Kicking strap mast connection

[SteveGorst]

While doing some vigorous downwind sailing last weekend the kicking strap connection at the foot of the mast gave out. I've tried removing the old fitting but the bolts just start turning with the nuts so it looks like a dismantling job to get inside the mast step assembly. This would mean taking the mast down which I don't want to do at this stage of the season.

I have been thinking a good idea would be if you could buy a fitting that slid up the sail track that would lock itself into place with a locking nut. I can't find anywhere that sells such a thing though.

Does anyone know if such a thing exists or have any other ideas?

Cheers
Steve

<hr width=100% size=1><A target="_blank" HREF=http://"www.nwcc.info">North Wales Cruising Club</A>

 

[flaming]

Having broken 2 kicking straps on 2 different boats over the years I would advise against anything that went into the mast slot, unless there is another deliberately weak point in the system.
The first kicking strap we broke broke a shackle at the base of the mast and was easily replaced. The second boat had an altogether stronger kicker and ripped the bottom of the mast out. We were fortunate not to lose the rig and had to have the base of the mast rebuilt. It now has a deliberate weak point.

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[SteveGorst]

Thanks for the reply.

The shackle at the bottom of the strap isn't a big heavy one so I would have felt that would be the weakest link, as Anne would say. I'm surprised it wasn't that that broke really. The real problem is getting the old fitting off to fit a new one as I said I can't access the back of the bolts.

It's a good point though about having a deliberately weak point. It is a temptation when something breaks to replace it with something just a little bit stronger. This could obviously lead to something expensive breaking, such as a mast, instead of a cheap shackle.

How was your shackle that was easy to replace attached? I have seen some plates with rings on that you can attach with rivets but I wouldn't have thought the rivets would be strong enough.

Has anyone seen any kind of fittings that you could put around the whole step assembly, this is a box about 250mm x 200mm (10" x 8") I don't think any force that the strap assembly could generate would rip this off.

Thanks for any help

Steve

<hr width=100% size=1><A target="_blank" HREF=http://"www.nwcc.info">North Wales Cruising Club</A>

 

[flaming]

Had a sort of pivoty bracket thing with holes in...... Can't really remember the details, was a while ago.

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[aitchw]

If the bolt head is standing proud you may have no choice but to grind it off and let the other part fall into the mast to be dealt with next time it is down. You will need to cover everything for yards around to protect from the grinding dust. Alternatively, if you can stop the head turning. you can drill through the centre of the head with progressively bigger drill bits until it falls of.

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[boatless]

Not sure I agree about deliberate weak points. The kicker should be capable of bending the boom if overtightened (not advising that you should noticeaby bend the boom of course!). It's fittings and fastenings will reflect that on a boat designed and equipped for hard sailing.

Is there anywhere on the mast step strong enough to take it?

<hr width=100% size=1>my opinion is complete rubbish, probably.

 

[SteveGorst]

Re: weak points

On the point about deliberate weak points. I remember reading in a book about an incident with a hydraulic back stay tensioner.

Apparantly the manufacturer took their state of the art yacht to the boat show complete with a hydraulic back stay tensioner. Throughout the day the occasional person gave it a pump or two to see what it felt like. At the end of the day their was a huge crash and the mast came down.

I think the moral of the story is that there should be a weak point designed to fail before a huge structural failure such as this. Off course you could have further safety features such as designed slippage so that it is impossible to tension to such a high tension.

Cheers
Steve

<hr width=100% size=1><A target="_blank" HREF=http://"www.nwcc.info">North Wales Cruising Club</A>

 

[boatless]

Re: weak points

Not heard that one Steve!

There may be a case for designed failure, but if you look all around a sailing boat there are systems which, given enough misguided application, something will break. Mainsheet, halyards, genoa sheets. In fact I can't think of any with an actual limit to load applied or designed failure - with one exception - backstays. There is usually a travel limit (espec with hydraulics). Not to say that the travel limit is always well chosen!

If you take a boat like an X-Yacht, as a production example, winches specified are considerably larger than the average JenBav, and the opportunuities to break things come within the range of even those with average strength! Thouroughbred racing yachts let you break stuff with just a little finger if you're silly enough. It wasn't much more than wrist action that tensioned TNZ's rig to the point that the hull snapped after all...

So rather than have a weak point, if you feel that you really do want to stop your crew breaking your boom you could arrange that the kicker goes block to block at your chosen max tension. Do bear in mind though that there are times when a tight kicker will be bending the boom. It's like aircraft, if the wings didn't bend they'd be too heavy to take off!

<hr width=100% size=1>my opinion is complete rubbish, probably.