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Global Positioning System (GPS)

Boating Tips

Anchors - how they work


Generally, anchors penetrate the seabed and use suction created by the bottom, plus the weight of the material above to create resistance. In rocky or coral bottoms, anchors can’t dig in, so they hold by snagging on protrusions and hold on more precariously.



Bigger is better. Bigger anchors have more strength to resist bending or breaking. The have more surface to create more suction and more weight to penetrate the seabed.


A 15 knot wind produces about 150 kg of force on a typical 12 metre motor cruiser. A 5 knot current produces about the same force as a 15 knot wind. The same typical 12 metre cruiser in a 40 knot wind produces around 1200 kg of force.


There are various suggestions as to the proper method, but the following generally works on a sandy/muddy seabed. Select an area large enough to allow your craft to swing a full 360 degrees well clear of other craft and the shore.

Select and go to a spot where you think the anchor will hold. (Unless you’ve got x-ray vision or a direct line to the Almighty, this is usually a fairly good guessing game.) Start to slowly reverse from the spot, at the same time dropping the anchor and “laying” the anchor chain along the bottom. The more chain you can lay out the more weight there is to lift before the anchor is effected. Lock off the chain. The boat should come to a stop indicating that the anchor has taken hold. Take up any slack on the chain and satisfy yourself that the anchor will still hold.

Boating Etiquette


Etiquette, a french word which first meant a label or ticket.The new  meaning was added during the reign of Louis XIV. His court functions became so elaborate that the master of ceremonies had to provide each guest with a ticket (etiquette) on which was noted the formalities expected of him. Proper behaviour, then, was "according to the ticket". In this sense the word etiquette was adopted into English at the end of the 17th century. The foundation stones of etiquette - kindness, fairness, self-control, gentleness and self-respect have, in every age, been the same. The most important aspect of etiquette is to make other people feel at ease.


When approaching an area occupied by moored vessels slow down when well away and approach at "No Wash" speed. Remember, your wash will follow you. Consider the discomfort you may so easily and unintentionally inflict on others.

It is the responsibility of the skipper of the vessel coming alongside to ensure that ropes are in readiness and adequate fenders are in place.

Always request "Permission to come aboard" before boarding another vessel.

It is not considered good form to request that a vessel be moved off a mooring after sunset. Remember, your Burgee is an indication to Non-Club members tied up to our Club Moorings


Don't start up your 240 volt generator in the early morning hours if there is any chance it will disturb your moored neighbours or those rafted up alongside you.

When moored overnight in close proximity to other vessels, remember, even the softest sound carries for long distances over water, especially at  night. Have respect for your neighbours

Copper Pipes, Fittings and Saltwater

Has your boat had its 10th birthday? Have you recently checked any copper pipes and/or fittings in the proximity of your through-the-hull skin fittings and sea cocks? Did you know that copper isn't all that fond of saltwater? Copper pipes and fittings have a variable finite lifespan. They may visually look fine from the outside, but apply just a little pressure and they may well fall apart in your hand. If a pipe of fitting associated with a sea cock gives way and you're not about the consequences don't bear thinking about! Well worth getting into your bilge and having a poke around!

Flags - Dressing your Boat with Flags and Pennants

The origins of the Gin Pennant are uncertain, but it seems to have been used since the 1940s and probably earlier. The distillery manager of Plymouth Gin was quoted some years ago as saying that the firm started supplying gin pennants in the 1950s, but usually they were made up on board ship. Some remember using a small green triangular pennant emblazoned with a white wine glass, hoisted rather inconspicuously on an inner halyard. More usually, the green-white­green starboard pennant (the old pennant 9) was used, and no doubt still is, with a green glass in the centre. The signal means that the wardroom invites officers from ships in company to drinks. Today it is used to signal celebrations on the water and on land. A miniature gin pennant is often hoisted above the bar to signify that drinks are "on the house". Similarly the Red Wine Pennant is used for occasions of celebration and is especially popular with connoisseurs of a good drop of an Aussie Red.
The design reflects the great history and heritage of Sydney and features the naval cross of St. George emblazoned with the stars of the Southern Cross as depicted on the official emblem of New South Wales.  The crest of the city of Sydney with its golden anchor, crown and star, alludes to Sydney as a great sea port.  The six pointed star "Sirius" (the guiding star of the Dog Star constellation) reminds us of the flagship of the First Fleet, HMS Sirius.  The fully rigged sailing vessel in the first canton, HM Bark Endeavour, pays further tribute to Sydney as a major mercantile and naval port.  It represents all forms of shipping and boating from the time of Aboriginal canoes.  The civic crown indicates the status of a great city and reminds us of the achievements of Captain James Cook RN, who explored Australia's eastern coast and named the whole region New South Wales, initially including the areas now known as Queensland and Victoria. This attractive flag was raised in 1988, the bicentenary year, by Sir David Martin, Governor of New South Wales, and it commemorates the vexillological work of Captain John Nicholson RN and Captain John Bingle who designed the first Southern Cross Flags for Australia in the 1820s and 30s.  The Greater Sydney Ensign may be flown by Sydneysiders in the area bounded by Wollongong, Newcastle and Bathurst, including the Southern Highlands and Central Coast.  It is a popular design flown on land, sea, rivers and harbours.

COLOURS: Ship - Blue; Cross -Cardinal Red; Crest - Gold; Field & Stars - White.

Global Positioning System (GPS)


The GPS system is a satellite-based radio navigation system designed to provide global, continuous 24 hour-per-day all weather, accurate position data for navigators worldwide. The GPS is based on a GPS receiver's ability to accurately measure the propagation time of signals transmitted from orbiting satellites. These satellites transmit accurately timed signals along with a navigation message containing the satellite's position, precise time correction signals, as well as almanac data for all of the satellites in the constellation.

The on-board GPS sensor measures the time-of-arrival of each satellite signal and calculates the range (or distance) to each tracked satellite. When the range to the satellites is known, the position of the vessel (i.e. the location of the GPS receiver) is determined by triangulation of the range data of the satellites in view, and presented in terms of Latitude and Longitude.

The satellites continuously broadcast their navigation messages at a frequency of 1575.42 Mhz (for civilian use). Superimposed on the navigation message is a high rate C/A (Course Acquisition) code used for  precise positioning measurements and positive satellite identification. The C/A ID code permits the user to determine and select the "best satellites" to use in position calculations. If it were possible to measure true satellite ranges directly, it would only be necessary to track data from any two satellites to obtain a vessel's latitude/longitude. In actual practice, for marine navigation the receiver tracks a minimum of three satellites in order to resolve timing errors; including the receiver's own internal clock timing bias error which must be factored into the various range calculations.

A typical GPS system will track up to five satellites (if visible) and use the best four of the five for calculating position fixes.  By using four satellites, the processor can determine the amount of clock error in each calculation. The receiver subtracts the error bias equally  from each range solution until the LOP's intersect.  Theoretically this process can produce highly accurate position fixes for navigation. (+/- 15 Metres).   Continuous tracking of each satellite signal allows the receiver to perform this timing adjustment process and to calculate accurate measurements to the satellites.  

The GPS satellite system we use was originally developed for military purposes by the United States and has proved to be an enormous benefit for extremely accurate position fixing. GPS underpins all computer based mapping systems from Google Maps to Raymarine Chart Plotters.

Unfortunately, for civilian usage, the United States Department of Defence has included in the design of the GPS satellite system a special mode which introduces variable timing errors into the satellite  signals. This mode, activated from time to time by the US, is known as "Selective Availability" and when it is enabled. It is designed to provide less accurate fixes for all users (except authorised military users). Accuracy in the order of +/- 100 meters 95% of  the time when SA is ON. This means that 95%of the time the position will be within a radius of 100 meters; 5% of the time the position will be outside this 100 metre circle.  

Marine Toilets and the Siphon


Water flows downhill whenever it can. It will do so even if it has to rise at first, provided its final level is lower than its initial level and there is no air in the  connecting pipe work. A system in which water rises and then falls as it flows of its own accord under gravity is called a siphon.

Manual and electric marine toilets flushed with sea or river water require connections through the hull below water level. If the toilet is installed below the boat's waterline, the possi­bility of flooding the hull through an open sea­cock must be prevented, not only for the dis­charge pipe, but also for the inlet pipe. If no precautions are taken, a toilet below the waterline is at risk of flooding at all times when the discharge or inlet seacock is open. A loop of pipe above water level may pre­vent flooding, but there remains a risk that a siphon will be created by pumping the toilet, or when the boat heels, or by wave action. To break the siphon, air must be let into the top of the loop of the pipe, allowing water to drop back on both sides of the loop and stopping it from flowing into the hull. This is achieved by the installation of a vented loop. Detailed information and advice should be obtained from manufacturers.


Vented loops are anti-siphon safety devices for use with both manual and electric marine toilets installed below the waterline (static or heeled). A Vented Loop is fitted with a one-way valve at the top, permitting water to be pumped through the loop and out of the hull, but preventing the formation of a siphon that would allow water to flow back into the hull. It is most important that the one-way valve is regularly checked and serviced to ensure that it functions correctly.    Detailed information and advice should be obtained from manufacturers.

Wash - what is it?

Wash is the wave created by your boat as it moves through the water. Generally a large cruiser will displace a lot of water creating a big wash and would virtually have to idle to obey a "No Wash" sign. However, a small open run-about travelling at speed would make very little wash when planing.

"No Wash" signs are placed in areas where wash can cause serious safety and environmental damage. Sometimes the sensation of speed can be deceptive; 8 knots might feel slow after a period of wide open throttle operation. Look behind you occasionally, to see if your boat is creating wash. It can take a while before your wash spreads and affects others, so it's important to gauge its effect on the shoreline and other boats.

Above all, be considerate of other water users. Even when there isn't a "No Wash" sign you should still drive your vessel so as to minimise wash effect on other boats, people, wharves and similar. OK, so it might take an extra five minutes to reach your destination ... but will that really make much difference to your day? After all, your wash might just ruin someone else's.

Boating Etiquette
Copper Pipes, Fittings & Salt Water
Flags - Dressing your Boat
Anchors - How they Work
Marine Toilets and the Siphon
Wash - What is it?
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