Tensioning Rigging

[graham]

I have just lowered and re raised the mast on my Anderson 22 to do some maintenance.

I deliberately did not alter the forestay rigging screw so that the mast rake wont alter(almost perfect helm balance tiny weather helm.)

I have done this job many times by trial and error but could someone advise me of the correct method and order of tensioning the shrouds and back stay.

It is a 3/4 rig with swept back spreaders ,the lowers are also pulling back but not as much as the upper shrouds going through the spreaders.

The single backstay splits into 2 parts about 6 foot up and a 4 part tackle gives backstay tension adjustment.

I dont do any serious racing but like the boat to be sailing well. The mast is heavier and stronger than is typical for a 22 footer. Have a look at the link to photobox for pics of the boat if that helps.

Thanks in advance. Graham

 

[TigaWave]

Try this,
http://www.zsparsuk.com/mhsstune.htm

 

[graham]

Re: Excellent Thanks

I have just printed out their pages on single spreeader fractional rig.Exactly what I needed. SWMBO is laminating it in plastic so it can stay on the boat.

 

[manimbored]

Would this be the same rig as is on a Jag 21. I know it has swept back spreaders, but not a masthead jib. The only other option on the website is a fractional rig.

 

[graham]

Yes mine is a fractional rig. Thats the page Ive printed off.

I sailed on Lough Neagh once or twice in a GP14 about 20 years ago with someone I new in Antrim.Expecting it to be like a mill pond found it more like the South Atlantic when we nosed out of the river!

 

[manimbored]

Yea it can really blow a gale! Havn't been as far as antrim yet. Have tried racing once, and felt we could have paddled faster! a guy with a J21 sped straight past us, but we have adjusted the rig after we put the mast back up again.

The other J21 has quite a bend in its mast, i presume this helps its speed?

 

[Viking]

Re: Tensioning Rigging in theory???

It all well and good on paper but it never works practically. First the main halyard never comes off the back edge of the mast head, theres usually a bracket which push it out and away from the mast 3" or 4" so you can't measure the 50mm or 60mm at the foot. They them say measure to the same point on the toerail or chainplate each side of the mast. But again you usually have two rollers (cant remember the tec name shivers?) at the top, side by side, main and topping lift, so your 'out' again. Then they say the boat as to be afloat and level, which is impossible, your movement let alone, let alone, wind and of course wash. /forums/images/graemlins/confused.gif

 

[PeteCooper]

Re: Tensioning Rigging in theory???

To adjust the rigging, your backstay needs to be completely slack. Loosely attach the shrouds. Centre the mast by using the main halyard to a fixed point on the deck at each side and adjusting the shrouds which go to the top of the mast. When you are happy that the mast is centred start tensioning the lowers until they are just tight and the mast is straight laterally. This can be checked by looking up the luff groove. Next you need to know how much pre-bend your mainsail requires, and I would suggest your local sailmaker can give you some help here. The final tensioning is then done on the water in about 12knots of true wind. Remove the slack from the leeward shrouds, but count the number of turns required to do this. Tack and apply the same number of turns to the other side. What you should do next is increase the tension by half a turn, constantly monitoring boat speed, but if you follow the instructions upto this point you will be close enough. If boat speed goes up try another halfturn, but stop when there is no change in boatspeed. Make sure that any adjustments are mirrored on each side.

 

[Viking]

Re: Tensioning Rigging in theory???

I go back to my point that the ONLY central thing off the top of the mast is either the backstay or the forestay. The Main halyard is off set to port or starboard by the topping lift. And to measure the angle of the mast, for example 60mm back, the halyard and the topping lift are on an arm off the back of the mast.
And to top it all the nearest sailmaker is in Trondhiem some 350km away. But I manage. Cheers. /forums/images/graemlins/crazy.gif

 

[graham]

As luck would have it on my boat the main halyard is in the centre and the topping lift is a single line spliced aft of it to a pin in the mast crane. Saying that as boats are built by eye its unlikely to be an exact science anyway.

I do know that on my boat if the shrouds are too slack she will not go well to windward.

Thanks for all the advice.

 

[PeteCooper]

I have just done a quick calculation, and with my 30ft mast I reckon that an offset of 1" on the halyard at the top of the mast only makes a difference of about 1/10th of an inch in the distance from masthead to toerail. My maths is not good, so I am quite prepared to be wrong. If you are using the halyard as a measure then I think that this is an acceptable margin of error.