Sail-World.com : Practical Boating - Capsize - how to minimise the danger
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Practical Boating - Capsize - how to minimise the danger |
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'“Broaching typically occurs when the boat slews uncontrollably down the face of a wave, and the bow digs in. The boat is then caught beam on, and rolls violently.”'
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Many first-timers to boating may be unnerved by the vessel’s rolling motion, but boats rarely capsize, and when they do, it’s usually only in extreme weather. But even in such conditions, there are numerous ways to promote stability and safety.
Boat stability is all about maintaining a low centre of gravity (C/G), says Neil Murray, training and development manager at Coastguard Boating Education.
'Keelboats already have a low C/G thanks to their heavy keels, and most launches benefit from the engines, water tanks and fuel tanks being placed low in the hull. Trailer boats are light and generally have a fairly shallow draught, so their C/G can be enhanced by people - as long as they are sitting low in the boat.'
'Typically, therefore, capsize is only likely to occur in really rough weather, and in such conditions, there are a number of tactics the skipper/crew can employ to minimise the danger'
Ensuring Stability
Distributing/securing weight: Launches with flybridges may have a higher C/G than single-level launches, says Murray, and in rough conditions, when the vessel is rolling excessively, it would be prudent to keep the crew/guests down below rather than up on the flybridge.
'Skippers should also ensure that all heavy objects are secured, such as toolboxes, jerry cans, dive bottles – low down and as close to the boat’s centerline as possible. If left unsecured, they not only become lethal missiles (in a heavy roll), but will also contribute to the boat’s momentum when rolling.
Waves coming into boat: 'A trailer boat’s stability is quickly compromised when waves slop over the side or over the transom. This typically happens if the engine fails and the bow falls off the wind, leaving the stern exposed to breaking or steep seas.
'When water comes over the side – the surging action of the water inside the boat accentuates its tendency to roll excessively (called 'free-surface effect'), increasing the possibility of capsize.'
To minimise any chance of this in rough seas, the golden rule is to steer into the waves. Monitor the bilges and pump out any water as soon as possible.
If the engine does fail, and the bow falls off the wind, move everyone forward to keep the stern as high as possible. 'Do not fall into the trap of allowing three or four people crowding around the engine – that simply increases the chances of a wave breaking over the stern.'
 | Capsize close off the Southport Bar - .. . |
Overloading: This is a big no-no, especially in boats such as 'tinnies' with a low freeboard. 'Such vessels are susceptible to swamping, particularly if its occupants stand up and raise the C/G. Every boat is rated for a maximum number of passengers – do not exceed that.'
Boat handling: In rough conditions, you will have to make a judgment. 'The safest ‘attitude’ for the boat is heading into the waves – the bow is the most buoyant section of the boat. The outboard or stern leg should be trimmed in, to keep the bow down.
'If you’re running downwind, and you have sufficient power, you can outrun the waves, but you must remain extremely vigilant. Accelerate away from breaking seas and crests to avoid being ‘pooped’ over the stern. Keep the trim tabs up (outboard/leg trimmed out) to help the boat maintain a bow-up attitude.'
Running downwind also increases the danger of broaching – so careful, controlled steering is paramount. 'Broaching typically occurs when the boat slews uncontrollably down the face of a wave, and the bow digs in. The boat is then caught beam on, and rolls violently.'
Crossing a Bar: Bars (at the entrance of estuaries or rivers) are particularly dangerous for the unwary. This is where boaties are most likely to encounter big, unpredictable seas. 'Talk to locals about the conditions at the bar, and ideally, take someone with experience with you for the first few times. Lifejackets must be worn and all heavy items should be secured as low down as possible.'
If the Worst Happens
Despite all your efforts, it happens. What to do? The golden rule, says Murray, it to stay with the boat. 'Chances are the boat will stay afloat – especially if it’s CPC-rated – even if upside down. It not only provides flotation, but is easier to spot by rescuers. A person’s head is very difficult to see in the water – and impossible to spot in rough seas.'
If you can, clamber on top of the up-turned hull, to make yourself more visible and reduce the chances of hypothermia. If that’s not possible, and there is a group of people in the water, stay together in a huddle to preserve body heat.
For more information on courses offered by Coastguard Boating Education download Coastguard Boating Educations brochure or visit their website www.cbes.org.nz
by Neil Murray.
9:54 AM Tue 9 Jun 2009 GMT
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