Tensione sartiame - misurazione

[Luciano53]

Mamma Beneteau la fa ancora più facile, apparentemente senza bisogno di misurare alcunchè.
Effettivamente, con crocette acquartierate e V1 discontinua, più si cazzano le V1 e più l'albero assume pre-bend, che andrebbe fermato e corretto con con le basse.
Però le V1, che fanno perno sulla testa delle crocette, hanno molta più leva delle basse.
Per cui se si aumenta la tensione delle V1 credo che l'effetto più evidente sia la curvatura longitudinale dell'albero (pre-bend) prima che l'allungamento del cavo.
E siccome per correggere il pre-bend bisogna cazzare le basse, vista la pericolosità da te segnalata aspetto fiducioso indicazioni.
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13.16.2. Tuning

TUNING A MASTHEAD RIG

6/12/2008 9:16 AM


! WARNING

Before un-hooking the mast from the crane used to step the mast, for safety, make sure that the minimum amount of thread of the turnbuckle is engaged. Ensure that at least 1-1/2 times the thread diameter is engaged or that the holes for the split pins are visible through the turnbuckle body - this is refered to as the minimum safety position of a turnbuckle.

When making any adjustments to the mast, always make sure that the mast is straight and that there is no lateral or sideways bend. Fore and aft pre-bend is acceptable but must never exceed half the fore and aft dimension of the mast section.

If, at any step, you are having difficulty keeping the mast straight you have probably over tensioned the stays and shrouds causing excess compression loads on the unsupported mast panels between the stays and shrouds. Reverse the steps and re-tension the stays and shrouds using fewer turns.

Always make sure that all turnbuckles are clean and properly lubricated with a non-graphite grease.

When adjusting a turnbuckle, it is best to make less than three turns of the turnbuckle before adjusting the opposite turnbuckle.


Set the rake of the mast by adjusting the forestay to the pre-determined length according to the standing rigging specification sheet. TIP: Set the forestay to the correct measurement before installing it on the mast and note the distance between the threaded stud and the turnbuckle body. After stepping the mast you will be able to know the forestay length by comparing this measurement.

Make sure the intermediates (D2) are released to their minimum safety position.

Center the mast athwartships, using the capshroud (V1) turnbuckles. TIP: Using two pieces of rigging tape, mark the port and starboard toe rails (opposite the mast) at an equal distance from the forestay. Use a tape measure hoisted on the jib halyard (it does not need to be hoisted all the way) to check the port and starboard measurements at the toe rail rigging tape mark. They must be the same. When taking these measurements, ensure that you are taking a straight line measurement from the jib halyard sheave to the toe rail mark and that no equipment is fouling the measuring tape overhead.

Tension both backstays equally. This will introduce pre-bend in the mast and make it easier to tension the cap shrouds.

Tension the cap shrouds (V1) an equal number of turns on port and starboard. Do not allow the intermediates (D2) to become tight. At this stage you will have more pre-bend than is required.

Oceanis 381 Rev. 01

120

9:16 AM

Release the backstays equally until they are slack or to their minimum safety position.

Tension the lower shrouds (D1) so as to remove the excess pre-bend. Make sure that the mast remains

straight athwartships (make sure there is no lateral/sideways bend).

Tension both backstays equally. TIP: Compare the distance between the threaded studs of each turnbuckle.

Tension the intermediates and ensure a straight mast athwartship. Very little tension is required on the intermediates.

The mast should now be perfectly straight athwartship and fore and aft.

Lock all turnbuckles with split pins.

Test sail the boat in 15 knots of wind with the boat heeled hard on the wind the mast must remain straight on both port and starboard tack. Adjust the rigging as necessary so that the mast will be straight on both tacks in these conditions.