Bob McDavitt's ideas for sailing weather around the South pacific

14 April 2019

Bob Blog 14 April 2019



Compiled Sun 14 April 2019


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.


Now that cruising sailors are on their final preparations for departing New Zealand/ Australia for the warmth of the tropical Islands, ‘tis is a good time to review the ways to obtain weather forecasts and/or provide position reports when at sea.


Let me know if any of this has changed and I’ll add an addendum to my next blog….

1. For those depending on Shortwave radio, ZLM/ Taupo Maritime Radio offer a continuous 7/24 Trip reporting service see

The HIGH SEAS forecast for the area SUBTROPIC from MetService is read out in English via ZLM at 0903hr, and 2103hr NZST/NZDT on 6224 and 12356KHz and repeated an hour later on 8297 and 16531 KHz.  A copy of the Radiofax sked is at


2. Northland Radio ZMH292 is owned and operated by Peter Mott and provides a free of charge (donations welcome) check in service on multiple maritime frequencies. Northland Radio tracks vessels and has a formal policy for dealing with a missed check in. To use Northland Radio, operator requires Maritime Restricted Radio Operators Certificate (MRROC). In the maritime radio service, the callsign is assigned to the vessel, and in New Zealand it starts with ZM. See


3. Another SSB service is offered by Yachts in Transit. Patricia and David from Gulf Harbour Radio use the web site to keep track of boats that listen to their rollcall/weather service. FIRST You need to register on this web site with your boat and crew details and then you simply email or radio in your position and conditions in preferably each day ( or via SSB). These reports are plotted on a webpage for you and your friends.

FROM 1 MAY to 25 NOV, Patricia/Dave is on air, Mon-Fri 07:15NZST on ZMH286 on 8752Khz or 8779KHz or 8297KHz in that order depending on interference. Other frequencies have been allocated for far away yachts. After the reports are taken, at around 07:30 NZST Dave does a round-up of the weather in each island group, including passage weather from east to west. The website offer live streaming and has several good background weather and radio/comms articles.


4. AMATEUR RADIO / Ham net: PACSEANET is a ham (amateur radio) network providing a free of charge check in service on amateur frequency 14300KHz USB in the 20 metre band (at 0300UTC). To participate, operator needs to hold an Amateur Radio Operators Certificate (General class or above). In the amateur radio service, the callsign is assigned to the licensed operator, so this is a different callsign from using a maritime callsign. In New Zealand amateur callsigns start with ZL. See Position reports are received and reported in the well-know YOTREPS format (but missed calls may not be followed up). People onshore can listen in to a transcription of the roll call from the website. The net features 17 listening station dotted between Australia and Alabama.


5. EMAIL: Those who have access to EMAIL have several options.

Saildocs may be used to relay the text details of a webpage even if you only have email and no access to the Internet.

They are able to order the latest edition of MetService warnings by sending an email, no subject necessary, to with message


For subtropics use SEND

This system also works for coastal sailors using a mobile phone with email.

The formula to get a copy of the latest coastal area BRETT via email is to send an email to with message SEND

A new provider is using sophisticated filters to reduce the text of a weather forecasts and warnings to a pithy TEXTABLE alternative, free of charge to the average user. They also have a forecasting option based on NOAA weather models.


6. Smart phone apps: Some satellite phones now provide wifi that allow nearby smart phones to use apps. makes good use of this and as an app that supplies forecast model data, observations and, at the Professional Account level, tools for routing and comparing departure dates. It also has a position tracking tool. There is also a app (free of charge) and, I think, it has a position tracking option.


7. MetBob. See my website to study more of my services at

WEATHERGRAM (This blog) is available in different ways :

Internet illustrated edition is at

To get a one-off (text-only) weathergram via email:



For a one-off: Send an email to, no subject needed with message

SEND nz.wgrm

To subscribe: use SUB nz.wgrm (or SUBSCRIBE nz.wgrm)

To cancel: use CANCEL nz.wgrm or UNSUB nz.wgrm or UNSUBSCRIBE nz.wgrm



For full text (Ok for Sat Phone or HF SSB with sailmail/winlink)

To subscribe, send email to, no subject needed with message subscribe boatname (replace boatname with name of your vessel, up to 20 characters).

For the whole weathergram reduced to 4 SMS text messages, for Satellite messengers such as Garmin inReach:

To subscribe, send email to, no subject needed with message subscribe boatname (replace boatname with name of your vessel, up to 20 characters).



Latest cyclone activity as at and TCFP tropical Cyclone Formation Potential as seen at

There is a complex gathering of tropical lows to NW of Fiji tonight, and one of these is expected to go off to the southeast, and the others are likely to fade in a few days.


Rain in the past week was strong over NW Australia from TC WALLACE, and also across Vanuatu, associated with a a zone of low pressure forming

For rain in the past two weeks see

The “mirror CZ” continues just south of the equator in the eastern Pacific, affecting those those sailing between Galapagos and Marquesas.



SPCZ=South Pacific Convergence zone.

The SPCZ is expected to be active until mid-week and linger from Vanuatu across Fiji and occasionally across southern parts of Tonga, and should weaken by end of the weak.


Subtropical ridge (STR)

HIGH in southern Tasman Sea on Monday is expected to build to 1035hpa over South Island by mid-week and then travel east across northern NZ on Tuesday and then weaken and travel eastwards along 40S. There is likely to be a squash zone of enhanced trade winds on north side of this High near 20S from southern Tonga to New Caledonia, easing after Thursday.

Next HIGH is expected to travel east across Tasmania on Thursday and then across the South Island on Saturday.


Australia/Tasman Sea / New Zealand

A week of easterlies to north of 35S, OK for getting to Australia.

Active trough is expected to cross Tasmania on Wed and then over South Island on Holy Thu/ Good Friday (Passover) and then may stall over North Island on Easter Sat/Sun. This trough is something to consider in Easter Sailing.


Panama to Marquesas

Gulf of Panama is expected to have northerly winds this week, so it’s ok to go.

This week it is looking OK to go to NW of Galapagos and the SW to around 5 or 6S 100W.


Port Vallarta to Marquesas

Best looking northerly winds for departure this week are from Tue to Thu, otherwise light winds.

ITCZ likely between 9N and 5N, and another convergence zone between 4S and 6S.



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

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