For me too!!! I’m complitely addicted :spin::bouncy::drunk: I’m just finished to build my 4th boat in two years!!!
Yeah and the sad part about Matt …is that is has his partner (Sara) is now heavily addicted too sheesh …now I will have a woman beating me too !!! 
no offense to Sara but please ask her not to be holding her GUCCI hand bag as she crosses the finish line in front of me please Matt :lol::lol::lol:
Sara during the first Round Robin 2010/11:
that is ABSOLUTELY the best view I have ever seen at a regatta!!!
Guys - just a reminder that the thread was originally intended to identify US sailors building to this class so they can tie in, and correspond with other builder/owners to further the class here. 
ok-i am starting to cut forms for the America3. I plan to build three boats total because there is NOBODY in my area sailing. This way I can take all three to the lake and let anyone interested have a turn. BTW i am in east Texas near Tyler.
Mike,
I have not yet started an IACC 120, but I am planning to this winter. Since I live in Dallas, we will have to meet up in the future. If nothing else, I will help you trial your building fleet when you have a cople of boats ready.
Cheers,
Eric Rosenbaum
Well, what is everybody using to build theirs? Everyone pretty much going straight fiberglass, or carbon fiber, or a combination? The ones I’ve seen in cruising around look pretty high tech, which also translates to high cost.
Hello, you can use fiberglass for the hull without problems, the final boat performances are the same respect a carbon hull.
I suggest you to use a little quantity of carbon only to reinforce the points with major stress (contact between hull and keel, rudder, mainmast supports, prinicipally).
The final cost of a IACC120, I calculated, could be nearby 600 dollars for the first boat (130 dollars for wood master, 26 dollars for fiberglass mold, 440 dollalrs for the boat) and 440 for the other new boats, using the same mold.
Cheers
Matthias
Hi Zimmermann,
The AC120 requires about 1.2m² of tissue to build an hull.
The costs for a full fiberglass hull will be 17.40€ or 23.50$ … (3 layers of 105g/m²)
the costs for a full carbon hull will be 95.40€ or 96.75$… (3 layers of 90g/m²)
the delta cost will be 73.25$ all the rest remains the same !!
Best regards
ClaudioD
I agree with the above, A fibre glass hull is the way to go, especially for a beginner like me. I think I did 4 layers of Glass (3 oz), but in order to get a 45 degree weave pattern, there tends to be a fair amount of clippings. I paid $6 a meter and used about 6 meters for the hull (4 layers) and deck (3 layers). add to that $50 for a meter of carbon cloth (6 oz) for appendages and reinforcing. Carbon or FBG, you still have to get the epoxy and assorted epoxy tools (scale, cups, syringes etc) to the tune of $65. I just did a rough estimate of my total building cost (not including tools) and I suppose the biggest shock was the Rig cost. There is so much talk about building the hull, but the Rig is where things count. While I clearly over built my Rig, weight wise (perhaps 100g or more over weight), I am extremly happy with the scale look, and the boat glides gracefully over the water.
In the end, Just Build it! The designs are top notch, you cannot fail!
Mike
Pictures ! Pictures ! Pictures !
claudioD
Hi Claudio,
I have my initial supplies and I am about to cut out stations for USA-36! Before I start a build thread, I had a couple questions about the drawings. I thought I’d share with everyone in case it helps someone else down the road.
Anyway, I downloaded the full drawing package from the iacc120 project site http://iacc120cup.altervista.org/Main0E.html
[ul]
[li]On the drawing page “YAM-A2.pdf”, on the side view of the boat, there are 2 horizontal lines. I assume the gray line is the waterline. What is the blue line?
[/li][li]On the page “YAM-0-5.pdf” there is a small station ahead of station #0 that is narrow (only 13mm). how far forward from station #0 does that fall? It’s not clear on the side view of the boat.
[/li][li]Last, on all the stations (should I be calling them “shadows”?), I am assuming that those reflect the final hull size and shape, and that I should subtract the thickness of the balsa planking that I will be using. Is that correct?
[/li][/ul]
Thanks in advance for your help!
Hi lamminkainen,
a) The blue line should represent the real water line according to some pictures seen here : www.martin.raget.com - obviously to meet the AC120 Rules some changes were necessary.
b) Correct is the base frame for the elastomeric bumper in case it is required, otherwise a bloc of balsa will be sufficient - this red marked frame is at 49mm +/-1 from frame ‘0’
c) Yes, you can call them shadows, sections or frames as you prefers. The dimensions and form refers to the finished product.
I do suggest to use different wood like samba or obeche because will be more resistant during sanding and will avoid to get at the end an ondulated hull skin.
Please to know you are starting this construction, you will be second so far I knows.
In attachment the drawing with more data - the balsa blocs are intended for the wooden master mold.
Cheers
ClaudioD
Ok, assembling materials here. I have access to 5 oz cloth or 3/4 ounce. I was thinking two layers at a 45 degree bias should do the trick. I also don’t want to go through the added expense of a female mold, and I saw on the building tutorial on the website someone using the plug as a male mold. I’m interested in this technique, anybody done it? Note, I don’t care about having to finish the outside of the boat, I’ve got some glassing skills, wont be hard. Also, what is everybody planning for the keel and rudder? Layups, or the more traditional formed wood and glass? It seems like a plaster mold would do the trick for these. Also, I plan on using polyester resin, as I have a bunch on hand.
Sorry for all the questions, every boat I have built was balsa with a glass skin. Pulling molds is gonna be a new one for me!
Kurt
I just built an IOM by making a balsa hull, glassed over, then used that as a male mold and made an all glass hull. Finish the wooden hull and cover it with glass, one layer of 5 oz and one layer of 3/4 oz should be fine. Wet the hull with resin, lay on the 5 oz and roll out, then lay on the 3/4 oz and roll on. Once dry, sand to remove wax, and add a finishing layer of resin. On the plug, polly resin should be ok. No need to use diagonal as the cloth is flexible. Once sanded smooth, I cover the hull with 2 inch packing tape, laid across the hull (not along), with small overlaps. Coat that with parting agent. I have not used this technique with polly resin, but it works with epoxy.
Lay up the new hull, use 2 layers of 5 oz with the 3/4 on the top. I would not use polly for this, buy a good epoxy resin. Use the same technique as for the plug, ie wet the surface and roll one one layer, then the next etc. Leave on the plug for a few days to fully cure. It pops of quite easily.
Here are some photos.
http://s642.photobucket.com/albums/uu146/hiljoball/
John
Okay, but why use packing tape? Why don’t you wax and PVA it? Also, why wouldn’t you use polyester for the actual hull? Is it something to do with the flexibility, as I’ve noticed epoxy is way more flexible than polyester? And, why bother with the 3/4 ounce on the plug?
Thank you for your speedy response, and sorry if I ask too many questions. There just seems to be alot of different way’s to do this.
Thanks!
Packing tape - faster, less cost, than wax plus PVA for release. John didn’t note it, but if you use packing tape, apply at a slight diagonal angle to keel so it will take a compound bend near bow. Otherwise difficult to get to lay smooth due to compound bends.
Epoxy is a glue as well as a laminating resin. For me, it is easier to mix than polyester - but that is just me (and my experiences)
When building over a foam plug (male) I use two layers of 4 oz. over the plastic covered foam, and a final layer of 1/2 oz. more for pinhole leaks and some spot strengthening around keel and rudder. 1/2 ans 3/4 oz. is very fine weave and easier to fair - plus it takes less epoxy/resin to fill the glass fabric between threads. You could use 10 oz. cloth, but the hull will become resin rich which equates to “heavy”.
In the end, the deck will/should provide a lot of strength to any flex in the hull. (“Oil Can” flex of the sides.)
Interesting, do you use a solid blue foam for the plug? I would imagine it would need to be solid.
I’m asking about the polyester more because that’s what I have on hand, and the model boat supplies fund doesn’t look good. I’ve got materials, but not sure if I have enough west sytems left to do a hull and deck.
Packing tape is a really good idea, does it release clean from the glasswork, or does it destroy the foam mold?
By the way Dick, hows your rg65m going? I’ve had nothing but problems with mine, kinda looking forward to building something bigger!
The foam I used is either blue/pink/gray (depends on supplier) and is the extruded (NOT EXPANDED - the white “bubble” stuff) and is more dense. You can cut with saw, shape with 80 grit sandpaper or belt sander, and finish with medium sandpaper. Any dents, dings, etc. can be filled with wall board compound (used for taping the seams) as it sands well. Apply tape on diagonal to allow it to conform to compound curves/bends. Overlap sligtly to keep epoxy away from foam and allow glass hull to be removed. I usually run a popscicle stick around the perimeter of the hull/deck edge and it takes a bit but you can “spring” the hull enough to remove. Put back on to allow full cure - and give a base for fairing and fill of exterior of hull. You WILL have lines inside the hull where tape overlaps, but they don’t transmit to exterior of hull layup… don’t worry about them. Leave bow and transom open as it will help you spread hull enough to remove from plug. You can glue bow together (or add a flat panel of balsa) to which you can glue bow bumper if used/needed. I only use epoxy - so can’t comment on polyester - other than it will “melt” any of the foam it comes into contact with.
You can carefully remove the tape from the foam - and it seems to come off clean and without problems, if you left the sanded surface finish a bit rough … go figure. That’s why I use about 150 grit sandpaper. If you go at it with the belt sander (or orbital) keep watch - as when the foam heats up it turns into a very hard “plastic” finish and you will have to cut out that part once it gets hard and fill with joint compound. Not to worry - but just practice shaping on scrap first. If you remove tape slowly it will not destroy the mold.
In the photos below, the two of the pink “cat” hulls are of rg65 size for the 65M Class (25.5 inches long) and the photo of the tirmaran in the bed of my old truck is a 1 meter size - hollow hulls that were glassed over a foam male plug. As for RG65 - Finished the first three (last one was for son-in-law) and now working on swing rig for my own. Check RG-65 thread - don’t want to bring that here in this topic.