Challenge 72 Class Guide to Service & Maintenance Mast & Boom



© Alistair Hackett / Ken Collins 2008

All rights reserved.

Reproduction in full or in part is prohibited without prior written permission from:

Alistair Hackett
Oceans 17


This document relates to the service of Challenge 72 Class yachts.  It is a guide to the service of Challenge 72 Class yachts – and ONLY a guide.  There are no expressed or implied warranties or guarantees provided with this manual.  The Challenge 72 yachts are semi-custom vessels that are operated on the open seas where the conditions can be reliably predicted to exceed the design specifications of any vessel on occasion.  The operator of any sailing vessel must act diligently to ensure the safety of his/her own vessel. 

Table of Contents

Table of Contents. 3

Introduction. 5

The Mast & Boom. 5

WindeXL. 5

Brookes & Gatehouse Vertical Wand. 6

Mast Head VHF Aerial. 6

Mast Head Light – 24 volt 7

Spinnaker Halyard Masthead U Bolts. 7

Spinnaker Halyard Blocks. 8

Mast Head Halyard Sheaves. 8

Clevis Pin for Main Halyard Dead End. 8

Welding Around the Masthead Box. 8

Top Cap Shroud Tangs. 9

Mast Steps. 9

Top Spreaders. 10

Sta Lok clamps. 10

Aluminium Block in the Spreader End. 10

Compression Tubes and bolts. 10

Runner Tangs. 10

D3 Tangs. 10

Staysail Halyard Sheaves and Boxes. 10

Inner Forestay Tang Box. 11

Staysail ‘Spectacle Swivel’. 11

Middle Spreaders. 11

Intermediate Shroud Tangs. 12

Steaming Light – 24 volt 12

Additional Hole below the Steaming Light 12

Lower Spreaders. 12

Lower Shroud Tangs. 12

Babystay Tang Box. 12

Deck Flood Light – 24volt. 12

Spinnaker Pole Inboard Up-Haul Sheave Boxes. 13

Spinnaker Pole Tracks and Cars. 13

Mast Steps. 13

Appendix 2        Index to Maintenance Tips. 14




This document is produced with the intention of highlighting areas of the specification and running of a Challenge 72 that may become useful as the yacht is operated. It aims to highlight certain areas of the specification and why certain items were specified in the build of the yachts, in turn this will also illustrate areas that will require special maintenance during the course of normal use.

This maintenance schedule and thoughts are based on lessons learnt during the operation of all 29 of the Challenge yachts and nearly 3 million miles sailed. It does not take into account any changes made to the vessel since leaving the control of The Challenge Business and it should be noted that any changes made to specific areas might also have implications on other areas and systems onboard, care should be taken when reading this document to ensure that any changes of equipment etc are taken into consideration.

When navigating around the yacht this document assumes that it starts at the Masthead then moves from Bow to Stern both above and below decks.

The Mast & Boom.

The Mast & Boom sections are unique to the Challenge 72 Class and were specifically extruded for the yachts. The extrusions themselves were designed specifically for the rigours that the yachts would be put through when sailing around the World against the winds and currents. It is over engineered in many areas and was constantly developed as each set of spars was manufactured.


*    The Mast

At least annually some lucky person has to be hauled up the mast and should check all mast hardware starting at the top and moving in a controlled manner back down to the deck.  Check each external surface for signs of corrosion or cracking.  Remove any dirt or stains with a brillo pad and water to see what is underneath.  Check beneath peeling paint.


*    The Boom

Annually inspect each point of attachment of fittings to the boom for corrosion or cracking. 


On the masthead a WindexXL is fitted using a standard Windex fitting. This unit is not a commonly available Windex as it is designed specifically for large yachts and whilst not a custom product it will not be readily available.


*    The WindeXL

The WindeXL should be removed before the mast is unstepped.  Leaving the base fitting on the mast, the stem should be removed from this base.


Brookes & Gatehouse Vertical Wand.

The Vertical Wand is not a standard fitting from B&G. The attachment and the plug arrangement are not standard. This is principally based around the idea of being able to use a standard B&G cable with a conventional B&G fitting which would normally be used to fit a forward facing wind wand. This means that the cable exit from the bottom of the Vertical Wand has the same plug as would normally be found on the end of a standard forward facing wand.

If a Mast Cable (the cable running from the mast head to the bottom of the mast) failure occurs this can be replaced using a standard 30m B&G cable. Should the Vertical Wand fail in some way and a replacement is unavailable then the option to fit a standard forward facing wand is available because the ‘block’ this fits into is already in place.


*    Vertical Wands

It should be noted that the Vertical Wands are very expensive and must always be removed if the mast is unstepped.


Mast Head VHF Aerial.

The Comrod 1m Fibre Glass Aerial was fitted for the first time for the 2004 Global Challenge to increase the range of the VHF reception. With the aerial nearly 30m above sea level the range is increased dramatically and instances of VHF communications over a distance of 80miles have been noted.


*    Mast Head VHF Aerial Connector


This connector must always be protected from the wet as much as possible and as a minimum must be wrapped in self amalgamating tape.

When unstepping the mast the aerial should be unbolted from the mast wall and turned through 180deg. There should be no need to disturb the coax wire connection at the mast head.


Mast Head Light – 24 volt

The Tri Colour light fitted at the mast head was initially fitted to cover the need to have ‘emergency navigation lights’ under MCA Category 0 regulations.  Given the length of the Challenge 72’ class, its use is against Navigation Regulations.  It should be removed and replaced with an all round white anchoring light.  The fitting used is an Aqua Signal ‘quick fit’ light meaning the lens, bulb and bulb holder can be removed from the base unit. The same brand can supply an anchoring light that will fit the base ubnit.


*    Changing the Mast Head Light Bulb

To change the bulb the lens section of the unit unscrews from the base. If the mast is unstepped and left for any period of time it is recommended that this is removed and the base unit covered with tape.


Spinnaker Halyard Masthead U Bolts

These U Bolts are custom made for the mast. They will show signs of wear during normal use that may appear alarming. This is principally because they are made from 316 Stainless Steel and the shackles on the Harken blocks are made from 17/4 Stainless. 17/4 Stainless is stronger and harder and means that the shackle is of a comparable breaking load to the rest of the block. During the course of both the 2000 and 2004 Global Challenge events all combinations of U Bolt verses block were tried including having 17/4 U bolts made however these proved cost prohibitive and very difficult to manufacture. It was decided to use the 316 U Bolts with 17/4 shackles as this would mean that the U Bolt would wear however there is far more material to wear in the U Bolt than the shackle.

The U BOLTS can be sourced from Hercules CMSD in Dartmouth.


*    Spinnaker Halyard Masthead U Bolts


Always ensure that, once 30% of the metal around the bearing surface, has worn away the U Bolt is replaced.

Experience shows that the U Bolts will wear more when the spinnaker halyards are NOT being used and are not made up tight. If this is the case the block is allowed to ‘chatter’ at the masthead and will wear the U Bolt surprisingly quickly.

If no spinnakers are to be used or the yachts is going to be left for a length of time it is recommended that the spinnaker halyards and blocks are removed.


Spinnaker Halyard Blocks

The loads on the spinnaker halyard blocks are high Harken Blackmagic 125 blocks, or similar, should always be used at the masthead

Mast Head Halyard Sheaves

The sheaves used for the halyards are made from a plastic called Ertylite. All 4 are the same dimensions however the Main Halyard sheaves have an Oilite, self lubricating, metal bearing in them because of the increased load that is exerted by the 2 part Main Halyard. Because it is only single part the Spare Main Halyard sheave may not have this bearing fitted.


*    Mast Head Halyard Sheaves

Sheaves are easily replaced by removing the cover plate from one end of the pin for either the forward or aft sheaves and knocking the pin out. Clearly there must be no load on either sheave! Replacing the principal Main Halyard sheave with one that does not have an Oilite bearing will result in a significantly shortened life and risk possible failure.



Clevis Pin for Main Halyard Dead End.

When refitting the Dead End a ‘Blood Knot’ should be used around the pin, this will self tighten.  Both ends of the standing parts are tied in interlocking half blood knots with the standing part passing around the pins mating part to hold the pin in place.


*    Blood Knot – Clevis Pin

 This knot will be impossible to untie once it has been loaded and the knot will need to be cut using either a very sharp knife or hacksaw.


Welding Around the Masthead Box.

Experience has showed that the corners around the bottom of the Sheave Box that holds the Yankee and Main Halyard Sheave are prone to small cracks appearing along the welds and at the corners. If small these cracks are not of structural concern.


*    Welding Cracks – Masthead Box

Even if small the ends of the cracks should be drilled using a small drill bit to stop the crack moving any further. Once identified they should be monitored weekly and, if they continue to grow around or passed the drilled hole, they should be shown to a mast builder or rigger for further work.


Top Cap Shroud Tangs

The Tangs should be checked during each rig check with particular note being made of any movement of the machine screws holding the Tang fitting onto the Mast wall. If necessary these can be marked using a pen to identify any movement. It is recommended that every 4 years the Compression Tubes and bolts are checked. The tubes should be checked for any wear caused by Halyards running over them inside the mast.

Mast Steps.

These Steps are provided to allow someone working at the top of the mast to have something to steady themselves on. As these are an Aluminium casting there have been two known occasions of them snapping due to casting failures. It was concluded at the time that they were part of a bad batch and all replaced.


Safety First:           Mast Steps

NEVER rely upon the mast steps until you have tested them under load.  Always retain a weight bearing line attachment when up the mast.


Top Spreaders

The design and construction of all the Spreaders is conventional. As small amount of articulation is needed only the leather end caps should be used. The use of tape should be avoided if at all possible as a build up of tape can cause a lack of articulation and lead to fatigue.

Sta Lok clamps

The Outboard Spreader End is held in place by using Sta Lok clamps, these are semi custom Sta Lok fittings which clamp around the wire top and bottom. The cones or wedges inside should be reusable but they should be checked for tightness during each rig check.

Aluminium Block in the Spreader End

The Aluminium Block in the Spreader End that the wire runs over should be checked annually for wear and if the wire has scored the Aluminium, the block can be rotated through 90deg by removing the retaining pin.

Compression Tubes and bolts

It is recommended that every 4 years the Compression Tubes and bolts are checked. The tubes should be checked for any wear caused by Halyards running over them inside the mast.

Runner Tangs

The Runner Tangs are constructed the same as all the other Tang fittings however because of the nature of Running Backstays it is imperative that the stay attachment is allowed to articulate fully.

D3 Tangs.

As per Runner Tangs although because of the different use articulation is not so vital but still should be restricted.

Staysail Halyard Sheaves and Boxes.

The Staysail Sheave Box is welded into the Mast extrusion and contains the 2 Ertylite sheaves for the Staysail Halyards.


*    Yankee Halyard Sheaves

As for the Yankee Halyard Sheaves and welding precautions are as per the Mast Head Box.


*    Staysail Sheaves – Chipping

Because these Halyards also get used for the Spinnaker Pole Topping Lifts they are subject to greater low load movement as the pole end moves up and down therefore there is great risk of the sheaves becoming chipped as above.


Inner Forestay Tang Box

The fixing for the Inner Forestay is welded into the mast with a protective cage around it so as to avoid damage from any wire halyard.

The welding should be checked for cracking as per above and according action taken.  The cage should be checked that it is secure each rig check.

Staysail ‘Spectacle Swivel’.

The so called Spectacle Swivels are the sheaves on the outside of the Mast wall that are able to articulate so allowing the Staysail Halyards to be used for the Spinnaker Pole Topping Lifts.


*    Trapping of the Spectacle

As per above. To eliminate the risk of each Spectacle getting trapped on the wrong side of the Inner Forestay it is a good idea to attach a length of Bungee cord to the D3 stay to allow the swivel to be pulled out of the way when not in use. This method also stops the Swivels banging on the Mast when not being used while at sea.


Middle Spreaders

Technically these are the same as the Top Spreaders however the Outboard End is significantly different as the Top and Bottom sections of the Cap Shrouds join here as well as the Small Bottlescrew for the D3 stay.


*    Middle Spreaders – Joining Pins

During regular rig checks the joining pins should be checked paying particular attention to the plate covering the end of the pin. This is the only thing that stops the pin from working out and, whilst never seeing true rigging loads it is vital that the plate and machine screw holding it I place are in good working order.


*    Middle Spreaders – Bottlescrew

The care of the Bottlescrew is covered later however because this stay will become loose when on the leeward side it is important that no articulation is lost through too much chafe protection.


*    Lacing Cord in the “V”

It is also good practice to fix some lacing cord between the D3 and Cap Shrouds such that spinnakers and Halyards can not get caught in the ’V’ created at the Spreader End.  


Intermediate Shroud Tangs.

As per above.

Steaming Light – 24 volt

The Steaming Light is a conventional Navigation Light and will require normal Maintenance. The cable supplying power to this light runs in an internal conduit inside the Mast.



*    Steaming Light

Maintenance Tip: During any rig check ensure the protecting cage around the light is secure. History shows that these can get damaged by the wire halyards.


Additional Hole below the Steaming Light

It should be noted that just below the Steaming Light on the Starboard side of the mast there is an additional hole with a rubber grommet into, it should also have a ‘mouse line’ coming out of it.

This was fitted during the mast build should there have been a need to fit a Spreader Camera. As such it could be used for any form of wire needed if anything was mounted on the Starboard Lower Spreader, as the mouse line runs into the conduit inside the mast.

Lower Spreaders.

These are as per the Top Spreaders however the Aluminium block in the end obviously has two grooves machined into to allow for the two wires.

Lower Shroud Tangs.

As per above.

Babystay Tang Box.

As per the Inner Forestay Tang Box.

Deck Flood Light – 24volt.

The Deck Flood Light is just a plastic fitting hence it is fitted under the Babystay to gain as much protection as possible. It provides a very effective lighting system for the Foredeck. However care should be taken that it is not damaged by loose wire halyards.



*    Deck Flood Light

Maintenance Tip: when replacing the bulb always ensure that the correct bulb is fitted. The manufacturers make two bulbs that look identical, one with a lens and one with a clear glass front. The correct bulb is the unit with a lens. 


Spinnaker Pole Inboard Up-Haul Sheave Boxes.

As per the Staysail Sheave Boxes.

Spinnaker Pole Tracks and Cars

These tracks are a custom extrusion as are the bodies of the cars. They have caused no problems during the life of the yachts.


*    Tracks and Cars

To avoid potential damage to the track always ensure that the sliders in the cars are secure. If a slider should become damaged or lost it will result in damage to the track which is a large job to replace.


Mast Steps.

As at Mast Head



Appendix 2  Index to Maintenance Tips

·      The Mast 5

·      The Boom.. 5

·      The WindeXL. 6

·      Vertical Wands. 6

·      Mast Head VHF Aerial Connector 6

·      Changing the Mast Head Light Bulb. 7

·      Spinnaker Halyard Masthead U Bolts. 7

·      Mast Head Halyard Sheaves. 8

·      Blood Knot – Clevis Pin. 8

·      Welding Cracks – Masthead Box. 9

·      Yankee Halyard Sheaves. 10

·      Staysail Sheaves – Chipping. 10

·      Trapping of the Spectacle. 11

·      Middle Spreaders – Joining Pins. 11

·      Middle Spreaders – Bottlescrew.. 11

·      Lacing Cord in the “V” 12

·      Steaming Light 12

·      Deck Flood Light 13

·      Tracks and Cars. 13