IACC 120 Fleet grows by 1 more again.

There you go , raising the bar again!!!..oh to have a toy shop like yours to play in mate…

Love to see a pic of the keel/ mast step frame work installed.


The mast structure is already installed, but I have chosen to keep this part under wraps as it is a significant design advantage…
I have shared much of my key ideas, they are discussed on here and seem to be incorporated into the rest of the class… and I want to be a little ahead of the game still!

Great to see you back with the ultra-lite Jim … had to laugh like hell when you were talking a mast structure, this was the major floor on my two NZL’s having the mast step “on top of the deck” I’ll never build another boat with that set-up again …current build is with mast through to the bottom of hull with mast ram.

Looking forward to seeing your new boat hit the water Jim, any idea when ?

Cheers Alan

Bit more progress this week… ‘put the roof on’ (deck) today and had the traditional beer to follow…

I am experimenting with a new mast as well, Its Pre-preg hi modulus… The test piece came in at 94g 2000mm long and over width. Its going to be a bit deeper so its quite stiff fore and aft with a width less than 7mm.

I propose that we make Astute and Claudio carry a brick in their hulls to even out the field some! JK!
I gotta say that I am more than a little bit jelous of your skills. I guess I spent to much time with balsa…
Looking at your mold, it doesn’t appear that the bow is closed off? And what is the material, and how was it machined?
I know I ask too many questions, if I impinge upon a trade secret, feel free to let me know that you could tell me, but then you’d have to kill me!

please go there, it is in Italian but the pictures are helpfull.
for the mould search part 4,5 an 5 annex
The reasons why my composire epoxy/glass mould are open, it is because is easier to pass through with a flat brush during lamination to ensure good adherence of tissues without air bubles.
4/5mm thick mould is very strong an rigid.

well that makes sense! I went through the above mentioned site, and have a couple of questions (surprise, surprise!) Do you know what caused the surface imperfections in the first mold? I tried to do a footy once, using polyester components, and wound up with the same problems in the gelcoat, albeit at a much larger scale. I attributed it to using a brush to apply the gelcoat, and started working on shooting the gelcoat on. I never continued in that vein, as it became apparent to me that glass was not the way to go with footies. I have since moved on, footies are nasty to sail well and my son was unable to control it. I used three layers of carnuba car wax, then a layer of PVA, then gelcoat, cloth and mat. Released well, but the mold sucked.
Is there any benefit to using cloth on the master plug? I know that many full scale boaters just use epoxy by itself over the wood.
Thanks for helping out a newbie!

Apparently the problems I met with the gelcoat are to be found in the poort mixing , probably too short time dedicated to that operation.
The second question : personally I cover the master with glass/epoxy in order to protect the wood from water, expecially during wet sanding.

Just gotta say that I will be carrying a brick in my boat, one to get to the minimum weight and not a gram more…
Not too many trade secrets here, the mould has been explained before as a cheap/low tech solution to a female tool.
You are correct, the front of the mould is left open… It would be very hard to laminate in a space that small without having a void.
The mould itself was from white cement mixed with fibre glass strands of various lengths to prevent cracking. The ‘plug’ was made from foam, and machined by me and using my ‘eyecrometer’.

I have another progress report and will post asap.

Cheers, Jim

Here is the yacht in the ‘official’ team colours…
I have used Durepox black for the hull the same as SWE 96 … no skimping on the original details here… I forgot, however to take a picture of the cockpit after it was clearcoated, so I will do that tomorrow. The whole yacht is now coming together, I am now starting to get the new mast and boom together and finish the fit out. The sheeting system and steering are halfway there.One feature is the new boat and the old rig are interchangeable but I would really like to do some 2 boat testing from the outset…

After a long day at work… here is the cockpit in clear.

Looking great Jim, did you consider adding a “adjustable mainsheet post” so that you can change the geometry of the main sheeting (relative to pulling toward centerline) for different conditions ?

Cheers Alan

Hi Alan,

Yes, the post will be adjustable… Just not for the maiden voyage probably. I am concentrating on getting into a sailing mode at the moment.
I have to utilise my time effectively to maximise progress without compromising on weight or quality.
Fine tuning will evolve later!
Thanks for the input…

Hi Alan, You can get the same main boom adjustment vs. centerline with a Servo Stretcher found at Servocity.com. Regards
PS. connected between servo and RX and controls the the throw of the servo to one side or the other individually

Hi Norman, maybe a little misunderstanding, it is not for adjusting servo throw, the sheeting post adjuster moves up & down (slider inside the sheeting post) to allow to have the main sheeting point as close to the main boom as possible following mast tiliting etc, as Jim says it is a fine tuning feature.

Cheers Alan

Thanks Alan, I finally know how it works. I will install one. Someone had suggested this to me but I didn’t listen.

Alan - just curious … why the mainsheet is attached so close to the mast - and not further back to improve leech tension as the boom is sheeted in closer to the centerline? Not enough “throw” on the servo arm for the amount of main sheet needed?


The whole idea of the main sheeting post is to use the main sheet to bring the boom closer to the centre without exerting any downward pull (that closes the leach).
The leach (twist) is controlled only by the vang tension, and the main sheet controls the angle of attack.


Thanks John, I should have explained the purpose …Dick I’m using a winch not arm, throw is not an issue. Maybe bit of optical illusion with the pic cut-off, hopefully new pic shows better perspective, if not I need to buy new camera :stuck_out_tongue:

Cheers Alan

my thoughts were …
the vang is not adjustable once on the water, whereas, a mainsheet nearer the end of the boom would provide leech tension in addition to the vang. Setting up the vang for minium twist before launch, but using the mainseet to add less twist is what I was looking at/thinking about. To move the boom attachment point further aft does take more line, more servo travel. If there was an adjustable traveller, it also could function in place of a vang with mainsheet further aft. Of course, whether vang or traveller - either would require an additional servo.