The wind speed indicator is at the Spit on the mast at the VMR so I always take off 5 knots to allow for the protection from land .

However on a fast out going tide using a SE wind as an example what do you allow for the increase in apparent wind.

In other words 20 knots on the chart ,take 5 knots off , then add say 3 for apparent wind due to tide, giving 18 knots .

How much does tide effect the wind over the bow ( apparent ) on the BW .

at a guess, would SW have a 3knot current approx when fully running?

i've always reckoned you could subtract 17% off whatever the seaway observations say. the same goes for redcliff and now the coolangatta one too.

coolangatta readings used to be quite honest till just a few years ago

brisbane airport still seems pretty reliable for wello

the worst is double island point. we've stood next to the meter on top of the hill, checked it's current reading on the phone/bom which said 20knots, but there was really barely 10 knots

i'd say there would be a lot of SEQ sailors thinking they've been sailing in 40+ knots, when in reality it's barely 30

I did yesterday scientific wind speed measurement at Shearwater about 1 to 4 pm

Wind speed measured at the open beach was 22 ktn in gusts and the avarage SB chart show at same time about 25-27 ktn

So formula to deduct 5 ktn from SB could be accurate enough - or bottom of the green arrow seems to represent reality ( without taking our tide current into account)


BTW very convenient will be CHOP METER on Broad water. Device that could measure waves high and frequency characteristic.

Then very interesting could be to see the graph from sites like KFC, Shearwater, Train etc.

Then interesting could be to see comparison between chop characteristic here and on Wellington Point.

The height could be sometimes the same but shape or wave length completely different making our sailing less or more difficult.

wind guru's graph/forecast seem pretty close to reality

Wait till they build the CST, you'll need to subtract 15 knots then

But how much is tide effecting the apparent wind on the BW ?

If macroscien's sientific measurment was 22knts ( Hope it was calibrated and in test ) then the port tack return would have been 25knts of wind over the bow .

How many people were overpowered on port tack yestersday ? I felt like a rag doll tired to a greyhound . I know i was overrigged with a 6.4 sail but genreally I can handle it up to 18 knts and the starboard tack I was overpowered but in control . I'm staring to think that when the tide is running at is quickest you can basically add 3 maybe more knots to true wind .

i'd say a fair bit at the SW and less the train/kfc end. The banks at KFC/train would slow it down and change the flow so it's across wind rather than with/against wind (unless you are in the main channels). I've noticed that once the tide covers the banks, the effect is greater

some over-analysis creeping in

basically, regardless of where one is sailing >> wind against tide = goodness

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Haircut said..
some over-analysis creeping in

basically, regardless of where one is sailing >> wind against tide = goodness

Im still pissed I broke my my number one rule . "Thou shall only come down the mountian with a full compliment of bords and sails " I left my brand new wave board and 4.7 sail at home it would have been perfect .

Its not that I want to know the exact windspeed I do however want to better estimate what to take. You answered it with wind against tide = goodness . Goodnes means knots

It was also the daily conversation during the latest Americas cup due to the windspeed limits and how the SF bay tide greatly effected windspeed . I know SF bay has a lot faster current than the BW just curious to how much it effects us.