Apparent Wind

The concept of apparent wind is largely unknown to non-sailors but if you sail a boat it’s a fundamental fact of life: Apparent wind is what you sail in.

Apparent wind is the wind you experience when the boat is moving – it’s the true wind modified by the boats motion. A 15-knot breeze coming at you from 45 degrees off your bow when you’re stationary becomes a 20-knot breeze at about 35 degrees off your bow when you’re moving forward at around 6 knots. The boat speed adds to the true wind speed, and modifies its angle of approach.

Conversely, when the wind is from behind its speed is reduced by the speed of the boat. A 15-knot breeze from dead astern is an apparent wind of just 9 knots when the boat is moving at 6 knots.

When you’re sailing you don’t really think about apparent wind – it’s the wind you’re sailing in and that’s that. However, there is a time when you really need to consider the effects of apparent wind and that’s when you change from a course off the wind to a course on the wind. If you’re running downwind in 20 knots true wind it will feel like a perfectly manageable 14 or 15 knots apparent. But as you slow and turn onto the wind things will become a bit more of a handful, unless you’ve anticipated it.

Apparent wind – the wind you sail in.

Pride comes before a fall

George Town in the Exumas, Bahamas, has a small saltwater lake, Lake Victoria, in which the dinghy dock is located and it’s accessed via a narrow cut passing under the road. People stop and chat on the stone bridge parapets, watching the dinghies buzzing backwards and forwards beneath.

One afternoon Carol and I were about to enter the cut en-route from the anchorage to the Two Turtles for the Friday night jump-up when we had to do a hasty about-turn to accommodate an outbound eighteen-foot speed boat.

Standing at the steering pedestal were two hot-shots, looking cool in their reflecting sun glasses and baseball caps worn backwards for greater aerodynamic efficiency. An enormous Mercury outboard, ninety horses at least, was popping and spluttering on the transom. With the acoustical enhancement provided by the stone bridge it sounded like the grid of the British Motorcycle Grand Prix waiting for the flag to drop and all eyes were upon it as it emerged from the cut.

The pilot jammed open the throttle and they were off, the bow straining skyward and the stern squatting deep as the big prop bit, sending a rooster tail of water billowing behind them. One nano-second later there was a “WHAM!” and then total silence. The speedboat bobbed in its own wake and the crew sprawled in an undignified heap in the bow. Of the monster motor there was no sign, just a jagged hole in the transom and a small cloud of blue smoke drifting over a growing oil slick, just where the submerged sandbar is at the entrance to the cut.

Adriana

It was the spring of 1989 when I first saw her, Adriana, in a canal off the Intracoastal Waterway in Boca Raton, Florida. If you half closed your eyes you could see her pedigree. Her lines were drawn by Phil Rhodes, a master of lovely boats and this was apparent in her sweeping sheer, the bold curve of her bow, the neat, tight transom. If you opened your eyes fully you saw the grime, the decrepitude, the sun-baked weariness of her. Her white painted hull was chalky, her canvas sun-bleached, her teak was grey and dry. She was a tired boat, was Adriana.

She was owned by sailor, writer and magazine editor, Dan Spurr. As we stood on that dock in Boca Raton together Dan looked apprehensive, waiting to see how I’d react. I stayed calm. We’d committed to taking Adriana north together, from Boca to Annapolis, and that’s what we’d do. I’d reserve judgement until we arrived in Annapolis. My friend Wayne was along for the ride and after Dan picked us up at the airport we’d gone to the supermarket to provision for the fifteen-hundred-mile trip, and then made Adriana ready for sea.

In the morning we fired up the Yanmar diesel engine and puttered out into the main Intracoastal Waterway (ICW) and headed north. The ICW is the network of interconnected canals, rivers and sounds by which it’s possible to travel between Miami and Chesapeake Bay without ever going out into the ocean. But it’s shallow, interrupted by bridges and impractical to sail. It’s possible to travel the ICW by night, but not advisable. We had no intention of motoring up the ICW in day time stints, it would take a month, and so at Fort Worth we went out through the cut into the ocean, set the sails and pointed Adriana northeast.

Two days later we were becalmed, drifting, out of sight of land. Not a breath of wind to fill the sails or ripple the water. We were being carried slowly north by the Gulf Stream, the mighty ocean current that flows relentlessly up the eastern seaboard of America. It was hot, the horizon shimmered. I was floating on my back in the relatively cool water looking at Adriana. She was splendid if you saw past the neglect. I ducked under so I could see the dark silhouette of her semi-full keel that gave her such good stability and doggedly determined tracking through the water. She was going to be OK, she’d do the job. She just needed some tender, loving care. I realised Wayne had jumped in and was breast-stroking away from the boat. I looked behind me and there was Dan lazily treading water. I quickly swam back to Adriana mindful that a puff of breeze might take her away from our ability to catch up to her. Standing on deck drying myself I could see a wind line approaching and summoned my crew mates back to the boat. Soon we were under full sail and making solid progress. The wind held all night and through the next day but died again and we decided to start the engine and head into Savannah to top up the water tank and refuel before motoring up the ICW and popping out into the ocean again at Charleston.

On the eleventh day we entered Chesapeake Bay and traveled overnight to the marina on South River where I planned to renovate Adriana before heading for points south again in the autumn. Although she was shabby and neglected I’d fallen for this boat and after a little haggling over some items that were less than described in the specification we shook hands on it – Adriana was mine.

The Khyber Pass

This post has absolutely nothing to do with sailing or boats.

Many, many years ago I was a fresh faced young apprentice engineer at a company that built grain mills all over the world. A need arose for a commissioning engineer to go to Peshawar on the northwest frontier of Pakistan and by a stroke of good fortune I was available when all the other more likely candidates were occupied elsewhere. My boss took a chance and sent me. I was there for three months. As part of a bigger project I’m working on, I recently wrote this snippet about my visit to the Khyber Pass:

For some time I’d wanted to travel through the Khyber Pass to the Afghanistan border at Torkham but so far had been too busy with the mill. Throughout history the Khyber Pass has been an important trade route between Central Asia and the Indian Subcontinent, part of the Silk Road, and I didn’t want to miss the opportunity to see it. One day Salahuddin told me that Marooh and Hammadi wanted to go to Landi Kotal, a town at the highest point on the Khyber Pass, to buy some duty-free goods. He suggested I go with them and while they shopped the driver would take me another three miles to the border so I could look into Afghanistan. I quickly agreed and we set off early the next morning to cover the thirty or so miles to Landi Kotal, me up front with the driver and the odd couple on the back seat, holding hands as usual.

From Peshawar we took the Asian Highway up through the Spin Ghar Mountains, through the Khyber Pass. The road snaked this way and that as it gained altitude, a precipitous drop to one side, my side, a steep rock wall to the other. Down in the valley I could see concrete anti-tank structures strewn like giant children’s jacks, a legacy of the Second World War. We passed convoys of gaudily decorated buses belching black smoke, their roofs piled high with baggage and bicycles and boxes, and trucks staggering under massive loads of timber, scrap metal and grain sacks.

At Landi Kotal, the western end of the Pass and highest point at 3,500 feet above sea level, we dropped the boys, made arrangements to meet them in an hour and set off for the border. Parked at a spot just off the road I looked down into Afghanistan, the valley floor broadening out to an endless plain framed on each side by mountains. In Pakistan they drove on the left and in Afghanistan they drove on the right. This conflict was resolved at the Torkham border post below us where a sort of miniature spaghetti junction directed the opposing flows of traffic across each other to continue their journeys on the other side of the road.

Back at Landi Kotal the driver went off to round up the others and I wandered through the town in the increasing heat as noon approached. The bazaar appeared to have grown haphazardly over the years with crude structures erected here and there with no logical layout. There were stalls offering leather goods such as Peshwari sandals, belts, holsters and bandoliers, there were colourful mountains of fruit, piles of exotic eastern spices and bolts of material in every hue. Goat carcasses hung from steel hooks outside the butcher’s shack, the proprietor occasionally flicking a whisk to momentarily interrupt the gorging of the black flies which encased them. Men squatted in groups drinking green tea, smoking and chatting, their eyes following me as I strolled by, an alien interloper.

Further on I came across some rough brick buildings and in these were several gunsmiths. I watched a worker boring out a metal rod by hand to make a gun barrel and stacked against a wall were several completed rifles. This area had a reputation for producing unlicensed, homemade copies of firearms using whatever scrap metal was available. They’d make anything from a perfect copy of a British Army revolver to a musket and the quality would vary from superb to dangerously rubbish.

Pashtun tribesmen with Kalashnikov rifles slung over their shoulders strolled in twos and threes. The pungent smell of hashish was all around, mingling with the tang of wood smoke from the small bakeries churning out coarse chapattis. I returned to find Hammadi and Marooh cuddled in the back seat of the Toyota enjoying the air-conditioning, surrounded by boxes of electrical appliances and stainless-steel pots and pans. Then we were wending our way back down the Khyber Pass to Peshawar, dust billowing behind the car and the boys chattering happily together.

I hope you enjoyed this little excursion away from the sea and boating.

Lancaster Canal

There’s nothing quite so relaxing as a stroll by the Lancaster Canal on a sunny afternoon. So much to see: A pair of nesting geese, ducks, boats, cows, wildflowers and a pink flamingo. Wait a minute! A pink flamingo? How did that get in here?

Antenna cable connectors

Here’s a short look at the type of coaxial cable connector you might encounter when installing your radio and AIS antenna systems.

Boats use 50 ohm coaxial cable for their radio and AIS systems – it comes in different sizes but the three you are most likely to encounter are RG58 (nominal size 6mm, but rarely more than 5.5mm), RG8X (nominal size 7mm but usually 6.5mm and the best choice for boats up to super-yacht size) and RG213 (nominally 10mm, actually about 9.5mm – the cable you need for long runs, 30m or more). Coax cable comprises an outer jacket covering a layer of fine mesh or braid, an insulating layer called the dielectric and then the centre conductor. The outer braid and the centre conductor must never meet. Whichever coax size you have you’ll need to join it to the equipment, and to itself, using a variety of connectors:

The PL259 and its female partner the SO239. This connector pair was developed in the late 1930’s by a designer with the fantastic name of E. Clark Quackenbush. He worked for Amphenol at the time and I wouldn’t have mentioned him at all were it not for that magnificent name. Anyway, he designed what was to become the most widely used connector in the amateur radio field.

PL stands for plug and the number, 259, is the inventory number assigned to it by the US military. The socket into which it plugs is given another inventory number, 239, and the prefix SO for socket.

All marine VHF radios have a built-in SO239 antenna socket to accept a PL259. Top quality marine antennas use the same connector, so the antenna cable will have a PL259 at each end, whatever other connectors it has for intermediate joins.

The PL259 is simple, mechanically rugged and relatively easy to fit. That’s why it’s popular on boats. Purist radio techies will tell you about its non-constant impedance but at marine frequencies, around 150 MHz, this doesn’t matter a jot.

Fitting: Most PL259s are the solder type but usually only the centre conductor is actually soldered into the pin, the braid being held mechanically. In some cases the cable is crimped onto the cable, making contact with the braid through the pvc jacket. For this you need an appropriate crimping tool so this type is more popular for industrial application. The leisure sailor is more likely to choose a screw-in-earth type, where the cable is screwed into the threaded inlet of the plug once a section of braid has been exposed, and then the centre conductor is soldered into the pin. Many top quality PL259s are made for the bigger cable size and have an adapter insert to suit the smaller sizes of cable. Using an adapter is convenient because it grips the coaxial braid firmly. I like silver plated connectors because they avoid corrosion and they solder very well – and I’d always have silver or gold plated centre pins for this reason.

You can get PL259s that require no soldering, they are entirely mechanically assembled. The Shakespeare Center-Pin connector is a good example. A little expensive, perhaps, but they are great for solderphobes.

The PL259 is not fully waterproof and the join should be protected with silicone self fusing tape when used outside.

When the cable run on a boat encounters a bulkhead or the deck you have a choice – do you drill a hole and pass the cable through it, continuing the unbroken run, or do you use a bulkhead connector of some sort? I’ll save the debate over the relative merits of deck plugs, deck glands and the various joining methods for another time, but no discussion of the PL259 would be complete without a mention of the barrel connector.

The barrel connector is a double female – you can plug a PL259 into each end and make a mechanically strong connection between two sections of cable. The barrel connector comes in a variety of lengths starting with the small, discontinuously threaded version about 1” long, up to a 12 inch long monster.

The short barrel connector is called a PL258. This shows that the bloke in the spares department in the US military wasn’t on his toes when it came to designating inventory numbers because this is clearly a double socket (SO) and not a plug (PL).

The longer versions are often called PL363 barrel connectors, or bulkhead connectors, or double-females and some other weird designations. You have to specify the length. The PL363 comes with a pair of nuts to secure it through the bulkhead or the deck or a radar arch base. The standard nuts are a bit wimpy but you can buy more substantial ones – the thread is 5/8” 24 tpi.

The BNC connector is a bayonet connector designed for applications where frequent connecting and disconnecting occurs, such as on laboratory oscilloscopes. Despite this it has found its way into applications such as connecting the antenna to an AIS unit, or even for cable to cable connections.

BNC stands for Bayonet Neill Concelman, after its two designers.

Aware that the bayonet design allowed noise to intrude when the cable was subjected to vibration the Neill Concelman partnership came up with a more secure variation, the TNC, for Threaded Neill Concelman.

Both connectors have male and female halves – typically the male bit is attached to the AIS unit and the antenna cable is fitted with the mating female connector. Barrel connectors are also available for cable to cable joins. BNC and TNC connector sets are often chosen as cable to cable connectors when the reliable but chunky PL259/barrel connector/PL259 connection is unworkable.

BNC and TNC connectors are fiddlier to fit to the cable than the good old PL259 but they are high performance connectors, used for frequencies as high as 11 GHz. That’s a gazillion times more critical than the simple 150 MHz of VHF.

Another connector you might encounter on boats is the N connector – named for that prolific connector designer Mr Paul Neill of Bell Labs who designed it in the 1940s. This is another connector set that has high performance, being suitable for frequencies up to 11 GHz. Large commercial VHF antennas often come with an N connector and RG213 cable.

If you have satellite communications on your boat you may encounter the F connector to attach to a remote antenna system and if you want to connect your handheld VHF radio to a fixed antenna you might use an SMA connector, although some manufacturers have their own proprietary antenna connector.

So there you have it, the low down on RF connectors for boats.

By the way, many of my blog posts and some of my articles have been compiled into a book, you can see the link over there on the right. There are over 100 snippets of sailing lore and comment – for less than the price of one sailing magazine.

A pretty picture

I’ve been very busy these past couple of weeks, with this and that, and it’s led to guilty feelings about my lack of attention to the always demanding blog. Then I recalled the words of Charles Caleb Colton: “When you have nothing to say, say nothing”

So here’s a pretty picture.

Out of the mouths of babes

I found this short article by a ten year old boy explaining why he wants to be a captain when he grows up:

“I want to be a captain when I grow up because it’s a cool job that’s easy to do. Captains don’t have to go to school such a long time. They only need to learn figures so they can read instruments. I think they also have to be able to read maps so they don’t get lost when they sail.
“Captains have to be brave so they don’t get scared when it’s so foggy that they can’t see and when the propeller falls off they have to know what to do about it. Captains have to have eyes that can see through clouds and they mustn’t be afraid of thunder and lightning which they have closer to them than what we have.
“The captain’s wages is another thing I like. They earn more than they can spend. That’s because most people think it’s dangerous to drive a boat, except captains, because they know how easy it is. There’s not much I don’t like, except that girls like captains. All the girls want to marry a captain, so captains are always having to chase them away to get some peace.
“I hope I don’t get seasick, because if I get seasick I can’t be a captain and I’ll have to start working.”

Says it all, really!

The gua-gua ride

It’s 1992 and Adriana is anchored in the small port of Luperon on the north coast of Dominican Republic. The choice of provisions was sparse in Luperon so Carol and I decided we’d take the gua-gua to the much larger Puerto Plata in search of more interesting items, perhaps with sell-by dates still in the future:

Early morning, pleasantly cool, the sun still only a splash of lilac on the eastern horizon as we make our way to the bus stop where the gua-gua for Puerto Plata is boarded. We sit on the back seat of the Mitsubishi mini-van watching in growing wonder as a steady flow of passengers file down the bus and take their seats. Carol and I scrunch closer together as we’re joined by four others on the rear bench. As each subsequent row is filled short planks are deployed to span the passageway so extra passengers can be seated and before long the capacity of the bus as contemplated by its manufacturer is impressively exceeded. In fact, fourteen passengers and a driver are aboard the eight-seater as the journey begins.

On the outskirts of Luperon we stop to pick up a policeman and his wife, a youth with a broken arm, a woman towing a small child, and a cock-fight enthusiast with his prize bantam held aloft, presumably to avoid injury.

With a mind-boggling twenty-one souls (not counting the chicken) squashed within, the gua-gua bounced on its way over hill and dale, weaving an erratic course around pot-holes and ruts, toward Puerto Plata. Julio Inglasias at 50 watts per channel tried vainly to drown out the happy chattering of this compressed humanity.

Dreaded bird poop

There are few things as annoying as birds pooping on your nice clean boat. It’s particularly distressing when they choose your expensive, dark coloured, Sunbrella canvas work to do it on. Clean up is tedious and there’s a real danger of permanent staining. So, what can you do about it?

Have you noticed how some boats are targeted by birds and others aren’t? I’ve walked around many marinas in my time and I’ve always been struck by how some boats attract birds and others don’t. I’m told that once a group of birds selects your boat as their privy they’ll keep coming back to your boat, to the exclusion of neighbouring boats, until something changes. No-one seems to know precisely why one boat is selected over another but it seems that once one bird has pooped this gives the signal to the others to follow suit. Clearly, if you’re near habitat that supports birds you stand a greater chance of becoming a convenience than if you’re located well away from a bird-friendly environment. So, don’t be a victim. If you’re a chosen one, clean the boat meticulously and move to another berth.

For the most part the birds sit on your spreaders and boom and drop their gifts from on high. Sometimes they’ll stand on the boat rail or spray hood and crap but that seems a less frequent procedure. So, it’s important to make perching on your appendages difficult. One way to do this is to run a length of fishing line – I actually use old fly fishing lines – from mast to topping lift, about a foot above the boom. You don’t need to add pieces of ribbon or, heaven forbid, old CDs, it’s the line that prevents them landing.
That saves your boom cover from boom perchers but you still need to tackle the messages from higher up. A line running from mast to shroud a few inches above each spreader works well. On smaller boats it’s a good idea to stow your halyards in clips half way along the spreaders – I guess the smaller area for perching is less desirable.
If you don’t give much of a damn for flag etiquette it works to have flags hoisted on port and starboard flag halyards – the flapping puts the little crappers off. At the masthead a burgee is effective. Other masthead deterrents include a VHF whip antenna and a spike on your Windex – standard on the Davis model. One thing that doesn’t deter birds are those bottle brush type lightning dissipaters; I’ve seen a bird nesting in one!
The triatic stay on ketches can be a problem and I can see no easy solution. Perhaps a fishing line running along above it, or flags suspended from it? Or just do away with the triatic stay altogether and stand a better chance of keeping one of your spars in place if you’re dismasted. A bit drastic, perhaps.

On power boats with full length stainless tube safety rails you get unwelcome perching. In a marina in Majorca I saw a large power boat on which cable ties were wrapped around the rails every few inches with the tag ends pointing up. A deck hand told me it worked well but it certainly looked like sh…,err, the thing we’re trying to prevent.

Last, and definitely least, are the rubber snakes, lizards, alligators or what have you intended to scare off birds. In my dock walking research the incidence of guanoed boats with a snake lying in the cockpit suggests that they aren’t an effective deterrent – they may even be attractors.

Of course, the best deterrent of all is to keep moving – birds can’t hit a moving target – so, if you needed another excuse to go full time cruising, this is it.
I’m not even going to mention a shotgun.