Celestial Navigation

Thursday 30th May 2024


In the Begining

I have had a love/hate relationship with Celestial Navigation since first looking at it in school. I studied for a Navigation 'O' Level back in the late 1970's. It has always been something I wanted to be proficient with, but was totally discouraged 'put off' due to the rather bamboozling text book, Mary Blewitt's Celestial Navigation for Yachtsmen ISBN-13 : 978-1408132128. Clearly written for a different era. I'd suggest the Jurassic age with enough spherical trigonometry to put me off geometry for life, but there has always been a little voice inside that said, 'You should really understand this stuff'.

Playing with the Subject

Over the years I've had books out of the library that I've picked up, looked at, tried to get my head round some of the language and concepts then quietly returned them to the librarian just as confused, sometimes even more so!

A Quite Night at Anchor

From time to time you sail with some amazing people. One such occasion we were sat quietly at anchor and the subject of astro came up in conversation. The skipper spent about half an hour explaining the basics and that little voice inside said, 'see I told you so – it is not that difficult'.

A few months later I was sailing with the same skipper and explained that I had a 'bad experiance' with the Blewitt book and could they recommend something that led me by the hand in very small steps. They kindly suggested David Burch's Celestial Navigation: A Complete Home Study Course ISBN-13 : 978-0914025511, one birthday present sorted.

Celestial Navigation: A Complete Home Study Course

The book arrived and a quick thumb though it and it was exactly what I needed. Step by step with worked examples and a bit at the back with all the details, the boring bits well hidden until you were ready to read and digest them. Even so it was some time before I got stuck into the book, but thankfully there was not a haversine in sight!

With the wet, miserable winter of 2023/24 I had no excuse as there was little work I could do on the boat, it being so cold and damp. I set too working my way through the chapters slowly working out in my head what I needed to do and how to do it.

I did take a look at David's YouTube Channel, but quickly left as he rambles on like an absent minded professor and is extremely frustrating to listen to! After several weeks of reading and a lot of Internet searches I found The Nautical Almanac where they post both the Nautical Almanac and Sight Reduction Tables (Pub 249). In turn that has lead to me printing out the daily pages, some of the tables and sight reduction tables for the days and latitudes that I'm sailing in allowing me to great my own document. Which now resides in a large ring binder neatly sectioned off for different topics.

The Sextant

The decision to buy a sextant was logical, I really did need one, but which one. I've played with a Davis Mark 25 for some sun sights, but my research suggested that it was not great for stars and planets. The one that a lot of diffrent sources suggested was the Celestaire Astra IIIB so I dug deep into my pockets and contacted Alice at Crews Navigation in Plymouth and ordered one.

image host

Astra IIIB Deluxe Sextant
Picture: Celestaire.com

My initial thoughts are that the instrument has a more solid feel that the Davis and once the boat is back in the water, June 2024, I'll need to put theory into practice. I'll mention in posts how I get on.

Given what I now know I wonder if picking up Mary Blewitt's book would be a good idea?


OYT: Trip 09 of 2024 - Day 4

Friday 26th April 2024


0000 hrs

Lat: 50° 45.70'N Long: 001° 17.67'W

1300 hrs

Slipped lines and headed out past the the Cowes Breakwater. On the main hoist a line got tangled and it took some time to fix. I helmed, attempting to keep Prolific 'on station', using a couple of transits. A useful exercise in keeping the boat still.

1500 hrs

An afternoon in the east Solent tacking and gybing in some fresh winds.

1900 hrs

At anchor in Ryde Bay, dinner and sorted out the night navigation exercise back to Ocean Village.

2100 hrs

Anchor raised crew take over command and pilot Prolific into the north channel, then up Southampton Water to Ocean Village.

0000 hrs

Tied up alongside, time for a coffee and then bed.

All times are UTC.



The Log


Distance
NM
Underway Avg SOG
knots
Max SOG
knots
Night
Hours
Day: 20.00 9h 45m 10.00 17.00 3h 00m
Trip: 148.00 7h 15m 3.80 17.00 3h 00m
Year: 140.00 31h 26m 3.84 17.00 3h 00m


Crew: Constantinos, Lauren, Glyn, Katie, Willoughby, Vince, Sandy and the school crew.


Sunrise: 0425 hrs Sunset: 1950 hrs


Weather: Forecast valid from: 01:00 (UTC+1) on Fri 26 Apr 2024 until 01:00 (UTC+1) on Sat 27 Apr 2024

Dover, Wight, Portland, Plymouth

Cyclonic 3 to 5, occasionally easterly or northeasterly 6 in north Wight and north Portland. Slight or moderate, but rough for a time in west Plymouth. Rain or showers. Good, occasionally poor

© Met Office Synoptic Chart 26/04/2024

© Met Office Synoptic Chart 26/04/2024


OYT: Trip 09 of 2024 - Day 3

Thursday 25th April 2024


0000 hrs

Lat: 50° 45.70'N Long: 001° 17.67'W

0705 hrs

Cast off from the quay. The crew had been advised that we were leaving early, but still managed to go ashore to use the facilities and got back on time, just.

1200 hrs

Lat: 50° 37.62'N Long: 001° 43.28'W

Having made good time running on over the bay with both the main and mizzen well out and preventors deployed. The watch on deck were informed that we would be entering the Solent via the north passage, to dodge some of the tide, and get a good look at Hurst Point.

In a big boat it looked like we were going to ram the beach, lets not mention the poorly marked pots! Eventually we changed course by 90° and were running parallel to the beach with the wind building. With one reef in the mizzen, a full main and the jib hoisted we were charging along at about 8 knots.

Passing Hurst Point we noticed a catamaran to port that was exiting the Solent and was either asleep or looking at their phone. Lauren, on the helm, let go with five blasts on the horn as both vessels were travelling at speed had a huge grin on her face.

Vince came forward and reported that we were recording a F7, wind against tide would be interesting, but we were still making 7 knots over the round. Things were brisk!

1650 hrs

All tied fast back at Cowes Yacht Haven. As we were entering Cowes I noticed a World War II Spitfire overhead.

All times are UTC.



The Log


Distance
NM
Underway Avg SOG
knots
Max SOG
knots
Night
Hours
Day: 59.00 9h 45m 10.00 17.00 0h 00m
Trip: 129.50 18h 51m 3.80 17.00 0h 00m
Year: 140.00 31h 26m 3.84 17.00 0h 00m


Crew: Constantinos, Lauren, Glyn, Katie, Willoughby, Vince, Sandy and the school crew.


Sunrise: 0425 hrs Sunset: 1950 hrs


Weather: Forecast valid from: 01:00 (UTC+1) on Thu 25 Apr 2024 until 01:00 (UTC+1) on Fri 26 Apr 2024

Dover, Wight, Portland

Variable 2 or 3, becoming west or southwest 4 to 6 for a time. Smooth or slight, occasionally moderate in Dover and Wight. Showers. Good, occasionally moderate.

© Met Office Synoptic Chart 25/04/2024

© Met Office Synoptic Chart 25/04/2024


OYT: Trip 09 of 2024 - Day 2

Wednesday 24th April 2024


0000 hrs

Lat: 50° 45.70'N Long: 001° 17.67'W

0730 hrs

Awake and quietly left the boat to check out the showers. Oh dear, another marina who's architect has no idea what a sailor needs from an amenity block. I want somewhere that I can undress with ease, can hang up my kit, can sit, has a screen that keeps my kit dry and don't need to press a wee button to keep the supply of warmish water running.

Despite not being the greatest showers on the planet the place was busy – even with muzak playing insistently. Showered and shaved I returned back to the boat for breakfast.

0954 hrs

Cast off from the pontoon heading for Weymouth, Dorset. On leaving the river Medina we turned to the west, raised the sails and motor sailed down the western Solent in light winds.

1500 hrs

Just off St Albans Ledge, an interesting standing wave on the ledge, the wind filled in and we were able to turn off the engine and properly sail. Man overboard under sail followed in quite quiet conditions.

The ranges were pretty active and the sound of the guns could clearly be heared.

1815 hrs

Lat: 50° 45.70'N Long: 001° 17.67'W

Arrived Weymouth. My second visit to this wee town, must try and get back and explore it one day.

The crew departed for a walk round town and to the beach. Where one or two got rather wet.

2200 hrs

The day's work done I finally was able to have a shower.

All times are UTC.



The Numbers for Prolific


Distance
NM
Underway Avg SOG
knots
Max SOG
knots
Night
Hours
Day: 50.00 6h 21m 7.90 10.00 0h 00m
Trip: 60.50 9h 06m 6.66 10.00 0h 00m
Year: 140.00 31h 26m 3.84 12.00 0h 00m


Crew: Constantinos, Lauren, Glyn, Katie, Willoughby, Vince, Sandy and the school crew.


Sunrise: 0425 hrs Sunset: 1950 hrs


Weather: Forecast valid from: 01:00 (UTC+1) on Wed 24 Apr 2024 until 01:00 (UTC+1) on Thu 25 Apr 2024

Wight, Portland, Plymouth

Variable 2 to 4 in Portland, elsewhere north or northwest 3 to 5, becoming variable 2 to 4. Smooth or slight, occasionally moderate. Showers. Good, occasionally moderate.

© Met Office Synoptic Chart 24/04/2024

© Met Office Synoptic Chart 24/04/2024


OYT: Trip 09 of 2024 - Day 1

Tuesday 23rd April 2024


0000 hrs

Lat: 50° 53.71'N Long: 001° 23.50'W

I had driven up to Southampton the previous day to assist on one of Prolific’s maintenance days. After doing several tasks the Sea Staff went out for dinner and a couple of pints at one of the places in Ocean Village.

1300 hrs

The group from Greig City Academy, who run the boat Scaramouch, from north London school joined the boat.

1515 hrs

Cast off from the pontoon heading for Cowes. We had left the pontoon with enough tide to get out of the berth and then slowly motored down the Itchen and Southampton Water giving the usual winch drills.

Before entering Cowes we watched, Triana, one of the Golden Globe Race 2023 competitors complete their round the world adventure. While not a fan of these 'back to the golden age of sailing' events it was interesting to watch a lone sailing boat surrounded by lots of excited people in ribs.

1800 hrs

Lat: 50° 45.70'N Long: 001° 17.67'W

Alongside at Cowes Yacht Haven, a new venue to me as we usually come alongside at Sheppards when in Cowes.

All times are UTC.



The Numbers for Prolific


Distance
NM
Underway Avg SOG
knots
Max SOG
knots
Night
Hours
Day: 10.50 2h 45m 3.80 5.00 0h 00m
Trip: 10.50 2h 45m 3.80 5.00 0h 00m
Year: 81.50 22h 20m 3.65 12.00 0h 00m


Crew: Constantinos, Lauren, Glyn, Katie, Willoughby, Vince, Sandy and the school crew.


Sunrise: 0425 hrs Sunset: 1950 hrs


Weather: Forecast valid from: 01:00 (UTC+1) on Tue 23 Apr 2024 until 01:00 (UTC+1) on Wed 24 Apr 2024

Wight, Portland, Plymouth

North or northeast, backing northwest for a time, 3 to 5. Slight or moderate in Plymouth, but elsewhere smooth or slight. Occasional rain. Good, occasionally moderate.

© Met Office Synoptic Chart 23/04/2024

© Met Office Synoptic Chart 23/04/2024