How to handle your boat in heavy weather

Doug King | Volume 31, Issue 4
Boating in heavy weather will test your skill and nerve.
I vividly remember a puzzling call received while working in the Victorian Water Police. Making our way up Port Phillip Bay from a coastal patrol, a 16m motor cruiser powered by two 500hp engines was calling for any vessel to assist. It had been blowing from the southwest for a few days which, in Port Phillip, sets up steep confused seas. This type of sea state is typical in bays and large inlets right around Australia.

The skipper indicated that all his machinery was working okay, but he had so much trouble with the vessel rolling and pitching that he and his five family members were violently seasick, and beginning to panic. The boat should have been handling the weather okay – we were in a similar-type vessel and making 15 knots comfortably.

We found them right in the centre of the 2000sq km bay. The boat was travelling slowly, pitching, rolling and heaving. We put a crew member onboard and – after checking the occupants, assessing the boat and determining where they were headed – the cruiser was quickly running smoothly through the following seas at 15 knots. With a reasonable amount of power and the bow trimmed up, it ran comfortably and quickly through the water.

Talking to the skipper at his marina, the problem became obvious: while he had a lot of experience in displacement cruisers, he was new to this type of boat. He was simply unaware of techniques used to handle large semi-displacement cruisers in choppy weather and was impressed with how his boat handled when trimmed and operated properly.

Despite the fact that his boat could handle the weather, he also failed to consider other open-water risks, such as seasickness, broken glasses, crockery and equipment strewn about the boat, and stresses on the boat and equipment.

Handling a vessel in heavy weather takes experience, skill and the right temperament.

This time of year is a good time to review heavy-weather handling techniques and tips, with long periods of rough conditions experienced around the country from August to November. Getting caught out in rough weather is not fun and obviously not something careful mariners deliberately do. There are times, however, when making your way through rough conditions is unavoidable and being prepared is good practice.

I know this is my mantra, but I can’t repeat it often enough: good preparation really is the key to safe and enjoyable boating. Consider conditions carefully and only go if your boat is suitable and up to the task in all respects.

Apart from the normal safety and mechanical checks, heavy weather dictates wider thought and planning.

On larger boats, secure loose objects inside the boat. Close internal doors and cupboards after making sure objects inside are packed properly. Turn off the water to the heads, then empty the bowl. Take bags off bunks and place them on the floor, providing they won’t be in the way. Mats on the deck can slip if not properly fastened, so secure them, along with fold-down tables and similar fittings.

Check that windows and portholes are closed and rig deadlights. On flybridge cruisers, do a quick check for security. In severe conditions, I have seen clears torn apart by the wind, so consider opening your clears to allow wind to flow through.

If you have a tender, recheck that it is tied down properly. Around the boat, tie the anchor down (you don’t want it becoming a missile), double-knot the fenders and secure any lines, boat hooks and life rings.

The engine room needs a check-over, too. Secure any loose items and check fluid and oil levels. Test bilge pumps for proper operation.

On trailerboats, the process is similar, albeit on a smaller scale. While there isn’t as much to do, preparation is just as critical. Additionally, select the fullest portable fuel tank, if you have more than one.

Brief your crew or passengers to hold on – legs slightly apart and relaxed, with knees bent, is the most comfortable stance. Suitable protective clothing is a good idea – wet-weather gear and warm clothing may be appropriate and consider wearing PFDs from the start. If seasickness is a problem, take precautions … remembering that medications may take some time to take effect.

Understand and assess your boat’s stability factors. Different types of boats will handle differently but, in general, keep weight low and evenly distributed. Don’t let waves pass you at a period that equals the period of rolling and pitching (up and down), as this configuration can destabilise the vessel. Change speed as needed to avoid this condition.

It’s essential to remove any excess water that builds up from spray and to trim for the sea conditions. Use the vessel’s trim tabs, or move weight around, to keep the keel meeting the water at a 90-degree angle. Having the boat lean to one side means the flat hull surface will pound and slap.

Typically, you’ll encounter three types of sea conditions:

  • Head sea – going into the waves
  • Following sea – going with the waves
  • Beam sea – waves are coming from the side

Good power management is important. You may not be able to set the power and leave it – adding or reducing power as you encounter waves will mean a more comfortable ride. To maintain a comfortable ride, the speed should be reduced from your normal, smooth-water running speed. This will also reduce stress on the boat’s hull.

Into a head sea, reduce the boat speed. For cruisers, the bow should be trimmed down slightly – do this with the trim tabs or by moving the outboard engine. The trim position will depend on the boat and the conditions. You’ll want a comfortable ride: trim too far up and you run the risk of launching the boat skyward up the face of a wave, resulting in anything from an uncomfortable crash down the other side, to flipping or flooding the boat. Downward trim setting is a matter of compromise: too much and you will bury the bow into the oncoming waves; too little and you will not track truly through the sea.

Use power wisely to keep the bow controlled into the oncoming wave, reducing power as you rise over it, smoothly powering again toward the next wave, and taking advantage of lulls or calm periods. You may make a head-sea ride more comfortable by ‘quartering the wave’. Commonly called tacking, this technique involves meeting waves at about 10 to 15 degrees off square – however you might take more spray into the boat. The course will be zig-zagged, taking longer and using more fuel.

In a following sea, trim the boat bow up – this stops the bow burying as you go over one wave and into the next. If possible, get onto the back of a wave and stay there.

Larger, more powerful boats can drive from wave to wave with the bow up. In lower-powered vessels, keep a lookout for waves behind that are travelling faster than you, as they may break across the boat. These are rare but can occur in tidal waters and confused seas. Again, power management is important.

If you do power over the back of a wave be careful of ‘broaching’. Broaching is when you lose steerage going down the face of a wave. When you reach the bottom, the boat can be forced sidewards and may be rolled. Powerful boats are able to recover from broaching by the application of power.

Although considered a dangerous practice, boats can be driven along a beam sea quite safely under certain conditions. Generally, where there is a constant, steady pattern of waves that are not breaking and with a reasonable distance between them, running along a beam sea may be achieved safely. Good situational awareness and keeping a lookout are paramount. Remember: the danger lies in short, sharp, steep seas that tend to roll or swamp a boat.

Most of the techniques and general preparations for heavy-weather handling apply to crossing ocean bars – except that bar crossings involve short, sharp pressure waves which have to be handled very carefully. Additionally, room to move is generally limited and depths may vary.

When preparing to cross a bar, use local knowledge, wear PFDs, follow navigation marks and notify the local VMR by radio of your intention to cross.

Getting back to that boat in trouble on the bay – the skipper had a boat that could handle the conditions, but he lacked the experience and the knowledge needed to deal with them. As a consequence, a reasonable trip turned into something they would talk about for a long time. If you’re not experienced in rough weather, try these techniques in a small chop and work your way up to larger seas, but always be aware of you and your boat’s limitations.

Also, it is extremely important to remember that fuel consumption will increase up to 25 per cent in heavy weather.

On a final note, remember that the ability to deal with rough weather is limited by the least-experienced person onboard. Don’t make others uncomfortable or put them in danger … what one person may think is challenging or good fun may terrorise the crew or guests.

And before you go out in heavy weather, always consider the risks carefully.

  • Secure anything that could move around, come loose, be damaged, or let water into the boat
  • Ensure engines, bilge pumps, systems, radios etc are in good working order
  • Adjust the boat’s speed, trim and centre of weight to the conditions and wave direction
  • Calculate the fuel requirement for the trip, keeping in mind that consumption will increase in adverse conditions
  • Wear weather-appropriate clothing and a PFD
  • Check your emergency equipment and know how to use it
  • Notify your local VMR of your intentions and log off when you return
  • Consider conditions carefully and only go if you and your boat are suitable and up to the task
Give us a call on 1300 00 CLUB (2582)
Any discounts offered are applied to our standard rates. Promotional or other discounts may apply from time to time. Minimum premiums may apply. Any discounts/entitlements only apply to the extent any minimum premium is not reached. If you are eligible for more than one, we also apply each of them in a predetermined order to the premium (excluding taxes and government charges) as reduced by any prior applied discounts/entitlements.

Any advice here does not take into account your individual objectives, financial situation or needs. Terms, conditions, limits and exclusions apply. Before making a decision about this insurance, consider the Product Disclosure Statement (PDS)/Policy Wording and Supplementary PDS (if applicable). Where applicable, the PDS/Policy Wording, Supplementary PDS and Target Market Determination (TMD) for this insurance are available on this website. We do not provide any form of advice if you call us to enquire about or purchase a product.

Club Marine Limited (ABN 12 007 588 347), AFSL 236916 (Club Marine) issues this insurance and handles and settles claims as agent for the insurer Allianz Australia Insurance Limited (ABN 15 000 122 850) AFSL 234708 (Allianz). Club Marine is a related body corporate of Allianz. Copyright © 2024 Allianz Australia Limited