Friggin' with the riggin'

Topcat47

Topcat47

Well-Known Member
Joined
2 Jun 2005
Messages
5,035
Location
Solent, UK
Visit site
Friggin\' with the riggin\'

OK, so now I'm confused. I've never had a lot of bother setting up my mast until this year when it's all gone pearshaped. Actually reverse banana shaped actually. In what order should I adjust my rigging? And what's the best way to ensure it's set up OK.

My mast seems to be bent forward at the top. I've released the backstay and the after babystays and it still looks skew from the pontoon.Tightening the Fwd baby stays and then adjusting the after ones doesn't seem to help. Furthermore, with the main up, the boom seems to hang down a bit at the back. Last season, I had a boatyard set my rigging up for me but I replaced the mast myself this year. The bottle screws were in exactly the same place as they were taken off at the end of last season and the mast was severly raked backwards with the boom bouncing off the sprayhood.

Do I really need to call out a riggger, or have I missed something fundamental? /forums/images/graemlins/confused.gif
 
Re: Friggin\' with the riggin\'

I'd start by slacking it all off and getting it vertical by sight with floppy rigging.
Then get your rake settings by tightening fore and backstays gradually. Side to side you can measure with the main halyard gunwhale to gunwhale. Set that with you cap shrouds. Then you can put some bend in the mast if it's needed for you sail shape using the lowers. Forward ones to get the bend then rears to secure the settings (ie: not too tight)
You can check the bend with the main halyard held to the gooseneck or mast base and viewing the bend away from the halyard. This will also show any sideways bend you have introduced with your lowers.

That's how I've done it and seemed to get it pretty square. Apart from the fact the guy I bought it from had a very short backstay, so I had to put extra components in (very bad)
 
Re: Friggin\' with the riggin\'

Here's a comprehensive procedure that I compiled some years ago. It is intended for single spreader rigs only.

Mast tune
Mast rake decision
Raking the mast aft from vertical will influence the feel of the helm. Masts are virtually never raked forward of vertical. Generally, more aft rake increases weather helm while less rake reduces weather helm and can ultimately lead to lee helm. Most sailors like a little bit of weather helm for the "feel" this gives while steering. Too much weather helm makes steering the boat difficult and can quickly tire out the helmsman. Excessive lee helm can make a boat uncontrollable.
Mast rake adjustment
Start by slackening all shrouds and stays until all feel very slack. Then, set up the forestay a few turns tighter than hand tight, with the backstay so that it is only hand tight. Any runners, check-stays or other running rigging should be slack. Haul a thin line attached to your main halyard shackle to the top of the mast and tie on a plumb bob at the level of the boom gooseneck. Using thin line and a symmetrical weight will minimise the influence of any halyard stiffness or shape, especially with wire halyards. Adjust mast rake by adjusting the rigging screws on the forestay and backstay and referring to the plumb bob. Most cruising boats have a mast rake somewhere between upright and a few inches back. Once the desired amount of mast rake has been set, tighten the rigging screws on both forestay and backstay one turn at a time to achieve the amount of tension you want. The tension required for these two wires is quite considerable and the wires will not move more than inch or so to a good push or pull by hand. The actual value will be determined later when sailing. Check again that the rake is as you want it.
Loos Gauge
There are shroud/stay tension adjustment gauges available that will give you a numerical method to adjust the wires. You can check with others to see if your tensions are greater or less than the wires you are comparing to.
Adjust and tension cap shrouds
Begin by determining two reference points on the toe-rail, hull-mounted chain-plates or somewhere well outboard, approximately in line with the mast fore-and-aft. Make no assumptions about symmetry; boats can often be different on each side. Measure aft from a single, central point on the stem fitting and then exactly the same distance out from the mast step and of equal height.
With a keel-stepped mast, centre it at the partners by measuring from the reference points and chock it fore/aft at the partners to the maximum "J" value.
Now begin to centre the masthead by measuring from the main halyard to the reference points. This can be done using the halyard itself, but stretch is difficult to estimate. One way is to use a spring balance attached to the end of the halyard to give a constant value each side, perhaps 10 kg. The best way to do it is to attach a steel tape measure to the main halyard’s headboard shackle. Hoist the halyard and extend the tape measure aloft. The distance is now measured from the masthead to each reference point. Adjust the cap shroud rigging screws to give the same measurement on both sides of the boat, ensuring that the mast is centred in the boat.
Now begin to tension both rigging screws, keeping the mast straight up. Turn the rigging screw barrels either one or half a turn at a time. The tension needed on the cap shrouds is almost as much as on the forestay/backstay. A useful guide is that they should produce a deep musical note when struck with the flat of the hand. Final adjustments will be made later.
Adjust forward lowers or baby stay
Now sight up the mainsail luff track. Compression from the cap shrouds may well cause it to be slightly bent or bowed. Tension on the baby stay will pull the mast forward, normally taking out either of these. With twin lowers, take up the one that will pull any sideways bow straight, then tension the other one to match. At this point, the mast should be raked the desired amount and exactly straight up and down relative to port or starboard lean.
A decision now needs to be taken regarding pre-bend in the mast. Pre-bend has the effect of pulling some of the fullness out of the mainsail to flatten it. It is normal to have a small amount of permanent pre-bend on a masthead rig, whereas tension on the backstay of a fractional rig will apply bend when required.
Increase the tension equally on both forward, lower shrouds, or the baby stay, until two or three inches of bend is pulled into the middle of the mast. A normal amount is a little less than half the mast diameter. Sight up the mast to ensure that it is neither bowed left or right or forming an "S".
Adjust aft lowers
The aft lowers balance the forward lowers or baby stay, fine-tune the rig and give additional support to the mast. All that is needed at this stage is tighten the rigging screws about one turn past "finger-tight". Sight up the luff groove to make sure that the mast is still straight.
With these steps complete in the berth, it’s time to set sail and make final adjustments.
Fine tuning the rig on the water
Sail the boat on a series of upwind tacks in 10-14 knots of breeze and examine the rig on each tack. There are three main points for the rig, and three more for the sails:
1. Ensure that slack in the leeward shrouds is not excessive. The wire should loosen but there should be no clearance in the swivel or other pin joints. This applies to cap and lower shrouds. If slack is excessive when hard on the wind, adjust by equal numbers of turns on each side.
2. Keep sighting up the luff groove to ensure that the mast remains in column. If the top of the mast is falling away tighten the cap shrouds, if the centre is bowing upwind loosen the lowers, if it is bowing down wind, increase tension. Increase backstay tension and check mast straightness with the added compression load. Check on both tacks.
3. Check head stay sag with maximum backstay tension. It should be no more than two to four inches for a 35 ft. boat in this wind range. If it is greater than this then tighten the head stay. If it is less than this loosen it, otherwise the head stay will be too tight to provide proper power in the lighter air. Most jibs are cut with some head stay sag designed in. If the backstay is not adjustable, then do these tests with a moderately tight backstay
4. Pay attention to mainsail shape, especially down low, as the luff curve should be matched to the mast pre-bend. Pre bend is adjusted on a keel-stepped boat by moving the mast at the step and partners but on a deck-stepped boat by increasing baby stay tension. Make this adjustment if the mainsail is either too full or too flat in the lower third, with respect to the rest of the sail (i.e., the sail is out of balance).
5. Check helm balance with the main and jib sheeted for upwind sailing. If weather helm is excessive with the mainsail flat but not back-winded, jib sheeted in to maximum, and enough backstay on to yield about 3" of forestay sag, then the rig should be raked forward a little. Too little helm, or poor pointing ability, and rake needs to be increased aft. This adjustment is done by tightening or lengthening the forestay, perhaps three to ten turns, preferably when moored alongside. Be aware that changing forestay length will also change baby stay tension.
6. After doing this, re-check head stay sag, mainsail shape, and rig athwartships position in 10-15 knots of wind. If rake has been increased, check that the genoa clew is not too close to the deck or the sheet lead is not too far forward to be sheeted properly.
Recheck the Tensions and the Alignment
On returning to the berth, carry out final checks. First, verify that the relationship in tensions between the forestay/backstay and upper shrouds is still about the same. The forestay/backstay should still be slightly tighter than the cap shrouds. Next, measure the distance from masthead to toe-rails again. The measurement should be the same to both starboard and port toe-rails. Sight up the luff groove again and make sure that it forms a straight line. Make the appropriate adjustments to the rigging screws.
Secure adjustable rigging
With everything set correctly, secure the rigging screws so that they won’t back themselves off and loosen the rigging. With closed barrel style rigging screws, there is a locking nut on both bolts. Turn these nuts down to the barrel and use a small spanner to lock them tightly. With open style rigging screws; use split-pins or seizing wire through the openings of the barrel and the small holes in the bolt ends.
Periodic checks
Over time the rig will loosen somewhat. This may be due to sailing in strong winds, changes in temperature, or combinations of other factors. Periodically, at least annually, check the standing rigging for tension and condition. Check the system both while at the berth and while sailing.
The combination of pre-bend and mast rake can change the weather helm feel of the boat; the boat’s pointing ability and the boat’s speed and efficiency through the water. So, don’t forget to check the standing rig from time to time. As sails age and become fuller, increased mast pre-bend will improve upwind pointing ability and will decrease the angle of heel in stronger breezes. The boat may also develop more weather helm. Reducing mast rake will improve this tendency.
 
Re: Friggin\' with the riggin\'

[ QUOTE ]
My mast seems to be bent forward at the top. I've released the backstay and the after babystays and it still looks skew from the pontoon.Tightening the Fwd baby stays and then adjusting the after ones doesn't seem to help.

[/ QUOTE ]

If it's bent forward at the top, then the forestay is tighter/shorter than the backstays, so slackening off the backstays ain't gonna help - in fact the opposite. Loosen the forestay until vertical, then tighten the backstays.

Like when a mast has been brought down for repairs, etc, with all the rigging slack the idea is to tighten gradually and evenly. I walk around and do about 3 turns on a stay and then its opposing stay, and then check the tension by feel. I don't recall whether I do the inner baby stays first or last, probably first.

Granted, the forestay needs to be tightish, but I would tend to have it a little facing astern or vertical rather than foreward. The backstay(s) being tightened will pull back into shape until it is in the correct alignment and then both fore and backstays tightened gradually until they are tight enough.
 
Re: Friggin\' with the riggin\'

get this book its so simple and deals not only with rig set up and tuning but also sail trim etc.
done 2 fasnets and still use it. on offer at amazon currently £9 or so
Sail and Rig Tuning (Paperback)
by Ivar Dedekam (Author)
 
You must log in or register to reply here.

Share this page

Top