Mast Raising and Lowering Systems?

[u4ea32]

Originally Posted by BATAAN

In Santa Cruz, California, many of the sail boats have to go under a bridge to get in and out of the marina and all seem to have pretty much the same system. The mast is in a tabernacle that allows the mast to tilt forward, the lower shrouds have a rigidly fixed pivoting joint right co-axial with the tabernacle pivot pin, the boom with taut topping lift is used as a compression strut to give a favorable angle in lowering with the main sheet being the lowering tackle. I haven't done it myself, only watched from another boat, but what I saw was basically casting off the backstay and lowering away the mast forward, motoring under the bridge and the rig went back up quickly and the backstay was set up, then the boat scurried to its berth and I heard corks popping.

This is the way to do it. I grew up in Huntington Harbour, in Southern California. The bridge crossing the harbor entrance was only 26 feet at low water, so everything larger than a very small dinghy needs to drop the mast every time out, and every time back in. Its really cheap, easy, and in general, safe.

The full details for the best set up:

1) Deck stepped mast
2) Tabernacle, basically two strong vertical plates on either side of the mast, with a big bolt going athwartship through the mast. Cut a radius off the front low edge of the mast for clearance while lowering. The base of the mast can be raised off the deck, with turning blocks actually under the mast step, so all halyards lead across the deck, into the blocks within the mast step, and then up inside the mast.
3) Weld or bolt a bracket at the back edge of the mast, to carry a bolt that goes vertically into the mast step on deck. This bolt acts like the wood blocks you jam in front of the mast in a deck stepped rig to lock down the mast so its stiffer down low, reducing forward low mast bend. You remove this bolt before lowering the mast.
4) The mast must be supported athwarthship as the mast is lowered forward. This is often done by having some (lowers) or all shrouds with a pivot point in line with that bolt through the tabernacle, so the shrouds are more-or-less tight as the rig lowers. This is often done by having lowers on the cabin top, in-line with the mast. Some people put a compression strut on the uppers under that in-line pivot point, with a removeable strop that leads aft.
5) The boom must also be supported athwartship as the mast is lowered and the boom goes up. This is usually done with a bridle that attaches to the shrouds at the pivot point.
6) Either the main halyard, topping lift, or (better) the backstay is attached to the end of the boom. Using the backstay is the best, as its certainly stronger, and certainly fixed length, and you need to disconnect the backstay anyway in order to lower the mast forward.
7) Use the mainsheet as the tackle for lowering (and later, raising) the mast.
8) To fully lower the rig, ensure your bow pulpit can take the weight, most can. I put a life jacket or similar padded-and-slippery thing on the bow pulpit. When the mast is fully down, one can remove the bolt through the mast, and slide the entire mast aft.

[CatBuilder]

Some excellent advice. Thank you very much.

I now have a good general understanding of how to do this. Key is to support the mast athwartships as it goes up or down, keeping it from swaying or getting out of control.

Thanks for the input.

Keys: That situation stinks. Glad you got out of it.

[u4ea32]

Originally Posted by tom28571

I've seen the same thing in Santa Cruz Bataan. The one I saw was a Columbia 50 and the mast dropped aft. Don't think there was anything special about the location of the side stay attachment though I could be wrong about that. As soon as the the mast started to drop, the stays went loose and the tabernackle prevented any side tilt. An electric winch at the mast base did the work and the mast dropped only far enough to clear the bridge. No rough water to contend with. Did not get to have a close inspection but it looked simple and very neat. With a Wednesday night racing crew aboard to keep the stays out of trouble, there were no snags.

That Columbia 50 set up is pretty cool. It works quite differently from the simpler and more common approach, and was substantially more expensive and heavier, and so I am pretty sure no one else did their mast in a similar way in California. It was taken from how dutch barge boats lower their masts.

The mast pivot point is several feet above the boom, so the boom and mainsail can stay in the boom gallows and on the mast.

Below this pivot point, the oversized mast was cut: starting at the base of the mast about where the round leading edge of the mast changes to the flat sides of the mast, a vertical cut was made up about 8 feet (above the mainsal headboard), then the cut curved aft and back vertical, with the diameter of this curve barely more than the flat surface of the sides of the mast section, down about a foot, then curving sharply aft again to horizontal, around the back of the mast (cutting the mainsail luff track), and then curving back to vertical again up a foot, curve over and back down the other side of the mast to the mast step. The top "ears" were where the pivot point goes through the sides and the top mast. The resulting two pieces of aluminum were boxed, where heavy aluminum plate was welded to those cut lines: for the lower part, the heavy plate was bent on a mandrel (they might have used another piece of mast section) and welded to the cut lines. So the lower part of the mast, looking down on it, looked sort of like a taco shell, and the other part of the mast looks like its somewhat smaller than it should be, but it fits cleanly into the "taco shell."

The sides of the mast lower than that pivot point are strong enough to keep the mast from swinging to the sides while being lowered. The mast itself continues down all the way to the deck between these strong sides.

The forestay is disconnected, then the topping lift gets the mast leaning aft. As soon as the mast starts going aft, all shrouds are slack, as Tom observed. The big electric winch mounted on deck just aft of the mast slowly eases out the wire rope cable attached to the back side of the lower extremity of the deck stepped mast. There is a lot of leverage for that winch, because the pivot point is about 8 feet above the deck, and the mast is only about 50 feet high. The mast can be easily lowered to horizontal and left there. Press the button on the electric winch again, and up goes the mast.

So for just raising and lowering, this rig is pretty cool. For sailing performance (mast bend tweaking), weight and expense, its not so cool.

You could probably use it as a dinghy hoist!