Southern Peninsula (SP) – Tide Tables
Fig 5.20 shows page 72 of the RYA Training Almanac and lists the tide tables for Hamilton Sound. Again the tables are split into individual months and days and shares exactly the same format as all the tide tables in the training material. Again we are given times in 24hr clock format and heights of high and low water, in metres, above chart datum.
The biggest difference with using the tide table from the Southern Peninsula and Neptune Islands is that they are 1 hour ahead of UT/GMT. This means that they are in Zone -0100. We must subtract one hour from the times given in the tide tables to convert SP time to universal time. This information is presented in the time zone box in the top left corner of the Tide Tables page (Fig 5.20).
So 1500hrs in Zone -1 is the same as 1400hrs in Zone 0. The French like the British adjust clocks for summer time. The southern Peninsula is the RYA’s training equivalent of France and we would add an hour for the day in the unshaded areas in the tide tables to get Southern Peninsula Daylight Saving Time SP DST, ie French Summer Time
If we were in the Souther Peninsula or France on the 19th April the afternoon high tide is printed as 1632 hrs Zone -0100, Because this is in the non shaded areas of the tide table we add 1 hour to get summer time which can write as 1732hrs Zone -0100 or 1732 SP DST, which is the local time you would have on your wrist watch.
So if we use our example of 19th April at Hamilton Sound (Fig 5.21) we know that at 0409 hrs we have a high tide of 5.1m, then a low tide of 1.2m. At 1632 hrs another high tide 5.0m then another low tide at 2219hrs. Remember all these tide level are measured from chart datum. There is only 10cm of difference between the high tides.
In this example the tide times are given in SP Zone-1 time, so we need to add an hour to each of the time above to get the local time, the time on your watch. These new adjusted times are called the SP DST which is equivalent to French Summer Time.
By now you are probably asking yourself what all the fuss is about with time zones, why do we need to convert them back to UT. The fact is that most of the tide tables, tidal curves, tidal diamonds and tidal flow charts relate to our standard port Victoria which is in UT. The secondary port differences are all calculated in UT. It is therefore imperative when we using any of these to be able to work our time to UT then back to our local time.
You must be cautious when using tidal information in the real world and what Standard Port and Time Zone the information and calculations must be referenced to.