WIND SHIFTS-using the boat’s COMPASS to know WHEN to tack
WIND SHIFTS..... using the boat’s COMPASS to know WHEN to tack.
Wind flow direction is usually never constant; the wind will usually contain ‘unstable flow’ – veering and backing constantly (or cyclically), etc. Veering is the wind ‘going to the right’ and backing is wind ‘going to the left’.
When your are beating or close-hauled when on starboard tack, if the wind ‘veers’ (goes right) you will get a ‘lift’ and the boat will point higher towards the mark or your destination. Conversely. if the wind ‘backs’ (goes left) when you are on a starboard tack you will experience a header as the boat points further away from the ‘mark’ or destination; and, if you are on the ‘wrong tack’ when you get a ‘header’, your speed (VMG) to your ‘mark’ or destination will decrease, sometimes significantly depending on the magnitude of the degrees of the shift. (Note = veering and backing winds are for the NORTHERN HEMISPHERE; in the Southern Hemisphere, all the above is 'reversed'.)
How to predict the shifts – (without looking at the water).
In the Northern Hemisphere and especially in those ‘zones’ that have predominately westerly or south-westerly wind flow, the wind will usually (but not always) first ‘back’ (goes to the left) and then it will usually then ‘veer’ (goes to the right) before it ‘backs’ again and then returning to the ‘base’ wind.... and will continue in this constantly shifting pattern. Back/veer/back/base --- port tack/stbtack/port tack/stbtack(base) .... repeat. Usual shift pattern; but, not ‘always’
Additionally, If the wind strength increases, it will usually veer (goes to the right) as it increases. So, if the wind is predicted to increase or is increasing, its better when beating to be on starboard tack on the RIGHT side of the course or rhumb line to take advantage of the ‘shift’. Decreasing winds will do just the opposite ... they usually ‘back’.
USE YOUR COMPASS to know when to tack.
Simply note/record the best angle (compass degrees sailed) on one tack, tack over and note/record the ‘best’ sailing angle on the opposite tack. Additionally before starting on your course, it best to initially ‘go head to wind’, with the sails luffing straight back and the bow exactly pointing to your destination and then record the compass heading. You now have heading to the ‘mark’, the best sailing angles on each tack. (Note - I typically use a #2 lead pencil and WRITE DOWN the compass numbers direct to the bulkhead gelcoat when I'm sailing 'serious' ... easily erased with 'soft-scrub'.)
If while on a tack and the bow begins to point higher and the compass shows a ‘lift’ (decreasing angle to the ‘mark’) of 8-10 or more degrees on the compass ..... ‘hang on’ as you are now ‘making money to the mark’ and your VMG has just increased. If however your sailing angle on the compasshas decreased by 8-10 or more degrees .... its time to tack over.
The attached chart will show that if you get a 10° compass angle 'lift' your VMG (corrected speed TO the ‘mark’) will increase by 16%!!!!!; and, the total distance to the ‘mark’ will be shorter in total distance sailed. If you get a ‘header’ and you dont soon tack-over you will suffer a 16% + 16% = 32% LOSS of VMG (corrected speed TO the ‘mark’) and will need to sail a LOT more ‘distance’.
But wait ..... in the northern hemisphere the wind usually (but not ‘always’) first ‘backs’ then ‘veers’ and then ‘backs’ again in a ‘cycle’ – goes left, then right, then left again ... and then repeats (favoring the ‘starboard tack’). At first, dont do ‘anything’, just hold your course and note the magnitude and ‘timing’ of the backing/veering/backing – get the compass degree changes and the ‘seconds’ or period of the shifts. Once you know the ‘timing’ of the (oscillatory) shifts, then if you get a header (bow drops lower than before) of more than 8-10 deg., then its best to tack over, and be prepared to eventually tack back to the original heading on the ‘veer’, then tack-over on the next ‘backing’ header. 16% + 16% + 16% = 48% .... every time you tack over on a ‘header’ you get a lift on the opposite tack ... and you can easily SEE this on your compass .... and by comparing the numbers/degrees you write down on the gelcoated bulkhead.
Simple speak:
1. Know your apparent tacking angle;
2. Know the relative compass angle to the ‘mark’ (go head-to-wind if necessary to find out),
3. if the apparent tacking/beating angle to the ‘mark’ decreases by 8-10 degrees .... hold the course; if, the tacking angle on the compass to the mark increases by 8-10 degrees tack over to the opposite tack ..... WATCH the COMPASS.
4. Favor the right (starboard) side of the rhumb line to the ‘mark’ or destination, especially in an increasing wind. Favor the left side in decreasing winds.
5. backing/prt-tack – veer/stb-tack — back/prt-tack .... then repeat.
6. Note: all this ‘reverses’ when going downwind .... the side of the course that ‘pays off’ going ‘up’ will be the SAME side that ‘pays off’ going down.
7. Always favor the side of the course or rhumb line where you expect the ‘new’ (persistent shift) wind will come from.
WIND SHIFTS..... using the boat’s COMPASS to know WHEN to tack.
Wind flow direction is usually never constant; the wind will usually contain ‘unstable flow’ – veering and backing constantly (or cyclically), etc. Veering is the wind ‘going to the right’ and backing is wind ‘going to the left’.
When your are beating or close-hauled when on starboard tack, if the wind ‘veers’ (goes right) you will get a ‘lift’ and the boat will point higher towards the mark or your destination. Conversely. if the wind ‘backs’ (goes left) when you are on a starboard tack you will experience a header as the boat points further away from the ‘mark’ or destination; and, if you are on the ‘wrong tack’ when you get a ‘header’, your speed (VMG) to your ‘mark’ or destination will decrease, sometimes significantly depending on the magnitude of the degrees of the shift. (Note = veering and backing winds are for the NORTHERN HEMISPHERE; in the Southern Hemisphere, all the above is 'reversed'.)
How to predict the shifts – (without looking at the water).
In the Northern Hemisphere and especially in those ‘zones’ that have predominately westerly or south-westerly wind flow, the wind will usually (but not always) first ‘back’ (goes to the left) and then it will usually then ‘veer’ (goes to the right) before it ‘backs’ again and then returning to the ‘base’ wind.... and will continue in this constantly shifting pattern. Back/veer/back/base --- port tack/stbtack/port tack/stbtack(base) .... repeat. Usual shift pattern; but, not ‘always’
Additionally, If the wind strength increases, it will usually veer (goes to the right) as it increases. So, if the wind is predicted to increase or is increasing, its better when beating to be on starboard tack on the RIGHT side of the course or rhumb line to take advantage of the ‘shift’. Decreasing winds will do just the opposite ... they usually ‘back’.
USE YOUR COMPASS to know when to tack.
Simply note/record the best angle (compass degrees sailed) on one tack, tack over and note/record the ‘best’ sailing angle on the opposite tack. Additionally before starting on your course, it best to initially ‘go head to wind’, with the sails luffing straight back and the bow exactly pointing to your destination and then record the compass heading. You now have heading to the ‘mark’, the best sailing angles on each tack. (Note - I typically use a #2 lead pencil and WRITE DOWN the compass numbers direct to the bulkhead gelcoat when I'm sailing 'serious' ... easily erased with 'soft-scrub'.)
If while on a tack and the bow begins to point higher and the compass shows a ‘lift’ (decreasing angle to the ‘mark’) of 8-10 or more degrees on the compass ..... ‘hang on’ as you are now ‘making money to the mark’ and your VMG has just increased. If however your sailing angle on the compasshas decreased by 8-10 or more degrees .... its time to tack over.
The attached chart will show that if you get a 10° compass angle 'lift' your VMG (corrected speed TO the ‘mark’) will increase by 16%!!!!!; and, the total distance to the ‘mark’ will be shorter in total distance sailed. If you get a ‘header’ and you dont soon tack-over you will suffer a 16% + 16% = 32% LOSS of VMG (corrected speed TO the ‘mark’) and will need to sail a LOT more ‘distance’.
But wait ..... in the northern hemisphere the wind usually (but not ‘always’) first ‘backs’ then ‘veers’ and then ‘backs’ again in a ‘cycle’ – goes left, then right, then left again ... and then repeats (favoring the ‘starboard tack’). At first, dont do ‘anything’, just hold your course and note the magnitude and ‘timing’ of the backing/veering/backing – get the compass degree changes and the ‘seconds’ or period of the shifts. Once you know the ‘timing’ of the (oscillatory) shifts, then if you get a header (bow drops lower than before) of more than 8-10 deg., then its best to tack over, and be prepared to eventually tack back to the original heading on the ‘veer’, then tack-over on the next ‘backing’ header. 16% + 16% + 16% = 48% .... every time you tack over on a ‘header’ you get a lift on the opposite tack ... and you can easily SEE this on your compass .... and by comparing the numbers/degrees you write down on the gelcoated bulkhead.
Simple speak:
1. Know your apparent tacking angle;
2. Know the relative compass angle to the ‘mark’ (go head-to-wind if necessary to find out),
3. if the apparent tacking/beating angle to the ‘mark’ decreases by 8-10 degrees .... hold the course; if, the tacking angle on the compass to the mark increases by 8-10 degrees tack over to the opposite tack ..... WATCH the COMPASS.
4. Favor the right (starboard) side of the rhumb line to the ‘mark’ or destination, especially in an increasing wind. Favor the left side in decreasing winds.
5. backing/prt-tack – veer/stb-tack — back/prt-tack .... then repeat.
6. Note: all this ‘reverses’ when going downwind .... the side of the course that ‘pays off’ going ‘up’ will be the SAME side that ‘pays off’ going down.
7. Always favor the side of the course or rhumb line where you expect the ‘new’ (persistent shift) wind will come from.
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