Standing rigging: step by step guide on how to tune it on your sailboat

In this article we will deal with the tuning of standing rigging of a typical sailboat. Speaking of standing rigging we have to open a parenthesis on the types of rigs possible for a sailboat.

Please note this article is a translation and may contain some errors for which I hope you’ll forgive us!

Armo frazionato di un Class40
Fractional rig on a Class40

Standing rigging: the evolution of rig types and their tuning

Historically, the most traditional rig type is the masthead one. That is with the forestay and backstay attached to the masthead as fixed standing rigging that create traction in the opposite direction. The spreaders, in this case, are in line, perpendicular to the fore and aft axis of the boat. With a masthead rigged boat, the backstay can be used to increase forestay tension in high winds. At the same time, by vertical compression of the mast, tensioning the backstay causes a bending of the mast that flattens the main. The backstay is both an element of the standing rigging but can also be tuned.

Global Ocean Race - Hugo Ramon costretto a districare cime impigliate
Global Ocean Race

Tensioning the backstay, the central part of the mast advances forward creating a slight “C” shape of the mast seen from the side. This curvature lets you bring the “fat” of the mainsail forward flattening the sail. Therefore, with a strong breeze, we can intervened on the backstay to reduce the forestay sag and flatten the mainsail. Both operations improve upwind performance.

Fractional rigs

For decades now, however, “fractional” rigs with swept back spreaders have been increasingly widespread. In this case the forestay does not reach the masthead but only up to seven eighths or nine tenths of the mast height and so do the attachments of the shrouds. The spreaders are not perpendicular to the fore-aft axis but swept towards the stern on the horizontal plane. The swept back spreaders ensure that the mast can stand up even without the backstay, which is no longer “structural”. That is, it is no longer one of the elements of the standing rigging (albeit adjustable). It becomes simply the means to adjust the mast bend and curvature and would be considered and its control line is therefore part of our running rigging.

Armo frazionato di un Mini 650
The fractional rig of a Class40

This development has become more and more marked with boats with very wide spreaders and without backstay. The evolution started with offshore sailing boats such as the Mini 650s and Class40s and now it is very widespread also among cruising sailboats. By completely eliminating the backstay from the the list of elements constituting our standing rigging, which presented itself as an obstacle to increasing the roach of a mainsail, it is now possible to have all the roach we want and even “square top” mainsails.

Standing rigging tuning on fractional rigs with swept back spreaders

We will talk here specifically about boats with swept back spreaders. We have chosen a Class40, a sister-ship of the boat with which I competed in the Global Ocean Race 2011/2012. It’s a popular model of Class40, a first generation Akilaria RC1, designed by Mark Lombard, from around 2006. The rig of this boat is not particularly “extreme” or delicate, being the Class40s designed for great ocean navigation. The standing rigging is all rod on this boat.

L'attacco delle volanti alte visto dalla testa dell'albero
Runners attachments seen from the mast top

Although the mast is made of carbon rather than aluminium, the rig is the same as that of a Mini 650 Pogo2 from Structures shipyard. The Pogo 2, designed around 2003-2004 is the Mini 650 with most boats built. This type of rig, nine tenths fractional, has two orders of spreaders. There is no backstay at all, which is common on many modern boats. By now, I would say, even on cruising boats it is one of the most common rig arrangements. It is adopted by shipyards such as Jeanneau and Beneteau, even for boats without oceanic ambitions.

Volanti in tensione a su andatura al lasco
Tensioned Runner and Checkstay on a run

This type of rig is fitted with a runner at the mast top and a checkstay at the height of the inner forestay. Runners and checkstays are not structural, therefore are not to be considered part of the standing rigging per se, the mast does not need them to stay up. I jibed without runners in 50 knots of wind and nothing happened. That said, runners and checks play a very important role in stabilising the mast and reducing its stress. When I run my training centre I used to say that they were not part of the standing rigging but that for good practice we would treat them as such.

Standing rigging and structural lazy jacks

As said, the backstay is simply not there, to make room for the “square top” mainsail. This is the same both on Mini 650s and on Class40s. There isn’t even a topping lift to support the boom when reefing. On a Mini 650, to avoid too many lines, and with a boom that weighs a few kilos, nothing replaces the topping lift. This means that when the main halyard is released, the boom falls onto the coach-roof. The boom will rise again when we tension the reef line and this rarely even needs the boom to be helped by hand.

Lazy jack strutturali su un Class40
Structural Lazy Jacks on a Class40

On the Class40, even though the boom is made of carbon, we can imagine how much the boom plus mainsail would weigh especially if full of water. The problem is solved with the introduction of “structural lazy jacks”. What is meant when we say they are structural? Their role is not simply to contain the main when dowsing it. They replace the topping lift and support the boom. Usually they are made with dyneema and not just simple polyester. They are adjustable both to raise the boom in port and to put them at rest during navigation.

Standing rigging and runners and checkstays

On boats with swept back spreaders, runners and checkstays are not structural. Despite the absence of a backstay it’s not runners or checkstays that keep the mast up. That said, they play a very important role – they help provide additional support for the mast. For example, for ocean-crossing boats, runners and checkstays help stabilise the mast and prevent it from pumping or bending. In addition, runners reach the masthead. With a fractional rig they provide extra support, and become partially “structural” in reducing the workloads of the last part of the mast not reached by the shrouds.

Volanti sopravento in tensione - Class40
Runner and checkstay under tension on the windward side

That said, on a nine-tenths rig it is unlikely that you could break the mast tip under spinnaker just because you did not set the runner. I am not aware of any such cases among Class40s. Certainly distributing the tension between runner and checkstay greatly reduces the load of the standing rigging. The checkstay, on the other hand, usually points where the foresail forestay attachment is located. In addition to acting as a support for the mast in general, it allows you to decrease forestay sag without adding compression to the mast.

Standing rigging: how to proceed with tuning your standing rigging

After this introduction, let’s move on to a practical case. Let’s consider the mast of a Class40, with two orders of swept back spreaders and its standing rigging. Hence, we have non-structural runners and checks, no backstay and no topping life. When I arrived on this boat to check the mast, there were two problems noticeable with the naked eye. First of all, the mast was not straight, it pulled to the left until the first set of spreaders. Then it made a bend to the right and then back to the left between the second set of spreaders to the masthead.

Manovre fisse - situazione iniziale
Standing rigging – the initial situation

Seen from the side, the mast showed excessive rake and pre-bend that needed correcting. So we had left-right and fore-aft problems. In addition to this it was clear that when the starboard runners and checkstay were tensioned, the mast deteriorated in shape. In particular, the curvature between the first set of spreaders and the masthead increased. To fix a mast like this, with multiple problems, you need to have a method to get to a satisfactory result.

Manovre fisse - eccessivo rake e sbananamento
Standing rigging – excessive rake and pre-bend

As for the adjustments to runners and checkstays, I leave them last, as we will see there are various options on how to use them. First we wanted to take care of putting the mast straight and solve the problem of its excessive rake. The rake shifts the sail centre aft and the bend in the mast flattens the sail, both of which we do not want in light winds. Since this boat is sailed in the Mediterranean we must have a good light wind setup and be able to intervene on the shape of the sail as the wind increases.

Standing rigging: how to put straighten the mast

The boat was in the water, we first had to avoid the risk of unscrewing a turnbuckle and accidentally unhooking a shroud. Since it was not me who had mounted the mast, I could not be sure that the turnbuckles had been inserted correctly, i.e. be exactly level with the same number of turns on the upper and lower par. This means that the threads are not screwed in equally. The lazy rigger screws the turnbuckle on deck a few turns so that he has only to hook the vertical shroud, the V1.

Manovre fisse - misurazione degli arridatoi
Standing rigging – measuring the tensiones

So, in order to avoid any dangers, we set the inner forestay (to double up with the forestay). We also set runners and checkstays just for safety. These work laterally to support the mast. We also attached spinnaker halyards one to the left and one to starboard to an eyebolt.

Manovre fisse - misurare tutto prima di cambiare qualsiasi cosa
Standing rigging – measure everything before changing anything

With a bent mast the first thing really is to understand was why it is so. So we measured the total length of the left and starboard turnbuckle system for both the vertical shrouds (V1) and the low diagonals (D1). Differences emerged immediately, the D1 on the left was about 1cm shorter than the one on the right. This explained why the mast started veering to the left. The port V1 was 2cm shorter than the starboard V1. This explained why the head of the mast pointed to the left after the initial bend. The curve to starboard between the first and second set of spreaders was attributable to the upper diagonal D2 on the starboard side, which was tighter than the left one.

Standing rigging: resetting everything to zero

With the boat in the water and not wanting to take any risk, we didn’t want to get to unhook any turnbuckle. This is to avoid the unpleasant situation of having a hard time getting to re-attach one. This could happen if there’s something inherently wrong with the measures taken that would forced you to work at the limit of the available turns. However we had to make some assumption and one was that each