June 2013 – Salty John : The Blog

I’ve just had my fifteen minutes of fame – my ebook hit number one in the Amazon UK ebook rankings in the watersports category. Huge fanfare!

This equates to number 8,500 in the overall rankings which is pretty good considering how many million titles they stock.

All royalties are going to Leukaemia research: http://leukaemialymphomaresearch.org.uk/

My Dad was taken early by this awful disease so I’m in a personal war with it.

You can help to keep the book in the best seller rankings, and help the charity, by clicking on the link up there on the right which takes you to Amazon. You can also buy the book at Kobo, WH Smith, Waterstones, Barnes and Noble and the Apple iStore. Royalties from all sources go to the charity.

If you don’t have a Kindle there is a free app at Amazon that lets you read Kindle books on your computer. 

I hope all those who buy the book find it entertaining and informative.

The dinghy is an essential part of the cruising life but can be a challenge to stow. The best solution in my experience is a pair of davits.

A balanced connection between the davit falls and the dinghy is best accomplished with davit slings – usually one at the dinghy’s bow, one at the transom. 

On most cruising sail boats it’s desirable to have the dinghy hoisted as high as possible, with the stern slightly lower than the bow so that water can drain away. 

But how do you know what length of davit sling you need? They’re different for bow and stern. Well, the solution is a pair of adjustable davit slings. 

And if you don’t have davits, preferring instead to lift the dinghy on deck, davit slings provide the lifting point. You need davit slings.

Stainless steel ones, actually. Friction is the big enemy of multiple block systems so ball bearings are used to keep things moving freely – friction loss is kept below 3% as opposed to more than 10% per block with plain bearings. That’s really important for mainsheets and vangs.

Some single block applications don’t require movement under load. For instance, halyard blocks are used to hoist a sail but once that job’s done they just sit around waiting for the next hoist. In that application there is a danger that the balls, plastic ones in particular, will deform under the constant single point load so the large load bearing area of a sleeve might work better. 

Stainless steel balls give you low friction and low distortion. 

Over on the website there’s an article about using blocks to tame your mainsail, and you can also browse our range of Viadana reinforced stainless steel ball bearing blocks.

Sunsets are awesome things on so many levels – they’re beautiful, romantic, inspiring – astronomical events of mind-boggling magnitude. 

Sailors are particularly fortunate because we get to see the sun setting over the ocean even on eastern facing coasts, as long as we’re a few miles offshore. And ocean sunsets bring with them that 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.

No, I don’t mean the destruction of the economy by irresponsible banking behaviour; I mean the interaction between the banks of a waterway and a vessel travelling through it.

A vessel moving close to the bank of a river, a cut or a canal will find the stern tends to move 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 40 or 50 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.

VHF antenna systems comprise an antenna, a feeder cable and a few connectors. If you have a really good quality antenna such as the Metz and use good quality connectors, you’ll want the correct coaxial cable to complete the system.

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

Furthermore, marine cable needs to work in a hostile and constantly moving environment. That’s why it needs to be tinned copper to resist corrosion and the centre core needs to be stranded so it can bend without breaking. Really low loss cable will also include a foil barrier between the braid and the centre conductor.  A good PVC jacket will keep sunlight degradation at bay. 

The top picture shows the anatomy of a good, marine quality, RG8X cable.

And what size cable should you choose? 

You’ll want to restrict the line loss (known as attenuation) to about 2.5 decibels (dB) in the run from radio to antenna. This will ensure you don’t lose more than about 40% of the signal power in the antenna system – a requirement, by the way, of the offshore racing authorities.

RG213 (or its slightly lower spec but similarly stiff cousin, RG8U) is a whopping 10.3mm diameter, nearly half an inch in old money. So it’s heavy and doesn’t like to go around tight corners, but it only loses 2.2 dB per 30m length. Alongside it is its less uptight little brother – RG8X. This flexible fellow is only 6.5mm diameter, much lighter and easier to work with – it loses about 3.5 dB per 30m. 

(RG58, which sometimes comes with cheap aerials is 5.5mm diameter and is very lossy – about 5 dB per 30m. OK for short runs, perhaps, but not for masthead installations).

So, if you have a cable run of up to about 25m or so you can go with RG8X, for much longer runs you’ll need to wrestle with RG213/ RG8U. 

Masts are back up, boats are out on the water and VHF radio problems are emerging. It’s like this every year.

Tracking down VHF radio receiving and transmitting problems is a fairly logical procedure and there’s some advice in the ‘articles and links’ section of the Salty John website. Link is over there on the right, just below the link to my eBook which you really should check out.

When your VHF radio fails to communicate, defective cable and connections are the overwhelming favourites to be the culprits so check them first before ditching antenna or radio.

The picture has nothing at all to do with troubleshooting your VHF system, I just like it and thought I’d share it.