Monday, 25 February 2008

How do the Thorn Birds do it?

Cruising the Bahamas and the Eastern Caribbean sure sounds like a dream come true. Like they say in Queensland, it's "beautiful one day; perfect the next". So it might come as a surprise to hear that to reach paradise, cruisers heading south must leave Georgetown (Chicken Harbor) and sail the Thorny Path. Thorn Birds are no chickens. They pluck up the courage to leave safe harbour and push through the Thorny Path despite tales told by fellow cruisers, of certain seasickness and fright.

What's there to be afraid of? Well.... there's the notourous Mona and Anegada Passages, more than 1000 miles to the Leeward Islands via the Bahamas. It's a battle all the way against the prevailing tradewinds and ocean currents, so popular folklore goes.

Unless the Thorn Birds carefully plan a route and time departure when weather and sea conditions are optimal, cruisers may wish they'd never left the safety of Georgetown. Bruce Van Sant, in his guide A Gentleman's Guide to Passages South, advises cruisers leaving Georgetown to head northeast to Conception Island via Long Island, then to Rum Cay and south-east to the Turks and Caicos.

I have to say that we've never taken this path. How can we be better prepared when we do?

I've plotted wind and sea conditions according to NOAA bouys in the Bahamas and Caribbean, over the 45 day period from January 10 to February 24, 2008. There are some interesting observations for leaving the Bahamas:
  • Wind blows ENE to SSE 58% of the time and averaged 12.8 kts, see chart above.
  • Periodically the wind shifts South, around to the West then to the North before settling back East.
  • If your course is SE to get to Mayaguana you will only get favourable wind condition for sailing 40% of the time.
  • Factor in winds strength of less than 20 kts and height of waves of less than 8ft and swell direction, you find favourable conditions are now down to less than 1 day in 4.
  • If I plan to motor east and look for less than 10 kts I will only find this 27% of the time.
  • That trip NE to Conception Island - favourable conditions only 32% of the time.

The good news is that favourable conditions do exist for departing Chicken Harbor; the bad news is you have to wait and know when to leave. "Depart only when favorable conditions prevail and shall be sustained for a day longer than you need to make safe harbor"

More thorns along the coast of Hispaniola! "sailing to windward on this coast during full trades is flat out suicidal ".

By the time cruisers get to the Dominican Republic and have to head east, favourable conditions are now down to only 5% of the time. The trades are due East most of the time. "If you press on in 20 knt Trades and 5 to 8 foot seas in a 40 foot boat ... you are pleading for disaster to overtake you"

Van Sant and others use to advantage a night-time phenomenon when it is calm, upto 30 miles offshore (note the NOAA data is taken well off shore). This calm coupled with Katabatic Winds from the cooling mountains enable a boat to sail east, along the coast of the Dominican Republic at night.

Monday, 11 February 2008

We Have a Food Blog!

Check it out at BYOG & Tucker