Laurence Andrews

Dent Reckoning

The dents are gone! I don’t know why I didn’t do this sooner… There have been two dents on the car that have been driving (hah!) me crazy for months now, one was on the rear quarter which has obviously been caused by somebody opening their door, not very big but it stood out when I was washing the car or whatever. The other was much more severe and was caused when I reversed into a metal pole in a car park, it was overhanging the wall and so the parking sensors didn’t pick it up. Luckily the paint and everything was intact or it would have looked much worse.

I took the car to a scratch and dent place on the city estate and they said that everything would need to be resprayed. That seemed a bit nuts so I just left things for another day. With not much to do with the ‘Rona going round I messaged Kent Dent Repair who fix dents without needing to do any respraying. They turned up a few days later and after two or so hours of banging away everything was back as it should be! I don’t know how the bloke did it, but I handed him my credit card and that was that. The price was pretty reasonable, £180 for both and it must have taken him about two hours. Very pleased, glad to have my car back the way it should be. Just need to deal with some of the tiny hairline scratches now!

There’s a new trend going around where people record themselves doing a short activity after being thrown a toilet roll. Those videos are stitched together into one bigger video and the idea is that people throw the loo roll from one person to another. Some of them are pretty funny, and it’s all in aid of mental heath awareness week. This was the perfect opportunity to get my scuba gear on, seeing as it’s almost six months since I last used it. I don’t recommend wearing a dry suit in the summer sun, it was CRAZY hot. You can see the full video here.

Fun and games aside it was also a Sailing School night. This was the hardest lesson yet, I really struggled. The theory of each step makes perfect sense but to calculate each thing is quite challenging especially when trying to do it quickly. Wednesday’s lesson of converting compass headings from true to magnetic and vice versa (TVMDC) was complicated enough on it’s own but is then just a part of the process used when working out estimated positioning. Here’s my brain dump on the process used to calculate an estimated position, there are three steps:

  1. Water track. For this we need to convert the vessel’s magnetic heading to true using the TVMDC process. Once we know the course we can note this on the chart with a long line with an arrow indicating direction. We can then calculate the vessels dead reckoning position by using the speed (knots to understand the distance that will be covered. Since 1 knot is equal to 1 nautical mile per hour this is relatively easy to establish. This position is then noted with a small perpendicular line along with ‘DR’ and time it was noted.

  2. Tidal Vector. This is the impact of the tide on the vessel’s direction. For example, if a vessel is travelling from north to south and the tide is running from east to west the vessel will be moved off course to the west despite it maintaining the same heading south. We can calculate how much the vessel is moved off course by understanding the rate and direction of the tide. To calculate the tidal rate we need to understand the date and time of our passage, we can then look up the tides in the closest port’s tide table. Once we’ve found that information we can calculate the tidal range (by subtracting low water from high water) and using this to check if it’s closest to a spring or neap tide. We will also note how many hours before or after our passage is from high water. With that information we can look up the speed and time of the tide. We can check this information in one of two places, either using the tidal diamonds on the chart or by using the tidal atlas in an almanac. In either case it’s necessary to look at the speed/direction based on the time before or after high water. Once established another line can be drawn from the dead reckoning position based on the direction of the tide and the distance can be calculated using the speed of the tide (which is shown in knots) and noted with a dot and a surrounding triangle along with ‘EP’ and time it was noted. The line should be noted with three arrows.

  3. Ground Track. This is a line which is drawn on the chart from the vessel’s position to the estimated position. The line should be noted with two arrows. Once drawn it’s possible to reverse calculate the course over ground (COG) and speed over ground (SOG). Using this line we can check that the vessel isn’t going to pass any obstructions in reaching it’s estimated position.

It’s worth noting that these calculations assume that the sailing vessel is running or reaching, if the vessel is heading to windward then it’s necessary to tack which will need to be noted on the chart accordingly. A similar process is followed to complete this (which hasn’t yet been covered in the course).

Tonight I’m going to run through some more exercises to make sure that I know what on earth I’m talking about. but it seems to be making sense in my head…

Sailing aside, today I went to London. Projects at work are all largely continuing despite the current situation and one of the projects we kicked off this year is to replace all of the internet for UK branch offices. As the lockdown has slowly been relaxed it’s allowed for an opportunity to go and connect up the new lines and get them tested. Being a good citizen and following government guidelines I decided to drive in, something I’ve only ever done to this office once before. There was very little traffic at all and took just over an hour, I drove through the city and passed Picadilly Circuis which is now all up and running! At work we got what we needed to get done, had a little time for some lunch and enjoyed the peace and quiet, there were a fair amount of people walking around but a lot less then you’d normally expect to see on a Saturday.

Anyway, I should probably get back to work and drive home rather than typing up a blog post. Verdant beer awaits at home!!

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