I'm writing a story that's an AU on an alien planet, but for all intents and purposes the ships are similar to British and Spanish vessels of 17th and 18th century Earth
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The time it would take would depend very much on the wind, both direction and speed. If one was downwind of the other, it would have to heave to (stop moving) for the other to come to it. If the wind was abeam (from the side) of both, they could sail towards each other. If the winds are light it could easily take many hours for them to meet. Have you checked actual sailing speeds in various conditions?
mmm...that's one of the problems I'm running into. I'm just trying to stick travel times in for seeing an island and reaching it, seeing another ship and reaching it, and so on, but most ship info just lists top speed or record speeds. And even when I decrease the speed I seem to be moving them too fast...
10-14 kts for a Frigate is assuming ideal conditions and full sail. The descriptions you're reading are taking into account weaker than ideal winds, varying wind directions, stopped ships, etc. Also, you have to remember that the wind can and does gust - there will be periods where your Frigate may very well get it's theoretical 10-14 kts/h, but only for 5 minutes or so.
Also, here's a pretty good pic of the points of sail if you don't have one yet. The shaded area is the No Go zone, where your ship's not moving at all, regardless of how your sails are set.
My former roommate, who went to sea on a tall ship for six months, tells me the *normal* good speed of these ships is more like 6 to 8 knots. Theoretical speed is pretty much assuming freshly tarred hull (no barnacles/damage), perfect loading, perfect winds...etc. Not real life at all.
From the top of your ship you can see the horizon x miles away (I make it about 12 nautical miles for a height of eye of 125 ft). From the top of another ship the same size, you can see the horizon x miles away as well. This mean that from the top of one ship, you can see the top of the other ship 2x miles away, eg 24 nautical miles by my numbers or 28 miles by yours. This also means that your priest will be able to see the ships at 15-20 miles, whatever. Whether or not the visibility is good enough to see anything 20 miles away is up to you.
It's quite normal to be able to see the tops of ships before the hull. It can be quite difficult, especially without nice binoculars (but have never used an antique telescope so can't actually compare) to tell whether the dot you can see is a small thing close to or a big thing further away. The likely visibility depends a lot on where you are in the world and, if somewhere with weather rather than climate, what the weather's like.
OH AND ALSO, it is totally possible to be sailing, with quite a few sails up, going what feels like fast through the water ... and still be going backwards relative to where you want to be going. Especially when there are currents or tidal streams involved, but also, obviously if the wind is going in an unhelpful direction.
Oh, currents, yes. I think I've concluded that no one can say one way or the other if my ships are moving "realistically" in the story if I'm not getting technical about weather and currents and so on (and why would I?), so I should be okay having them move at a speed that matches what I need for the pace of the plot. Thanks!
Did you take into account optical effects when you did you horizon calculations, due to the atmosphere bending light? There are versions of the calculation that involve an optical correction, but sometimes, depending on weather and climate, the optical effect can be very much greater than the average, so that ships on the horizon might be a lot farther away than you'd assume.
Also, people already pointed out that 10-14 knots is going to be unusually high to sustain, but also, it's not unusual for a tall ship to furl some of the sails and slow down during the night watches, if it's not in a tearing hurry to get somewhere, especially near shore. (Pirate ships would sometimes even anchor overnight if they could, so they didn't have to have a full night watch.) So over sunset-to-sunrise it might be going even slower than usual.
...Also, frigates were particularly light and quick ships. If the Spanish ship in your account isn't specifically a frigate, it might be going even more slowly.
One of the ships is specifically a brigantine, the MC's ship is a sloop, but there's more information out there about frigates so I'm using that as the base and getting faster or slower going down to the corvettes and up to the man of wars.
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It's quite normal to be able to see the tops of ships before the hull. It can be quite difficult, especially without nice binoculars (but have never used an antique telescope so can't actually compare) to tell whether the dot you can see is a small thing close to or a big thing further away. The likely visibility depends a lot on where you are in the world and, if somewhere with weather rather than climate, what the weather's like.
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Also, people already pointed out that 10-14 knots is going to be unusually high to sustain, but also, it's not unusual for a tall ship to furl some of the sails and slow down during the night watches, if it's not in a tearing hurry to get somewhere, especially near shore. (Pirate ships would sometimes even anchor overnight if they could, so they didn't have to have a full night watch.) So over sunset-to-sunrise it might be going even slower than usual.
...Also, frigates were particularly light and quick ships. If the Spanish ship in your account isn't specifically a frigate, it might be going even more slowly.
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Thanks for the input!
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