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Old 12-03-2017, 02:35 PM   #21
David Johnston2
 
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Default Re: Sailing ships at TL3

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Originally Posted by roguebfl View Post
The whole point of triangle sail rigged ships is to change the direction of the motion, hence why they can sail in every direct except directly into the wind. If they didn't chnage the diraction the could only sail down wind
Yes but I was talking about the idea of towing a barge. Of course it only converts a fraction of the wind.
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Old 12-03-2017, 03:22 PM   #22
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Default Re: Sailing ships at TL3

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Originally Posted by David Johnston2 View Post
Yes but I was talking about the idea of towing a barge. Of course it only converts a fraction of the wind.
Looking at GURPS Magic, I see that it envisions the spell in question in terms of two different devices. One device acts as an energy source, converting energy form A into energy form B. The other device acts as an output, converting energy form B into work. So, for example, you could have a windmill whose blades convert the linear kinetic energy of the wind into the rotational kinetic energy of a shaft; and then you have the millstone that uses that energy to grind grain, or the pump that uses it to raise water to a higher level. Or you could have a photovoltaic cell that converts light into electrical potential, and a calculator that uses the resulting current to perform calculations. Or a steam engine could convert the thermal energy from burning coal into rotational motion of a shaft, which would then power a propeller to push a ship through the water.

If you cast the spell, you're taking energy off from the first device so that it doesn't reach the second. The shaft of the windmill or steam engine doesn't turn with as much force, as if it were experiencing friction; or the photovoltaic cell doesn't provide as much current, as if some of the current were flowing in a different circuit, or as if the resistance internal to the cell were higher and there was a voltage drop. In effect, you've added impedance to the system.

I suppose you could imagine the sails as a power source. But I don't think the body of the vessel quite works as a device that uses the power to do work. The work you are having done is the work of moving the vessel itself, and that work is done by the sails and masts. The body of the vessel isn't really a "device," any more than a rock that you throw is a "device," even if you take your arm as a power source. The vessel isn't a thing that does work; it is a thing on which work is done. So the paradigm doesn't quite seem to apply, except perhaps in a really artificial and abstract way. It really seems like a more modern, "industrial" way of looking at the matter.
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Old 12-03-2017, 03:25 PM   #23
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Default Re: Sailing ships at TL3

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And just about every mechanical advantage system, gears, levers, transmisions, etc, changes scale/speed of movement for force... what's your point. You taking a natural source of kinetic energy and re-purposing it to act by moving you, your cargo, and your machine (boat) in whatever direction you want...
My point was that your statement about sailing straight upwind is not literally true.
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Old 12-03-2017, 05:57 PM   #24
Žorkell
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Default Re: Sailing ships at TL3

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My point was that your statement about sailing straight upwind is not literally true.
"You can in fact effectively move due north, with the wind blowing due south." Nowhere does it say that the ship is sailing straight upwind.
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Old 12-03-2017, 11:27 PM   #25
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"You can in fact effectively move due north, with the wind blowing due south." Nowhere does it say that the ship is sailing straight upwind.
Due north is diametrically opposite to due south. If due south is downwind, due north is upwind.
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Old 12-04-2017, 04:06 AM   #26
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Default Re: Sailing ships at TL3

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Due north is diametrically opposite to due south. If due south is downwind, due north is upwind.
hence the word "effectively" meaning in context while not directly moving in that direction that is your over all movement direction.
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Old 12-04-2017, 04:32 AM   #27
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Default Re: Sailing ships at TL3

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And in real world terms, you take care of that little into the wind problem with a technique called tacking...You can in fact effectively move due north, with the wind blowing due south.
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Due north is diametrically opposite to due south. If due south is downwind, due north is upwind.
Yes but as temp says you zig-zag back and forth across the face of the wind "beating", meaning the net result is going in that direction while also moving side to side a lot. Now how wide the zigs and zags are, and at what angle they are to the wind and thus how efficient the technique is depends on just how close into the wind your line is, your sails*, your boat* and how many fat blokes like me are hanging off the side in order to keep your keel in the water ;-)!

EDIT: actually you mention this yourself in post #17, so going by that post your objection seem to be that you don't travel in the net direction very fast and you do so by a series of course changes none of which are directly into the wind (for very long)?



*some can't do this at all, some do it better than others, and ultimately sometime's its easier or more efficient to just go faster a different way and hope for a change in wind direction, or arrive at your destination from a different angle (not applicable in races of course)

Last edited by Tomsdad; 12-04-2017 at 08:49 AM.
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Old 12-04-2017, 06:05 AM   #28
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Default Re: Sailing ships at TL3

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The america's cup yachts are cutting edge TL8, that one of the other changes to the 4e tech levels, is the current modern age is TL8 not TL7. They spend fortunes and get every edge the rules allow in that particular race
<digs out the can opener> Are these yachts really TL8 or are they TL5 devices made with TL8 materials? I remember that being a thing in High-Tech.
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Old 12-04-2017, 06:11 AM   #29
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Default Re: Sailing ships at TL3

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<digs out the can opener> Are these yachts really TL8 or are they TL5 devices made with TL8 materials? I remember that being a thing in High-Tech.
given one of them had sail that was more like an vertical airplane wing than then a canvas sheet yeah it more that just material sciences.
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Old 12-04-2017, 06:24 AM   #30
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Default Re: Sailing ships at TL3

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<digs out the can opener> Are these yachts really TL8 or are they TL5 devices made with TL8 materials? I remember that being a thing in High-Tech.
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Originally Posted by roguebfl View Post
given one of them had sail that was more like an vertical airplane wing than then a canvas sheet yeah it more that just material sciences.
while I think the most extreme boats which also have the most high tech materials and science behind them will be best at this*. It's a matter of degree not either/or. Tacking is an old technique.

I've done it on a Toledo 30 that is in terms of what you might see in your local marina a TL7 "racing boat" i.e. "handles like a witch"**, but is bloody uncomfortable. But is certainly not at the cutting edge, and still looks and works pretty much like an older boat.


EDIT: also when you say "like an vertical airplane wing", do you mean rigid and curved?

*which doesn't just mean doing it closest to the wind, but also being able to do it in less favorable conditions for doing it at all.

**according to my wife who gets all nautical about stuff, that's a thing!

Last edited by Tomsdad; 12-04-2017 at 08:05 AM.
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