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May 15, 2012, 10:09 AM
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numanair's Avatar
Build Log

9 inch sailboat

I built a 9 inch sailboat as my second venture into sailing. My first boat was about half the length and didn't really ever sail. This one sailed well enough, though the design was no where near perfect. It seemed nose heavy and was not very controllable in higher winds. Sadly, I lost it last night when the wind died. I should never have launched as I knew that the air becomes dead calm right around that time. Now it's sitting in a lake behind someone's house. I try to retrieve it latter.

When I sailed at the local boat pond, my boat got a surprising amount of attention, especially from the 4 year old boys.

The hull is made of a sheet of foam with balsa for the keel and rudder. I used hxt900 servos for both sheet and rudder.

In the videos, the fins I added to the front (they are to help keep the nose up when heeled or running downwind) are visible. The winds were really light, so I didn't get a lot of speed while filming. Besides, I had to hold the camera in one hand and sail with the other.
Also an osprey flies past at one point.

9 inch rc sailboat - light winds 1/4 (1 min 14 sec)

9 inch rc sailboat - light winds 2/4 (2 min 45 sec)

9 inch rc sailboat - light winds 3/4 (2 min 1 sec)

9 inch rc sailboat - light winds 4/4 & osprey flyby (2 min 18 sec)
Last edited by numanair; Jun 13, 2012 at 02:01 AM. Reason: changed from discussion to build log
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May 15, 2012, 09:57 PM
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numanair's Avatar
Thanks to my brother the boat has been recovered. It was on the water for about 22 hours and did take on some water. Still, it was floating when recovered. I don't know if the electronics are any good yet.
May 18, 2012, 03:50 PM
made of fire and pop rocks
bgnome's Avatar
good that you got her back! how are the electrics? and you got any close up pics of her?
May 21, 2012, 07:10 PM
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numanair's Avatar
I cleaned off the bits of rust on the rudder shaft. The electronics survived! When I was drying the servo's, I found that one of them was filled with water!

I took some pictures. They Show the new sail. For $0.96 after tax, I got enough ripstop nylon for three sails. I'm pretty sure it's 1.9oz, so it's fairly heavy (the whole rig is about 2g heavier than the one with the plastic sail). The new sail is detachable, like the old one, but is not fixed to the mast. I've changed the ballast a bit, and it's now 40 something grams if I remember correctly. The whole boat without the battery is 111.5g (including ballast, etc.), plus 4.2 grams for the battery. Keel, rudder and other bits are balsa. The keel has a layer of fiberglass on the leading edge. I need to figure out a better way to attach the ballast, as right now it's attached with packaging tape. The two green cylinders are probably steel, but the part on the back is lead.
The keel and mast are quite far forward, as is evident in the pictures. The fins are my attempt to solve the plowing that this causes.

I'll try to get better video when the sun comes back out.
May 25, 2012, 01:33 AM
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numanair's Avatar
Absolutely perfect weather today. Light wind, moderate gusts, sunny and cool. I had a good couple of minutes of sailing. A power failure put an end to that. When it lost power, I had the sheet out and the rudder to one side. It sailed in circles like this, which surprised me. After an hour the wind let up and it drifted into some lily pads. It's too far off shore to reach with a pole. I'll have haul over a real boat or see if it has gotten any closer tomorrow. Once again it's stranded out in the lake.
May 28, 2012, 12:54 AM
made of fire and pop rocks
bgnome's Avatar
It must be taking on water, and when it took water the last time the electronics were damaged. when you took on water again, it shorted again.

have you gotten her back yet?
May 28, 2012, 01:55 AM
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numanair's Avatar
Originally Posted by bgnome
It must be taking on water, and when it took water the last time the electronics were damaged. when you took on water again, it shorted again.

have you gotten her back yet?
The first time I lost her was not because of an electronics failure. The second time (power loss) might have been related to taking on water, but it also could be related to a bad connection with my battery cable.
I actually got her back today! It required rowing across the lake (around 520 feet) on one of those inflatable air mattress things for pools. The lack of lateral surface area meant that going straight was not possible (or not easy anyway). When I got out I stepped in underwater muck that went up to at least my knees. I'm glad I got it back. There was a bit of water in the boat when I got it, but I'm not sure how much it really was. Everything's drying out right now.
Part of why I think the power failure was caused by a faulty connection was that the battery did not swell like the last one from being over discharged.
Jun 13, 2012, 02:00 AM
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I applied epoxy to the foam hull to make it more resilient. A cracked mast prevented me from sailing last time I brought the boat to the lake, but it has since been repaired and reinforced with carbon tow.
Jul 12, 2012, 05:02 PM
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I made a box to fit the boat and all the parts. Unfortunately it doesn't fit in my bag I bike to the lake with, so I think I might try to attach a strap to the box. I forgot to mention that I scrapped the fins idea and it's been sailing just fine.
I'm worried about more plant growth in the lake now that it's summer. Anyone else ever find this to be an issue?
Jul 12, 2012, 05:12 PM
made of fire and pop rocks
bgnome's Avatar
if the water is still you'll have lack of oxygen and that spur algae growth. If there are a bunch of non migratory geese there, then the droppings will elevate the phosphorus levels in the water, acting as fertilizer in the water for said algae and other plants.

And yes, its an issue for the boats of course.. it'll snag the keel and slow you down or catch you, and in a prop boat, it'll tangle the prop.

the pond I ususallly float my little steamer was a pond made specifcly for model boating back in the 30's and for years it was neglected and became known as the lilly pad pond because it had silted up and became over run with.. well.. lilly pads.

it was restored about five years ago and it's restoration is what spurred me into model boating.

the woods have grown up around the pond so there is no wind to speak of for a sail boat, but because there is no wind, the water is always like glass. so it's perfect for a scale electric. or steamer.
but there is always the danger of it silting up again and growing weeds.
Jul 12, 2012, 07:49 PM
Rusty Nail's Avatar
A cheap way of controlling algae that is effective in my little lake are straw bales. Added in the early Spring at 10gm/m2 in the presence of oxygen it rots to produce anti algae chemicals.
Aug 02, 2012, 06:16 PM
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numanair's Avatar
Thanks for the input guys. I brought my boat camping with me so I could meet up with a group that sails 1 meter boats on the lake there. They thought my boat was funny just because of how small it was by comparison. Because I was sailing on a larger lake there was a lot more chop, and so my boat got thrown around a lot. I kept getting stuck in irons and didn't have the momentum to get it turned around most of the time. It was rather frustrating so I didn't sail for long.
One of the members who I had talked to before let me sail his Soling. It was a lot easier to sail and didn't mind the chop. However, I don't think I'll be getting into bigger boats. I like this size for it's portability, cost, and ease of building.
Aug 02, 2012, 07:43 PM
made of fire and pop rocks
bgnome's Avatar
Ive heard it been said that sailing smaller boats is often like trying to sail a cork.
if size is the big consideration you might want to check out the world of Footy's or go a bit larger with the RG65 development class.. plenty of support and info on the inter-webs for all that.
I dare say that wee little guy would probably be best sailed in a swimming pool with a large fan off the side. And that's not to be a critical comment, heck, I don't have enough sailing experience myself as it is. to make any critical comments, but the folks in my club have allowed me to sail their RG-s and seawinds and yes, the larger the boat in this regard, the better the experience in bigger water.
RG65 class are bigger boats, but not HUGE boats and can be easily transported in the cab of a truck ( if you dont have a passenger ) or a small car. and because both footy's and RG-65 is considerd developmental class you are more or less free to explore your building options.
Aug 03, 2012, 08:43 PM
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Yeah I might build what would essentially be a longer version of this boat. By extending the bow and making it rounder it would have less tendency to go under. A longer boat would also seesaw less. It would probably do quite well in a swimming pool, but the small lake where I sail is almost always smooth enough for it. Maybe my next build will be closer to footy size.
Aug 04, 2012, 05:23 PM
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Ět looks very cute, and I like small boats. Looking at the vids in the beginning of this topic, with the light winds, it seems the boat doesn't convert much wind into speed. I can see the wind wasn't very strong, yet I bet something like a Micro Magic would have been running rings around this small boat in the same conditions. How about changing the single main sail for a swing rig with small front sail and main sail? Would be just as easy to control with a single servo, but the small front sail increases the efficiency of the main sail.

If you want something not too big, but sailing well, even on a little "choppy" water, I would recommend the Micro Magic. Here's a vid of mine on some rougher water surface:

Sailing on "choppy" water with my second Micro Magic (2 min 7 sec)

A Footy can also be an option, might be even easier to carry along, although on the MM you could opt for removing keel and rudder, along with rigging, for more portability. Personally, I just keep everything on, and lie it in the back of my car.

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