Select Page

All competent sailors need to have a good basic understanding of how to interpret a weather forecast. They also need to be able to interpret the actual conditions they are experiencing.

Most weather forecasts present a general picture of what to expect in a given area over a period of time. We rely on such forecasts to provide basic information, but the actual weather and sea conditions we experience don’t always tally with the general view.

This is not necessarily the forecasters’ fault, as it is the local tides, topography and sea breezes that interact with this basic picture and give rise to the actual conditions we experience out on the water. To make more accurate predictions of the weather in your specific area requires more in depth knowledge and skill.

This section through a depression has wind moving from left to right. High cirrus is followed by layers of cloud which gradually become lower as the warm front passes, bringing rain. Thick stratus cloud in the warm sector is followed by heavy rain and eventually cumulus cloud appears, eventually giving way to sunshine:

A typical depression in the northern hemisphere moves in an anti-clockwise direction with low pressure in the centre:

A cold front is approaching with towering cumulus and heavy rain. Squalls are common accompanied by high winds exceeding 20 knots:

It is up to the skipper to make a calculated interpretation of the available forecasts and to decide whether it is safe for their vessel and crew to go afloat.  At the same time by studying the weather conditions they can check:

  • Where in the forecast weather pattern they actually lie?
  • Has the predicted front passed through yet?
  • The current wind strength. Has it changed through the last few hours?
  • The atmospheric pressure. Is it rising or falling?

Sources of weather forecasts

If you are planning a trip, it is best to gather as much reliable information as you can.  Sources of weather forecasts include:

  • Weather apps – I use PredictWind, Windfinder and Windy. There are many others.
  • National meteorological offices.
  • Internet – good source for GRIB forecasts (Gridded Information in Binary files),eg UGrib, weather charts, web services eg Windguru also back-up to VHF, NAVTEX, INMARSAT-C and SSB radio.
  • MSI (Marine Safety Information) broadcasts on VHF and SSB radio.
  • Public service broadcasts on radio and tv.
  • NAVTEX, Weatherfax and INMARSAT-C.
  • Harbour and marina offices.

Caution: The internet is not part of the MSI system and should never be relied upon as the only means to obtain the latest forecast and warning information. Access to the service may be interrupted or delayed from time to time, updates may also be delayed. Refer to GMDSS services, INMARSAT SafetyNET or NAVTEX for the latest information. When using these web pages, check that the page on your screen is not from your cache. Use the Refresh button if in doubt.

Compare a number of pressure charts to see how the weather patterns have been forecast to evolve in your area over a number of days. This will help you to judge when fronts will pass through, what local conditions will be as a result and how this tallies with your planned departure and route plan.

Before you go

Study your charts and estimate when and where you can expect wind against tide. Are the elements going to clash severely and if so when is this going to happen?  Will you need to avoid being in that area or will the conditions be manageable?

Always study the weather forecast thoroughly before going afloat in order to remain safe and to make an efficient passage plan. Before departure, download forecasts to cover the anticipated length of your passage. Be prepared to delay your departure or change your destination if the weather forecast is unfavourable.

Once committed to going, ensure that you have the means to get regular, reliable weather forecasts if you are at sea for any length of time.  This will allow you to change your plans and head for a safe haven if the forecast is for stormy weather, and to take advantage of detailed weather information when planning your route.

Tips:

  • Study the Beaufort scale and use it to judge wind strengths.
  • Practice how to interpret barometric pressure charts.
  • The barometer is arguably the most useful forecasting tool. Keep a note in the log to monitor change in barometric pressure.
  • Learn how to observe cloud formations to forecast the weather.

Engine failure at sea – common causes and how to avoid them

Many engine failures are caused by lack of maintenance, resulting in fuel filter blockages, water pump failures, overheating and other breakdowns. Indeed, one of the most common reasons for marine rescue service call outs is for one of the most basic reasons possible – boats that have run out of fuel.

Marine engine electrical system

The typical basic electrical system associated with a marine engine includes a dedicated engine starting battery, a starter motor, a charger in the form of an alternator, a solenoid and some engine sensors and instruments.

Tidal terms and definitions

Getting to grips with tidal terms and definitions can seem a little daunting, even to the most experienced sailors! Here we look at some of the key terms and definitions associated with the language of tides.

Boat engine basics

Boat engines come in all shapes and sizes and include inboards, outboards, petrol, diesel, electric and hybrid systems. Some engines are...

Boat engine cooling systems

Some boat engine breakdowns are unavoidable but those caused by lack of maintenance or regular checks can be avoided. Failure to maintain an engine’s cooling system is a well known example of this, so it is well worth spending time checking over the cooling system both when the boat is ashore and afloat.

Wooden Hulls – Part 2

It is important to ensure the essential hull maintenance of a wooden boat is done, even if you are paying others to look after your boat for you. The priority is to prevent rot from taking hold. The protective layers of paint and varnish over wood are far more critical than on GRP boats, where the topsides are painted more for cosmetic reasons.

How to ensure your boat is in proper working condition

In this article Eva Tucker from Volvo Penta presents a handy check list of all the things that you need to check regularly in order to make sure that your boat is in a seaworthy condition. Including maintenance, safety gear and electrical checks.

Estimating your position at sea

Navigators use a combination of techniques to estimate their position at sea. The primary method used today is GPS (Global Positioning System), a network of 24 satellites that became fully operational in the 1990s and was originally restricted for use by the United States military.

Sailboat rig checks – Part 2

In part two of Sail boat rig checks we run through some useful rig maintenance tips and then finish with a brief look at what a professional rig check involves.

Light characteristics – how do navigators identify lights at night?

How do navigators identify the different types of light around our coasts at night and what are their characteristics?Navigating at...

Estimating and plotting your position at sea

This post covers how we go about estimating and plotting our position using traditional methods, when out of sight of land – covering Dead Reckoning, Estimated Position, Tidal Streams, Leeway and more…

Tidal heights and the rule of twelfths

For those skippers who need to make a quick calculation or don’t have access to specific tidal curves for their location, it is possible to make an approximation using a system called the Rule of Twelfths. This is a simple method used to estimate the height of tide at any given time during the tidal cycle. It is based on the idea that the rise and fall of the tide is not constant, but follows a predictable pattern than can be divided into twelve parts.

Rudders and steering systems – Part 3

In the third of our three blog articles on rudders and steering systems, we look at how to replace rudder bearings and repair a water-saturated core.

First aid at sea – four common emergencies

In this blog we look at what to do in the event of a crew member choking, drowning, or suffering from hypothermia or fatigue. Knowing how to cope with them could well save a life, while not knowing could result in an avoidable tragedy.

Sailboat rig checks – Part 1

Sailing boat rigs need to be checked regularly to reduce the risk of rig failure at sea. In part one of Sail boat rig checks we run through a series of useful checks that owners and skippers can carry out.

Jester Challenge 2022 – Sailing single handed from Plymouth UK to the Azores: Part 5 – Boat Management

Jester Challenge – A modern experiment in old-fashioned self-reliance, self sufficiency, and personal responsibility. This is the fifth of a 10-part post where solo sailor, Bernie Branfield, shares his first hand account of his single-handed, 2022 Jester Challenge, from Plymouth, UK to the Azores, in his 26′ Invicta Mk2, Louisa.

Boating emergency – how to broadcast a MAYDAY emergency call

How to broadcast a MAYDAY emergency call   How to broadcast a MAYDAY emergency call if a vessel or person is in grave...

The give-way hierarchy – sail boats and power boats

Who gives way to who at sea? Even seasoned sailors sometimes get this wrong and in a crowded harbour this can easily lead to a collision or at best considerable embarrassment for a boat that mistakenly thinks it has right of way over another.

Diesel engine winterisation

An inactive boat engine needs to be protected from corrosion during the winter, caused by the rising humidity levels through the cold months and the salty coastal air. This applies whether the boat is left afloat or hauled out over the winter. Read here about the two important stages of winterisaton for a diesel boat engine.

How to cope with an emergency at sea

A safe skipper will be mentally prepared for all kinds of potential emergencies happening at sea, including medical emergencies, engine failure, fire, a holed hull, capsize and dismasting.

ColRegs Nav Lights & Shapes, Rules Of The Road and IALA Buoys Apps

ColRegs Nav Lights & Shapes, Rules Of The Road and IALA Buoys Apps Make Learning Rules on iPhone, iPad, iPod and Android...

Boat Improvements

My Boat - practical improvements Author - Mike Rossiter Most boat owners who have had their craft for any length of time will have made what they...

Stern gear maintenance

The stern gear of a boat needs to be checked carefully when the boat is ashore as this is something that can only be done when it is out of the water. The same applies for any maintenance and repairs that may need doing, so it is best to check it all over as soon after an end of season lift out as possible.

First Aid Afloat – fish spine injury

First Aid Afloat - Here is what to do if somebody stands on a fish spine: • Check for dangers. Is it safe for you to enter...

Navigation safety: a quick-reference mobile app to learn the ColRegs NavLights and Shapes

 Safety at SeaSafety at sea will always remains a topical and important subject that will no doubt dominate the syllabuses of nautical...