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-   -   How to read wind off water? (https://www.pprune.org/pacific-general-aviation-questions/492843-how-read-wind-off-water.html)

damo1089 13th Aug 2012 08:36

How to read wind off water?
 
Naturally I tried Google with not much avail because it thought I was a sailor. Does anyone have a good infographic or link about how to read wind off water?

Thanks :)

Widewoodenwingswork 13th Aug 2012 08:43

You should be able to see the shoreline, the smoothest part of water by the shoreline is the upwind side.

In my experience, this doesn't always work if there is a shallow grade on the upwind side and a steep angle up the bank on the downwind part of the water body, this tends to indicate the opposite way.

I'm sure someone can put it a lot more eloquently than me!

VH-XXX 13th Aug 2012 08:43

Being a sailor and an aviator I find the two remarkably similar. What are you trying to achieve exactly, reading dams for a forced landing or float plane ops?

A few years back I could tell you the difference by looking at the water between 12 and 14 knots so if you are preparing for float plane ops you'd be amazed what you can learn with some experience.

Di_Vosh 13th Aug 2012 08:43

Try this:

Beaufort wind scale

Bureau - Beaufort Wind Scale

Not sure if that's what you're after.

DIVOSH!

damo1089 13th Aug 2012 08:52

Yeah for float planing. I just assumed that the view one would have from a boat and the view one would have from the sky are different and maybe different techniques would be used.

Thanks divosh, that looks pretty good. :)

Exaviator 13th Aug 2012 09:02

When judging wind direction and strength from the air look for the smooth side and the wave or ripple side. Wind blows from the smooth side, so this determines direction.

Over the sea, wave foam also indicates from which side the wind is blowing, as it falls off the back of the wave.

Use the Beaufort Scale as mentioned above to determine strength. :ok:

Fantome 13th Aug 2012 09:14


After many hours flying floats and a tad over 3000 water landings, (in my case), I'd say you get to read the water perhaps a bit like a black-tracker sees indicators invisible to city-slicker eyes. There can be a world of difference between looking and seeing.

Until you get your eye in , so to speak, it's best to never rush it. If the sun is out it's simpler. Just orbit once or twice sussing out your chosen alighting path. Any wind over ten knots means you'll be seeing wind lanes, sometimes subtle, sometimes as plain as any discharging smoke-stack.

As the late Fred 'A Shower of Spray and We're Away' Ladd used to say, a seaplane pilot can have more fun on and off the water than in and out of bed
.

VH-XXX 13th Aug 2012 09:18

Unfortunately there's no smooth side when you are out in the middle of the Great Barrier Reef or similar unless there's a platform or a reef nearby. Shouldn't be a drama for planned landings, it's the unplanned that can be tricky. You'll probably always have GPS to confirm your initial thoughts.

WannaBeBiggles 13th Aug 2012 09:59

There are any number of indicators for wind on the water, most of which should have been covered in your float rating.

As fantome said, it's something you get an "eye" for with practice. If you're having trouble judging the direction then try to use as many things available to you as possible, smoke, boats, flags, birds, foam streaks from waves etc.

Learning a bit about sailing won't hurt you either, not only will it help you understand a bit about reading the water, but it will also give you and understanding as to how the sails of a boat are positioned in certain wind conditions, another good indicator of wind direction when there are sailing boats around.

Also remember that some local winds may change direction quite quickly when they follow coastal contours or mix in with a sea/land breezes and may not always be the same as the predominant wind you've observed.

Piano Man 13th Aug 2012 10:05

Something which I struggled with at first, and used to take the 'easy' option in looking for flags.

As others have said you develop this skill with time and one Bill Lane was fantastic with pointing out how it was done.

-In a body of water, if it is sheltered then you can see where the water looks like glass up against the edge of the lake/river/etc. This then will show which way the wind is blowing

-Ripples will normally be in the direction of the wind and you will see what direction the white caps are moving. Very handy if you have boats that are pointing a different direction (e.g with tides).

-Boats CAN show wind direction (nose pointing into wind) but be careful. As aforementioned tide can ruin this trick.

-If in a seaplane and unsure, bring the power back to idle and lift the water rudders. The nose should then spin into wind

-Check GS verse AS (GPS against ASI)

Mach E Avelli 13th Aug 2012 10:28

It pays to know the state of tide and which way it ebbs and floods, particularly near reefs and in narrow channels. As mentioned, tide may influence anchored boats more than the wind. Sailing boats with deep keels will generally be more influenced by tidal flow i.e. will face into it, or perhaps lay at an angle to it if the wind is moderate. Power boats with shallow hulls and lots of top-hamper will usually face into wind, with perhaps a bit of angle off the wind if the tidal flow is strong from another direction.
If wind is against tide and both are moderate to strong, the waves will 'stand up' quite vertically and sometimes there is even an illusion that they are running into wind rather than downwind as you would expect.
In these conditions, in the absence of cues from windsurfers, smoke, trees etc, the way waves are breaking along the shoreline or reef is probably the best indicator of approximate wind direction, bearing in mind that wind direction inshore could be deflected by the shape of the local terrain.

Arm out the window 13th Aug 2012 10:33

You can see 'wind lanes' on the sea and on big lakes when there's 10 kt or more, sort of thin lines running parallel to the direction the wind's blowing.

As mentioned above, there will often be an area of calm water on the upwind side of a dam or lake with ripples downwind.

Horatio Leafblower 13th Aug 2012 11:10

I usually just watch to see where the bubbles come up :}

Fantome 13th Aug 2012 23:30

BA hope you got blown a few kisses too sailor

werbil 6th Sep 2012 12:58

Sail trim (how the sails are set) on yachts can be a trap - it depends on who's sailing - I've seen some interesting attempts around the Whitsundays on what I can only assume are bareboats.

Current or tidal effects around islands can also create misleading cues. In light conditions the smooth patches can end up on the windward side of the islands.

My tip is to check local indicators (water or other) just before you land. I've seen winds coming from opposite directions less than 10nm apart, and I've been into one port several times in the one day and each time the wind was coming from a different direction.


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