New Tabernacle - designs

I need a taller tabernacle to enable the mast to be lowered for passage under bridges but my mast has been damaged at what would be the tall tabernacle pivot point, by a previous owner, which I must now repair. Currently it has a "slipper" at the base of the mast and I would prefer to keep the bolt at this position, but have a vertical slot in the new tabernacle up which the bolt through the base of the mast will travel when the mast is lowered. Does anyone have this arrangement, and if so, does it work efficiently over the raised cabin access? All views gratefully received, thanks.

My father's SeaHawk, (See Jemima in the Gallery) was supplied with such a tabernacle when he bought the boat from Reedcraft.


As you suggest, it did allow you to keep the original mast unmodified, which was similar to that on my own boat (shown here before I had my tabernacle fitted).


Jemima's tabernacle was awkward in use, and thinking about it now, that was because the tabernacle slot was vertical. Ideally, it should curve slightly, following the radius that the foot of the mast takes as it rises when pivoting on the cabin doorway notch.

Initially, as you lowered the mast, its weight kept the mast at the bottom of the slot and everything worked well. It was only at the point where the mast was laying in the notch at the top of the cabin hatch that the bolt would would attempt to rise in the slot. By this stage the notch was bearing virtually all the weight of the mast and effectively acting as a fixed pivot point.

As the base of the mast attempted to rise it pressed against the forward edge of the slot as it tried to push the mast slightly backwards. The slot in the galvanised metal was not smooth and the mast would always stick. Rather than try to ease the mast backwards or lift it out of the notch, which I realise now is what I should have done, I would simply press down on the mast over the cockpit. Doing that, I once even managed to put a bend in the mast. Almost the first thing the next owner did was replace the mast, as in spite of my attempts to straighten it, you could see the bend if you looked for it.

If you can't have the slot curved, then I would very strongly recommend that you fit a small roller just forward of and level with the doorway notch, so that when the mast was part way down and resting against it, it would allow the slight movement needed to allow the base of the mast to rise easily in the slot.

Thanks Greg, your points are exactly what I wanted. I had thought about the shape of the slot and had come to the conclusion that it would be best if it was inclined forward about 5 or 6 degrees as it rose to the top, but I like the idea of a roller better. Of course none of this would be necessary had the mast not been damaged. I propose to pop-rivet two 8 inch, shaped plates (one each side) of the damaged pivot hole in the mast, which will reinforce the weak point (the holes are torn, enlarged and the mast slightly kinked at this position) which will mean that my new tabernacle will have to be slightly wider to accommodate the plates. This will be easier than putting in an internal sleeve, then I will insert two thick nylon washers either side on the bolt to make up the extra width. these will also (hopefully) help the mast to slide up the slot. I can then change them as they wear.
How does that sound to you?
Incidentally, the two pulleys at the base of the mast are side by side on your photo, but one above the other on my mast. I am therefore going to have to think of another way to fix the lower kicking strap bracket as currently it is fixed to the plate and it fouls the higher halyard where it exits the mast when the boom is out.      

Greywing wrote

I propose to pop-rivet two 8 inch, shaped plates (one each side) of the damaged pivot hole in the mast, which will reinforce the weak point (the holes are torn, enlarged and the mast slightly kinked at this position) which will mean that my new tabernacle will have to be slightly wider to accommodate the plates.

When Marine Weld converted my mast they inserted a tube through the mast, welding it in on each side. See the picture and further explanation of the conversion at:
http://www.seahawk17.org.uk/owners-custom-sailing-tabernacle.php#installation

Depending how damaged that area is on your mast and whether it is practical additionally to weld washers onto a tube, I guess it might be possible to reinforce that area without making the mast any wider? I'm no expert on the practicalities of this and the business of welding aluminium, so don't treat this as "advice".

Incidentally, the two pulleys at the base of the mast are side by side on your photo, but one above the other on my mast.

If yours is the later Holt Allen mast found on Moore's boats, then take a look at the most common tabernacle found on those boats at:
http://www.seahawk17.org.uk/boat-description-rigging.php#mooremast
You'll see it has a shackle on the base plate intended to secure the kicking strap, whereas Marine Weld provided a rigid loop on my tabernacle welded on higher up. I have no problem with fouling a halyard, and I have not seen any comment from a Moore's owner suggesting there is a problem with that design.