remove tabernacle

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remove tabernacle

Postby SkinnyPete » Sun Feb 05, 2023 11:59 am

On my Daysailer II, the tabernacle hardware failed and the mast fell down. Is it possible to remove the tabernacle and step the mast without it?
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Re: remove tabernacle

Postby nickc » Sun Feb 05, 2023 1:02 pm

I’m not one of the experts on here but it might help if you posted a picture. Greenlake and several other people really know these boats well, they’re always very helpful.
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Re: remove tabernacle

Postby GreenLake » Mon Feb 06, 2023 4:57 am

The purpose of the tabernacle is to
  • act like a hinge and provide a pivot for raising the mast
  • keep the mast aligned with the mast support, so compression loads are properly transferred while sailing
  • prevent the mast from getting bounced off the mast support (compression post or lower half of the mast) in a sea way

All of these functions can in principle be handled by different solutions. For example, if your tabernacle is the common kind that connects a short lower and long upper piece of mast profile, you could wrap the joint with a sturdy piece of flat aluminum. You would bend it tightly around the mast profile to eliminate wiggle room and then rivet it to, say, the lower half. Now you have a cup or socket into which you could lower the upper part of your mast, to keep it aligned and prevent it from being bounced off. But you would then need a different technique to getting the mast vertical, because you no longer have that hinge.

You can get a mast vertical when it's on the ground, by having a helper step on the bottom end, while you push up the other end until the mast is vertical. You could then, together, maintain the mast in a vertical position while moving it over and inserting it into that cup or socket. And then one person can connect the stays while the other one holds up the mast. (This is how it's done for many types of dinghies with desk-stepped masts, but they generally sit lower to the ground on their trailers, which makes transfer from ground to deck a much easier proposition. Alternatively, you could try to right the mast in the cockpit and, once vertical, lift it up from there).

If this sounds cumbersome, that's because it is a very roundabout way to do something that is made very easy by the tabernacle. I'm only mentioning it in case you need a short-term emergency solution, or a reason why repairing or replacing the tabernacle is generally the best option.

Note that the tabernacle is never intended to hold the mast upright without the stays; if you try that, it will most likely pull out of the bottom of your mast, or the top of your compression post / lower portion of mast profile.

Without a picture, we can't assess the actual damage, but it's often possible to straighten a tabernacle and re-attach it. Or replace it (source: DR Marine). You may need to drill holes in new locations, which is fine as long as not too much material was ripped out. In the worst case, you might need to cut a little bit off the bottom of your mast or the top of your compression post. Sometimes, you can make up for the lost length with some kind of shim on the mast step in the cuddy, sometimes, the best option may be to shorten the stays so they match a now shorter mast.
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Re: remove tabernacle

Postby SkinnyPete » Mon Feb 06, 2023 12:43 pm

I'm asking about removing the tabernacle because Rudy at D&R Marine states on his website that he doesn't recommend tabernacles for boats on moorings, and because my tabernacle failed while it was on a mooring in a harbor where it is exposed to rough weather (but the hardware may just need to have been replaced sooner). But if you're saying the tabernacle shouldn't be a problem, I can leave it on when the boat is repaired (which will not be by me, by the way).

I'm afraid I don't know how to post pictures in this forum.

Thanks.

Paul
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Re: remove tabernacle

Postby nickc » Mon Feb 06, 2023 1:43 pm

The previous owner had to cut the mast to put the tabernacle in. I don’t know enough to suggest a way to rejoin the two pieces of the mast back together. Although pricey, buying a new mast would certainly solve the problem and prevent it from happening again.
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Re: remove tabernacle

Postby nickc » Mon Feb 06, 2023 1:45 pm

You might be able to find someone who welds aluminum who could possibly weld your mast back together but i’m not sure how straight they could get it
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Re: remove tabernacle

Postby Dirtybug » Mon Feb 06, 2023 3:45 pm

I believe a section is removed from the mast when adding a tabernacle. Maybe .75-1” whatever the thickness of the tabernacle is. So if you have it welded or make another fix keep in mind your stays will need to be adjusted shorter or the mast foot raised with a wood block or Azek.
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Re: remove tabernacle

Postby GreenLake » Mon Feb 06, 2023 6:41 pm

SkinnyPete wrote:I'm asking about removing the tabernacle because Rudy at D&R Marine states on his website that he doesn't recommend tabernacles for boats on moorings, and because my tabernacle failed while it was on a mooring in a harbor where it is exposed to rough weather (but the hardware may just need to have been replaced sooner). But if you're saying the tabernacle shouldn't be a problem, I can leave it on when the boat is repaired (which will not be by me, by the way).

I'm afraid I don't know how to post pictures in this forum.


OK, this gives a bit more context for your question. By "removing" that tabernacle you meant "joining the mast".

If your boat is on a mooring, a single piece mast is attractive. The main benefit of a tabernacle (easy mast raising) doesn't apply.

What you want then, is a replacement for the tabernacle that is stronger and better able to guarantee that the bottom of the mast stays in place. For that, wrapping the joint to form a deep cup as described might work. Now, on a mooring, there will be some pounding of the mast because the boat is constantly moving (and perhaps exposed to waves strong enough to kick it up a bit so that the stays will then pull it back down). That constant action is probably what caused your tabernacle to fail.

Now, the obvious extension to that would be to rivet (or bolt) both top and bottom of your sleeve to mast and compression post respectively. At that point your repair looks more like a full join and needs a larger overlap. An alternative is to make the sleeve internal. This can be done by obtaining a short length (say 24") of mast extrusion and cutting out the sail track from it. The rest can then be bent to a slightly tighter curve so it fits snugly inside the mast profile. You can then bolt, or preferably rivet, that inner sleeve in place. That repair should be strong enough.

Aluminum rivets would avoid the use of dissimilar metals. Because the mast would experience a bending load if you join it, that inner sleeve needs to be long enough, so it has a longer lever arm and room for more rivets. From what I remember reading I'd go with at least 24". I'm thinking that 9 rivets in three rows on either side of the gap might work, but unlike the length I don't have a reference for it. An inner sleeve not only is optically nicer, it's easier to extend it farther down below the deck (unless your tabernacle is so high off the deck that it doesn't matter).

My understanding is that many people have used this method to fix a broken mast, so I think that it could work for you.

Did you have other damage to the boat?
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