this does allow for more air and more resin to be introduced during the lamination and for best results the use of a vacuum or other system to compress the fibre is recommended.
The use of a very light glass cloth on the outside is recommended too as this will eliminate the problem of a porous laminate.
Really, you are free to dream up the layup weight and schedule you feel suits your mould type, your skills and the tools that you have at your disposal and all the suggestions on here are equally viable.
If you have any questions on the laminating process or about the technical properties of the fibres mentioned here then feel free to ask away.
One last thing, here is a particularly good site that supplied my fibre needs - http://shop.r-g.de/

Cheers, Jim.

35

Just to add -
The site that I recommended also supplies a ‘pinhole filler’ designed to eliminate pinholes in clear-coated carbon products.
This would also work for sealing the pinholes in our hulls… I have yet to try it, but the next time I am making some furniture for a yacht, I will give it a go.

36

Hi

I’m changing my mind all the time here, but have come to the conclusion that I will have to go for carbon, to get the stiffest possible boats, with the skill, knowledge and money that I have available. I will be investing allot of time in the builds, so it would be stupid to not to give it my best.

I will convert my present male mould into a plug to make a female mould, and if the money allows it, I will invest in a vacuum system.

Still have my doubts regarding the composition of the laminate. When building the first boat with my father, it was the first practical encounter with GF and CF, so I bought a little piece of CF 200 gsm twill. I made a cast of the last 230mm of the boat using two layers, and applying a minimum of epoxy. I covered the entire mould surface with epoxy, and laid in the first layer of CF right away, then applied another thin layer of epoxy followed by the last layer of CF. All of this in one work flow (wet in wet).

Attached a picture of the result. It weighs in at 26 g, and full of pinholes. If I compare the volume of the rear 230 mm of my CAD model to the volume of the entire hull, it is around 13%. So if I made the boats like the test, the hull would weigh in at just under 200 g. (Including all the pin holes.) This sounds like an okay result, but then I think I didn’t use epoxy enough for maximum strength.

So I think I will go for a layer of light glass of 50 or 80 gsm on the outside, followed by two layers of carbon of 160 gsm, oriented 90deg and 45 deg. Then hopefully vacuum bag the fucker…

Next question(s): Plain or twill weaves? Is plain weave stiffer/stronger than twill? What are the pros and cons? From my, still very limited, experiences twill seems very easy to shape to our hull shapes, haven’t tried plain weaves, so can’t compare…

Then some other things. I have decided to buy profiled taper masts from TD-models, still have to figure out the exact layout of the cockpit in the mast area. Because the mast is all the way to the cockpit level, I can place the vang low and hopefully gain better control of the big-head mainsail. Se picture…

Then some bad news… Because I’m getting a garage/workshop 1st of mach, “The Home Command”, aka “The Big Boss” aka my girlfriend, has ordered a new kitchen to be installed before I get the key to the workshop. So February will not bring much progress…Will try to get the materials ready for March and hopefully also finish the CAD model, so have no doubts what I have to build when the workshop is ready…

This is all for now…

/Anders

37

Hi Anders, It is so easy to get a new girlfriend! HA,
Norman

38

Hi Anders, firstly apologies as I did not have time to prepare latex info, have only just got back home & leaving tomorrow on bus travel again, but promise I will have it when I’m back next weekend. :slight_smile:

Just observation on your vang graphic, not sure if it is to scale or optical illusion from the viewing angle but be sure you can get the vang to move freely @ 85-90 degree’s off the centre line…look tight especailly if you step mast forward.

Cheers Alan

39

Hi Allan

You are right, it is a very tight fit, and the edge will have to be straight foreward/aft.

By the way found the answer to the plain/twill weave question. On the web page that Jim proposed “R+G” there is a handbook available, with many good explanations and valuavle information. It turns out that twill actually will give better performance than plaine weave, even better is satin weave. This is due to the way the fibres run through the weave. Plan weave is up and down all the time, Twill (2/2) is half the ups and downs. In the satin weave it is maybe only 20% of the ups and downs making the fibre almost straight like the optimal situation would be.

Then the question is if satin is as easy to work with as twill. I would think uni carbon is difficult to work with, and not something I should try with my skills. And satin looks more like uni than plainweave to me. So can anybody tell me how satin weave is, compared to twill? When talking the skill needed to get a good result?

/Anders

40

Hi Anders,

You are on the right track and have come up with a pretty sensible idea of using the light glass cloth with 2 layers of woven

Looking closer at the picture of your laminated part I’d say the resin content is close to okay, maybe a little more next time.
The best thing to do in this situation next time is apply a “peel ply”. Normally a nylon fabric that you place as the last layer.
You apply it firstly with a dry brush, when it comes into contact with the carbon you see it wet out as well. If you have applied the correct amount of resin, it will wet out almost completely, but you then have to apply just a little more.
Any dry patches mean the carbon underneath is too dry. Pull back the peel ply and wet the carbon again, or work the resin through the peel ply.
Peel ply will also help with the pin holing. You can hold the finished component up to the light and see the pinholes, but, they are sealed over with resin. The peel ply form a very thin resin rich surface layer with fewer pinholes than a layup without.
Another good wet out guideline is to take the ‘square area’ (in meters) of cloth you wish to wet out, and multiply this by the weight of the carbon fabric you are using. This is normally the minimum amount of resin the job will need. Then add another 20% for the peel ply etc…

The only difference between Plain and Twill weave is that Twill is much easier to drape over complex shapes, particularly when you use it on the 45 degree bias.
However, Twill is a harder fabric to handle as it ‘frays’ from the edges easily and I have seen many beginners struggle with sticky fingers and strands of carbon all over the place… That’s followed quickly by frayed tempers!
There is no difference in strength as they are both a woven type cloth.
I have used a plain weave in my yachts female mould twice and it was a little close to the limit.
Just a word of warning - The plain weave tightens up quicker than a twill alternative, so if you have the option then twill will help in this area.
I would use the vacuum if you have the chance, especially in a female tool that is as tight to work in as these.
In my case - The ‘knuckle’ of the bow is the tight area that the cloth does not like to conform to without the addition of a vac bag.

I have a question, do you intend on dropping the boom height or are you purely looking for a better vang angle? (if you do lower the boom, it will drag in the water on a reach…):wink:

Good luck with the kitchen & workshop, maybe try and score some points with the GF and go ‘all out’ on Valentines day… Might just work!

Cheers, Jim