Today Sarah finished her audio tour of her boat. She also had some visitors this week that you will hear about.
I apologize for the audio quality in a couple spots, satellite phones are amazing but not perfect.
It was great hearing your Easter Podcast.
It’s probably better to hear you that way than on the radio.
Thinking of you on Easter Sunday, as I do all days, Charlie
You are supposed to row Westerly
And we all know it’s your besterly
So what’s happening girl
Your tracker shows a curl
But you are still on your questerly
Parson from RPYC (Wed) Says: April 12th, 2009 at 8:34am
“Can I ask why you are now so far north of the Rhumb line?”
Sarah’s Google Earth track shows she is a little over 300 klms north of the line – Mon, pre dawn WA time.
The easiest way to see why she is way up there and also to see how she will do over the next few days, is to simply look at the Synoptic Chart. As per her original “outen back” trip, Dippers will once again only go where the winds are blowing to. On calmer days, rowing will assist progress, but any ocean currents will influence direction.
For the first few days of this second trip, Sarah enjoyed a perfect easterly breeze and was headed for Africa, but around Thursday it went more SE, so Sarah went NW. Now, a small low pressure area (anticlockwise in Aust.) is causing her to do a bit of a circle, but during Tuesday the charts show she will be off to Africa again, albeit pointing a little high (too far NW). It wont be until later in the week that the winds will help her drift closer to the Rhumb line as she rows.
Here is the link for the current chart: http://www.bom.gov.au/cgi-bin/nmoc/latest_MSLP.pl?IDCODE=IDY00050
and here is one for the 4 day outlook: http://www.bom.gov.au/products/IDG00074.shtml
This link: http://www.bom.gov.au/cgi-bin/nmoc/latest_D.pl?IDCODE=IDX0033 is for the Indian Ocean. It shows a massive “low” heading towards Australia, but a lot lower down than Sarah. The top of the low may give her some easterly winds, taking her back to Australia for a day or two, but things change daily and it may stay low enough down to not affect her greatly.
Summary: Sarah’s journey at sea will only go in the direction of the breeze on the day. If she gets lots of easterly type weather, she will progress towards Africa and if she gets lots of westerly stuff, she will head to Australia. Her direction made good is very much in the hands of the weather systems.
writ large on Sarahs rear bulkhead (so she can study it while rowing – questions will be asked on arrival) is Geoff’s Equation for Elective Progress For Ocean Rowers (GEEPFOR); –
EP is elective progress
S is speed
r is rowing
c is current
w is wind
ww is waves
n is hours factor present per day
GEEPFOR is no internationally recognized as the multi variate model to trans ocean rowers. (or it soon will be)
A regression analysis of Sarah’s performance so far to solve for r,c,w and ww it became evident that w is big and c is next biggest, and that as w and ww are invariably additive, that c, w, and ww will nearly always sum > than r.
The implications of this are amplified when the weighting of n comes in to effect. It means that if Sarah can row twice the speed of c+w+ww and keep it up for 12 hours,she will remain stationairy when c+w+ww are in oppositin to r.
Accordingly the quickest route to Mauritius is the most wind favored route. And that is, the bottom of the trade wind belt. It is not the shortest route by any means but as the mid Indian Ocean, where the rhumb line goes, has lots of winter westerlies, it may well be the shortest route is not possible.
So it is probable that Sarah’s northerly route is largely where the wind has blown her, but it will probably have been a deliberate decision by her router anyway. She will probably head well noth of Mauritius’s latitude for the crossing and then have to row south to actually arrive there.
It goes some way to explaining whey no-one has rowed Mauritius to Australia.
There are a few different ways to compute Sarahs’s voyage.
On Monday morning she is 12 days out and has covered 315 N miles in a straight line from Fremantle. An average of 26.25 miles a day.
She is presently 2,914 miles from Mauritius, and based on her past average, she requires a further 111 days to complete the initial 3181 mile row. Her northerly postion has added an extra 38 miles to her trip. These maths are based on the Earth being a perfect sphere with a radius of 3443.9 nautical miles.
So she has to row 50 kilometres a day, every day for the next 111 days, without a day off. I suggest that all us Fremantle supporters should go out and paddle our canoes 50km in one day, just once, to show support for her project.
Course from Shoalwater to the River, Sunday 3rd May, entry fee $20 plus $2 fine for every uncompleted kilometre. All proceeds to Sarah’s Charity.
Weather Watch: “Sarah’s journey at sea will only go in the direction of the breeze on the day. If she gets lots of easterly type weather, she will progress towards Africa and if she gets lots of westerly stuff, she will head to Australia. Her direction made good is very much in the hands of the weather systems.”
Geoff: “It (weather/currents along the Rhumb line) goes some way to explaining whey no-one has rowed Mauritius to Australia.”
Remora: Bearing in mind that her little boat will only be going where the winds allow, I reckon it would be far easier to hit the big Australian coastline coming from Mauritius, than it will be for Sarah to target and hit tiny little Mauritius from Australia.
hi sarah,just listened to your podcast,i am in awe of this adventure you are engaged in and wish you well as you progress.hope you enjoyed the chocolate eggs!