Waves – the wind’s assassin

The BBC is today carrying the story of a new record wave height for the North Atlantic, nineteen metres, or about sixty-three feet, measured by an oceanographic buoy. A few years ago I heard a report by the Irish Met office of a wave off Donegal that measured in at over twenty metres, sixty-seven feet. The Irish Met Office says the buoy that measured that wave is 11km off the coast; it too was generated in deep water by persistently high winds. Whichever claim is actually the record, they’re both pretty big waves and I wouldn’t like to meet either one in a small boat.

By the way, these are wave heights measured by buoys, there is a report of a wave measured by a ship which was a staggering ninety-five feet.

The probable maximum height of wind waves is around 80% of the wind speed. So, a 50 knot wind blowing over an area of ocean with unlimited fetch would produce a maximum wave height of about forty feet. This height is achieved after it has been blowing for a day, having doubled in height since the first four or five hours of the storm. Further maximum wave height increase is more subdued, it takes two days to get that wave up to fifty feet in height.

The average wave height in a storm is about half the height of the top ten percent of waves and one third of the highest wave. So, if the maximum wave height in our 50 knot blow is forty feet, the top ten percent of waves will be about twenty feet and the overall average will be about fourteen feet. It doesn’t sound so bad when you put it like that, does it? Except that you still have to survive those forty-footers.

The Compass

I don’t suppose anyone would argue with the proposition that the wheel is the most compassimportant invention in the history of mankind.

I do realise that some folk think it was the thermos flask:
“The thermos flask! That only keeps cold things cold and hot things hot!”
“Yes, but how does it know?”

Even so, most don’t seriously doubt the impact the wheel has had on mankind’s development. And I don’t think there’s any doubt the compass is up there with the wheel as a significant invention.

The compass was discovered in 11th century China when someone realised that a lodestone suspended from a thread always pointed the same way. What a ‘Eureka’ moment that must have been!

Unfortunately the Chinese marketing organisation of the day didn’t immediately see the navigation application as worthy of pursuit, seeing more potential in the Feng Shui application. So property developers concerned with the spiritual well-being of their building’s occupants, rather than explorers, were the first beneficiaries of this new technology.

Eventually, however, word spread of the lodestone phenomenon and the compass was put to proper use and the rest is history.

Then came GPS, but that’s another story.

Boat food

Looking through the old recipe books built up over five or six years of liveaboard cruising I’ve spottedrecipe-book-300x275 an old favourite: Maddie bread.

Maddie bread is a great treat for breakfast or as an anytime snack. We liked it in place of toast, which was a pain to make using those stupid wire racks over a cooker burner.

Maddie bread is short for Madeleine’s German Graham Bread: Our friend Madeleine introduced us to it, she claims it’s German in origin, Graham is a type of wholemeal flour and it’s a kind of bread. So, it’s an accurate if not succinct title.

By the way, don’t confuse Graham flour with gram flour; the latter is made from chickpeas, not wheat.

Anyway, on with the recipe:

1 cup of all purpose flour
2 cups of Graham flour. (Substitute wholemeal outside North America)
1 ½ tsp baking powder
1 tsp salt
½ cup brown sugar
2 cups of buttermilk. (A substitute for buttermilk is ordinary milk with 1 tablespoon of lemon juice or vinegar added per cup).
Cinnamon or raisins, optional.

Blend all dry ingredients in a mixing bowl. Add buttermilk – mix with spoon. Add cinnamon or raisins if desired. Turn into greased bread pan and bake for 1 hour at 180ºC (350ºF).

Delicious with butter and jam. Enjoy.

Oh, and here’s a tip for keeping your flour, rice, pasta and other dry staples weevil free – put a few bay leaves in the storage container. Put unopened bags or boxes of these products in large plastic bags with a few bay leaves. I don’t know why this works, but it does.

The Dream

I’ve read somewhere that the most widely held dream in the western world is to set off in aIMGA0014 small boat to sail around the world. It’s the lure of total freedom that does it, of course, and as dreams go it takes some beating – master of all you survey, no schedule, no boss, tropical beaches, gin clear water, fun in every port.

As you acquire more knowledge, however, reality draws closer and you have to address some of those inconvenient concerns that intrude – the ones that make you bash your pillow, turn over and try to recapture the dream as it was, unadulterated. Concerns like: How much money will we need? What if we get ill? What about storms? Will I get seasick? But then you tell yourself these are just speed bumps on the road to freedom. Many, many people have been this way before and they overcame all kinds of obstacles. You know for sure it’s possible and, of course, you’re right.

But I’d suggest that those who have actually sailed beyond the horizon are less likely to Adriana Culebradream of a life on the ocean waves than those who have barely set foot on the deck of a boat. A rough three day offshore passage during which you’re debilitated by seasickness can’t intrude unless you’ve experienced it. Running aground, dragging anchor, the constant motion and having a clogged heads won’t disturb the dream because they’re concepts beyond your ken. Ignorance is, indeed, bliss and a little knowledge is dangerous.

I sailed in an offshore race with a very experienced man and wife team and two days out the wife stood in the saloon and screamed at the top of her voice “Get me off this fucking boat!” Then she went on deck and stood her watch. And then I’ve listened to people who have done no more than coastal hop from marina to marina expound their plans to set off around the globe.

Far be it from me to discourage anyone from seeking adventure in a small boat, I’ve done it twice, but beware the little devil who whispers in your ear, “set off now, before you’ve learnt enough to know this isn’t the life for you.”

Coaxial cable for VHF

OK, so you have a superb radio and a top class antenna. What do you use to connect one to the other without losing the potential of these fine pieces of kit? Coaxial cable is the answer, but not all coax was created equal.landfallnav_2247_118626322

Coaxial cable for VHF radio and AIS is 50 ohm – your TV cable is 75 ohm so you can’t just use some coax left over from your satellite dish installation.

Furthermore, marine cable needs to work in a hostile and constantly moving environment so conductor and braid need to be tinned copper to resist corrosion and the conductor needs to be stranded so it can bend without breaking. A good PVC jacket will keep sunlight degradation at bay.

But what size cable should you choose?

You should aim at a transmission loss of no more than 50% in the run from radio or AIS engine to antenna. In fact, the requirement of the ISAAF for offshore racing is no more than 40% loss in the radio antenna cable.Cables

A loss of 3 decibels (dB) halves the signal so you’ll want to restrict the line loss to no more than that. Signal loss in the cable, known as attenuation, is determined by the size and construction of the conductor, the quality of the shielding and the operating frequency.

Good quality RG213 will lose about 33% of the signal strength in a 20m run, about 45% in a 30m run, so for very big boats it’s the way to go. However, RG213 (and its slightly lower spec but similarly stiff cousin, RG8U) is nominally 10 mm diameter, nearly half an inch in old money, so it’s heavy and doesn’t like to go around tight corners. It’s difficult to work with.

RG8X is nominally 7mm diameter, although actually about 6.5mm diameter unless it has a particularly thick outer jacket. This cable is much lighter and easier to work with than 10mm cable. Good quality RG8X will lose a little less than 50% in a 20m run.

You may also see RG58 cable, it sometimes comes with cheap aerials. It is nominally a 6mm cable, but usually closer to 5mm diameter, and is very lossy. OK for very short runs, perhaps, but certainly not for masthead installations. It loses a whopping 65% of the signal in a 20m run. That means 15 watts of your 25 watts maximum power is lost just in the cable run. It’s scandalous that this cable is offered in ever increasing lengths, factory crimped to an aerial. It used to be offered in 5m lengths for power boats but just recently I’ve seen it offered in 25m lengths. Don’t use it for anything more than 6m runs or you’ll lose more than half your signal power.

So, make sure your cable is of marine quality with good shielding and for a cable run of up to about 20m use RG8X, for much longer runs you’ll need to wrestle with RG213/ RG8U. Don’t use RG58 except for very short runs, up to 6m.

And remember: “A penny in the antenna system is worth a pound in the radio”, so don’t skimp on your antenna, cable and connectors if you want to unlock the full potential of your radio or AIS unit.

Bank effect sucks

A vessel moving close to the bank of a river, a cut or a canal will find the stern tends to bank effectmove towards the bank. This effect is due to the water being squeezed between hull and land, increasing its rate of flow and creating a low pressure area which the hull is sucked towards. I was blissfully unaware of bank effect until I set off from Houston to New Orleans by way of the Gulf Intracoastal Waterway.

In my case, however, it wasn’t the tendency of the bank to suck my little yacht towards it that was the problem; it was the tendency of the huge triple wide ‘tows’ to suck my little yacht towards them – a potentially fatal variation of the bank effect – that had me worried.

This particular stretch of the Gulf ICW is extremely commercial; leisure boats are rare, a minor irritation to the waterway’s regular traffic. One foggy morning we had pulled over to the side of the waterway to keep out of the way of the barges until visibility improved. The bank was grassy and too high to climb but a small sapling overhung the canal and I was able to get a bow line on it – or should that be bough line? The boat lay comfortably against the bank whilst we sipped coffee and waited for the fog to lift.

A booming fog horn indicated the imminent arrival of the morning’s first traffic and shortly thereafter the grey outline of a lumbering behemoth appeared, moving through the gloom some 30 or 40 feet abeam of our snug berth. As the monster triple-wide tow thundered past we found ourselves in the hitherto purely theoretical low pressure area between bank and barge. We were sucked towards the barge at a frightening rate until we were hanging perpendicular to the bank clinging tenuously to our sapling. Oh how I begged that little treelet to maintain its grip on the soil.

As the thousand-foot long iron wall of interconnected barges rumbled past, the sapling bowed and stretched, its immature foliage dipping underwater. Two minutes later, an eternity it seemed, the barge had gone and we settled back against the bank.

Bank effect sucks, I can tell you.

Sunsets

Everyone loves a sunset. Sailors are particularly privileged because we get to see the sun 6 Nov sunsetsetting over the ocean even on eastern facing coasts, as long as we’re a few miles offshore. Ocean sunsets bring with them the extra tingle of excitement that comes from anticipating the green flash – the fabled emerald green glint on the horizon just as the sun disappears below it.

I have hundreds of pictures and miles of film of sunsets; in none of them is the green flash present. But I have seen the green flash several times. Maybe it’s in the eye of the beholder.

Some people will go to considerable trouble to see the sun go down – the chap standing on the spreaders has a granBoot-Key-Sunsetdstand view. The picture was taken at Boot Key, Florida.

Cableport – a safe, waterproof deck entry for mast cables.

There are several ways to get the cables from your deck stepped mast into the boat without allowing water in with them.

Deck plugs are inclined to corrode and fail unless meticulously maintained. Typ12vat9909
Deck glands are a better choice because any joint is made below decks.
Both deck glands and deck plugs are vulnerable to being stepped on by crew working the busy area around the foot of the mast. If you use them, buy metal not plastic versions.
A swan neck is a popular choice on bigger boats but they can snag sheets and halyards if you’re not careful.
An excellent option is the Swedish designed Cableport.

The Cableport is a polished stainless steel entry port that takes electrical and 147communication cables through the deck via a 49mm shrouded opening.

Cableport can take 6 cables up to Ø12mm, or more of smaller diameter. It can accommodate connectors up to Ø 45mm. (A typical PL259 radio connector is Ø 20mm)

It can be easily opened to remove cables and connectors when the mast is unstepped or when wiring changes are made. (No silicone or other sealant is required after initial installation).

Cableport does not catch rigging and lines and can be stepped on without damage.220

It measures a compact 160mm x 100mm x 45mm.

The Cableport is available from Salty John – there’s a link over there on the right.
American customers can buy in UK pounds and there will be no additional shipping charge to anywhere in USA or Canada.

The Beaufort Scale of Wind Force

The Beaufort Scale of Wind Force has been around for over 200 years; it’s still used in the BBC shipping forecast, issued by the Met Office on behalf of the MCA. You don’t hear much of it across the pond in America, though, or Down Under.

When Sir Francis Beaufort first devised the scale in 1805 it was simply his assessment of Beaufortthe wind strength, based on the observed sea conditions, so that a mariner could decide how much sail to carry. It was intended to describe the conditions under which various amounts of sail could be carried by a man-o-war, the principle warship of the time.

The scale ran from a Force 0, dead calm, in which all sail would be flown, to a Force 12 in which the winds were ….such that no canvas could withstand.

In 1831, when anemometers had been around a bit, wind speeds were applied to each of Sir Francis’ 13 levels of wind force. A Force 6 was described as a fresh breeze of 22 to 27 knots …or that in which a well conditioned man-o-war could carry, in chase, full and by, single reefed topsails and top gallant sails.
Very useful if you know your top gallants from your tam o’shanters.

Over time the scale was further modified and modernised. Wind speeds were added and a ‘state of sea card’ was produced bearing photographs of the sea state to be expected for each Beaufort force. Further Forces were added to cover the conditions that might prevail in tropical cyclonic storms. Wave heights are now seen on many versions of the scale.

The wind speeds which were applied to each of the Forces were, presumably, those that most closely related to the conditions that Sir Francis described. For instance F0, dead calm, is given a wind speed of less than 1 knot, something of a no-brainer, but F5 is 17 to 21 knots – it must have taken some serious debate to arrive at that range of figures. And, inevitably, the progression of wind speeds up the scale is not linear, reflecting the exponentially increasing force on the sails as the wind speed climbs. F5 is 17 to 21 knots, whilst F10 is 48 to 55 knots – as we see, an F10 is not merely twice an F5.

The Beaufort scale is seen as an anachronism by many sailing newbies. There is a temptation to assume the Beaufort scale is simply an illogical grouping of wind speeds with no obvious conversion rate to anything else. Why not, they might think, devise some logical groupings: 0-9 knots, 10 -19 knots and so on, if it’s necessary to group wind speeds at all. Such logic is all very well if you think of Beaufort Force as simply another form of wind speed measurement such as knots, miles per hour or meters per second, for which there is a mathematical conversion.

But that isn’t where it came from; it might have been diverted to that use, but what Sir Francis Beaufort devised was a means of establishing the force of the wind by looking at the sea, a reference source to tell mariners how much sail to risk in any given condition.

And still today merchant ships at sea determine true wind speed from sea conditions – and they supply this information to the MET office. The reason they do this is that anemometers mounted on large fast moving ships don’t tell the true wind speed, they measure apparent wind speed – the wind speed modified by the ships own, often very high, speed and by the effect of the ships superstructure. To get the true wind speed they rely on their deck officers who are skilled at estimating it from the sea state. Sir Francis Beaufort would be proud of them.

Thinking about boats

My favourite philosopher is Anonymous, or Anon as he’s known to his friends. He’s thethinker bloke who said: The final test of fame is to have a crazy person imagine he is you.

It was another of Anon’s pearls of wisdom that sprang to mind as I was pondering how the cruising boat has changed over the past thirty odd years, trying to keep an open mind, trying to see the positive benefits of new materials and designs:
Don’t limit a child to your own learning, for he was born in another time.

When I dreamed of setting off into the wide blue yonder I followed the teachings of the Hiscocks, the Pardeys and Bob Griffith. My boat would be simple, rugged and seaworthy. It would carry stout ground tackle, fly hanked-on sails and be worked from the deck not the cockpit.

And that’s pretty much how it was. Adriana was 33’ overall, heavy displacement, a simple sloop rig, boom gallows, a massive bronze windlass to handle the all-chain rode and CQR anchors. She was classically pretty, (being from the board of Phil Rhodes she could hardly be anything else), with long overhangs, sweeping sheerline, wide decks and cramped accommodation.

We planned to navigate by dead reckoning with a compass and a set of charts. We carried a plastic sextant for when we were out of sight of land. Fortunately, GPS became available and affordable at about the time we cast off so my astronavigation was never seriously tested.

We had a shiny new Yanmar diesel engine and this begat a battery bank and a big alternator and this in turn begat a fridge to keep the beer cold and the veggies crisp.
This could have been the thin end of the wedge, or as my mate Anon would have it: If the camel once gets his nose in the tent, his body will soon follow.

But no, for this long term cruise we managed to stave off any further adulteration of the hair shirt cruising ethos and had the adventure of our lives. After all, as Anon is fond of saying: Footprints on the sands of time are not made by sitting down.

Anon’s camel did shuffle a bit further into the tent when we set off again a few years later – the boat was bigger and the “keep it simple” principle somewhat further eroded by watermaker, forward-looking sonar, radar and wind generator.

The bigger boat served us well but the watermaker, radar and sonar didn’t make it. They failed to live up to their billing: The watermaker didn’t make water, the forward-looking sonar didn’t look far enough forward and the power-hungry radar didn’t earn its keep. I’ve always seen this as justification for my continuing view that avoiding unnecessary complications on a cruising boat is the way to go despite the current obsession with all things electronic, high tech and led aft.

Of course, my failure to keep what would now be considered essential equipment fully functional is addressed by Anon in one of his more profound thoughts: The man who can’t dance thinks the band is no good.

A great little thinker is old Anonymous.