Tabernacle for CS 20 Main Mast -- Any Thoughts?

[Reacher]

I have a CS 20 with a mast tube/mast step. The CS 20 plans include a tabernacle option that I am considering as a retrofit. I know Don Silsbe is looking at this issue for a CS 17. The purpose is easier up and down as I stare at 70. I have no experience in seeing a CS tabernacle.

 

Essentially, does it make a significant difference? How is it to walk the mast up while stepping up onto the deck and holding it in place while securing the hold down bolt? 

 

What I am most concerned with is lowering the mast. As you walk it back it seems like the weight will rapidly build while you are still on the deck.

 

Are there plugs in the mast at the pivot and hold down bolt locations? I can't make any out in the plans.

 

Thanks in advance for your observations and opinions.

 

 

[Don Silsbe]

The answer is yes to all your questions!

 

It does make a difference.  When I used PadrePoint’s CS17.3 last winter, I quickly became a believer.  It is easier to walk the mast up the picot than try to hit the hole with a long awkward pole.  Once in position, while on my knees to secure the bottom nut, I simply applied pressure with my shoulder.  I am so convinced of the tabernacle’s benefits that I will retrofit one to the mark 1 I am refurbishing later this year.  That retrofit is going to be a challenge, to be sure.  I will document the mistakes, er, progress here on the forum.  But first, I need to complete a trimaran build.  
 

Since I am halfway on my journey from 70 to 80, I see the tabernacle as a good plan for the next “couple” of years.  Then, I might need to drop down to an Amanda.

 

The plug on the bottom keeps out critters, and also the rain while driving down the road at 70 mph (or so).

 

 

[Reacher]

Thanks Don. I am now a believer, too. I made a little mast stepper device and was amazed at the difference in lifting the mast. 
 

Fitting this to the thwart for the mizzen mast should be straight forward. Making one for the main mast will take a little more thought to come up with a good release mechanism to hold the foot in the swivel while lifting then releasing it into the tube when vertical.

 

The mizzen has been the more difficult one to step and instep. On windy days (of all times) I didn’t use the mast float because it added resistance to getting it up and down. Today it was a breeze.

In a half hour of testing the swivel concept I raised and lowered the masts more times than I will in a summer of sailing.

[Paul356]

Pretty neat.

[Hirilonde]

I like it.  I have been pondering such a thing for some time now.  That looks like you are on track.

[Reacher]

This photo shows Plan A and Plan B for the swivel. Please contribute more ideas if you have them. I am very happy with the mechanics of the swivel in lifting the mast and positioning it over the hole.

The next design issue is that the mast must not protrude through the swivel until it is vertical, then it needs to be released into the hole. And similarly, during takedown the mast must be lifted to the level of the swivel then the bottom of the swivel blocked to retain the foot of the mast.

 

Plan A refers to the channel cut into the swivel. A small key or stopper would be attached to the mast three inches above the foot. The mast would be inserted into the swivel with the stopper resting on the rim. When the mast is vertical it would be rotated so the stopper would go down the channel and down a corresponding channel cut into the thwart mast hole.

 

For Plan B the stopper/channel is omitted. Instead, as in the picture, there is a rod through the swivel with a hook on each end. The rod is turned one way to capture the foot of the mast and turned the other way for a clear passage. I was concerned about having to stoop to turn the rod so the picture shows a notched stick that does the trick.  This worked well in the backyard test.

 

Either plan concept would work with the mizzen mast where I don’t have a tube between the thwart and the mast step. Plan B, the rod, will work for the main mast where there is a tube that I don’t want to cut a channel into.

 

All comments are welcome.

 

[Paul356]

I think this is really neat.  The issue still to be addressed is pulling the mast -- especially the main -- out of the mast tube, which always seems to me to be a problem.  Once it was up in the swivel, backing it down would be good, but we need to think of a good way to get it up out of the tube.  That's not a problem with a full tabernacle, I guess, because there is no tube; you just swivel the whole thing back.

[Hirilonde]

On 4/27/2024 at 10:12 PM, Reacher said:

The next design issue is that the mast must not protrude through the swivel until it is vertical, then it needs to be released into the hole. And similarly, during takedown the mast must be lifted to the level of the swivel then the bottom of the swivel blocked to retain the foot of the mast.

 

I made this collar to help foot the mast as I raised it.  I think it will work for a stop while using the swivel.  I may have to extend it a bit, we sill see.

[Reacher]

I think you can make it work fine and I’m planning to add a collar piece at least a few inches wide for the front edge of the swivel to land on so it doesn’t rotate past vertical.

 

On my prototype the bottom of the swivel is 1.5” above the deck in the mast up position. So that will be the height of the stop piece.

[Hirilonde]

Because my mast will be able to slip into the mast tube as I get to vertical, I don't think I need a stop.

 

I think that once you get your mast near vertical you can twist it to slip through the key hole and it will drop onto the thwart, just forward of lining up with the hole, then slip in as you go vertical. The force on your stop piece might be huge as the fulcrum is just a few inches from the bottom, and many feet from the top.

[Hirilonde]

I have made my collar, test installed it, and tested it using the mast support that goes in the main mast tube for trailering. I used this mast support to line up the collar for installation.  The hole in the collar is 3 1/4" and my mast is just a hair under 3" (My mast tube is a 3" ID PVC pipe).  When my mast is up, it will not contact the inside of the collar at all. The wood is Sapelle, to match my deck.  The collar is 2 layers, each with the grain 90° from the other. I will give the pieces a couple coats of varnish before final installation.  Then the collar can be removed for more varnishing. I tighten the bolts to barely snug.  They nuts shouldn't move, I used nylok nuts.

[Reacher]

Good work. Simple and nice looking. Thanks for posting.

[Don Silsbe]

I’m interested on hearing how these perform.  Please add a performance report to this thread, once you’ve used these for a while.  My concern is how they hold up to all the stresses.  After all, those masts are gigantic levers.  I am clumsy, and would break mine in a New York Minute.

[Hirilonde]

Will do Don.  I think the greatest stress will occur taking the mast down. That is the most difficult thing to control without a swivel/collar or what ever we end up calling these things. For the main mast I have to lean forward over the fore dech, lift the mas to just out of the tube before lowering.  At this point my hands as the closest to the pivot, hence the greatest lever arm force. When raising I start at the mid point of the mast and move down as the mast goes up.  So not quite the same ratio until the mast is almost up. Like everything about sailboats, I am sure there is a learning curve for using this thing.

[Reacher]

Yes Don I will also report back. Today I mounted the swivel/collars temporarily (screws, not bolts) and tested them out. They made a big difference in terms of pivoting the masts to a vertical position and lowering them down. A go sailing or leave the boat in the garage difference.
 

The process still requires some handwork to lift the mast out of the hole and transition it to the swivel. This was more noticeable with the main mast because the mast is bigger, the lift higher, and you are standing way forward on the deck rather than snug in the cockpit.

 

I agree with Hirilonde about the learning curve. As I see it now, the mizzen mast swivel is a clear winner for the future. The main mast swivel will keep me on the water for this year, but I think that retrofitting to a tabernacle is probably worth it going forward. In my case.

 

As for durability and strength, I think they are well up to the job but they aren't foolproof. You still have to be careful about alignment. As Hirilonde pointed out, once the mast is stepped it doesn’t touch the swivel so there are no stresses from sailing.

 

Pictures after the parts are finished.

[Paul356]

I have a collar similar to Don's on my foremast.  I made it out of the tube when I installed the tube.  That is, I left the tube about 1" or 1.5" proud sticking out of the deck, then cut the shape back so it had the lip in front, flush in back.  Boat is in storage now, so no picture.  The front lip is not very high, but it's plenty, so I think Don's lip will work fine.  I bolstered the outside of the tube lip with some thickened epoxy, which is due for a renewal this year.  It's just enough to push the heel of the mast against as I raise the mast, to keep the heel from sliding as it gets ready to drop into the hole.  Raising the mast hasn't been the real problem for me, although I can see where the pivoting ring would help me some.  

[Don Silsbe]

There is no lip on mine.  I’m preparing (mentally) to retrofit a tabernacle to the CS17 I bought.  Hirilonde has a lip on his boat.

[Don Silsbe]

On 5/2/2024 at 12:15 PM, Hirilonde said:

Will do Don.  I think the greatest stress will occur taking the mast down. That is the most difficult thing to control without a swivel/collar or what ever we end up calling these things. For the main mast I have to lean forward over the fore dech, lift the mas to just out of the tube before lowering.  At this point my hands as the closest to the pivot, hence the greatest lever arm force. When raising I start at the mid point of the mast and move down as the mast goes up.  So not quite the same ratio until the mast is almost up. Like everything about sailboats, I am sure there is a learning curve for using this thing.

I envision the greatest stress being mast wobble.  That occurs when you have the mast is in the pivot but not the hole, and a gust of air (or touch of vertigo) causes the mast to swing from port or starboard.  That’s what worries me.

[Reacher]

I have some progress to report. No sailing yet, but several dry trials.

 

I made a keyway swivel collar for the mizzen and cut a slot in the thwart mast hole to allow the key (a 1/4” x 3/4” long stud) to to pass through the collar and thwart and set the mast into the mast step. The best part of this method is that at all times you have both hands in secure positions on the mast and need only to rotate the mast 90 degrees to align the key with the slot. No nuts and bolts to connect. During takedown I can see the key coming up through the slot and lift the mast just enough to allow the key to rest on the lip of the collar. 
 

Regarding safety and stability, for me it is night and day from the task of lifting the mizzen and freehanding it into the mast hole. The foot isn’t locked into the collar but it is well stabilized. It is important for the mast to come cleanly out of the mast hole and up into the swivel.

 

To make a long post longer, I decided to retrofit a tabernacle for the main mast. Mainly because popping the foot of the mast out of the mast tube was always a struggle, and because I wasn’t sure about cutting a keyway slot in the mast tube. I have gotten as far as installing the support structure, making the tabernacle, and test mounting it to confirm vertical alignment, rake, and ease of lift.

 

The retro fit is a pain unless you want to cut the deck off your boat. Think it through before committing. My CS20.1 has a big enough hatch and below deck area that I could get down into it for access. And cutting the swing slot into the deck ahead of the mast gave some access from the front. But you are still working somewhat blind at times and awkwardly. I was able to construct the new bulkhead in one piece so that was a plus.
 

As far as operation, the foot of the mast is secure, the lift is easy, but it does require holding the mast up while leaning over to attach the hold down nut. Easy two person job.

 

Before I would do the retrofit again I would seriously look at replacing or improving or eliminating the existing tight fitting tube with one that allows smooth extraction of the mast. Then installing an easy to make, easy to mount, simple keyway swivel collar.

 

Final note: Retro fitting a tabernacle for the mizzen mast is much easier except that it requires the mast to be mounted off center because of the centerboard.

 

Final final note: Thanks to Alan from B&B for supplying plan sheets and information about the tabernacle.
 

 

[Don Silsbe]

7 hours ago, Reacher said:

keyway swivel collar

I’m having a hard time visualizing what this looks like.  How about taking a photo of it?