Would This Work?

[knarf]

I'm trying to help my wife build a fantasy setting (for Pathfinder, so bear that in mind) and an idea struck me for an interesting detail for a culture of ocean-going nomads: A wind-compass.

The main part of the compass is a broad, flat disk a few inches across, possibly with a hole in the middle. It is suspended from a stout string or light chain (I'm thinking it might be worn around the neck when not in use) so that it can rotate freely to indicate wind direction.

Below the disk, hanging from another length of twine or chain is a lodestone or small magnetic compass, both to indicate North and as an anchor to prevent the disk from simply being blown around while taking a reading.

I'm thinking that such a small tool would likely only be useful in the crow's nest of a ship, away from the subtle, but continuous breezes of the ship's crew milling about.

I am also see this used as an oracular device. Since the culture's ocean goddess is also the goddess of luck, I can see priests or mystics using it to read "the winds of fate" or somesuch.

Or a magical version that can tune the lodestone to point towards another location or object (since this culture is nomadic, you could use this to maintain a family or other bond regardless of where either party is).

Would this work? What would it need to be workable/practical?

[malloyd]

Originally Posted by knarf

Would this work? What would it need to be workable/practical?

As fancy prop for a ritual for receiving messages from the ocean goddess? Sure, if she wants it too. If it's supposed to do something else I can't tell what from your description.

[Dammann]

You might make it work, but I see some problems.

You need the windvane to turn freely in order to indicate gentle winds. Putting the windvane between the hand that suspends it and the compass means that there are two points where friction works against you. Also, if you use rope or chain, the weight of the lodestone/ compass will tend to pull the windvane toward a particular orientation. You could overcome that by having something like a bearing on each side of the disk, but bearings might be more high precision than you want? Also, saltwater mist may make bearings susceptible to corrosion. I would think that nomads would go for hardy design over high precision crafting, but who knows.

Another way to get this information (wind & direction) would be to attach fine fibers around the outside of a traditional compass, or hanging in a tuft from the back/bottom. The fibers blow in the breeze, and give indication of strength as well as direction.

You may want to give some thought to how these sailors determine latitude. If your wife's world is flat, it might be tricky! If not, do they use astrolabes? Maybe you could hang that between the hand and the compass, and get a similar look.

[johndallman]

Real-world sailors haven't needed a device to find wind strength and direction. The behaviour of the ship and sails seem to suffice. They steer a course by compass, but it's an average course, being actively steered by a helmsman, because gusting wind and the random variations imposed by waves make a fixed position of the rudder pointless.

The device makes perfectly good sense as a prop for some kind of divination.

[malloyd]

Originally Posted by johndallman

Real-world sailors haven't needed a device to find wind strength and direction.

There's a reason "can't tell which way the wind is blowing" is a used as a metaphor for idiocy. It's not something you normally need a tool for. Anyway, on a ship you'd end up measuring the relative wind, the vector sum of the real wind and the motion of the ship, which there seems to be even less reason to determine very precisely.

[Lord Carnifex]

It's not uncommon to put a pennant on top of the mainmast for precisely this purpose as well. One problem that you'll run into with larger sailing ships is that the measured wind vector at the level of the sails or below is affectd by the presence of the sails themselves, which cadt wind shadows and otherwise redirect it.

[Humorme]

As for the magnet part, you can have some interesting effects. In real life, a compass doesn't point towards true north and neither do maps. Due to magnetic interference, a real compass points off from true north (dependent on what part of the world you're in).

Maps don't properly translate to true north due to the fact of "flattening" the globe into straight lines. Basic geometry.

On both accounts, a map has the deviation for the map and for the compass in relation to true north.

The reason I say this could be interesting is that coming upon large iron ore deposits, magical phenomena, or just simply having metal objects too close to the lodestone can all put the party off course into a barrel of laughs and doom.

As for the wind part, for the purpose of what you seem to be describing, I'd just go with what the other posters have said.