Hello Again Rebak

Hi everyone,
Zen Again is now back at Rebak Marina in Langkawi, Malaysia. We had a great passage from Phuket, logging 121nm in 24 hours. The nice westerley breeze (10-15 knots) and fine conditions lasted until 0300 this morning. Then we had a brief rain shower with 20-25knot winds. A good opportunity to try out the new reefing arrangements.

Zen Again's track

After the rain the wind was light but still westerly. We continued sailing at 2-3knots until about an hour away from Rebak. We motored in from there, with the only drama being when the motor stopped when just 100m from the entrance (and on a lee shore). We unrolled the jib, turned around and beat off under autopilot while I bled the fuel system. With the engine running again we entered the marina and tied up at pen B30.

There are several yachts here which took part in Sail Indonesia with us last year - good to see them. Some of the boats have had major "makeovers" as we have. An hour after we arrived a violent storm arrived and it blew 30+knots and poured rain for nearly two hours. Glad we arrived before that!

Moored at Rebak shortly after arrival

Rainstorm a short time later!

The direct passage from Phuket certainly exposed us to far fewer fishing boats and fishing nets. We passed half a dozen pair trawlers near Phuket but after that only saw individual trawlers occasionally, and stationary squid boats overnight. We passed through one big field of net floats in 50m of water west of Ko Rok Nok. Just after dawn we narrowly avoided a large tree trunk - just as well we weren't further ahead!

Zen Again at Rebak Marina

For those interested in single-handed short passage watchkeeping, I used the ten minute scheme. So day and night I set a 10 minute alarm, rested until it went off, looked out all round for traffic, checked sails, wind etc, and then set the alarm again. It worked well for me and it seemed it would be OK for up to perhaps 48 hours. Could be used when watch keeping on crewed passages too.

All in all, twas a great sail!

Farewell to Boat Lagoon

Hi everyone,
Zen Again departed Boat Lagoon, Phuket this morning after nearly 6 months of repair and refit. We fuelled up and then were guided out of the creek by one of the marina men. After clearing the creek I hoisted the main but had to motor for an hour until we excaped the lee of the island. We are now romping along in a great 10-14 knot WSW breeze, heading directly for Langkawi with the wind on the beam. No 2 and full main, logging 6.5 knots and about 7 over the ground. Dry bilge too!

About to depart Boat Lagoon

The weather has been improving as we sail south. In Boat Lagoon it was overcast with drizzle. Once away from the island there's been about 6/8 cloud cover and no rain so far.

Sailing out of Thai waters

It was a little sad leaving Boat Lagoon. They're a friendly crowd. Most importantly Precision Shipwrights did a great job on the repairs and refit, and everything appears to be not only looking good but working very well too. The dual mainsheet system atop the new s/s arch is working very well. The new cockpit teak is wonderful - no more sitting on a bed of nails!

New Sail Number - back to our old FSC 88
Note - not a bendy mast, rather a wide angle lens!

Right now we're in position 07 38.9N 098 39.5E, doing 7.2 knots over the ground. But you can see all that on our new PredictWind tracker page (on the right hand side of the blog home page).

Still charging mid-afternoon (speed or amps? Both!)

Trust all's well where you are.

GRIBs on PredictWind Satellite Communicator

Hi everyone,
An update on progress in obtaining GRIB files from our PredictWind Satellite Communicator.  Another geeky post!

SailDocs GRIB file received on our Satellite Communicator

At present PredictWind doesn't support the supply of GRIB files to the Satellite Communicator.  This is ostensibly because the Iridium Short Burst Data (SBD) service doesn't support email attachments.  However there is a way around this, as the above image shows!

By placing the email attachment (the GRIB file) into the body of the email the GRIB data can be communicated.  This isn't cheating in any way - you still pay for the data you transfer.  The overall email still has to fit within the 2KB Iridium SBD limit after compression.  The actual limit is about 4KB before compression.  This is about the size of GRIB file we normally downloaded via HF, and provides very useful data.

Unfortunately the GRIB files available via email from PredictWind appear to contain a minimum of 5 forecasts.  This means the area covered can only be about 5degrees*5degrees, with only a single variable (one of wind, rain, atmospheric pressure etc) in the file.  Anything bigger creates an oversize email.

SailDocs and zyGrib allow the user to define the GRIB file required with more freedom.  For example SailDocs allows a single forecast 10degree*10degree GRIB with two variables or a dual forecast 5degree*5degree with 4 variables are both well within size limits.


After researching all this we've designed and tested a system which allows us to get GRIBs on our Satellite Communicator.  At present we can get them from PredictWind, SailDocs or zyGrib.  We create request emails aboard in the format required by each service, but send them to one of our shoreside email addresses.  The email is automatically redirected to query(at)saildocs.com or grib(at)predictwind.com.  This results in the response email being sent to the ashore email address, where the GRIB attachment is reformatted to lie in the email body.  The modified response email is then sent to the Satellite Communicator.  All automatically.

The extra processing adds a only minute or two to the overall process, and as soon as the response is available it shows up in the Satellite Communicator email inbox.  No connecting twice as is the case with HF email!

Below is an example response email.  The dense block of text is the GRIB file encoded and placed in the body of the email.  It provides two wind data forecasts, each covering a 5degrees by 5degrees area. The block of text is about 700 bytes in size, yielding a GRIB file of about 500 bytes.  This is the GRIB file displayed in the image above.

Example response received aboard

Getting from the text block to the GRIB file involves running a simple script (program) to decode the text into the binary data which forms the GRIB file.

If anyone's interested in accessing our system for their Satellite Communicator let us know!