Preparation is key to safe bar crossing

Photo / APN.

The fast approaching Labour Weekend (just six sleeps away) is not only the first long weekend in almost five months, it is also generally recognised as the start of the summer boating season.

This means many of us will be dusting the cobwebs off our underused craft and quite likely heading off to a new piece of the coast or one visited some time ago. Given that so many of our harbours are "protected" by bars, we therefore have little time to get back on our game if we are to safely navigate our friends and family out to sea and back again.

In the latest issue of Propeller magazine, Mark Robinson, author of the well-regarded Rough Water Power Boating, stresses that there are no rules when it comes to crossing a bar, only principles. The difference: a rule, he says, is a substitute for thought; a principle is a guide to thought.

The first of his principles is to realise that nothing in a bar novice's experience in moderate or even rough water will prepare them emotionally for their first hairy crossing of a bar.

Another is that it is absolutely vital to have up-to-the-minute local knowledge of the bar.

He notes that bottom contours can change overnight, largely because of the settling of waterborne silt and the scouring action of storm seas and tides.

Worse, while channel markers may be accurate, they may only be a rough guide or even totally inaccurate. Lead markers are more reliable but even they can be off and the approach they recommend may vary depending on the conditions. Of course, in many smaller places, there are no markers at all.

Luckily, getting this vital local knowledge is often quite easy. Local Coastguard units should be a first point of call but police, boating clubs, tackle-shop owners and the local service station will all probably either be able to help or willing to recommend someone who can.

At Waihi Beach in the Bay of Plenty, for example, holidaymakers and newcomers to the area are encouraged to join the local Coastguard. As part of their membership, they will be given hands-on advice about how to cross the nearby Bowentown bar.

In some areas, local Coastguards or boating clubs will be able to offer hand-drawn charts showing the best way to negotiate the bar while others will have overlaid this advice on a proper marine chart.

Another of Robinson's principles for those boating a bar for the first time is to invite an experienced local to come along and point out the safe channels.

If none of that is possible, he advocates spending at least 20 minutes at a (preferably high) vantage point on land working out the channel location and entry and exit points.

Perhaps the single thing that makes bar crossing so challenging is their extremely changeable nature. As Robinson points out, what works well one day, might be a recipe for disaster the next.

He describes bar conditions in three ways - ideal, difficult and impassable - and points out that, in a very short time, conditions can go from ideal to impassable, completely bypassing difficult.

While there is no simple formula that works in all places and conditions, there are two general rules of thumb: the best time to cross a bar is likely to be on a flood tide; conversely, the worst time to cross is likely to be on an ebb tide.

Other factors that need to be considered are swells, tidal effects (both current and seasonal), the influence of the wind, heavy rain falling up river from the bar and the varying depths.

If it all sounds a bit too technical and dangerous, it is worth remembering that thousands of Kiwi boaties safely navigate their way backwards and forwards across bars every year.

They invariably use one of two methods: the "Power On" and the "Easy Does It".

The Power On approach is particularly suited to craft with a good power-to-weight ratio, either twin-hulled or moderate to deep V, solidly constructed with well-secured windscreens, and either no forward-facing windows or strengthened ones. The Easy Does It method is more suited to lesser-powered craft, to displacement vessels and to boats with self-draining cockpits. It is also particularly applicable in big, steep swells where a faster approach may simply be too dangerous.

While neither is intrinsically superior to the other; the best one to use largely depends upon the bar conditions, as well as craft design and the available power. Generally speaking, the Power On approach requires a craft with a realistic speed of 25-30 knots.

While some bars can only be crossed safely using the Power On method, others are more forgiving and will also allow the Easy Does It approach.

Robinson recommends being familiar with both.

Maritime New Zealand also have a handy dash sticker entitled: Before You Cross A Bar. This outlines 10 important safety tips to follow when crossing a bar. It and a DVD on bar crossing are available by email or by ringing 0508 225522.

By law, everyone on board when crossing the bar must be wearing a lifejacket and be awake at the time.

Want to know more?

Check out Mark Robinson's article Crossing A Bar in the October/November issue of Propeller magazine or get his book Rough Water Power Boating, available from Trans Pacific Marine.