Can I fit a tabernacle?

[charsmith]

Hi all,

First, I really appreciate all of the advice and wisdom that I have found on this forum! Really great people here!

I did my first dry-run today to see what parts I'm missing and to see how difficult it is to step the mast with my wife. Stepping wasn't too stressfull, but it could certainly be easier with the help of a tabernacle. However, I'm a little concerned that I won't be able to fit one. Does anyone know the thickness of the DR tabernacle from mast-section to mast-section?

As you can see, I only have about 1/2" between the top of the cuddy and the first bits of mast hardware.


The mast jack was all the way down when I traced the top edge of the cuddy and I have not yet raised it because I haven't installed my new spreaders yet. I did notice that I had to pull the forestay about an inch in order to engage with the front bracket (sorry, I'm still learning my sailboat vocabulary ), but the side stays seem to have plenty of slack...could I conceivably raise the starting height of my mast and still be able to have enough slack in the side-stays to pin them in place? Should I consider something like a mast sleeve instead?

Thanks
Stephen

[GreenLake]

Some of that mast hardware can be moved, just saying.

Now, I'm personally not a friend of tabernacles. I like the fact that a keel-stepped mast is stable even with the shrouds and forestay not attached. That makes it easier to single-hand in my view, because there's not the need to have anybody hold the mast in position while attaching the stays. Also, a mast-jack is one of the more convenient contrivances to quickly set the tension in the rig.

A previous owner of my boat figured out how to make raising a keel-stepped mast easier to raise.

His solution boiled down to making a sleeve for the mast and putting it on a hinge. You stick the bottom of the mast in, then raise it on the hinge, like a tabernacle. Once vertical, the mast can be dropped through the deck and stepped on the keelson. The genius is that the mast will naturally resist moving up and down through the deck unless it's vertical; therefore, until the vertical is reached, the hinged sleeve functions like a tabernacle. After that, it functions like an extension to the mast partners (the deck opening).

The writeup shows how this can be constructed. If you have hardware positioned low on the mast that you would really like to keep there, then you'd need to modify the design of the sleeve part by flaring the opening left and right so that the hardware can slide in. At the location where you need to access it, the sleeve would have a hole. (As you look from the top, the sleeve would no longer be oval, but have two "ears" so it can fit the mast hardware.)

K.C. Walker on this forum will be able to explain to you why keel stepped masts are sought after because of the way they can be trimmed.

[charsmith]

I'm liking the thought of a keel stepped mast more and more. That should be a pretty straight-forward project as well.

[jackal]

GreenLake:

I'm going to try and build the deck hinge setup. Just have a few questions before I go shopping.

The hinge looks like a standard door hinge you would find at Lowe's/Home Depot. Would you concur? I've also seen the "T" brackets there.

From what I can tell the aluminum disk is above deck and that means the plywood backing is below deck (hence the word "backing"). Is that correct?

If the aluminum plate is above deck, I'm guessing the hole in the plate is cut in the same shape as the hole in the deck (but cut bigger to allow for the raised lip (partners?) around the mast opening). This way the plate would be flat on the deck.

When you are in the cockpit and grab the mast 8" up from the sleeve and start to push up, how much force do you think you are having to apply? 80lbs? 100lbs?

When you lower the mast, is it the same procedure in reverse? Or do you start out on top of the cuddy, pull the mast up through deck and then jump back down in the cockpit to hinge it down?

On the drawing of the hinge setup, what are the two holes in the bottom of the sleeve for?

Thanks!

[GreenLake]

The hinge looks like a standard door hinge you would find at Lowe's/Home Depot. Would you concur? I've also seen the "T" brackets there.

Yes, these are standard hardware store items. I make sure that I keep them well painted and that has kept corrosion in check. (Hammerite spray paint works fine).

From what I can tell the aluminum disk is above deck and that means the plywood backing is below deck (hence the word "backing"). Is that correct?

Correct. Using a disk like that has the added benefit of allowing you to mount some fairleads on the disk. I have my spinnaker halyard and downhaul connected to rings I mounted on the disk.

If the aluminum plate is above deck, I'm guessing the hole in the plate is cut in the same shape as the hole in the deck (but cut bigger to allow for the raised lip (partners?) around the mast opening). This way the plate would be flat on the deck.

The hole in mine is precisely the same as for the mast partners. I picture the PO filing it to shape after mounting it to get precise alignment. Because the cuddy has a "lip" around the deck opening. the disk sits a bit above the deck. I bent a simple strip of aluminum around the front edge to prevent any sheets from getting trapped between disk and deck. (The strip is a bit taller than the gap, and the ends taper to the disk, at that point, I bent some of the strip over so I could bolt it in place into the disk from below (or you could use rivets). I'll post a picture of that strip if I can find it on one of my photos, but any design will do there.

When you are in the cockpit and grab the mast 8" up from the sleeve and start to push up, how much force do you think you are having to apply? 80lbs? 100lbs?

I'm strong, but I don't lift weights. I do find that if the winter has been exceptionally long, I like somebody to help me who stands on the cuddy and pulls up on the mast. It's also nice to have a helper to give the mast a little bit of a starting angle, but not required. If you do have a helper, perhaps make a "push stick" so that they can help you push the mast to a good initial angle while standing behind the transom. I usually stand no more than about 2' behind the thwarts when starting to push the mast up. One thing that can make a difference: if you have diamond stays, take them off. They are not really needed (lots of posts about this on the forum) and with lever arm, that could cut 5# of force or more from the original push.
The way I do things is that I first raise the mast to shoulder level. Then, I very carefully line up straight (although I stand to SB of the CB trunk - you have to pick some side). Then I push the mast up by extending my arms and then walk it forward into position. I usually step onto the thwarts to get some extra height.

When you lower the mast, is it the same procedure in reverse? Or do you start out on top of the cuddy, pull the mast up through deck and then jump back down in the cockpit to hinge it down?

If I have a helper, that person's job is to raise mast and hold it, while standing on the cuddy facing aft. Otherwise I just grab the mast at two locations and push it up while standing below. Placing my grip in the right place makes sure I don't lift the mast higher than the sleeve
The trick is to keep the mast vertical until you are ready to tip it. The sleeve will not hold the mast vertical by itself, all it's intended to do is to prevent the bottom from slipping sideways, as well as holding it in place while hinging.

On the drawing of the hinge setup, what are the two holes in the bottom of the sleeve for?

They were used for a pin to lock the mast foot.

As I note in the writeup, there usually is no need to lock the mast foot in the sleeve. At any angle between 10° and ~90° the mast foot will be held in place in the opening. At 90° it will go in, but if your mast partners are as tight as mine, it will only go in if you are within what feels like 1-2 degrees of the correct angle, if you are off, it just stops - nice safety feature and helps aim the mast. When you lower it, if you aren't "smooth" about it, but very slow, the mast can slip forward a foot once you have it near horizontal (it will no longer touch the hole and slide past it). That won't do any damage, so there's again no need to lock the mast foot. In raising, I've never seen it slip, probably because I quickly lift it to my shoulder level first.

These are some terrific questions. If you don't mind, I'll incorporate them as a Q&A section into my writeup.

[jackal]

GreenLake,

Thanks for taking the time to answer my questions. Feel free to use them in the Q&A section. I hope they will help others.

I'm really looking forward to building this set up. Before, it took two of us to step the mast. The mast would be horizontal, with the base stuck into/under the cuddy. My helper would push down on the base (about 1 foot from the end) as I walked forward pushing it mast vertical. I would use the starboard seats as I walked forward, then the thwarts. Once it was vertical, with the mast base resting to the right of the keelson, I would jump up on the cuddy deck, and we'd lift the mast straight up until the base was resting on the cuddy deck. Then we'd slowly walk it toward the slot (trying to keep it perpendicular to the boat) and lower it down to the step. When walking it toward the mast partners, my helper would hold on as low as possible (the first 4 inches it seemed like). My hold was as high as I could reach. Keeping one set of hands as low as possible and the other set as high as possible gave us more leverage for any corrections. Putting it up is easy. The hard part is taking it down after a long day of sailing.

I'm looking for a setup that will be a bit easier and less stressful. Maybe then I can go out by myself and sail.

I found a source online for 1/8" aluminum sheeting. How thick is your plywood backing? 1/2"?

Thanks again!

[GreenLake]

The backing is mainly needed to spread the load from the fender washers further across the fiberglass. 1/2" sounds fine for that purpose, but two layers of 1/4" might work as well (and be more able to conform to the curve of the deck). Even though the wood is usually protected and normally dry right under the cuddy deck, it doesn't hurt to either oil it really well, or seal it in epoxy. Mine was put up by the PO and it's suffered a bit over the years.

Make sure not to stint on the bolts holding the hinge and disk to the deck. I show 6 bolts in the drawing, those are the ones that go through. There are two more that I have added since, they just hold the hinge to the disk.

When I edited my replies for the purpose of adding them to the writeup, I realized that you wrote 8" not 8'. I hope that was a typo - no way can you push up a mast with 2/3 of a foot of leverage

If you grab the mast initially at 8', that's 1/3 of the length. The mast weighs, what, about 40 lbs. That weight will be at the mid point, more or less. The force required to push up (while the mast is near the horizontal) would be 50% more than the weight, or 60lbs. With each degree of initial angle, that force is going to be reduced.

[jackal]

Yes, it should have been 8' instead of 8".

60lbs. of force doesn't sound too bad. Is the lateral movement of the mast fairly stable when pushing it up? I guess this would depend on how worn out the hinge was, right?

Good idea on trying two layers of 1/4" plywood. I'll be sure and coat them with epoxy.

What is the outside diameter of the aluminum disc? 8"? 10"?

Any ideas how to cut a precision hole out of 1/8 aluminum sheeting? I've got a Dremel Trio I used to cut circles for inspection ports. I don't think that approach will work on aluminum. The Trio is mainly for tile (ceramic), wood, and/or plastic.

Thanks again!!

[GreenLake]

60lbs. of force doesn't sound too bad. Is the lateral movement of the mast fairly stable when pushing it up? I guess this would depend on how worn out the hinge was, right?

Don't count on the hinge to add any righting moment. It's job is just to hang on and allow the hinging. But while you are pushing the mast, sideways is not an issue, once vertical, you can lower it a bit and wedge it into the partners (cuddy deck opening) and that will help steady it. So the critical moment is in the transition from vertical to hinging.

What is the outside diameter of the aluminum disc? 8"? 10"?

Ah, I don't know, and I can't measure it right now. I seem to have 2-3" on either side of the mast. (I mounted some fairleads onto the disk next to the mast. I had no problem placing on on either side, hence the estimate. See the picture. Note also the size of the hinge in comparison.)

The critical dimension is that you can fit the hinge onto it and that is determined by the size of the wooden piece of the sleeve (which is approximately square, before you file a groove into it to fit the mast curvature). The sleeve needs to fit well, but without any binding. It should allow just a little play so that you don't have to have the mast aligned 100% perfectly in order to insert the foot. When I rebuilt the wooden part many years after the PO first constructed it, because it had suffered a bit in the elements, I had to do the operation twice, because I needed to file a deeper groove - the mast was binding.

Any ideas how to cut a precision hole out of 1/8 aluminum sheeting? I've got a Dremel Trio I used to cut circles for inspection ports. I don't think that approach will work on aluminum. The Trio is mainly for tile (ceramic), wood, and/or plastic.

I don't have such a tool and I would have attempted to use a power jigsaw with a suitable blade for a rough cut, then a file to precisely match the outline of the cuddy opening (after mounting the disk). I sometimes use those cylinders made of sandpaper that you can put in a drill to widen or smooth a hole. They work well on a soft material like aluminum.

[jackal]

Thanks for the info!!

Instead of a standard door hinge could I use a heavy duty tee hinge. I wouldn't need that separate T bracket then. Any thoughts?

Tee hinges have a long side that the wood/mast sleeve could mount too.

The short side of the hinge would mount in the plate/deck.

[GreenLake]

Sounds good. Make sure you get a galvanized part intended for outdoors and that the dimensions of the hinge part are the same size. You don't want to use a smaller hinge. Good luck.

[jackal]

GreenLake:

I picked up a galvanized Tee hinge today. The "deck side" of the hinge is the same width as a standard door hinge. I also found a machine shop in the area who can laser cut my aluminum deck plate to the exact dimensions of the DM-284 mast. We're getting close. I wonder if it would be worth it to upgrade to 3/16" aluminum plate since someone else is doing the cutting?

Deck plate dimensions: Outer 7"W x 9"L; Inner 2.12"W x 2.84"L (plus a hair or two- so the mast will move through plate)

Thanks for the help!

[GreenLake]

My advice - plan on using a file for fine adjustments - like making sure you have clearance for any rivets in the mast foot

My suggestion: if you start with a precision cut, then step your mast the old way, but slip the disk onto it first. Then drill through disk and deck (at least enough holes to fix the location of the disk). That should take care of your alignment.

You'll still want to file it open just enough that the mast doesn't "bind". What you call the "hari". Only trial and error will give you the required dimensions for that. I predict. Confidently. Actually, the clearance may end up being slightly different because despite all efforts you may not actually pull up the mast perfectly "in-line" (it's not actually vertical to begin with, hence I'm not talking about pulling it up vertically).

I see no problems with going 3/16". The disk is a useful attachment point for deck hardware. Stronger is better for that purpose. Let me know how you like the oval shape (mine is boringly circular...).

[jackal]

GreenLake:

I don't have the mast jack setup, so my mast is smooth at the bottom. What I'm going to have to do is relocate my cheek blocks and the boom vang bail.

I was looking at pictures of your setup. Where does your boom vang attach to the mast if the sleeve is there?

If the aluminum plate "floats" above the deck, what prevents it from flexing when the bolts (that go through the deck) are tightened down? Should I use some sleeves or bushings around the bolts?

In regards to shape, I'm not sure why I decided on oval. I guess maybe because it fits the shape of the mast more. Perhaps more of the aluminum plate would extend under the hinge with an oval shape.

Do you think a perfect circle would be better?

Thanks,
Matthew

[GreenLake]

I don't currently have a boom vang, but have been thinking on where to install one. If you go to 3/16" aluminum, your disk may be strong enough to serve as a strong point. You could fit one of the horse-shoe bails on the underside of the disk so that you can attach the van behind the sleeve. Or, if you trust the integrity of the sleeve enough you could drill a hole sideways through the wood block, closer to the hinge (bottom when raised) side of it and use that to hold the pin of a bail. (That is the plan I'm currently mulling over for adding a vang).

The only downside to that is that it would pull up on the cuddy deck rather than transferring that load directly to the mast. However, I think the deck should be strong enough (It holds 250# or more of crew weight), and disk and backing plates will distribute the force widely (my backing plates are 12" by 12" if not larger). If all else fails, adding a hollow fiberglass deck beam for additional support below the cuddy deck would not be that hard, but I don't expect that to be necessary.

The PO who installed the disk drilled through the raised "lip" which on my DS1 surrounds the mast opening evenly. That left the outer, not loaded, parts of the disk "flying" but there are no bending pressures.

A perfect circle, is, ipso facto, perfect

I want to encourage you to make it your design. This is not something where anyone can say what is "best". I was rather looking forward to you following your own instincts so that you are creating your very own solution and we can compare notes. (I have no skin in this game, as it's not my design. Just something I inherited and learned to appreciate. I think the PO used whatever parts he had lying around - there are indications to that effect).

As for the cheek blocks. If they are for a 90° bend at the foot of the mast to lead halyards to the cockpit you can either move them up, or, you could construct the sleeve so that it accommodates them, with an "ear" so they can slide in and a hole so you can reach in and attach the halyard - would require slightly thicker material for the sleeve.

Or, you can decide whether you really need these lead back. I have my halyards cleated on the mast, which allows me to pull down when raising the sail, something I find most natural.

Making all those decisions is the fun part of an upgrade, and the DS is a fun boat because you are so free to modify the rigging w/o running afoul of class rules (which otherwise would be either preventing you from racing or destroying the value for resell).

In case I didn't write this before - I'm definitely hoping for pictures!