Masts and Rigging

[Matthew P]

Like Rock Doctor, I have had a persistent problem with tabernacle screws loosening.  I have wondered whether it is caused by strain on the mast foot when lowering and raising the mast single handed and the mast pulls up on the tabernacle as I lower the out-of-balance end onto the rear deck.  But maybe it is incorrect shroud/jib tension.  Either way I have resisted the temptation to secure it with bolts through the deck for the reasons given by Peter ie, the screws fixing are designed to fail if the mast collapses, without causing significant deck damage. 

Any more light on this subject would be welcome.

Matthew
GRP BR20 Gladys

[Peter Cockerton]

Mathew

You may well have a point on the tabernacle screws being strained when the mast is being raised and lowered, this sounds very feasible. In all fairness i have not experienced this probably because it's left rigged most of the time. I'm pretty sure that my tabernacle is also bonded to the deck as well probably with Silkaflex so that may well help.

Rock Doctor is describing a different reason for the tabernacle screws lifting i.e under strain from normal sailing albeit with strong winds. Downward pressure from the shrouds and fore and aft tension from the shroud/forestay tension should keep the mast from applying any force to lift or move the tabernacle.

If the shrouds were too slack the mast could be pulled forward beyond the point where it could not pivot any more on the tabernacle and as such try to lift the tabernacle of the deck.

Just a thought

Peter Cockerton

[Rock Doctor]

Matthew and Peter,
re my problem with tabernacle screws pulling out, I suspect that it not due to mast raising/lowering, I doubt that the forces are sufficient in normal circumstances. I have noted that mine are lifting from the rear which suggests fore/aft movement, perhaps with a lateral component. I note Peter's comment re shroud tension and usually (except in light weather) tension the rig with the jib system (have recently changed to dyneema on the jib halyard) but note that there is still considerable slack in the leeward shroud. Even with sweating the jib halyard the rig cannot be tweaked to the extent that it is rigid, in any case the jib shape suffers at high rig tensions. I have concluded that in order to get sufficient rig tension and allow some latitude for playing with sail shape that a short bowsprit and dedicated forestay is in order.

Now I understand from Graham Wickenden that Matt Newland may enter with his comments and I will be very interested to hear those.

In any event it seems that this is a topic of great interest and I will be keen to read further discussions.

[Andy Dingle]

I too had this problem on my Wood Epoxy BR. The tabernacle sits on a thick wooden pad on my boat and I was frequently having to check and tighten the screws and I always thought they were too short.
On one occasion (as Peter mentioned) the whole tabernacle just lifted off when I was lowering the mast.
Eventually the screws would no longer bite into the wood so I resorted to drilling deeper holes, plugging them and used slightly longer screws.
So far - a couple of years now - there has been no further problems.

I am led to believe that the tabernacle is designed to break away in an emergency but I was more concerned with it moving or coming adrift in normal use, I think (hope) that my solution will still break away if needed but is now firm enough to meet the rigours of normal sailing.


Andy

[david]

Hi, I experienced a similer issue. The rear screws on the tabernacle were loose. I attributed it to loose stays. Once they were tensioned, I have not see the isssue reoccur.

D.