Convert from mast step to tabernacle, loose strength??

[SailorTom]

I have a Pearson Triton that I'm considering putting a tabernacle on. The question is the current mast base/foot seems very strong, an 8inch dia x 1.5inch high metal base through bolted to the main beam with 2 3/8" ss screws. then the foot is a piece fitted to the mast shape with a 1"x1"x4" bar that slots to the base. The weakest link at the 2 3/8"SS screws. 
Now I compare that where the foot is gone the tabernacle is just as or more secure to the deck but now the mast is held via a couple bolts through the sides of the "ears" of the base. The weight of the mast is now taken by these through bolts vs the full foot flat to the base. Side loading is probably better due to the tabernacle ears. I solo sail so thing do tend to get beat up more then a fully crewed boat. Any thoughts? Should I or not?

[Tim]

A tabernacle I had on a boat was slotted so that the base of the mast made solid contact with the base, which I think you want to maintain. If you are looking for ease of stepping, have you considered a hinged base. Ballenger makes several http://ballengerspars.com/hingedmastbaseinfo.pdf

[CapnK]

I had the same setup on the Ariel, except the round base was very thick heavy plywood, and wanted a better attachment. I had a tabernacle made of aluminum, and it will be glassed directly into the cabin trunk top. It has a much wider base (3" wide flat bar stock, about 20" long, positioned athwartships), and the tabernacle legs are also braced with 45* supports to this base bar. The plan is to have the mast sit, as Tim notes above, securely down onto the bearing surface between the uprights.

The main 'pivot hole' in the mast where it connects to the tabernacle will be of necessity a little elongated to allow the mast when upright to come down flat against the base when raised. A second hole will allow for 'locking' the mast in place once it is raised and in position. So neither of those bolts - or the holes in the mast wall - will be bearing weight or stresses of the spar, they will just serve to hold it in the tabernacle during the raising/lowering process and or secure it from being able to 'kick out' once raised. The legs of the tabernacle will help brace this lower mast section as well.

I may make the mast foot and base slightly angled on the diagonal (when viewed from the side, sloped down towards the bow a degree or 3) to make the elongated hole as small as possible, and the raising process just a bit easier...

[SailorTom]

If you are looking for ease of stepping, have you considered a hinged base. Ballenger makes several http://ballengerspars.com/hingedmastbaseinfo.pdf

I had looked at these hinged plates but the site seems to imply smaller masts, although my mast at 3-5/16"x5-1/8" foot would seem to fit the hmb e27 and the mast only weights about 75-80lbs, I picked it up yesterday to test for the center of gravity since I'm also thinking of just using an A-frame made of some electrical conduit I saw at Home Despot the other day. I'm starting to think the A-frame might be a better way to go since the original foot is used and the mast is more or less centered on the boat when lifting vs hanging about 27ft if front(using boom as a gin pole) or off aft 17ft(using a dedicated gin pole or A-frame).
CaptnK..not sure I see how the elongated hole would help things. Do you have a drawing of what you plan. Seems like the mast would need to be at the top of the elongated hole until vertical, then lowered in to the step. How is the lowering controlled?  Thanks for the brainstorming ;D

[Tim]

Here are a couple examples of slotted tabernacles;





Google "mast tabernacle" images and you will see quite a variety

[CapnK]

Here's a sketch of sorts to show you what I am doing.

My terminology for clarity/avoiding misunderstanding:
1 - Mast Foot is the piece at the bottom of the mast (red part).
2 - Mast Base is the structure on which the mast (and mast foot) will sit when upright (brown part).

In drawing labeled 'A' the mast (black lines) is down, in 'B' it is up in the tabernacle (light blue-gray lines), only the upper of the 2 thru-bolts is in when down, and that bolt is at what would be the *bottom* of the elongated hole. This elongation needs to *be long enough to allow the mast foot swing into the base* if the mast foot has a flat bottom. Those two things are important, doing it that way. The elongation would only be to allow for the back bottom corner of foot to clear the base as it was being raised and until the spar was upright; a round hole positioned so that the spar rested on the foot and base would not be high enough to allow a flat foot to rotate into position. Following me there? You can't rotate a square against a square, without providing clearance for the corners first. I think with a flat/square base/foot combo, you might need to elongate the upper hole by and inch or two to get that clearance.

The better solution I came up with, is to taper the foot and base in a complementary manner as shown by the red and brown parts. Doing that makes for minimal need of elongation of the upper hole; it only needs to be 1/2" or 1/4" out of round, just enough to allow the foot/base to be aligned before the entire weight of the spar is set down.

The lower hole in both cases is for a locking bolt to help secure the mast upright and to the tabernacle. If 'creep' was ever noticed from the mast being forced down and thus forward from rig pressure at the base/foot, a metal retainer band could be attached at the lower bolt around the outside and front of the tabernacle to keep that from happening.

The small drawing at low left is roughly what the tabernacle I had made looks like when viewed from the bow/stern.

For raising/lowering, I think a gin pole with stabilizing lines to the sides of the boat at the shroud turnbuckles would work fine. You would probably need to make a harness of sorts to raise their pivot points up to a level equal with that of the mast base. I've seen that done with short lengths of chain and it worked brilliantly.:)

[Snapdragon]

Here's a picture of the tabernacle and mast raising bipod on my Snapdragon 26. Hope it helps.