The missing intertidal zone

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The missing intertidal zone

Postby Sailorjohn » Tue Aug 28, 2012 10:35 pm

"Houston...we've got a problem!"

As I recently cruised through the latest RN update of the Florida8 scenery, I was distressed to find many of the buildings and other land objects in the water! My first reaction was "How sloppy! Why didn't he take the time to correctly place them on land, instead of awash!?!" I moved some back to dry land. I made sure my water height was 0. Then it hit me. Like most of us, he probably uses 'forecast weather' in VSF. That introduces variable water depths. South Florida and the Bahamas are very low-lying, and the tidal range is quite limited...generally under 1 meter. VSF uses randomly variable water height...the longer you run the sim, the greater the range...sometimes up...sometimes down...often by several meters. When you're modelling scenery, attention must be paid to water height...otherwise, especially in areas with very slight elevation, the shoreline varies dramatically with only a slight change in water level.

I strongly urge scenery builders to unclick "forecast weather" when placing coastal objects to avoid both placement of shore structures in the water...and float objects, piers, etc...on land. Make sure your water level remains at 0 default height!

VSF uses DEM elevations above mean sea level for land height...usually based on highest high tide. Bathymetry data on the other hand is based on minimum depths at lowest low tide. So when the two data files are merged, we have two dissimilar datums...leaving out the intertidal zone! That's why in VSF we see flooded buildings with a slight rise of tide (yeah, there's also global warming/sea level rise)...and why we run aground where there should be adequate depths, with a slight drop of tide. It's pretty much an unsolvable problem, because the tidal range varies so greatly with location. In the US for example, the NE coast sees a tide range of 2-3 meters or more as you move N...the mid-Atlantic (where I boat) about 1 meter...the SE, generally little or no tide (N Carolina where we purchased our next-to-last boat, had virtually no tidal range...water level variation was all due to wind and barometric pressure)...then there's Alaska, with a range of 8-9 meters, with each 25 hour period including a higher high, a lower low, a lower high, and a higher low! So I don't see any easy solution to this problem...like Ilan adding some constant to elevations (what happened to my fav beach!?!) or depths (what happened to the sandbar!?!). But at least it'd be easier to live with if all VSF coastal scenery were modelled with objects based on 0, or even slight positive water height. And when sailing these waters, we navigators need to check our water levels to get the best 'feel' for the area.
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Re: The missing intertidal zone

Postby MuLtIrAzOr138 » Thu Aug 30, 2012 5:50 am

i saw that too Sailorjohn,
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Re: The missing intertidal zone

Postby RobbyNeath » Thu Aug 30, 2012 2:19 pm

When I added: Port Canaveral, Port Evaglades, Freeport & Castaway Cay I did so with the tide set at 0.0 the only port in which I lowered the tide was Nassau.

All I did to the scenery was add these ports. I've not changed the map or most of its depths from its origional from VS7

Robert
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