Don’t worry Alan, the decoration is the only part that I din’t designed myself just copied !.
Cheers
Claudio
Hello Claudio…remember this lake(Idro)???
Now AREVA …
Very well Tiziano, in 1948, I put in the water my first sailing model the “Ninfea” a sort of Star 80cm long. I was only 12 years old.
Very nice to see another AC120 (?) in the water called AREVA. Hope to see more in future…
Sorry for this small OT, for those that like to knows where the Idro lake is :
Cheers
Claudio
Hi All,
I’m back from holidays, renderman I was looking closely at your AC 120 pictures posted, nice boat and there seems to be a pole on the fore deck, may I ask what this is/does ?
Cheers Alan
Hello K1W1…i have copy from Claudio…look this …it’s symply to manage…
Very interesting 
… there seems to be lots of options to consider when planning sheeting systems, I would like to have a clutter free deck and wish to run an all closed loop system below deck and have both main and jib sheet feeding (via pulley/block on at the base of shrouds) from the one fairlead in cockpit deck to increase water proofing (no Jib fairlead)
I have attached a sheeting plan I have been thinking about :rolleyes: it shows one pulley/block in the bow attached to one of two bulk heads (with spring tension) the two bulk heads are hull supports for jib pivot bridge (80 mm apart) and the jib slides fore and aft in a traveller on the deck bridge with the pivot point fixed on the boom.
Second block/pulley is in the stern, I need to figure out a way of fixing to the hull, would simple small piece wood with the block screwed to it, be enough Claudio ?
Further I need to plan for cutting inspection holes in the deck figure on 1) acess for winch servo/Rx/battery bridge on the fin box 2) Rudder servo inspection 3) fore deck inspection just in front of first bow bulk head for spring/block access … am I on the right track Claudio or do you have some tricks up your sleeve to make it easier ?
Finally (sorry for so many questions at one time) what is the best way to fix the sheeting trunk (6 mm CF tube) so it is strong enough, just epoxy on bottom of hull and underneath the cockpit deck ?
Cheers Alan
P.S broke 100 posting marker …Senior member !!! Dick I still have my “L” (Learners) plates on … lol :jump4:
error during reply
Cd
Hi Alan is ok .
Instead the jib sheeting need to be modified.
From the jib pivot to the boom sheet attachmente point, the distance shall be at least 10% longher then the one of the Main sheet.
The sheet attachment to the jib boom should be at 265mm minimum instead of 240mm.
For the access for inspections you are free to do what you prefers. The ‘holes’ will be covered with adesive film as used for real sail repairs
Cherrs
Claudio
The Sheeting System :
To remark that during Tuning it may be necessary to adjust the Jib sheet attachment in order to control the opening. In the drawing the basic selected distance is 270mm against 240 for the Main.
In the plan it is assumed that the Mainsail boom, when fully closed (close hauled) it is about 15mm from the fairlead or about 4° from the midle line. When fully open the boom is at 85° from the midle line.
The jib boom when is ‘closed hauled’ it is adjusted statically at about 50mm from the Mast side. When fully open (running) will be open at an angle lower then 80°.
This angle will be trimmed by moving the sheet attachment point on the jib boom
The back pulley shall be at sufficient distance from the Main fairlead in order to allow the sheet travel lenght, in this case for 240mm are needed 310mm of sheet lenght to allow opening of the Main boom of 85°.
Cheers
Claudio
When the servo winch power is not sufficiently powerfull, one possibe solution may consist in reducing the couple needed by increasing the swing arm. Compared with the above drawings the Mast-fairlead of 240mm is icreased to 255mm. The sheeting lenght is therefore increased to 330mm against the 310mm of the previous drawing.
The Iib boom is always closer (85° against 77° - to be confirmed by tuning) than the Main boom once ‘running’ , while is more open (10° against 4°) when in ‘close out’ - initial static adjustment. Someone may claims slight variations to what expressed above in view of personal experience.
This exercise is just presented in order to explain about the various possible solutions and compromises that can be choosen.
Cheers
Claudio
Claudio, great information which very helpful for set-up and tuning, thank you
I’m planning the hull fit-out now and wish to double check with you:
-
Measuring the position of the Jib pivot point for position of the jib slider on the deck, have the jib pivot point at 25% of boom chord, now need to calculate the position of the jib slider for positioning the fore deck bridge. Are my measurements that I’m working with (see attached graphic) are correct, including 35 mm between Jib Leech and the mast ?
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With the Main/Jib fairlead in a fixed position on cockpit deck, when changing between sails suits (78 & 74 dm2) the distance from mast to fairlead will change, example: if I set 74 mast position to be 240 mm from fairlead, when I change to 78 the distance from mast to fairlead will be 216 mm, what effect will it have ?
-
When assembling the main boom to the mast, is 75 mm from deck to top of boom ok for both sets of sails ?
Excuse my rough adaption to your wonderful graphics please !!!
Cheers Alan
Hi Alan
I hope this drawing will help you and the others in case is decided to use differente Sail Plans.
As a general view, the jib slide is non much different and a 60 mm length will satisfy booth jib, instead the change affect the fairlead for the Main.
The fairlead distance from mast remains 240mm, but the fairlead chenge position because the Mast step change to. In practice the solution of 2 fairleads is a solution. One could immagine a sort of bridge, wide enough to include 2 holes for the sheeting to the boom.
The mast step slide can be 70 mm long.
All that is of course valid for the sail plans configurations examined. Any change , i.e. in terms of surface ratio between jib and main will require e new check.
At glance it seems that a displacement of an additional 20mm Mast advance is tollerated to satisfy Tuning requirements for booth sails arrangementes.
…
The standard fairlead - mast distance of 240mm is valid for booth sails , nevertheless this distance may change if the servo power is not sufficient to keep the mainsail closed.
Doing that it will be necessary to readjust the jib boom set-up. - See previous drawings.
The Main boom height may be set between 65 and 85mm from the deck to the Top of the boom.
Please observe carefully all the recents drawings since all the informations you ask are included .
Cheers
Claudio
Wow !! … :what: that’s thrown a spanner into my planning … two fairleads !
Claudio I clearly understand the theory, however, I can’t see having two fairleads being very practical, changing sails for different conditions would be a major exercise in changing sheeting from one fairlead to another.
How does Matthias, Alessandro & Luca go about this ? I have not seen two fairleads on their boats or on any other RC yacht for that matter.
The first instant thinking is having dedicated sails on two boats (which I have) don’t change sails but change boats that have different sail plans, but I don’t think the IAAC 120 rules allow for this, Matthias can you give clarification on this ?
Having said all this, until I can test both sail plans in different conditions, at this point I have no idea if there is any real significant difference between my two sail plans (78 & 74 dm2) maybe I need to compromise here :watching_
Are there other options that can be explored ? :help:
Cheers Alan
Alan,
you can use a different boat per day of regatta. If the regatta goes on only for one day, obviously you can use only one boat. If the regatta goes on for two days, as during the IACC 120 Italian Cup, you can use one boat one day and another boat the day after.
Are you working for the Italian Cup on 3 and 4 October? We are waiting you :zbeer: !!!
Cheers
Mat
Regard the fairlead, we use only one; if you use a hitech 785 HB, and a fairlead distance of 250mm (as me) I can assure you that the servo’s power is perfect (if you use 6.0V).
Cheers
Mat
Hi guys…
Remember me? 
Man I have been swamped lately, but started building the keel yesterday so at least there is some progess.
Wow K1, you are streaking through this, great work mate. :zbeer:
Q: Is the keel a constant thickness of 8mm along the full length at 40%?
Or did you taper the keel down to say 6mm at the bulb end.
Cheers!
Goose
Hi Goose,
is tapered
I just taken part 2 of my constructional report , sorry is in Italian, but the images are self explanatory in showing the method used.
As a tracer I inserted, between the balsa layers, a carbon sheet (black) in order to observe the converging shaping during sanding. Any contrasting method would help in controlling the work, could be a red paper, or else.
Starting from 8mm and going to 6mm is OK
Cheers
claudio
Alan,
as as said , you can use a sort of bridge across the deck with 2 holes or a re-positionable one with a couples of screews.
Yes there is difference between the two plans as the wind grows.
In one of the last deck drawing I suggested a 255mm instead of 240mm depending on the servo capability to close haul the main.
Matthias has a large experience with this class and is the best person to ask suggestions in selecting the rigs adjustments.
Cheers
Claudio
Wow, that is very unusual and not normally allowed.
I would question the wisdom and legality of such a regulation.
Raised in the best interests of clarification only. :scared:
I LOVE IAAC 120 … lots of possibilities to work with and very little restrictions unlike the IOM class.
Ok … let’s see if I understand this correctly, the only reason for the different fairlead positions is so that servo works in it’s full capability to close haul the main ?
Matthias with you using Hi-tec 785 HB with one fairlead at fixed 250 mm position, you can change sail plans and the 785 HB works within it’s capability ?
Yes I working toward Italian Cup for 3 & 4th Oct, not sure if I can have one boat ready in time, but I’m trying, will send you seperate PM :zbeer:
Claudio, one minor point in regard to 78 plan graphic posted above, your graphic shows Jib foot length at 455 mm, my plan Jib has 439 mm foot.
Goose you changed out your Batman suit 
… great to hear man. A friend is looking onto making CNC alloy fins, would you be interested if we find out that it can meet all design & function creatrias ? in process of making CAD drawing first.
Claudio is there any chance you may have AC 120 CAD drawing in your files for keel & rudder fins ?
Cheers Alan