Mast Furniture

Mast Furniture   Download a .pdf version

The point of this article is to deal with some of the detailed aspects of mast furniture. A few caveats are in order. Firstly any such list cannot be comprehensive; so if I omit something which has just come to your notice, I apologise in advance. All I can do is offer the benefit of my own experience to date, and what I know of other peoples. And we are all still learning. Secondly, because I am necessarily talking in general terms, it is possible that what I say may not apply to your particular situation. I am not trying to be evasive here, but there are often so many ifs and buts that making a general case can become flaky. Finally, apologies for the laundry-list style of the article. But enough hesitation.

How to deal with masts, their stays and their fittings? I could just do a piece by piece description of the various fittings, but I think that in doing so you would miss the broader picture which does much to explain why masts and their associated pieces are as they are. So I’m going to follow the logic(?) established earlier by first addressing the engineering aspects of masts and stays. I should at this stage warn you that it is going to take a number of articles to do this, and it may initially seem to consist of digressions followed by sub-digressions before we tackle the more practical aspects. I hope you will bear with me.

Keeping the Standing Rigging Standing

Keeping the Standing Rigging Standing

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In the last article we got as far as putting terminals on to wire ropes. They are only any use if we attach them to the things they are meant to be supporting, so let’s look at attachments to spars.

Back(stays) at last

In the last article we covered stays and mastbands. To complete the picture for staying the mast, I’ll now look at chainplates, shroud tensioners and backstays.

Shrouded in mystery

As far as the connecting lugs on chainplates go, they should be at least of the same dimensions as those on the mastbands - see previous articles. It is also helpful if you reduce the work that a toggle has to do by bending the lug to align with the stay if the lug lies fore-and-aft.

But how big should the chainplates be? Well, in the words of a famous London actor, not many people know this, but chainplates are held onto the hull not just by their fasteners, but also by the friction between plate and hull which is generated by the fasteners. As in the case of the spars, the amount of friction you can generate is limited by the crushing strength of the wood. Plug in a few numbers and for each tonne of shroud load, you need 60mm2 total bolt area acting on 4500mm2 of plate area against the hull, and a plate cross section area of 120mm2. As an example, 4mm galvanised wire would therefore need a chainplate about 25mm wide x 200mm long x 5mm thick, held on with at least 2 6mm bolts. In an ideal world, one would fasten chainplates with bolts because they can be tightened up positively. In practice, it is often the case that the uppermost fastening hole has to be fastened by a screw because of the beam shelf or rubbing strake in that area. It is probably safest to discount the effect of this screw when totting up the fasteners required.