Tuning your rig

It’s really important to have a properly set rig to get the best performance from your boat without placing excessive loads on the rig or hull. The best way to achieve this is with a rig tension gauge made by rigging manufacturers Loos & Co, available from Saltyjohn.com here in the UK.

For the average cruising boat, you’ll be aiming to set up your rig like this:

Forestay tension – masthead rig: It is almost always advantageous to set the forestay tension as high as possible within the limits of structural strength. Generally, it is possible to use 15% of the breaking strain of the wire as the forestay tension. The backstay should be adjusted to maintain a straight mast with the desired forestay tension. The backstay tension will usually be less than the forestay tension because the backstay makes a greater angle to the mast than does the forestay – some catamarans are the exception to this rule.
Note that rollerfurling jib tension can only be set by adjusting backstay tension.

Forestay tension – fractional rig: Because the forestay tension cannot be directly balanced by the backstay tension some mast bend is accepted and the sails are cut to accommodate it. Forestay tension of at least 15% of the wire strength is desirable but, if this should result in excessive mast bend, it may be necessary to back off the tension.

Upper and lower shroud tension – masthead rig: The initial rig tension should be high enough that the leeward shrouds do not go slack when sailing close-hauled in a brisk breeze. The proper tension for your boat can be found by a few test-runs under sail and then the Tension Gauge can be used to record and maintain this value.
For many boats, a shroud tension of 10% to 12% of the wire strength is adequate. In some rigs it may be advantageous to carry a bit more tension in the uppers than the lowers.

Upper and lower shroud tension – fractional rig: In most cases the same comments apply as for masthead rigs. However, there is one exception. Where the upper and lower shrouds on a fractional rig lead to chainplates located aft of the mast – swept back spreaders – most of the forestay tension is balanced by the upper shrouds. A shroud tension as high as 20% of the wire strength may be required to achieve the desired forestay tension. Never exceed 25% of the wire breaking strength.

A well-tuned rig and correctly set up spreaders (ban the droop!) will ensure you get the best from your boat and avoid structural damage. The key is the Loos tension gauge.

Another job for the Metz VHF antenna

Lift boats are the service vessels of the offshore oil industry. Their most obvious feature is the three giant cylindrical legs towering 250 ft above the deck. When the lift boat gets alongside a rig these legs are lowered to the seabed and the whole boat is jacked up so that it can act as a work platform to service the rig a hundred feet above the surface.

They are hardly mere boats – these things weigh 2,500 tons, measure 200’ by 120’ and are propelled by a pair of 7’ diameter screws driven by two 1,500 HP diesels. They house 20 workers and carry all the equipment and spares necessary to service the rig. There’s a helicopter landing pad and a 10,000 square foot working deck.

Lift boats carry 2 or 3 cranes to assist in servicing, reconstruction or repair of the rig. Each crane can lift 200 tons and can reach out 150’.

And here’s why lift boats caught my attention recently – each of the cranes has a vhf radio to coordinate crane movements and the builders of the Dixie Patriot, the largest lift boat in the world when it was commissioned in 2003, specified Metz Manta vhf antennas.

So, we can add the Dixie Patriot to the list of Metz antenna users that includes the Clipper Fleet, the US Coastguard, several British Search and Rescue organisations and thousands of individuals who require the very best from their radios and AIS engines.

 

 

 

 

A summer sail in Scotland

Just back from a few days sailing in Scotland. The weather was disappointing for August but we got a couple of good days sandwiched between a major thunderstorm and torrential rain.

 

 

 

 

 

 

A boat with a pilot house is a definite advantage when the weather decides to be miserable.

 

 

 

 

 

 

The scenery is always spectacular in this part of the country and lovely anchorages abound. It was a most enjoyable time in excellent company  and in one of my favourite areas for sailing, no matter what the weather.

The Sea

I must go down to the seas again, for the call of the running tide
Is a wild call and a clear call that may not be denied;
And all I ask is a windy day with the white clouds flying,
And the flung spray and the blown spume, and the sea-gulls crying.
 – John Masefield

An albatross and a handful of shearwaters skimmed the tops of the waves, their wingtips impossibly close to the water as they swept and dipped and darted. The sea was grey green and white clouds scurried over a deep blue sky. The waves marched past, spume was ripped from their tops and scattered downwind. The wind blows constantly in these high latitudes and the ship was making good progress.

“Glass has been dropping these past three hours, Captain, I think we’re in for a big blow before nightfall.”

“Aye, I think you’re right, Jones, let’s get these topsails off her and the foresail, too.”

I heard Jones call an “all hands” and soon the men were swarming up the ratlines and along the yards to hand the sails and tie them firmly so the wind couldn’t tear them free.

By late afternoon the wind was howling, tormenting the sea, goading it higher. The ship was rolling like a barrel now, green water running down the scuppers.
I ordered the helmsman to steer five points lower to ease the strain. I’d have to take it back after this gale, though, to keep on course for Cape Horn. The English must have their tea and the best prices go to those first to market and that would be us, god-willing.

Through the night the tempest fought us, its army of watery dunes chasing and harrying the ship. She fought back, refusing to be overpowered, lifting her stern to the waves. Every now and again a monster would rise above the rest and crash down on the ship, shivering her timbers and sweeping away anything not firmly lashed; several pork barrels and one of the dories was lost but her precious payload stayed safe and dry in her holds. By the next afternoon the wind was down but a big sea was still running and the men had to take care as they went about their duties.

We’d be passed the Horn tomorrow and then we could turn north, bound for Blighty and the embrace of loved ones, the taste of fresh bread, foaming ale and a bed that stayed still.

And then I’d be yearning to be off once more, for I must go down to the seas again.

(This was an entry in a writing competition, a short story about the sea, with a quotation)

Rail mount brackets

These SeaDog Line rail brackets are the bee’s knees for mounting things to your boat rails – great for solar panels, drink holders, canvas work, cockpit tables and so on.

We use them as the basis for our Metz antenna rail mount. They come with shims for mounting on 3/4″ (20mm) and 1″ (25mm) diameter rail, without the shims they fit 1 1/4″ (32mm) rails. Heavy duty nylon construction and stainless fittings – the thumb screw is held captive when the bracket is open. An excellent product that does exactly what it claims to do.