Bob Blog 18 July 2021

Bob McDavitt’s ideas for sailing around the South Pacific.

Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world.

Compiled Sunday 18 July 2021

I thought I’d share with you today my Squall checklist. Note that I’m basically a landlubber rand have only been through two squalls, both near the shore.

APRICOT (mnemonic for remembering the checklist. A-P-R-I-C-O-T

And if you have any suggestions please reply with a comment.

1) ANTICIPATE: Go on squall watch when near a convergence zone. At start of your shift set your barometer (or note pressure reading). Scan: Get into routine of watching clouds on the horizon into the wind, into the lee, then left and right of the wind— occasionally check for a drop in the barometer.


2) PUT ON/ PUT AWAY. When you see a darkening cloud heading towards you, or feel the boat creak differently, put on: check that lifejackets/harnesses/ foul weather gear is on hand; put away- clear the decks of loose gear, close ports and hatches.

3) REDUCE: reduce sail. At first sign of wind on water, reef main. At first gust, trim jib.

4) IDLE? Shall we idle/park the boat? Turn engine off if under power. Consider idea of heaving-to if at sea or anchoring if in the shallows.


5) COMPASS: Hazards: If near land or a reef, take a bearing to nearest hazard before visibility reduces/wind changes. In mid-latitudes in southern hemisphere wind will probably BACK (go left) during the squall.

6) OVER: Its normally all OVER in 20 to 40 minutes then, Oh-O, there is a lull of 20-40 minutes with little wind to power the sails and chaotic steep waves, an unpleasant motion.

7) THUNDER: Time to turn off the electrics. Lightning is static electricity and takes the line of least resistance—along the rigging, Safest place is amidships.


If boat broaches (too much sail/structure caught by a gust), HOLD ON, take your time, ease the sheets, ease the boom vang. As the boat uprights, beware of flogging sheets


The latest cyclone activity report is at and Tropical Cyclone Potential is from


Three cyclones around at present: In-Fa is expected to visit Taiwan.

FELICIA and GUILLERMO should fade in the Northeast Pacific


Weather Zones Mid-week GFS model showing isobars, winds, waves(magenta), Rain (Blue),

STR (Subtropical Ridge), SPCZ (South Pacific Convergence Zone) and CAPE (in pink)


CAPE mid-week as seen by ECMWF and GFS from


SPCZ=South Pacific Convergence zone.

The SPCZ is expected to be about average stretching from Solomon Islands to Fiji/Samoa, and occasionally over Southern Cooks and Tahiti area.

Two passing troughs for the South Pacific this week. The first one fades over Tonga on local Monday/Tuesday and the second is expected to reach New Caledonia on local Tuesday, and deepen into a low south of Tonga by local Saturday. A good week for getting west from French Polynesia.


Rain Accumulation next five days from


HIGH over 1030 well south of French Polynesia is expected to travel off to the east along 35S.

Complex TROUGH below 990 over South Island tonight is expected to travel off to the east along 40S. This trough brought a large area of over 200mm of rain to The Sothern Alps in NZ over past few days, producing plenty of flooding, but less than the deluge in West Germany


HIGH over 1020 over central Australia expected to bud off a ridge around 1016 that crosses North Tasman Sea on Monday and then travels east along 25/30S

Complex TROUGH is expected to reach Tasmania on Tuesday and cross NZ on Thursday.

Another HIGH is expected to move off Australia into the Tasman Sea on Thursday and cross NZ on Friday/Saturday.

This weather traffic makes crossing the Tasman sort of like playing Fogger.


If you would like more detail for your voyage, then check to see what I offer.

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Weathergram archive (with translator) is at

Contact is or txt 64277762212


Published by metbob

Pattern and Chaos

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1 Comment

  1. Nice squall prep below. Xoxoxo

    All the best,

    Cheyenne | @cheywriter

    Coming Soon: The Prisoner’s Apprentice, inspired by the shocking true story from the 19th Century, where a child met a serial killer—and changed both their lives forever.


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