October 2012 – Salty John : The Blog

The UK sailing season is drawing to a close (although some intrepid souls will be sailing through the winter) and thoughts turn to winter projects. 

Antennas and cable are popular purchases at this time of the year – masts are coming down, providing the opportunity to check the masthead installation. Now you can fit that Metz Manta you’ve been promising yourself, and a good quality feed cable.

You’ll want to be tidying up your rope ends – a Hot Blade will help you with that. How about fitting midship mooring cleats – we have superb alloy cleats in various popular sizes. And what about a new set of mainsheet or boom vang blocks? Check out our range from Viadana of Italy.

Sales of Loos rig tension gauges to Australian sailors pick up dramatically at this time of year. Just as we in the northern hemisphere are putting our boats to bed, down under they are looking forward to the new season and, good sailors that they are, they want their rig tension to be right. Thanks mates!

There are hundreds, possibly thousands, of knots available to the sailor to accomplish his myriad of ropey tasks. These bends, hitches, loops and splices are documented in books, web pages and on knot displays usually found on the walls of nautical pubs and sailing clubs.

When I look back at my own sailing experiences I realise that I use relatively few knots. 

The first knot I, and probably most sailors, learn is the bowline. This is a useful loop knot – I use it for many things including attaching sheets to jib, tying up to rings, making a loop to drop over a bollard and for joining two lines together.

There are many variations on the bowline – bowline on a bight, spilled-hitch bowline, running bowline and so on. There’s even a one-handed bowline that my mate Captain Jim would use to impress the dock walkers – it looks like magic when you do it right.  I never learned any of these variations; the straight forward bowline did all I needed from a loop knot.

Hitches are used to attach rope to something – another rope, a rail, a ring or even back to itself. I use the rolling hitch a lot. Most often I use it to attach my anchor snubber to the anchor chain – I started out using a chain hook but after the first year or so switched to the rolling hitch for its reliability and simplicity. It’s also useful for attaching the hammock to the forestay. 

When I was first shown the rolling hitch I was told it was very useful for clapping a line onto a jib sheet to take the strain whilst undoing a riding turn on a winch; in all my sailing I have never encountered this circumstance but, should it ever arise, I’m ready.

I use a clove hitch for temporarily attaching fenders to the rail during docking. I use the round turn and two half hitches to secure to mooring posts and rings if I want them snugged up tight. I attach the polypropylene dinghy painter with a round turn and two half hitches and then seize the loose end to the standing part. Of course, like all sensible sailors, I tow the dinghy with a Salty John towing bridle but I still have a floating painter as back up.

Bends are next – I use a sheet bend to bend sheets together. To non-nautical types I suppose that sounds bizarre! It just means to join two lines together. You can achieve the same thing with two bowlines but this knot is more compact and simple when you know how. The double sheet bend is even better.

We all use the reef knot to tie in reefs, of course, and that’s a bend too.

I don’t use much else in the way of knots.

I came across this on one of the boating forums. It’s a 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!

It’s raining. We’ve just had the most dismally wet summer the UK has ever seen, certainly in my memory.

The scientists tell us that all the rain was carried here, not by the jet stream, although it is a factor, but by ‘atmospheric rivers’. These rivers occur in four or five places on earth, and we’re one of them. Lucky us. The Pacific coast of the USA is another susceptible area. 

Water evaporates from the warm seas to the south west of us, out in the Atlantic off Portugal, and forms into a relatively narrow ribbon of moisture in the atmosphere which meanders towards us. When this extremely wet air hits the west coast of Britain it drops out of the sky. 

These atmospheric rivers are notable because of the huge amount of water they carry, giving them the potential to spark serious flooding events. And ruin our summer.

The biggest factor determining the extent to which we suffer from this phenomenon is random chance, apparently. Weather patterns can be favourable or unfavourable to the formation of the rivers and to the route they take. Sometimes we’re lucky, other times, like this past summer, we’re not.

I think I’ll build an ark.

We looked at vhf coaxial cable a year or so ago but it’s cropped up again on the sailing forums so it’s worth a review.

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 it needs to be tinned copper to resist corrosion and the centre core 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).

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 10.3 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. It is also eye-wateringly expensive.

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 only in 5m lengths for small power boats but just recently I’ve seen it offered in 25m lengths!

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, if at all.

And remember: “A penny in the antenna 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.

There’s no doubt in my mind that the great emancipation of the cruising sailor came with the introduction of affordable GPS units. How many wannabe cruisers headed off to the wide blue yonder because they now had a reliable means of fixing their position is anyone’s guess but I’ll bet it’s a huge number.

It was President Ronald Reagan who made the decision to open up the Global Positioning System for civilian use after the USSR accidentally shot down a Korean Air Lines passenger plane that had strayed into restricted territory. 

The full constellation of GPS satellites wasn’t in place until 1994 but I got my first GPS set in 1991 and from that time on my sextant and my Loran receiver were condemned to the scrap heap. Initially, accuracy was restricted to around 100m but with the turning off of Selective Availability in 2000 accuracy, even for civilian users, improved to10m. When we installed our first unit it was the time of the Gulf War and, because the military were using civilian GPS units in the desert, SA was disabled – I remember commenting that our new GPS receiver didn’t only show which marina we were in, but which berth!

The Global Positioning System spawned an industry that has for more than twenty years churned out devices to receive, interpret and extrapolate the data from orbiting satellites. 

Palm-sized handheld GPS units with their own batteries free us from the worry of losing our way in the event of catastrophic electrical failure on the boat. 

We no longer have to take the written lat/long information from the screen and plot it on a chart; we have chart plotters that draw the pictures for us.

But that concept, going to sea without paper charts, is the biggie for me. I know it’s here, I know people who do it. I just can’t get my head round it. When I’m on passage I love working on the paper chart, plotting my position on it, making notes on it, seeing where I’ve been and where I’m going. There’s a satisfying tactility to it that I just don’t get from an electronic chart on a plotter. 

I guess I’m just old fashioned.