ETNZ IACC120 Dual build thread

[K1W120]

Nice looking hull, are the graphics under last layer of FBG Mat ?

Claudio, fitting out the inside of hull using mock balsa item to check everything works, two questions:

1. How far should the “top” of the rudder post be above the water-line ? hole at the bottom of hull is approx 4-5 mm below LWL. Was thinking of using 25 mm wide, 75gsm carbon band as support across width of hull, as shown pic with mock-up balsa.

Rudder servo is GWS IQ-200 MG

2. How low can I put the servo bridge ? thinking of keeping weight as low as possible, currently pic shows mock up of bridge positioned at the water line.

Winch servo is Graunper Regatta

Cheers Alan :zbeer:

[claudio]

Nice looking hull, are the graphics under last layer of FBG Mat ?

Claudio, fitting out the inside of hull using mock balsa item to check everything works, two questions:

1. How far should the “top” of the rudder post be above the water-line ? hole at the bottom of hull is approx 4-5 mm below LWL. Was thinking of using 25 mm wide, 75gsm carbon band as support across width of hull, as shown pic with mock-up balsa.

Rudder servo is GWS IQ-200 MG

2. How low can I put the servo bridge ? thinking of keeping weight as low as possible, currently pic shows mock up of bridge positioned at the water line.

Winch servo is Graunper Regatta

Cheers Alan :zbeer:

Hi Alan,

Question 1 see updated TNZ drawing here below - the stok should stay just below/flush to the cockpit floor. The minimum power needed for the Rudder can be around 3 kgcm - 6 kgcm is already high, you may use a smaller one if you like it.

Question 2 Which servo you refers to ? If it is the winch depend if you prefers running the sheeting above the cockpit floor or below. This will fix the height of the drum, if it is the rudder servo then so far the rods are working properly without friction let says at 90° of the rudder stock .

Cheers
Claudio

[K1W120]

Claudio, thanks for the update on mast positioning.

My apologies I was not clear about Question 2 above: I was reffering to the the sail winch position beside the fin box, in particular the beam which the RX, batteries and winch servo sit on.

I am running all sheeting below all decks and was asking if there problem lowering this beam down to the water line or lower if possible, providing all sheeting is aligned of course.

Cheers Alan

[claudio]

Claudio, thanks for the update on mast positioning.

My apologies I was not clear about Question 2 above: I was reffering to the the sail winch position beside the fin box, in particular the beam which the RX, batteries and winch servo sit on.

I am running all sheeting below all decks and was asking if there problem lowering this beam down to the water line or lower if possible, providing all sheeting is aligned of course.

Cheers Alan

Alan
you can put as as possible the winch and running all the sheeting under deck so far you will provide the exit to reach the boom. The only place is to pass trough the cockpit floor .
There is a danger tha the guide tube could also become a water passage. This what I have done on the AC33, but I decided to change even I did not experienced water leakage.
Ciao
Claudio

PS : I will work on a drawing

[K1W120]

Good news thank you Claudio as I would like to have as much weight as low as possible in the hull.

With the updated mast position posted yesterday the deck loop under the Jib boom has now moved to be approx 40 mm away the top of the Fin bridge, my concern is that there is no support for this deck loop (flexing FBG) in this area, my question here is, does this need support given the tension that will put on this loop ?

Cheers Alan

[claudio]

Good news thank you Claudio as I would like to have as much weight as low as possible in the hull.

With the updated mast position posted yesterday the loop under the Jib boom has now moved to be approx 40 mm away the top of the Fin bridge, my concern is that there is no support for the Jib boom loop (flexing FBG) in this area, my question here is, does this need support given the tension that will put on this loop ?

Cheers Alan

My answer is “yes”
You need all the times under deck suppots for all items to be fasten above deck like small bridges as here.
Here below the other set up for sheeting below deck and a view of sheets routing above deck as the mast and jib boom may move as function of sail’s plans. Personally I prefer to use obove deck sheeting since is less complicate.

[K1W120]

Thank you great graphics as usual I believe the small advantage of putting weight as low as possible in the hull out weighs the slighty more complication of putting sheeting below deck, personal limited experience.

One further question which may show my lack of knowledge in sheeting I would to have the sheeting to be as compact as possible, using your graphic, are there any implications of moving the stern pulley more forward, fixing it behind the rudder servo ? (see illustration 2)

Thinking behind this 1 less mounting point (little weight saving) 1 less cockpit deck inspection hole (waterproofing) no possible snagging with rudder horn as line does not cross over rudder linkages any longer and possible reduced line sagging (due to shorter line).

Cheers Alan

[claudio]

Thank you great graphics as usual I believe the small advantage of putting weight as low as possible in the hull out weighs the slighty more complication of putting sheeting below deck, personal limited experience.

One further question which may show my lack of knowledge in sheeting I would to have the sheeting to be as compact as possible, using your graphic, are there any implications of moving the stern pulley more forward, fixing it behind the rudder servo ? (see illustration 2)

Thinking behind this 1 less mounting point (little weight saving) 1 less cockpit deck inspection hole (waterproofing) no possible snagging with rudder horn as line does not cross over rudder linkages any longer and possible reduced line sagging (due to shorter line).

Cheers Alan

Yes Alan it is possible with the drawing you refers to, where the sheeting is inverted coming from the bow side. The problem is always the same , one should try to find a set up that allow the sheet travel lenght needed to open the main boom at least to 85°.
Actualy with the slope of the cockpit floor was not posible, with the pulley repositioned forward, to set the lenght needed of 33.6cm, therefore I have inverted the sheeting travel and reversing the pulley with spring. Probably you can close the servo to the stok and recessing the pulley. You will see anyhow once mounted and before closing the deck.
Do not worry too much about the servo weight positioning, changing the height of a couple of cm will not change the boat equilibrium : 110gr x 2cm against 2850gr x 38cm
I suppose you controls the boat weight progress, should not be a problem since you need to reach by the Rules, a minimum of 4500gr and if come out 4600gr will be still OK, remember the design lines are still ok with 4638gr , see ETNZ draving Plan.
By the ways all plans are revised to take into account the new Mast position. All plans should be soon availables with Matthias site.

Cheers
Claudio
I hope is OK for you

Cheers
Claudio

[K1W120]

Ok final check, have repositioned everything in this mock up, note that I have made allowance for 400 mm sheet travel from front block to fairlead.

Rear block is spring loaded and made front block out of 2 sheets of 4 mm play laminated together size 20 x 50 mm which will be epoxied to side of the hull …?

Claudio …everything look ok to you before I go ahead make final components and epoxy everything in ?

Cheers Alan

[claudio]

Very good Alan
Cheers
Claudio

[rfyacht]

Hi Alan (K1W1)

a quick question, what make is the block you are using? it looks like a very micro ‘micro block’ from big boats?

thanks

rob

[claudio]

Sorry Alan if I anticipate your answer.
Please see here : http://www.cap-maquettes.com/ You can choose your language.
Fist click on the left top corner ‘capmaquettes’ then ‘sailing fitting’ and then ‘blocs’

Various blocs models, from diameter to ball bearings.

Cheers
Claudio

[K1W120]

my teacher knows me too well :zbeer:

[Zaphod]

Ahhhhhhh…

Ok, I can’t resist anymore

Next new build will take place in Sweden. For the time beeing I’m searching for places to buy all material that I need. Updates will come as the build progresses.

//
Z

[claudio]

Most welcome on board, I’m delighted
Claudio

[Zaphod]

Tnx, I’ll try to make U proud of my work

//
Z

[claudio]

Tnx, I’ll try to make U proud of my work

//
Z

I’ m sure of that !
Thanks
Claudio

[Roman]

ok guys… just spent the last couple hours reading this whole thread…

And now you got me hooked!

I was actually just browsing the web to find some general information on composite boat building as I have the stupid idea of building my own (real size) boat for quite some time.

Building an IACC 120 seems to be a good starting point.

Claudio, I have downloaded your plans and will use them as inspiration to come up with a fictional ACC like boat, that will fit into the class rules (they are already printed out and will be studied tonight).

This will be my first build from scratch, but not my first RC boat. About 20 years ago I built a “Fairwind” (K1W1 seems to have one of them too )
and I still own that one.

Thanks to all of you for writing so much in this thread and all the experiances shared so far. Keep up the great work.

Roman
Switzerland

PS: the real size boat I plan will be just big enough to seat 1 crew and LOA will be around 11’ to 12’ and will also be ACC like.

[Zaphod]

Reading trough the tread (once again) I can’t find the hull former plan; see attached picture.

I’v looked trough all the files posted earlier, but no luck…

//
Z

[claudio]

Roman ,
I read you post and ti is interesting what you says.

The plans as they are are not suitable, in my opinion, to make a scaling-up.
You will get something that will be not what you expect.

assume 3.0 metres long boat 10’

Example : from 1.20mt up to 3.0 mt you have a scale of 1 : 2.75

the displacement of an enlarged boat will become : 4.5kg x (2.75x2.75x2.75) = 93.6 kg total displacement
the bulb at 65% of the total displacement will be : 93.6 x 0.65 = 60.8kg
It remains 33 kg for all the rest, including rig , hull and appendages.

To all that you need to find additional volume to support the passenger unless you remove the bulb
using only the fin blade !!!

Further the boat will be propably not nice to see.

Little step back to explain why :

the initial idea for the AC120 Class, was to make a replica of the recents America Cup boats scaled down to 1 :20

Fine, let see what appens!

AC Cup LOA…24 meters : 20 = IACC120 model LOA 120cm
AC Cup DSPL …24 tons / (20x20x20) = IACC120 model 3kg total displacement
AC Cup Bulb…20 tons / (20x20x20) = IACC120 model 2.5kg

From the above it is evident the difficulty to build a model of 120cm for only 0.5kg

In order to create a “feasable” model, was decided to “inflate” the hull loosing similitude from the real, but managing to obtain a displacement authorizing the construction. The “inflated” boat was displacing 4.5kg (50% more then the scale) and a bulb was fixed to 3kg equivalent to 66% of the total.
The real AC Cup had 20tons/24tons = 83%

So all that to demostrate that the “inflated” hull lost similarity with the real and now scaling up this model will produce …

By the way exsist already the International class 2.4 e sort of mini 12J developped in Sweden and actually gone all over with regular World Championship every year.

LOA 4,182 m
LWL 2,978 m
Beam 0,720 m
Displac. 259 kg
Sail area 7,39 mq

To knows more : http://www.inter24metre.org/photo/index.htm

I hope to have explained something about the origin of the AC120 Class and my doubts about enlarging the model over a certain dimension.
Any help don’t esitate.

Cheers
Claudio