iwindsurf forecasts

Woody · Since 08 May 2013 4 Posts Hood River, OR Kook

I love iwindsurf wind forecasts.
I have for a long time wondered why the forecasts are in knots and the observations/graphs are in mph.
Does any one know ( or care ) ? Very Happy

bmmiller · Since 20 Oct 2015 5 Posts Kook

The meteorologist forecasts are in knots because sailors have historically preferred knots over mph. However, I honestly have no idea why the classic iW maps are in mph. Happily, the mobile app and the new website both allow you to customize which units you prefer (knots, mph, km/hr, or m/s).

quenyaistar · Since 21 Oct 2011 416 Posts Cougar, WA Obsessed

I have been told knots line up with latitude and longitude lines on maps

Saildoogie · Since 16 Oct 2013 78 Posts White Salmon, WA

1 knot = 1 nautical mile per hour. there are 60 nautical miles in a degree. 90 degrees from the equator to a pole.

chrissmack · Since 08 Jun 2005 526 Posts portland Addicted

and...

Origin[edit]
Until the mid-19th century, vessel speed at sea was measured using a chip log. This consisted of a wooden panel, attached by line to a reel, and weighted on one edge to float perpendicularly to the water surface and thus present substantial resistance to the water moving around it. The chip log was "cast" over the stern of the moving vessel and the line allowed to pay out.[5] Knots placed at a distance of 8 fathoms - 47 feet 3 inches (14.4018 m) from each other, passed through a sailor's fingers, while another sailor used a 30-second sand-glass (28-second sand-glass is the currently accepted timing) to time the operation.[6] The knot count would be reported and used in the sailing master's dead reckoning and navigation. This method gives a value for the knot of 20.25 in/s, or 1.85166 km/h. The difference from the modern definition is less than 0.02%. [A fathom is 1/1000 nautical miles, roughly 6 feet]

moondog · Sun Jul 24, 16 3:35 pm

Believe it or not windsurfers/kiters are only a fraction of the iwindsurf(sailflow) business. They derive 96% of their business from Government Entities like the Coast Guard, Fire Services, Sailing Companies etc. So... in the Classic iwindsurf the actual reported wind is mph and forecast in knots, a 1.16 difference. The new iwindsurf you can pick kilometers, meters, knots, mph on your device. In the low speeds we are dealing with the difference is nominal but if you are flying your personal jet, 525 knots is 609 mph. You could overshoot your landing at the HR airport and screw up your day of kiting!