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Old Mar 05, 2015, 04:58 PM
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LEGO RC Trimaran Sailboat feedback please

Hi all,

I am new to this forum. Recently i have been trying to build a sailboat out of LEGO. As far as i am aware this is the first one in its sort. As such i don't really get a lot of feedback at the LEGO forum. I am looking to improve it further, as the sailing characteristics are hardly impressive. I have an idea to chance the jib to the sort you see quite often on model sailboats, where the jib attaches to a boom which in turn is attached to the boat at about 1/3 the length from the front of the boom. If you have any other ideas of how to improve the sailing characteristics i would be very grateful. Of course all suggestions would have to be possible to build with LEGO.



LEGO Sailboat in Action (3 min 7 sec)

Building a LEGO Sailboat Project (3 min 34 sec)
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Old Mar 05, 2015, 08:53 PM
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Welcome to the forum! Experiments are good-congrats for giving it a shot. Sail material looks pretty stiff. You might consider getting a model sailmaker to make you a set of sails. But the biggest drawback I see is that the main hull is waaaay too wide for its length and its power. The outside hulls look more or less ok.
Don't get discouraged-keep reading and learning and you may come up with a neat little trimaran.
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Old Mar 06, 2015, 06:39 AM
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Great Project!!! Keep moving forward and improving...

Some comments to help you out:
  • Lego is a heavy material for model boat building. So your goal should be to make it sail well and not to win races.
  • You overall geometry looks fine!
  • Yes, do use a boom for the jib. That geometry prevents the Clew of the jib from flying up. And do not forget you need a haylyard to control the height of the jib foot. Without it, the leech will be too straight.
  • I would make the fins bigger. In the video the boat seems to sail sideways. Do them longer, not deeper. 8-stud long should do the trick.
  • Sail material is very important to get proper sail shape. Get some mylar-acetate and cut the sail so that it has no wrinkles. Remember the air flow should be laminar. This is very important in small models and in light wind.
  • I like your rudder control. Maybe you should use cross-bar to make them move together, this way only one axle on one side is needed (less overall friction).
  • To control sails, a much simpler system is a build a open or closed loop (look at pictures below). Your boat being so wide, you can do this on the outside, over the whole beam!
  • You do not need to control sheeting sides: just let the wind push the sail to the proper side.


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Old Mar 06, 2015, 09:55 AM
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Thanks for the feedback guys. I see quite a few things i can work with. I have a question though about the sheet setup Tarmstro proposed, i don't have any experience with that. I can see how is works for the most part but i am unsure what the function of the elastic is. Is it simply to create some elastical force on the sheets?

About the centre hull, I know its wider than it should be but i am limited to the hulls TLG has fabricated. In the first version i used a smaller slightly slimmer hull and it sailed a lot better but the waves came dangerously close to coming over the sides. Given that LEGO hulls are not fully enclosed, that is a real worry.

I mostly want the sailboat to sail as well as is possible with LEGO, i know the material is far from ideal. If I will race with it it would be only against other LEGO sailboats, not against the stuff you guys make .

Thanks again!
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Old Mar 06, 2015, 10:49 AM
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Kelkschiz
Have to give you high marks for imagination! I think what you have there is more of an "Outrigger" rather than a "trimaran". Nonetheless a very creative piece of work!

Very interesting!
Boomer
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Old Mar 06, 2015, 11:43 AM
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Out of curiousity, is it permitted to glue the LEGO blocks together? What about using filler to smooth the foils to reduce the drag? That might help with leeway.
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Old Mar 06, 2015, 12:05 PM
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Kelkschiz: the only goal of the elastic is to prevent the line from falling from the drum, by ensuring there is tension all the time. This way the drum can be open and you never get any tangles.

I will try do shoot a video of the system on my boat to show it....

Thomas
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Old Mar 06, 2015, 12:57 PM
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Quote:
Originally Posted by lhurt View Post
Out of curiousity, is it permitted to glue the LEGO blocks together? What about using filler to smooth the foils to reduce the drag? That might help with leeway.
Most LEGO enthusiasts, including myself, don't like to modify LEGO in a way that it can't be used anymore as intended. This means gluing or smoothening is out of the question. Even using non-LEGO parts is frowned upon by a lot of LEGO hobbyists. However you can't build a sailboat without proper sails and rigging, so i had to compromise there.

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Originally Posted by tarmstro View Post
Kelkschiz: the only goal of the elastic is to prevent the line from falling from the drum, by ensuring there is tension all the time. This way the drum can be open and you never get any tangles.

I will try do shoot a video of the system on my boat to show it....

Thomas
Ah right, of course, now i get it! That is a useful function indeed. Thanks for the explanation.
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Old Mar 06, 2015, 02:21 PM
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Given the very sleek shape of the two outer hulls compared to the center hull, if there was a way to make the outer hulls taller (more displacement) perhaps you could make a catamaran instead.
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Old Mar 06, 2015, 02:24 PM
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Impressive. I'm a big fan of Lego Technic, and RC, and this combines both in a nice way.

As for the drifting, and keel, how about using a Duplo Airplane tailfin? http://www.bricklink.com/catalogItem.asp?P=53491pb02

It's pretty large and has a nice profile.
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Old Mar 06, 2015, 02:53 PM
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Quote:
Originally Posted by lhurt View Post
Given the very sleek shape of the two outer hulls compared to the center hull, if there was a way to make the outer hulls taller (more displacement) perhaps you could make a catamaran instead.
Hull-wise i am very limited to what TLG has produced. The outerhull have a very good shape indeed. Unfortunately they are the only LEGO hulls with that shape that LEGO has produced. I am thinking about making a catamaran build with just those hulls, however it will be impossible to make it remote controlled given the small displacement of those hulls. It may be possible to make an RC catamaran by using four of those hulls on either side, but it would look hidious...

Quote:
Originally Posted by SoloProFan View Post
Impressive. I'm a big fan of Lego Technic, and RC, and this combines both in a nice way.

As for the drifting, and keel, how about using a Duplo Airplane tailfin? http://www.bricklink.com/catalogItem.asp?P=53491pb02

It's pretty large and has a nice profile.
Thanks i am glad you liked it . About the Duplo airplane tailfin, it has e very nice profile indeed. However it is quite small, currently i am already using 6x24 plates, i doubt that the better shape will compensate for the decreased surface area. And then there is the problem of attaching it securely to the bottom of the hulls...
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Old Mar 06, 2015, 03:31 PM
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I think the shape is very important. When I have but the slightest piece of waterplant stuck on the keel of my MM, the ability to move up against the wind at an angle suffers. Area matters a lot, but flow around the blade is a key factor too.

Maybe putting tiles on the plates that are used as fins will already help? The studs will create a lot of drag and turbulence.
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Old Mar 06, 2015, 04:17 PM
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Originally Posted by SoloProFan View Post
I think the shape is very important. When I have but the slightest piece of waterplant stuck on the keel of my MM, the ability to move up against the wind at an angle suffers. Area matters a lot, but flow around the blade is a key factor too.

Maybe putting tiles on the plates that are used as fins will already help? The studs will create a lot of drag and turbulence.
Hmm I like that idea, thanks
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Old Mar 09, 2015, 08:17 PM
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Very Cool!!
No one made a joke about the Kra/Gl shocking...
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Old Mar 21, 2015, 11:29 PM
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Very Cool!!
No one made a joke about the Kra/Gl shocking...
Kra/Gl is evul we must resist using it!
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