Going to Rarotonga
Apr 2, 2014 | General
Going to Rarotonga. No on-board blog from Grey Wolf again today. We received this note from Peter, the skipper, however, which explains a lot! It’s addressed to Steve Dashew, but we’re all copied in.
GREY WOLF to Steve Dashew
Subject: Force 8, 5-6 m confused sea.
Just thought I would let you know that we are having a bit of fun!! Force 8 and 5-6 m confused seas. Thank God for your boat.
At 29/03/2014 17:04 (utc) our position was 23°16.37′S 160°14.81′W course 063T speed 7.8
The chart shows where they were at this point, and also the course and distance to Tahiti. Winds were being reported at Force 8 SE – not what anyone wants who is trying to steer ENE. This is a tricky one for Peter, but it also gives him an opportunity to find out how well all the talk about being able to work the weather given a good boat speed and seakeeping ability works out in real life.
MetBob responded shortly after Peter’s email with the following:
From MetBob 29th March 1704 UTC
Hi there Peter
Force 8?? If you are getting over 32 knots then let me know what your pressure reading is …
1) The tropical Low is expected to form near 22S 167W by 30 1200UTC (tonight) this is well to the west of your current position and as you go north , these SE winds and swell should start easing by the time you reach 22S . However after that the winds are expected to swing around and be from NE , bang on the bow— easing to 10 knots. SO going direct to Tahiti we do expect it to get better, but not entirely.
2) There is wisdom in going to Rarotonga for some ‘time out’. Avarua harbour is open to the NW winds (which are coming in a few days), but going there now will put the wind and waves more on the beam than the bow.
The wind should be easterly when you get there , OK for getting in. Wind at Rarotonga is expected to go NW during Sunday. This makes the harbour a washing machine, so stay away from the seawall, but if you can hang in there until Monday or Tuesday (local), you should have light tail winds to Tahiti (rather rare opportunity).
Steve Dashew – bless him, is keeping an eye on all this. Like me and probably you, he’s aware that the suggested new strategy could put biggish seas on the beam. He sent Peter this email pronto with the some important seamanship info, ending with a notable AVS (Angle of vanishing stability) figure:
Steve Dashew again
Another point of interest is the ability of GREY WOLF to take big seas on the beam (at some point on the storm scale she would be forced to head into the waves, but this is a long way off). The norm in trawler yachts is to take the seas on the nose, to avoid the risk of capsize, from which there is no recovery. The FPBs are designed to skid sideways with wave impact. This is similar to pulling up the leeward dagger board in a cat, or sailing with less board in the water with dinghies, so if a wave impact occurs, the boat slips with the punch, spreading the impact energy over time.
Also, the stability curve peaks at around 80/90 degrees depending on loading of tanks, and they have positive stability to beyond 140/150 degrees depending on how much liquids is on board.
Subject: Going to Rarotonga – from GREY WOLF
Due to weather we are stopping off in Roratonga (Cook Islands) for about 36 Hours. We are about an hour off it.
At 30/03/2014 00:02 (utc) our position was 22°35.80′S 159°42.90′W course 353T speed 9.6