Some pictures left before bonding the deck
Under the deck - the servo arm
The sub-assembly parts composing the forstays support
The support positioned inside the bow ready to be bonded.
Notice that the jib rack is recessed from the deck level as visible in this recalled drawing.
This solution should allow to put the jib much closer to the deck increasing therefore the efficiency.
Claudio
Hi Claudio,
My sense is that the ‘lead’ of 105mm will be way too much and that you will have severe lee helm. But with the long mast step, you will have plenty of scope to adjust fore and aft (remembering that this is a prototype).
Your design has a very flat run and should track well, but may be a bit slow to tack as there is virtually no rocker.
John
Hi John,
I like your interventions because are forcing me to see differently my own design. Thanks.
What do you think about Open 60 or VOR ?.
Why, according to you, the next America Cup boats should look like this sketch ?
My “bet” is to copy and elaborate around these designs. All these concepts have almost no rocker and the bottom is rather flat.
Some pictures of VOR and Open60 ‘seen’ differently :
Here, the mast step is closed to the fin beacause the CE is rather advanced due to to the large jib surface. Notice almost no rocker ! Very often the CE is closed to the mast as for the IOM model, therefore closed to the fin .
the same boat seen under :
A VOR type :
Another one :
Everybody knows that this type of hull is very fast in all points of sailing except in “close hauled”. In my opinion, one could win a race exploiting the reaching caracteristics.
Still remain the question :
Why America Cup AC33 boats, racing in close circuit (banana), should have choosen that hull shape ? Actually nobody knows what will look like the next AC boats !
My model, without pretending, will try to bring me some answers to my many questions, the simplest way is to design and make it. As said before, if will be a total fiasco I will tell it.
Being uncertain about, the mast position will be widely adjustable in order to cope with various sail design and surface"s ratios I have in mind . The fin/bulb are positioned under the CB and only one rudder is used but positioned more close to the fin otherwise will go out of water at 30° of heeling.
John, according to your experience, have you an idea of what could be the right proportion between main and jib in relation to the sailing points ?
Many Thanks
Claudio
PS: My FUXIA way of looking at
Last idea !
Stefano was searching how to measure the Bow and Stern height above the Water to verify the design conformances and to check if the boat is floating on his lines.
Further to measure the stern down position of about half cm to compensate when is navigating.
I proposed to him what I called the “floating decimeter”
Here is shown the prototype :
just a cork recovered from the finest wine bottle of the day before, a fishing lead of about 7/8g , a carbon rod of 2mm and 30cm long (luxe version) and a piece of paper marked every 1/2cm rolled around the rod (the chipest solution) !
This ‘instrument’ shall be used on calm waters, nevertheless is moving up and down like the boat model, therefore the relative difference should be rather constant and shall not be difficult to collect a measure.
Any other suggestions ,
Cheers
Claudio
PS: obviously the big tankers have the floatig/load levels marked on the Hull !
The “floating decimeter”
and the real application on the Stefano AC120 Alinghi SUI-100
This control is useful to check the horizontality of the water plan and to modify the setting of the boat. Of course the drawing plans are required for cross checking.
Claudio
ok now that is good… makes me feel kinda of dumb… that is pure genius…
I think i know have to realy look at a iacc 120… but i want oracle
that boat looks amazing
Hello World
you want to see a true AC?
You see here http://www.youtube.com/watch?v=L_yFy0Ai3yk
Others videos search ReArtùLunablu (I’m ReArtù and LunaBlu is my wife:))
It is my first boat …designed by Claudio:zbeer: I thank him very much:D
The lake is Etangs de Villepey St.Aygulf - France…guest of the club claudio with all my family,and I take this opportunity to thank the chairman Pierre and all members of the club for this initiative.
About floating decimeter I have a small problem with the LWL but it is enough to drink a bottle of finest wine and everything is back in place:D:D
Thank you for this small space
By by
Stefano
Hi Claudio,
I am not a nautical engineer; I am a sailor with (far too) many years of experience!
My thought is that these AC type boats are built to go fast in a straight line. In match racing, it would do no good to build a boat with lots of rocker and can tack fast (for a tacking duel), if the other boat just sails away from you.
As to jib sizes, it is hard to compare full size to models. The wind does not scale. And we sail at the bottom of the wind gradient.
Full size boats take down their jib/genoa and put up a spinnaker off the wind… options that are not available in most RC classes. We make do with a jib boom to project the jib area when sailing off the wind.
Also, the class rules dictate the shape of the boat and its sail plan - eg. if the head sail were fully measured in full size racing, there would be far fewer overlapping headsails. The rules usually measure the foretriangle and allow a 'free ’ overlap to some specified max. (eg 150% of J - the foretriangle).
My big boat experience led me to believe that the jib generates more power per square inch than a main sail. Back in the 1970’s I built an RM with an unusually large jib to main ratio - I finished second in the very first RC World championship at Gosport in England with it. I also had a 10R with a 50/50 jib/main ratio and masthead rigged. That boat was not competitive as it had too long a waterline and insufficient sail area. . .just shows that there are many factors to consider.
Now I race IOM and the sail decision is taken away. Sigh!
Your sail plan looks just fine to me.:zbeer:
John
Hi John
conclusions : I have to wait !!!
Cheers
Claudio
I have to wait more now that I have removed the ‘bridge’
I did not like it…
to remove it I was solid to break, too solid ! hope to spare some gramms…
the Floor
Claudio
While I’m thinking about a lighter solution for the “bridge”, I started making the 2.85kg bulb master shape in view of preparing a silicone mould. - I will use the RTV 139 that is specially supporting temperatures above 320°C and very good for lead melting.
Important to knows that the lead I use have a specific weight of 9.95g/cm3 as measured against the teorethical weight of 11.34kg/dm3. A friend of mine found a lead of 10.3g/cm3.
The bulb drawings are done with the Bulb Calculator and the correct values are inserted in the various cases.
The bulb will be larger of course. If at the end the weight will be more than required, I will drill some holes.
One hour and 30 minutes later :
Some mastic and warnish and the master is ready for the moulding
Claudio
Hi Claudio,
I have used a two part, RTV silicone, Mold Max 60 from http://www.smooth-on.com/Silicone-Rubber-an/c2_1113_1135/index.html to make a mold for pouring lead, but wonder if the expense and labor involved make it the choice for only one or two castings.
Has anyone used plaster, or similar, for mold making to pour lead? The one I tried to use must not have dried enough, and began cracking after the first pour, and after 3 pours was in 5 pieces instead of two! I have been meaning to try again, and let the plaster dry for several weeks before use. Or maybe try making a mold from concrete.
Hi Hew,
after the drammatic experience of a friend where the mould almost exploded and the breaks of my 1/2 mould dried for 3 months, I told myself , don’t do it again .
Plaster need several months to dry not simply weeks, most depends also on the ralative humidity left inside. Heating is not good, may start introducing invisibles cracks.
For the bulb I need 450 cm3 of silicone RTV139.
1 Kg RTV cost me 36€, let says now some 36$ - with 1.5kg I can make two molds of different size.
Obviously, following my way of looking at, is much cheaper than to go to the Urgency Care.
Not only I avoid toubles, but the bulb will be available in 24 hours.
Cheers
Claudio
The Bulb Box
The following images are 2 months old - this is a typical amateur bulb production.
Preparing the Mold - pouring the RTV 139 inside the box. Previous mapping all the surfaces with vaseline .
Here the dual box was made because the master was a full bulb shape. The bulb was pressed into plastline for one half.
The dual box:
24hrs later !! Stefano started pouring his first bulb
just cooling
The 1/2 end product for 1417g
Claudio
I was having trouble with the plaster mold breaking. With the last one I incorporated some fiberglass concrete re-inforcing fiber. It’s fiberglass that has been chopped into 2cm pieces and is mixed into concrete to add strength. I got a bag from my local ready-mix concrete outlet. I mixed it in with the plaster. It tends to lump up when you mix it but it seems to work. I have poured four bulbs with no sign of cracking. You do still have to wait til the plaster is dry and the longer the better, a month at least. Make it the first part of your next boat or better still, do it now and it may be ready when you need it.
Don
Thanks Don,
good to knows, but I stick to the RTV, any bulb form is ready in 2 days and no splash risks anymore ! like a burn cat is fearing now cold water !
Cheers
Claudio
A friendly warning: those appear to be lead fumes coming out of the pot. If so, they are the result of overheating the molten lead. Breathing lead fumes is the most efficient way of getting lead into your bloodstream.
It is very important when melting lead to heat it just up to the melting point and no further, do it outside (as here) and stay upwind (which I can’t tell from the photo). In the US, the Lyman Co. makes a thermostatically controlled “pot” used by the people who cast their own bullets and which reduces the chances of fumes.
A good friend of mine poisoned himself this way, just below the point where he would have required chelation therapy, which is no fun 
Of course, he was melting a couple tons of tire weights in a cast-iron bathtub for a full-size sailboat. Be careful with lead, the more we learn about it the more toxic it turns out to be. No reason to panic, just exercise ordinary care.
Again, not a criticism but just a caution.
Cheers,
Earl
Hi Earl
Thank you very much recalling the dangers !
VERY GOOD WARNING !!! VERY GOOD WARNING !!! VERY GOOD WARNING !!! LEAD IS DANGEROUS !!!
Stefano that day was outside and fotunately carying a mask !!
Cheers
Claudio
The master bulb is ready !
Some asked if it is an 1/2 bulb or a full one !
Claudio
Hi Claudio -
this one left me confused. Isn’t the red colored liquid the mould for the bulb? What is the “master bulb” and how is it different from the lead shown having been poured.
Also a personal question - is Stefano’s last name Sesso ? If it is, is he still involved in multihull r/c models? If not, must be a different person.