Accuracy of sensors

philodog · Joined: 28 Apr 2000 Posts: 209

Looking for opinions of the accuracy of the Gorge sensors. Seems to me Swell is right on but Maryhill/Wall are 5mph over. How is Arlington?

Temira · Joined: 15 Jun 1999 Posts: 94 Location: Hood River

For a reading of 30mph, I am on a 3.2 at Swell, a 4.0 at Arlington, a 3.2 overpowered at Rowena, and may not even be sailing at The Wall. In other words, Swell and Rowena seem similar, Arlington is in the middle, and I'm actually unable to tell what I'll be rigging from looking at the sensor at The Wall - it seems really direction-dependent. That begs the question of which one is the "real" 30mph. Just my two cents. Curious to hear the experience of others.

windfind · Joined: 18 Mar 1997 Posts: 1901

Hi Philodog,

The Maryhill sensor is actually west of the Bridge and at the top of the conveyer belt extending over the water. Is it has always read 3-5 knots high. My rule of thumb for the Wall is 27 knots at the Maryhill sensor.

The "Wall" sensor is on a nav. aid just west of the first narrow island you see as you drive down from Stone Hedge. So it is west of the actual Wall launches. Due to local topography this sensor receives southerly winds that often to not make it to the WA. side of the river. So it is common to have near glassy conditions on the WA. side when you can see mid to upper 20's wind around the sensor. Generally the more southerly the wind at this sensor the more it does NOT reflect the wind at the Wall launch sites on the WA. side of the river. That said... when this sensor reads above the upper 20's the wind generally fills in on the WA. side. So the sensor is a decent indicator for The Wall in very strong winds but not very good for low to mid 20's wind.

Since we are working on getting a better sensor location for The Wall I have spent many hours up at Stone Hedge and at the launch sites videoing really winds vs the sensor wind. The Wall is very direction sensitive due to vertical walls.

The new location for the Arlington sensor right next to the new launch on the OR side is pretty accurate and does not read as high as the old sensor. Using it for Rosie is tricky since the winds can be different with slight difference in wind direction. Perhaps someone who sails there more often than I do can help you more.

Mike Godsey
iwindsurf.com/ikitesurf.com
Weatheflow.com

isobars · Joined: 12 Dec 1999 Posts: 20935

1. What is a "real 30", and what would it tell us?

2. The number that counts (in the absence of a mid-river sensor) is sail size. The only way to gauge that is by experimentation at each site, taking into account the many local influences on the wind on the water vs the wind at the sensor.

3. A whole fleet of east coast sailors got their panties all knotted up when I questioned their insistence that they needed 90L boards and 4.5 sails for winds averaging 40 mph. They refused to believe that the wind on land at their sensor did not match the wind out on the water.

4. Yes, direction matters significantly at Roosevelt. "30" from 260 and "30" from 290 can differ by 20% in sail size. (Of course, rider preference can vary by 40%, so that 20% is often moot until an individual dials in a spot.)

5. The problem there is the influence of the Arlington wall on both the wind speed and direction at the sensor. That's why we keep pleading for a sensor near the water's edge at Roosevelt (on a jetty?). The local kiters say those (now missing) data are critical to estimating sailing conditions on and above the river's surface.

mac · Posted: Sat Jul 01, 2017 3:37 pm Post subject:

The river flow increases apparent wind, particulaly at the wall. I had to drop a sail size from what I saw on the water--because of the current.

philodog · Joined: 28 Apr 2000 Posts: 209

Well I got a good calibration at the Wall today. Between 1&2 I was just making a 4.7 work while the sensor was 24-25. It felt the same as the Hatch at 18-19. From 2-3 I was fully powered on the 4.7 wishing I had a 4.2 when the sensor was reading 28-30. Felt like The Hatch at 23-24 so the gap between the sensor reading and the real wind increases a bit with wind speed. Sensor reads about 5 high at 25 and 6 high at 30. Direction was a perfect 230. I don`t get to Arlington much so any local knowledge appreciated!

isobars · Joined: 12 Dec 1999 Posts: 20935

isobars · Joined: 12 Dec 1999 Posts: 20935

Invalid Session. Please resubmit the form.

OK.

OK ... AGAIN.

GODDAMIT! AGAIN!

ONE MORE F-ING TIME. JEEZ, IW -- THIS (AND OTHER FORMS OF FREEZING UP ) HAS BEEN GOING ON FOR WEEKS. FIX IT.

I GIVE UP.

anderson · Joined: 16 Apr 2009 Posts: 22

I was on a 4,7 all day at the wall today. It worked very well. Planing 95% of the time on a 78 l board. If not planning, just hopped on a wave and let it push me to a plane. I think the direction must have been perfect for the wall to be able to play all day on a big sail and think it was awesome. Fun day. Hope that is helpful.

scottwerden · Joined: 11 Jul 1999 Posts: 302

My advice is ignore the Wall sensor completely and rig based on what you see on the water. Actually that advice applies everywhere. If you are using the sensor as a deciding point as to whether you should do the drive, my criteria is:
Roosevelt > 24
Wall > 27
Swell > 21
Doug's > 22

My biggest sail is 4.7 so those numbers will get me going on that. I weigh 210.