Between the tropics of Cancer and Capricorn lie the tradewind belts, separated by the Intertropical Convergence Zone (ITCZ) known to many sailors as the Doldrums. The extent of the tropics is defined as the furthest north and south that the sun is overhead at the solstice – over the years it does move a little and is currently at 23°26’14’’ north and south.

For most of us the idea of tropical sailing is the tradewind passage across the Atlantic, followed by a time reaching between the islands in perfect sailing conditions. The stories of days of downwind sailing, occasionally punctuated by a short cooling shower, have become legendary and the passage is often classed as champagne sailing, or the ‘Milk Run’.

Some passages may be like this, but there is rather more to it than trimming the sails, setting the autopilot and getting a book out before lunch or having an afternoon snooze.

10 top tips for the Tropics

• Have an easy reefing system as squalls can arrive quickly.
• Deck-sweeping genoas are generally too big and collect water in the foot.
• A spinnaker pole is handy for ocean passages to pole out a jib.
• Mark your halyards.
• Some form of light downwind sail is desirable for light wind.
• Carry good ground tackle for anchoring behind reefs in the tradewinds.
• Fit a sunshade, a bimini or cockpit sun awning.
• Have good sunscreen and protective clothing.
• A cockpit table is good for outside living.
• Some form of refrigeration is definitely a boon.

The tradewinds

The heating and spinning of the Earth naturally forms semi-permanent cells of high pressure sitting north and south of the Equator. The wind revolves around these highs (clockwise in the northern hemisphere and anticlockwise in the southern) giving winds that are steady in both speed and direction. These are our tradewinds and the natural route of sailing vessels since we first started exploring.

As it is the heating of the Earth that causes these cells to form they do tend to follow the sun, moving north and south with the seasons with the tradewinds separated by the ITCZ, a band of low pressure with squally conditions.

The strength of the Trades will be driven by how intense the high pressure is and the depth of the lows closest to the high. The tradewind route to the Caribbean is driven by the intensity of the Azores High and any heat low over Africa.

A pole to support the headsail is a must. Without one you would be hard-pressed to maintain good VMG.

These variables that determine the speed of the tradewinds will not only vary with the summer and winter seasons, but also day to day and week by week. Other forces also come into play: El Niño will make a significant difference to the Pacific tradewinds and something known as the North Atlantic Oscillation (NAO) affects the Atlantic trades. While the average wind speed may be a Force 4 there will be a considerable variations.

Last November when we took our boat across the Atlantic with the ARC we had what I would consider a fairly breezy crossing, completing it in 16 days, which for a 40ft boat was quite quick. Owing to the position of the Azores High, we could make a reasonably direct crossing without dipping too far south to find wind.

The point I am making is that the tradewinds can vary from around ten knots to well into the 20-25 knot range, and even a period to 30 knots is not unheard of. Therefore you cannot expect to make the crossing without sail changes and, as it will be predominantly downwind sailing, some downwind sails are useful.

Downwind sails

Last year we sailed about 70 per cent of the time with a poled-out headsail and 30 per cent of the time with a spinnaker. Having a coloured sail makes life more enjoyable when the wind drops and prevents you wallowing around, but unless racing you will probably be wanting to drop the kite once the wind gets much above 20 knots true and before that if the sea state is rolly.

We bought a new sail for our crossing – probably not one that would immediately spring to mind: a fairly high-clew 110 per cent jib. The smaller sail with a high clew sets much better when poled-out and gives great visibility underneath it. Deck-sweeping genoas may be faster upwind, but do tend to give a large blind spot which is particularly worrying at night when short-handed.

A maximum sized sail you could fit will spend most of its life partly furled and will quickly lose its shape. Once in the Caribbean and reaching from island to island a smaller sail is much more use and does not scoop up water when waves cross the deck.

I would be very reluctant to make a crossing without a spinnaker pole so as to have the ability to pole out the jib as it is an easy and quick sail combination once the wind picks up. It may be possible to sail the angles without a pole, but it would need a great deal of concentration to maintain a good VMG. Spinnakers, A sails, Parasailors, etc, all have their place when the wind is light, but if short-crewed in a big seaway can be a handful.

Crews will often say that they do not intend to sail with a spinnaker at night and may well reef down when it gets dark; you do have to remember that nights in the tropics are long and restricting your sailplan through the hours of darkness does compromise your speed. With a light wind and full moon, running down the trades at night with a kite up is a great experience, and as easy as during the day, but on a dark night with a cross swell steering becomes very difficult and a kite can easily get wrapped.

A bimini to protect the crew while helming is a boon if not too big.

It also depends on how many people you have – I would rather have two- than single-person watches as I find it a pleasanter passage and the watches fly past when chatting, but can drag if you are on your own and a bit tired.

Rather than making rules on what sails we may or may not use at night we find a little preparation for sail handling goes a long way to improving efficiency. Marking halyards is essential – eg, how far to drop the main halyard when taking a reef, or when you have reached max hoist. This saves damage and makes life easier, and is something we can take from the racing fraternity.

Finding shade

We spend a fortune getting our yachts to the sun, but once there we spend even more keeping out of it. Biminis have become common on yachts, and boats without one are the exception rather than the rule. Aboard some boats with a substantial sprayhood and a bimini you can avoid the sun altogether, and looking around an anchorage in the tropics, I see there are a huge range of ideas to keep out of the sun.

It is a difficult choice; biminis do restrict upward visibility and therefore sail trim and, depending on the mainsheet system, can be hard to fit. On our yacht we do not have a bimini, which for the crossing was great, but for cruising in the Caribbean is probably a mistake as it does get hot and hard to get out of the sun.

Our mainsheet track is just in front of the helm, which makes all but a very small bimini difficult to fit; however we are looking at options for the Pacific leg of our voyage. Interestingly, quotes in the Caribbean were close to double those in the UK.

What we do have, however, is a sun awning that covers the cockpit when at anchor; after a bit of practice it only takes a few minutes to put up then gives great shade. We would have extended it forward to the mast, but this would shade the solar panels. Even so a great cooling effect is immediately felt once it is in place.

Over the past few years sunproof clothing has become readily available and without a bimini having long-sleeved sunproof tops and wearing hats has prevented any sunburn on the way across the ocean. Sailing in the tropics is different and although the sun is great when swimming it can all become a bit too much if at anchor in a well sheltered bay.

Anchorages in the full force of the tradewinds, but sheltered from the sea are great for power from wind generators and keeping cool, but do tend to defeat the object of a ‘sheltered’ anchorage.

This bimini offers fantastic protection from the sun, but can the crew see the sails?

Tropical weather

Tradewinds can vary greatly in strength not only on the passage, but when cruising in the tropics. It is not unusual to have in excess of 25 knots between Caribbean islands, along with a big sea. Squalls are a fact of life and you can get some strong to gale force gusts on their leading edge. Being able to reef quickly is therefore essential.

Between the islands of the Caribbean, particularly when heading north, it is often quite hard on the wind and a small working headsail is useful. Last winter we had long periods of strong tradewinds, which for some crews were more testing than they wanted. There is a standing joke for weather forecasting through the islands: that we can put up the forecast in November and take it down again in April – NE-SE 15-20 knots with occasional squalls.

We generally sail in the tropics during the winter months, which is the dry season. During the summer it can become very hot and humid, and of course there is a chance of hurricanes, which peak in the Caribbean during August and September, although the hurricane season extends from early June to the end of November.

An increasing number of yachts stay in the hurricane belt relying on forecasts and the fact that hurricanes are slow-moving so can be avoided. Others may leave their yachts on land, stripped of deck gear with lorry straps to the ground, relying on preparation (and luck) to keep safe.

This we have done with our yacht at Clarke Court in Grenada where a massive storage facility has been developed. Although Grenada is in the hurricane belt, statistically the island is hard hit only about once in 50 years, so fingers crossed!

Between the tradewinds of the northern and southern hemispheres is the ITCZ, which is a band of squalls and thunderstorms. Where you pass through this band is extremely important when racing, but as long as you have fuel the pain of passing can be minimised by the use of the engine when cruising.

Crossing the Doldrums

Boats on a tradewind circumnavigation will usually cross the Doldrums between Panama and the Galapagos Islands and when we last did this passage it took four days; two days’ sailing and two motoring. However a yacht that did not want to motor took 16 days over the same passage.

In the Atlantic, crossing is best done on the western side – as far west as possible, as long as it does not mean beating to round the corner of north-eastern Brazil.

Away from the ITCZ the tropics can generate some impressive thunderstorms, although these are most frequent when sailing close to large land masses. When crossing oceans in the tradewinds away from the land or the ITCZ, lightning strikes are thankfully quite rare.

Large squalls do occasionally grow enough to produce thunder and if a thundery trough develops (usually when close to the ITCZ) you can get a period of intense squalls and thunder with the wind jumping to gale force on the leading edge of the squall.

Generally tropical sailing is great: sunshine, warm water and good winds. However it does get a bit more complicated around large land masses and in squalls. The winter sun we seek is also the enemy, as it is very intense and can quickly burn. Having suffered from ‘surfer’s eye’, I always keep a good pair of sunglasses close at hand, along with sunscreen and a hat.

Dealing with squalls

As a rule, the higher the cloud, the heavier the rain in a squall and the stronger the wind will be as it arrives. A large squall carried along with a brisk tradewind can give a gale force gust on the leading edge as the wind and rain arrive close together. This gust front will normally pass through quite quickly, leaving you with torrential rain. At times groups of squalls occur when one is quickly followed by another. They can be best monitored by radar, although a hand-bearing compass will give you a good idea if you will be hit or not.

For more on squalls, tactics for dealing with them and a video briefing see www.yachtingworld.com/squalls

Sailing onboard Taistealai in Grenada and the Grenadines February 2016. Chris and Helen Tibbs
Photo Rick Tomlinson

Chris Tibbs is a meteorologist and weather router, professional sailor and navigator, as well as an ARC safety inspector. He is currently doing a circumnavigation with his wife, Helen, on their own boat, Taistealai