Does your boats weather helm bother you, or does she go better on one tack than the other? Toby Heppell explains how to iron out the foibles with proper boat rig setup
Boat rig checks: 18 ways to refine your yacht
Have you ever wondered why your boat seems to point better and sail faster on one tack that the other? Or found that the helm remains light in some conditions, but develops a mind of its own in others?
The answers to these and many other niggles with your boat’s handling, may lie in how you’ve got the boat rig set up.
Setting up your boat’s rigging can seem a complex task.
Each piece of rigging has a distinctly different effect on a boat’s balance, feel, and response, and each setting change can have a knock on effect, meaning a single adjustment often leads to something else being set up incorrectly.
Due to this, many of us tend to just set and forget our rigging settings.
When was the last time you thought about shroud tension for example?
I’m willing to bet not recently, unless you’ve noticed your shrouds going slack when they usually would not.
But setting up your boat rig properly can make all the difference to how a yacht sails, whether she is manageable in heavy weather, or can keep making headway in light airs.
Get it right, and sailing is much more fun.
I spent my younger years competing at international sailing events in dinghies before moving on to racing keelboats.
In both of these sports, keeping track of boat rig settings in minute detail was a major part of the sport.
When I moved into the world of cruising for fun, I was amazed to discover so many people barely touched their boat rig setup from year to year, let alone morning to afternoon.
Having raced on a great number of keelboats and tested many new yachts for magazines over the years, my obsession with understanding the numbers has not gone away and continues to be one of the first places I look when a boat is not sailing as well as I might hope.
The subject can be seem endless, but a number of simple concepts can make all the difference between a boat feeling like a dream to sail and one feeling like a pig.
Here’s the list I look over when I first start setting a boat rig up.
Boat rig checks: Static set up
Changes in mast rake have an effect on the balance of the helm.
The more the mast is angled aft (adding rake) the more weather helm you will experience.
Standing the mast up straighter reduces weather helm by moving the sails’ centre of effort forward relative to the centre of lateral resistance of your keel.
Completely removing weather helm, however, will make the boat feel unresponsive and will be detrimental to pointing.
Changing the amount of rake may be as simple as adjusting the forestay and the backstay, but it might involve moving the mast step on some boats.
The aim of rake adjustment is to have enough rake to provide some weather helm upwind in light air but not so much that in the heavier winds – when weather helm increases – it becomes too pronounced.
You want to aim for around 3-5° of weather helm.
It pays to adjust rake for the conditions.
Adding rake when the wind is at the top end helps the mainsail and jib to depower by allowing the air to more easily exit the top of the sail’s leech – often referred to in the racing world as the ‘fourth corner’.
This, combined with the opening of the leech by backstay and Cunningham, works in tandem to reduce power.
It’s a slightly tricky concept to get your head around, as moving the rake aft should, in theory, increase weather helm, but the benefits through depowering the mainsail are such that the net gain (reducing heel and so leeward drift and the boat’s want to round up around the keel) counters this.
This is a key reason adding backstay tension is important in heavier winds – it rakes the mast, depowers the mainsail and tightens the luff of the headsail.
If your rake is easily adjusted and does not involve changing the mast step it might be worth adjusting it based on conditions, but for most cruisers, once you have found the correct rake setting, it is easier to just leave it be.
Pre-bend is achieved by a combination of compression (by increasing rig tension) and adding mast blocks at the mast collar on a keel-stepped mast, or by tensioning a baby stay.
A modern fractional rig on a lighter boat will typically use more pre-bend, perhaps a few inches, than a masthead rig with large overlapping headsail, where pre-bend will be very slight, maybe an inch.
This can easily be measured by attaching the main halyard to the base of the mast, tensioning it and then looking at the bend characteristic.
If you have a tired mainsail that is starting to get too deep, consider adding a little more pre-bend.
It is worth noting that doing this with a tired mainsail will exacerbate the other problem of age – the draft creeping aft – but it is a good fix, on balance.
Boat rig checks: Masthead rig tuning
A masthead rig is the least complex option in terms of setup, though this simplicity does offer limited options in terms of adjustment.
Firstly, you want to ensure your mast is upright, side-to-side.
A tape measure from the masthead, or simply use a halyard, taken to each shroud base in turn, will quickly show any discrepancy.
Adjust the bottle screws until the mast is straight.
You will want to ensure that the upper shrouds are firm to the touch.
If they feel loose, tighten them equally on each side to keep the mast straight.
A tension gauge is a really good investment to give you a decent idea of that sort of rig tension you are carrying.
Boat, and mast-specific tension levels can be obtained from your mast or boat manufacturer. These will vary depending on rig size.
The common advice is to wind shrouds up to hand tight then add a little more tension with a spanner.
Be careful not to over tighten as this could strip the turnbuckles.
It also pays to err on the side of caution initially as you can always tighten the rig when sailing upwind.
Having your rigging too loose will cause it to pant and jump around in waves, leading to fatigue.
Typically you can go up to, but never beyond, 20% of your rigging wire’s breaking load.
It’s important to tighten all intermediates and lowers evenly on each side, sighting frequently up the aft side of the mast to make sure it remains straight.
This is the initial setting, with mast centered and straight, and all shrouds firm.
When you tension the forestay and backstay, the mast should remain straight side-to-side.
Mast alignment under load
Once you have this basic setting locked in, when you next go sailing in moderate breeze, head upwind and take the slack out of the upper shroud on the leeward side (and count your turns so you can replicate the amount on the other tack).
Tack, and then tighten the other upper the same amount.
Keeping your work to the leeward side shroud ensures you don’t strip the turnbuckle by reducing the rigging tension.
Once the leeward uppers are tight, sight up the mast on each tack to check for side bend.
If the middle sags to leeward, tighten the lowers.
If the top appears to fall off to leeward, it could be the middle popping to windward; either loosen the lowers or tighten the uppers.
Over-tight lowers and loose uppers allow the masthead to fall off.
Proper tension will leave the leeward upper shrouds taut with 15º of heel.
The uppers should be tighter than the lowers; they have more load and stretch more due to being longer.
Check the rig periodically, particularly after sailing in heavy winds.
Look for stretch in the uppers and for over-tight lowers, which can overload upper spreaders.
Backstay tension will bend the mast through compression as well as tightening the forestay.
With a stiff mast, backstay tension translates into forestay tension, controlling how much the forestay, and the headsail luff, sag to leeward.
If you do have a baby stay, this can be utilised to add bend. The backstay also contributes to the bend, particularly once it has been initiated by a baby stay.
Fractional rig tuning
The procedures for tuning a fractional rig differ slightly from those for a masthead rig.
There are many varied configurations of fractional rigs, which makes it difficult to generalise.
The most common type of fractional rig on modern cruising boats is with spreaders swept aft.
Fractional rigs with straight spreaders sit somewhere between masthead and fractional rigs in terms of setup and flexibility.
Swept back spreaders mean that shroud adjustments made will affect lean, side bend, pre-bend, sag, and mast bend.
For the most part, spreader sweep will be fixed on most boats, and their angle (if adjustable) is a level of complexity most of us will not need to worry about.
The first thing you will need to do is to ensure that the mast is centered and stands vertically.
This can be done by taking the main halyard and measuring down to the same point on either side of the boat to check it is centred.
Use a spirit level to check it is even vertically.
Then, with lowers loose, pull the backstay fully on.
Tighten the upper shrouds, keeping the rig centered and mast straight side-to-side.
If the mast tends to bend sideways, ease the backstay slightly.
Release the backstay. The mast will still have some bend.
Tighten the lowers to remove bend as necessary to match your mainsail.
You can get a good indication of luff curve by laying your sail on a flat floor, running a straight edge (or piece of string) from head to tack of the mainsail and measuring the difference along its length.
This does actually measure a bit of luff round (the shape cut into the sail by sticking), but it’s close enough.
The rig is now tuned for maximum headstay tension. Additional backstay tension will bend the mast and add some headstay tension.
To get the mast to bend more easily, ease off the lowers. To make backstay tension affect the headstay tension as much as possible, tighten the lowers.
Upwind in a breeze the top of the mast will fall off to leeward, and the middle will bow out to weather.
This side bend de-powers the rig to a greater degree than fore and aft bend.
Easing the lowers may reduce side bend, but it will allow more headstay sag and fore and aft mast bend.
In a perfect world, we would adjust shrouds each time we go sailing to achieve proper mast bend and headstay sag characteristics for varied conditions.
But realistically, that is not going to be something anyone will want or be able to do.
As such, aim for a setup which errs towards a slightly less bent, and so more powered-up mast and rig setup on the assumption that when cruising we are more inclined to reef earlier.
Using your boat rig
How your rig helps upwind
In light winds:
Pointing is not important, moving is. As such the main thing you are looking for in light conditions is to increase depth in the sail.
Easing backstay will straighten the mast and allow the mainsail to be a little deeper.
It will also increase forestay sag and allow the headsail to power up.
Both of these will mean you point less close to the wind, but you will only lose a degree or so and the increase in speed will more than make up for it.
Easing halyards and outhaul will allow for plenty of twist and depth in the sails by moving the genoa car forward and easing the sheet, then bring the boom to windward of the centreline and ease the mainsheet and vang, or leave it on the centreline and haul on the topping lift if you have one.
In medium breezes:
Tighten halyards and outhaul and flatten the sails. Also, with the main, use backstay and mainsheet tension.
‘Bending the mast is what you are after as you move into mid-range wind condition,’ explains Bill Gladstone from North Sails.
‘As you bend the mast, three things happen. First the sail gets flatter as the middle of the mast goes forward. The second is you increase twist and the third is that the draught moves aft. As you bend the mast to keep the same twist profile you might need to adjust the mainsheet and then pull on more halyard or downhaul.
‘With the genoa, move the car back a couple of notches and add some sheet tension but don’t let the leech touch the spreaders. If the wind builds, tighten everything further until you’re up to maximum luff tension, outhaul and backstay. Make sure the leech isn’t hooked, as that will also sag the forestay.’
In heavy winds:
You’ll need to reef. In theory increasing mast rake will help to decrease weather helm and keep the boat better on its feet.
As the boat rig moves aft, so the balance point moves aft, but the mainsail will be driving less hard, due to twist so you are reducing the effect of a full headsail overpowering a depowered mainsail.
That is the theory, but without easy access to adjusting mast rake, reefing is the easier option.
As pointing can be dependent on the mainsail maintaining proper leech tension, it is easier to keep the boat pointing well with a reefed main that can be sheeted than with a main that does not have enough leech tension.
When sailing downwind sailing, essentially we want the mainsail to be as full as possible.
Removing backstay tension is a great way to do this, straightening the mast and making the sail deeper.
Taking tension out of your halyards will help here too.
Easing the backstay downwind will also have the added bonus of keeping the rig further forward and so reduce headsail tension and increase the depth of your genoa (or spinnaker of you are flying one).
However, if you are using a cruising chute (and so not sailing dead downwind) it might be worth keeping a fair amount of backstay tension on and therefore increasing the luff tension of the chute, helping it to fly a bit more effectively.
Boat rig checks: Troubleshooting
The most easily noticeable issue that can come about from your rig setup being incorrect is the boat performing differently from tack to tack, which can cause much head-scratching and exasperation.
The large numbers of variables, such as wind strength, direction and tide can make it tricky to spot.
Typically the issue will present in a number of different ways.
It might be that you cannot make the same angle on one tack as you can on the other, or that speed through the water is different on each tack (remember to check if your paddle wheel is offset).
This intuition that you have a ‘bad tack’ is developed over time and with experience.
You might imagine a yacht built by a professional yard with modern construction techniques would mean everything lines up, therefore ruling out chainplate position as a possible cause, but it’s worth checking.
You could be surprised how much difference there can be in position from side-to-side.
A discrepancy doesn’t mean your boat is a dud, or in need of repair, but it means you can trim your sails differently to account for your boat’s idiosyncrasies.
To check, tie a tape measure or anything else that will not stretch to the forestay, then run it aft to each shroud base. Are they the same distance from the forestay?
Next, measure the distance between the two shrouds and half it to find the centerline, then run a tape measure perpendicularly from the centreline to each shroud base.
The distances should be the same.
If not, and you have a keel-stepped mast, you can centre it with chocks next time it’s re-stepped.
Are you genoa tracks symmetrical?
When you roll away some genoa, you need to move your genoa cars forward to keep the leech under control.
You might note that the leeward car is now a certain number of holes from the forward end of the track and move the windward one to match, but if the tracks aren’t positioned symmetrically, or you have a different type of track to windward, that won’t be the case.
Measure from the forestay to the forward end of each genoa track.
Do both sides match?
A bit of weather helm helps the boat point and tells you when it’s in the groove.
Too much and the rudder will be slowing you down.
Setting the correct amount of sail can reduce weather helm.
If it persists, look at your boat rig.
The centre of effort from the sails should be aft of the centre of lateral resistance.
The further aft, the more weather helm.
At a basic level, moving the mast forward, by moving the mast step forwards, or by reducing rake by easing the backstay and tightening the forestay, will bring the two points closer.
However, pulling on backstay tension will flatten the main and open the leach, spilling power and moving the centre of effort forwards.
Inducing mast bend, with shroud or baby stay tension, will also depower the main.
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Having the mast further forward or will reduce weather helm, but doing so by easing the backstay has the knock on effect of powering up the mainsail such that it will increase weather helm.
To reduce this, stand the mast upright via your shorts or mast step, but increase mast bend via the backstay to reduce the mainsail’s power.
Check you mast is straight
By sighting up the mast as in the previous set up information we covered, you can check that your mast is straight.
Check that it is vertical too and that the pre-bend settings have not changed.
Newly fitted rigging or re-fitted rigging does take some time to bed in and can do so at different rates.
If you stepped your mast at the start of the season, it could have changed over time, now giving you an asymmetric setup.
Replacing standing rigging
Some insurance policies insist on new rigging every 10 years, while others are satisfied with a professional rig inspection.
If you are replacing your rigging, you face the choice of whether to go for the cheapest option or to upgrade to something that will give you better performance.
The key characteristic is the amount the rigging will stretch, and sagging rigging leads to masts that flex more than they should, forestays that bag to leeward, and less control over the mainsail shape.
Wire is still the primary option for most of us, but there are three different kinds you can opt for:
- 7×19, or wire rope, is the most old- fashioned, and is suitable for running rigging where it needs to be highly flexible, but is not often used in standing rigging nowadays.
- 1×19, a single bundle of 19 thicker wires, is the standard wire for most rigging uses.
- Compact dyform wire is pressure-treated. It weighs a little more for its size but offers reduced stretch, increased breaking loads and with it significantly more cost.
Life expectancy for all three is very good with regular inspection, 7-20 years or 15-25k nautical miles, depending on use and region.
‘Wire does have its advantages,’ says Gordon Bonnay of Performance Rigging.
‘The biggest thing that wire has going for it is that it will advertise its failure. Generally a strand will pop out, and as soon as you see it you know the wire is compromised.’
Rod rigging has also been around a long time now. It has low stretch characteristics, a very long lifespan, and a minimum breaking strength beyond that of its wire counterpart.
‘Principally the thing that goes wrong with rod rigging is only really if there is a fault in the hydraulically attached fitting forcing the rod into a different shape, or if it is pulled out of line repeatedly,’ explains Bonnay.
Rod rigging has extremely long life expectancy attributed to design (mono strand) and the composition of the alloy making it very corrosion resistant.
However, it does require a more in-depth service protocol during recommended intervals, which includes unstepping the mast to inspect and re-head the rod as needed.
Therefore, rod clearly gives better performance, but its high cost and servicing requirements isn’t affordable for most cruisers.
Essential rigging checks
Check and tape split pins
They may seem insignificant but, properly fitted split pins can save your mast.
Without them, bottlescrews and clevis pins work loose and you’ll lose the lot.
Use the biggest split pin that will fit the hole, pack any space with stainless steel washers, insert the pin, spread both its legs into an anchor shape and secure with tape or a blob of silicone to prevent snagging on clothing, sails or skin.
Check shroud terminals
Securing mooring lines to shroud bases is never a good idea because the loading can deform rigging toggles and weaken bottlescrews, creating uneven loading and increasing the chances of failure through fatigue.
If there isn’t a cleat handy, use genoa cars, winches or padeyes instead.
For standing rigging, check the top of the swage and look for any broken strands.
If you find some, replace that shroud and its opposite.
Check your furler and line
Make sure the lead onto the drum is fair and that there are no chafe points.
If it’s looking tired, replace it.
Remember, if the furling line breaks on a windy day, you’ll have far too much sail up for the conditions, and the loads will be critical.
Also, check the grub screws on the collar where the drum meets the luff tube.
The forestay shakes tremendously during tacks and those grub screws can easily come loose.
Check mainsail track sliders, cars or bolt rope
Just as a snapped furling line will leave you with far too much sail up, losing a few mainsail track sliders or tearing out your main’s bolt rope can leave the sail bulging to leeward.
In a matter of seconds the wind can strip out the others, leaving you with a spinnaker where your mainsail used to be.
Check the fastenings to both mast and sail are secure, and consider repairing if you’re in any doubt.
Send a rigger up the mast
There is no tension in the stays of an unstepped mast, and that means broken strands can creep back into the swage, giving the appearance that nothing’s wrong.
Once a season, send a rigger aloft.
They can check for broken strands at the top of shrouds, cracks in terminals, or in the mast around terminal fittings, and make sure your shackles are properly seized and your sheaves are in good order.
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Source: Yachting Monthly