If you measure the direction of the arrow with your plotter you will find it is about 096°T. Remember that the spring rate will be about twice the neap. This means that the neap rate is 1.2 knots and the spring rate is 2.2 knots.
Just line the grids on the plotter up with the side of the chart.įind the east going arrow just south of Cape Woodward (46☇.8'N 006★.5'W), the rates of the tide are given as 12.22. If we want to find the direction of the tide a little more accurately, we can measure the direction of the arrow with our plotter. The information is given as an arrow in the direction of the current, the bolder the arrow the stronger the tide. Turn to it page 19 now and find the diagram for high water Victoria. Most almanacs include tidal stream atlases, they are small and not very detailed, but are adequate for most purposes, and they are all included in the price of the Almanac! We will be using the ones on pages 13-25 in the Training Almanac. Yachtsmen's Tidal Atlas There are several publishers who sell atlases with yachtsmen in mind, they often have other information that may be of use-such as tidal height calculators and can be very useful.Īlmanacs. They are very easy to use and cover a range of scales, from one that covers just the entrance to Portsmouth Harbour to one that covers the North Sea. Tidal atlases are used for planning passages, and can be used to find detailed tidal data for navigation.Īdmiralty Tidal Atlas The Hydrographic Office publishes atlases for most British and European waters. There are two sources of tidal stream data: Once you have been introduced to the concepts you will have to work out your own information. Tidal Streamsįor the first navigation questions you are given the tidal stream data. Most of the errors in navigation are not caused by a lack of understanding, but by untidy working. It may seem a lot of work to lay this information out like this for each question that you do, but if you can establish a thorough method of working from the beginning you will make fewer clerical errors. In the mean range box, the figures for a spring tide range is 4.9m and for a neap is 2.4m (these figures only apply to Victoria!). To decide if this range is a spring or neap tide. Remember, when you are skippering a boat, the navigation will be only one of your responsibilities, if you are untidy, you will lose track of what the numbers mean. Many of the problems people encounter during courses are caused by untidy working, get into the habit now of laying your work out in a standard manner and keep it tidy. This will ensure that if you look away, you will come back to the correct place! (In the real book, cross out each day when it is finished, you will not need the information again). When you are dealing with tidal information, it is valuable to rewrite the information you will be using, but I suggest that you start by drawing a box around the day in question. Under the time zone is written: For Summer Time add one hour to the non-shaded areas.ĭuring the period of the year when Summer Time is in force, we must add one hour to the times given in the table to bring them in to line with the time we are using. As far as we are concerned this is the same as GMT. In the top left corner there is a box noting the time zone the tables are correct for. Always check that you are looking up information for the correct port! Turn to page 33 in your Training Almanac. At the other end of the scale, if you only sail locally, you may find a simple tide table available at your local chandlers for 20p is sufficient. A publication of this type is invaluable if you are going to sail any more than a few miles from your homeport. It is published annually and covers many ports in Europe from Germany to Portugal. The Training Almanac is similar in layout to Reed's Almanac, which is one of the most popular almanacs available in Britain. Navigation and Chart work - Tidal Streams Tide tables
0 kommentar(er)
