Mast

Many boats were supplied with masts from Proctor. Unfortunately, spare parts appear to be no longer available. However Sailspar are reported to be able to make up spare parts such as spreader tubes.

Halyard sheaves

There are 3 fixed sheaves on the Corribee mast – one is a box sheave for the spinnaker halyard, one fixed in the crane fitting at the top of the mast for the mainsail halyard, and one fitted in the foot casting where the main halyard re-appears from inside the mast tube. All three are aluminium and prone to corrosion so they therefore need to be checked every so often. The consequences of a stuck mainsail halyard really don’t bear thinking about!

The box sheave for the spinnaker halyard is easy to remove – two self tapping screws are used to attach it to the mast. The nearest replacement I have found is made by Ronstan, product number RF41712, which has a Nylatron sheave mounted in 316 stainless cheeks, and will obviously not suffer the corrosion problems of the original:

Ronstan RF41712 box sheave

image © Ronstan Marine Division

The two sheaves mounted in the crane and foot castings are a little more difficult to source – The originals are 32mm diameter, with a 10mm bore and a width of 10mm. I have so far failed to find an exact replacement, so I used a lathe to make new ones. I used Vesconite, but acetal is equally good (both types of plastic which do not swell in the presence of water).

The fittings have to be removed from the mast by drilling out the pop rivets – some gentle tapping with a hammer and a block of wood might be needed. The sheaves are held with a form of roll pin. If you examine it closely you should see that one end of the pin is slightly smaller than the other – this smaller end is the one you need to tap (with a drift or punch) to remove it, and the sheave will then drop out. The two photos below show the dismantled components after cleaning up, and with the original aluminium and replacement Vesconite sheaves. In the top photo you can see the type of roll pin used to locate the sheave:

Cleaning was done by dipping in a hot caustic soda solution – this needs care as it very corrosive. Wear gloves and goggles, beware of the fumes, add the crystals to the water not vice versa, rinse everything in clean water and dispose of the used solution sensibly. You will be left with a chemically clean surface, so when dry give it a coat of etch primer (zinc chromate aerosol primer, available from www.lasaero.co.uk), followed by a coat of alloy wheel paint from a car accessory shop.

Reassembly is a simple matter of positioning the new sheave and inserting the roll pin, tapping it home. If the pin seems likely to fall out it is possible to open it up slightly with a hammer and punch. Alternatively you could use a centre punch to slightly deform the edges of the holes in the casting to ensure the pin doesn’t slide out.

When fixing the fittings back on the mast use the correct size of rivets. They should be monel, not aluminium, and all the mating surface should be coated with a barrier product such as Duralac (a barium chromate paste, also obtainable from LAS Aero). This will prevent corrosion in the future, and is necessary with any fittings or fixings in aluminium, especially if stainless or monel is involved. Pop rivets can also be used to secure the new spinnaker halyard box sheave, again using monel pop rivets and Duralac paste.

If you have trouble sourcing replacement sheaves I would suggest a local engineering machine shop or a model engineering society. To ensure the correct grade of plastic it is probably easier to buy it yourself – Vesconite may be obtained from Vesconite UK, tel UK 0800 731 97 45. Acetal is more widely available, eg from Metals4U – example 2011 price £4.50 per 250mm length of 32mm dia rod.

Removing the mast on a Coromandel

The photo below shows Roger Taylor removing the mast on Mingming using a set of sheerlegs. The sheerlegs are actually his sweeps.

20090802_sheerlegs_rogertaylor

Temporarily repairing a broken track

Nathan Whitworth had a track that was broken at the top. As a temporary repair, he turned it around and secured it with two large jubilee clips as shown below.

20090804_GooseneckBodge_NathanWhitworth

Contribute

Do you have a story, information, brochure, manual, link or other relevant content that should be on this page? If so, we would be very grateful if you would leave it as a comment or email corribeeeditors@googlemail.com so we can post here – thanks!

7 Responses to “Mast”

  1. New articles this week « The Unified Corribee Website Says:

    […] have updates on the Boat Register, Chain-hawse, Mast, Roger Taylor / Mingming and Spray hood pages. Would you like to contribute an article? Check out […]

  2. Dave Says:

    I have seen a Coromandel for sale that has has had it’s mast welded and sleeved after having been broken. Is this repair likely to be as strong as the original, or is it advisable to replace the entire mast with a new one? How much is a new mast likely to cost?

    • scorribee Says:

      If it has been repaired properly it should be strong, but it is very difficult to tell just by looking, particularly with welding of aluminium alloys. New spars are expensive – a company like Z Spars http://www.zsparsuk.com/ will be able to quote, and they have a good reputation. Try asking this question over at the Yahoo discussion group – link at top of page – as you may find someone with first hand experience.

  3. JOHN GOSLING Says:

    Does anyone know where I could obtain a replacement mast/deck moulding rubber BOOT and stainless steel Jubilee clips for a Coromandel mast?
    Thanks in anticipation,
    John Gosling and Ying Tong

    • Declan McKinney Says:

      I’ve been using Rubbaweld Mast Boot tape. It works perfectly and, especially in white, looks great.

  4. Steve Says:

    Roger Taylor has removed the mast on Mingming single-handed, using his sweeps as a set of sheer legs, as shown above.
    If you can dry out against a high harbour wall, you might be able to reach the top quite easily. I have used a ladder on my Corribee mast, but not to reach the extreme top. I wouldn’t be happy in a bosuns chair on a mast so slim, though I may be over-cautious.

  5. Alan McKeand Says:

    My junk-rig Corribee “Maridadi” has an unstayed mast and I now need to do some work on the top of it as the VHF aerial and windex have broken away. Does anyone know if it is possible to get to the top of the mast without unstepping the mast, e.g. with a bosun’s chair which seems a bit risky to me!
    Failing that, could anyone please tell me the best way to get the mast down (minimum number of people needed to lift it safely) and get it back up again with all the control lines, lazy jack and other attachments in the right places again?

    Alan McKeand

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