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Old Apr 06, 2012, 07:36 PM
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I forgot to mention, rather than using Testors model glue to glue the transom to the hull I used M.E.K. I held the transom in place and used a dropper to let the M.E.K. run down the seam. It worked really well. After that had hardened I took some of the hull scraps that I had cut off and dissolved them in some more M.E.K. and used that polystyrene paste to fill in the cracks around the edges. This was my first time to try this. I'd highly recommend it. Other than needing a little patience while the polystyrene scraps dissolved the process was very straightforward and resulted in a very strong seam.
Cory, the boat looks great. I have to say, thats got to be the highest tech(and well built) A3 around with all the vacuum bagging going on!! Nice.
The Victor Soling guys use MEK all the time. It does work well. I would think solvent welding like that would be better than glue. Keep us posted of your progress.
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Old Apr 06, 2012, 11:04 PM
I DS slower than I build!
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Thanks. I figure a little use of aircraft building techniques couldn't hurt a boat. I have to make a conscious effort to try to keep it light, though. Most of my planes are slope gliders and many fly with ballast, so I don't try very hard to keep the construction light on them. I only have one glider that is a light floaty thing.
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Old Apr 07, 2012, 04:41 PM
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I wouldn't be too concerned about weight with an A3. Its a heavy US1M by design. A few extra ounces down low won't make much of a difference. Keep the rig as light as you can, and as much ballast in the bulb as possible.
My carbon and kevlar ultralight US1M's need to be very weight conscience. I use a gram scale and weigh everything that goes into them. They are also between 5 and 5.5 lbs all up sailing weight.
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Old Apr 08, 2012, 01:52 AM
I DS slower than I build!
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So what's the main difference between a heavy and a lightweight US1M? Since the lengths are the same is it the beam measurement of the hull, which would affect displacement? So is a heavy US1M wider than a lightweight? Are there advantages to the heavy design in certain weather conditions?
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Old Apr 08, 2012, 12:59 PM
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So what's the main difference between a heavy and a lightweight US1M? Since the lengths are the same is it the beam measurement of the hull, which would affect displacement? So is a heavy US1M wider than a lightweight? Are there advantages to the heavy design in certain weather conditions?
The A3 is an older US1M design. The first US1M's were called Olympic One Meters and became a class in 1982-1983. I remember it well.

The first of the breed were wider and around 8 lbs all up(or more). Gradually they evolved into narrower designs with higher tech materials and they became alot lighter. The newest, most competetive designs are between 6-7" wide(some narrower) and displace between 5-6lbs, with 4 lbs of that being the ballast bulb.

The heavier designs can still show good speed with the proper rig fitted in heavy air conditions. Being heavier, they tend to come about better in waves having more momentum. In light air this extra weight is a disadvantage, as weight is the enemy of acceleration. My 5.5 lb Venom will absolutely crush my A3 in drifting conditions(and most other conditions as well) as it accelerates in every puff, whereas the A3 takes more consistent breeze to get it moving.

The ODOM(one design one meter) is based on a classic Mistral US1M, hence its 8+lb displacement. I think the other US1M that Victor offers is based on a Mistral as well.(can't think of the name just this minute)
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Old Apr 08, 2012, 01:11 PM
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Here are a few pics of my Venom and A3.
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Old Apr 08, 2012, 01:17 PM
I DS slower than I build!
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So by your description it sounds to me like a heavier boat is perfect for my needs; a beginner with no prospect of racing and young kids who will be learning to sail with me. The higher momentum and mass sound helpful since we just want to sail around and have fun.
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Old Apr 08, 2012, 01:19 PM
I DS slower than I build!
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Here are a few pics of my Venom and A3.
It looks like your A3 is rigged differently than stock. What is that line coming out of the transom?
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Old Apr 08, 2012, 09:12 PM
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It looks like your A3 is rigged differently than stock. What is that line coming out of the transom?
Don't get me wrong the A3 is a great starter one meter boat. It will be perfiect for the family. The lighter boats are fragile!

My A3 is "turboed". I put a much taller carbon rig in it, with a fat head mainsail, supporting about 1000 square inches of sail area.

In order to handle the increased sail area and power, I added a deeper carbon keel fin and bulb(pics earlier in this thread).

The line coming out of the transom is an adjustable backstay. I added a third channel servo in order to adjust the backstay while sailing. Great for depowering the big rig in heavy air.

Obviously, the boat is heavily modified and doesn't measure in for class racing anymore , which doesn't concern me. It was more of a design experiment to see how fast i could make the A3. (in the stock configuration it would get blown away by my CR 914, a 3 inch shorter boat).
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Old Apr 10, 2012, 12:43 AM
I DS slower than I build!
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I put the lead shot in the bulb tonight and glued in the keel. A lesson learned. I have a small void spot at the top of the bulb on either side of the keel. I had trouble getting the keel in. Since the bottom of the keel is flat it was just compacting the shot when I pushed it in. Next time I will sharpen the bottom of the keel so that it pushes the shot and epoxy mix to the sides when it is pushed in, rather than trying to compact it. Since the epoxy was exotherming a bit I didn't have time to sharpen the keel once I realized this, the epoxy was going to set up too soon. I'll just drill a couple of holes in the bulb to the side of the keel insertion, inject epoxy through a syringe, and after that's cured, bondo the holes.
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Old Apr 10, 2012, 07:41 AM
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Cory I cut the top off a beer can and mixed the epoxy in the can with the can in a pot of hot water making the epoxy loss or more workable, I poored the lead in the bulb first then the epoxy then the keel. All done with out sanding the bottom of the fin. Went in easy, your idea isn't bad at all. Good luck bro. PS ware a thick glove.
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Old Apr 10, 2012, 02:02 PM
I DS slower than I build!
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I did it pretty much exactly like the instructions said; an heated the epoxy bottles in a sink of hot water, then mixed it up, put an ounce or so in the bulb followed by shot, then repeated. The one difference I did was that I only mixed about half the epoxy at first because of lessons learned about exothermic reactions. I had thought that the mass of the lead would absorb a lot of the heat. I'm sure it did, but it didn't absorb as much as I had hoped. Several years a go I had an exotherm that caught my cup on fire. Luckily I was working on a project in my backyard so I just kicked it into the green grass. I'm a fire investigator. It would be humiliating to burn my own house down. Anyway, the first half of the epoxy shot mixture got quite hot, so I stopped and put the bulb in a sink of cool water. It was getting hot enough I was worried the styrene might melt. After that had begun to cool I did the second half, but this time I mixed it in 3 smaller batches. It got pretty warm, but did not get nearly as hot as the first half.
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Old Apr 10, 2012, 07:56 PM
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The smaller the batches the better. I remember when I helped my nephew pull the vermiculite out of his J24 keel sump. The repair is to fill the sump back up with thickened epoxy. It took about 4 gallons of epoxy and thickener to fill the sump and we did it in 18-20 batches. Had to wait for the previous batch to "kick" and then pour the next. Even so, it was getting a little hot, so we put water sprinklers against the outside of the hull to cool things down. worked great.
Took over 12 hours to finish all the pours. We drank alot of adult beverages that day!
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Old Apr 10, 2012, 08:31 PM
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LOL you both are making me laugh.
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Old Apr 15, 2012, 12:33 AM
I DS slower than I build!
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This was one of my most productive stretches. I took Thursday off (I always have Friday off) to watch the kids while my wife was out of town. I made a list of items I wanted to accomplish. I got 6 out of the seven done, and didn't ignore the kids. I even played home school teacher. It sure helps to have a few days in a row, since so many steps of a build like this go something like;
  1. sand a part until it fits
  2. epoxy in place
  3. do a chore or something with the kids for a few hours while the epoxy cures (I used West Systems G-Flex for most parts attached to the hull to "give" a little more...flex. I used West Systems 105/206 for most jobs waterproofing the wood. They don't cure fast)
  4. repeat...

I got the keel box and former installed in the hull, glued the keel screw into the keel, built the rudder, installed the rudder thwart and brass log, drilled holes into the small voids of the bulb, injected epoxy (didn't need nearly as much as I thought it would), faired over the holes in the bulb and the bulb/keel joint, and waterproofed almost all of the wood inside the hull. The only wood I haven't waterproofed yet are the balsa shear strips around the top lip of the hull and the top surfaces of the deck beams. I want them to bond well to the deck.

I also added some more polystyrene to the transom joint. I dissolved some scraps in MEK, then let it evaporate down to about the thickness of condensed milk. I applied it to the joint with a dropper and let it dry. I did it on both the interior and exterior of the joint. That joint should be both waterproof and quite strong now.

The only job I had wanted to get to but didn't was to straighten the warped mast pieces. My plan is to spray the warped pieces with a 50/50 household ammonia / water mixture and clamp it into the interior corner of a piece of angle iron until it dries. The only reason I didn't do that one was because this morning I couldn't get hold of a friend who has a long piece of angle iron than I'm going to borrow.

Next week I hope to get the internal trays for the radio gear installed, straighten the mast, and install the deck. One question I have is where do you put the battery? I imagine that for sailing performance it should be on the bottom of the hull, but for electronic longevity it should be elevated. A related question is where should the boat balance? The plan is silent on this. I'd guess it would be best at 25-35% of the mean chord of the keel like I balance gliders?
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Last edited by Cory; Apr 15, 2012 at 12:51 AM.
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