POSITION REPORT ON FRIDAY 6 OCTOBER 2017
POSITION REPORT ON FRIDAY 6 OCTOBER 2017 AT 0700
So far we've done 386 miles with 394 miles to go to Inhambane (23°47S 35°31E). We did 136 miles in the last 24 hours. We have blue skies with 20% fluffy white clouds and 15-20 knot ESE winds. We’re sailing on a broad reach at 6.55 knots with 1 metre seas. We appear to have found the elusive Mozambique Current and have a favourable current of 0.5 knots. Here's what we did yesterday and overnight.
5 October 2017 Madagascar to South Africa (Day 3)
Dawn brought us a nice ENE 10-15 knot wind, so Glenys was able to turn the engine off and sail on a broad reach. Even better, was that after motoring for nine hours, the damn counter-current finally disappeared.
When I woke up at 07:00, I downloaded new Grib files and plugged them into qtVlm. I created two routings to Inhambane – one based on RTOFS and one based on OSCAR Current data. I imported these routes into my OpenCPN chart plotter and then created a route that was an average of the two. It was more or less the same as the one that I created in the small hours of last night, so I’m using the new route for the next 24 hours and we laid a course of 250°T. At 07:00, we had 524 miles to go, but in the last 24 hours, we had only done 115 miles over the ground, which is a pathetic 4.8 knots.
Strong south winds are still forecast to arrive in Inhambane at 01:00 on Tuesday 10th, so we want to arrive there at 12:00 on Monday 9th, which will give us 12 hours leeway in case the front arrives early. We have 4 days to get there. This is an average of 5.2 knots or 125 miles per day, which should be easily achievable, provide that we do not encounter any more unfavourable currents. I’ll be keeping a keen eye on our progress.
During the morning, the wind gradually backed to NE 10-15, which allowed us to pole the genoa out to starboard on a broad reach. It was a glorious blue-sky day and we bowled along at 5.5 – 6.5 knots with no noticeable current.
As usual, we’ve soon dropped into the routine of a long passage – we do three hour watches from 19:00 at night; breakfast at 08:00; Glenys goes to bed for a couple of hours in the morning; I have a two hour kip in the afternoon; dinner is 20 minutes before sunset; we both have a shower and then I take the first night watch at 19:00, while Glenys goes to bed. It’s like Groundhog Day.
The wind started to drop in the late afternoon and at sunset we started to motor - we had less than 5 knots of wind all night. At the change of watch at 01:00, we encountered another slight counter-current of about half a knot. This was really frustrating because I knew that the Mozambique Current was somewhere to the west of our position - we’d chatted to Wairima yesterday on the SSB and they had 2 knots of good current on their track 35 miles west of us.
I did a little experiment to see the effect of our heading on the speed over the ground and I was surprised to find that a 20° change in heading caused a 0.4 knot change in speed over the ground (7.5%). Our speed through the water was 5.9 knots.
Heading COG SOG
255°T 270°T 5.8 knots
235°T 248°T 5.4 knots
215°T 226°T 5.0 knots
I wondered whether it be better to cross the adverse current rather than fighting it? I grabbed a piece of paper and did some basic trigonometric calculations. Wairima’s track in the south setting current was roughly 225°T, so if we continued to head on a course of 248°T then it would be 70 miles until we crossed their track. If we headed west, then we would cross their track in only 35 miles.
The extra distance doing this dog leg track would be only 6 miles, but if we pick up the 2 knot current sooner, then I calculated that we would take 11.4 hours instead of 13.1 hours to reach the same waypoint. I altered course to take us straight west - it felt much better to have a faster speed over the ground.