Mast Raising and Lowering Systems?

Discussion in 'Boat Design' started by CatBuilder, May 23, 2011.

  1. CatBuilder

    CatBuilder Previous Member

    Does anyone have any good links to mast raising and lowering systems for large boats?

    My mast height is about 65ft above the WL.

    I'd like to be able to lower it in order to be able to get up into rivers and places that boats with these large masts can't normally go.

    Here is a sistership.

    How would one raise and lower such a mast? Please pay no attention to the fact that the mast goes through the deckhouse in the picture. Mine will be on the deck level without going through the deckhouse. (I didn't want the leaks)

    However, it seems it may be a lot easier to lower it so that it hangs off the bow, rather than tilting it toward the stern, since the deckhouse will be in the way.

    Any creative ideas or existing lowering/raising systems?

    [​IMG]
     
  2. gonzo
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    gonzo Senior Member

    On workboats, they use a tabernacle and a counterweight.
     
  3. CatBuilder

    CatBuilder Previous Member

    Yup. I agree. a tabernacle is the way to go. Probably can't use a counterweight though, since it's a multihull and I have to keep the weight off.

    I figure some kind of winching system would do the trick.

    However, I've never seen one done before. Are there "quick disconnects" for shrouds, so you don't' have to deal with turnbuckle every time you raise and lower?

    Anyone seen a working system?
     
  4. TeddyDiver
    Joined: Dec 2007
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    TeddyDiver Gollywobbler

    On a deck stepped mast it's not needed if you have backstay tensioner (dunno if it's the right term in english) and shrouds are in line with the mast..
    That way you don't need additional tabernacle either instead you can use boom and winch..
     
  5. BATAAN
    Joined: Apr 2010
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    BATAAN Senior Member

    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.
     
  6. tom28571
    Joined: Dec 2001
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    tom28571 Senior Member

    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.
     
  7. CatBuilder

    CatBuilder Previous Member

    Hmmm... sounds easier than I'm thinking. Only problem is my stays are swept aft and I want to drop the mast forward because that way it will be able to go all the way down without hitting the deckhouse.

    Maybe a high tabernacle and pivot pin, then lower the mast aft using the inner forestay (pictured)?

    [​IMG]
     

    Attached Files:

  8. BATAAN
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    BATAAN Senior Member

    Mast must be supported side to side all the way down so needs some form of shrouds, and looks like your forestay angle gets very unfavorable when the mast is 1/2 way down also. Always remember your rigging triangles and don't let any of the 3 sides get too short as loads go up fantastically very quickly. The mast looks pretty rigid with all its struts and such so the main challenge is keeping it from breaking the tabernacle and falling over the side when the shrouds are slackened. Workboats did this with a heavy tabernacle and stout mast. Some other method is needed here with the light construction. How about some very light non-stretch rope "lowering shrouds" and a place to hook them co-axial with the tabernacle pivot. The place to hook them could be a beefed-up something in the lifeline system as its only used in lowering and hoisting when the main shrouds are slack. They could be Kevlar or something else very small and light and hook aloft to where the shrouds are and when not in use be tensioned alongside the regular shrouds. To use, take them forward and hook to co-axial anchor point.
    This way the mast is held athwartships by the lowering shrouds at all points in its arc of movement, can't pitch over the bow because of the real shrouds and can be lowered by a headsail halyard until about 2/3 of the way down, then that forward rope will get very highly loaded unless some form of spreader is used or something supports the mast from below, say an adjustable crutch, that lowers it the rest of the way.
     
  9. keysdisease
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    keysdisease Senior Member

    I once did a delivery of a large Wharram catamaram through the Okeechobbee Waterway across Florida and through the lake. There is a vertical lift railroad bridge on the East side of the Lake with a fixed height of something like 48ft, I measured the Cat's height at just over 50 with a tape measure I had brought just for that job.

    There was a beefy tabernacle so I was pretty confident, the plan being to lower partially using the mainsheet to boom to beefy topping lift added for just that purpose. I had enough crew to steady side to side.

    Worked great, we lowered the mast slowly and very controlled, tied everything off when I determined we had it at a safe height which didn't require too much lowering, we only needed to "buy" like 5 ft.

    Worked great until...a powerboat boat went buy throwing a large wake. The mast swayed from side to side and I heard a few loud cracks from the tabernacle. The oscillations continued for what seemed forever and luckily the only damage was a badly cracked but still intact tabernacle. After what seemed forever I started to breathe again. It could have been much worse and luckily no one was hurt.

    Point being, as a charter boat with green or short handed crew as long as everything goes as planned it can be done. But it only takes one fly in the ointment to endanger the vessel or crew. For us there was no way we could have controlled the port to starboard sway given the angles we had to work with.

    Also from my beach cat days, the primary failure of the shrouds was at the wire to swage fitting interface at the lower adjuster. This was because occassionally when raising the mast the adjuster would "stick" pointing down and when the shroud would come up tight it would stress the wire with an abrupt 180 degree turn, A few times of that and we got to watch the mast slowly fall off to leeward after a tack some afternoon, and it does happen in slow motion. Point here is its not just the actual lowering and raising, there can be other considerations.

    As you are planning to charter maybe think about having a surcharge for mast lowering and having it done at a yard or with a crane, its a legitimate cost to pass on. Better safe than sorry.

    Steve
     
  10. CatBuilder

    CatBuilder Previous Member

    The mast lowering has no place in chartering. Also, it will be lowered all the way to a safe position every time. Forgive me, but lowering part way, then making way was bad seamanship. It should have been secured to the deck before making way.
     
  11. philSweet
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    philSweet Senior Member

    I saw a tabernacle design that was a half pipe with boom and sailstack on the tabernacle and a high pivot point. A bridal to each bow could provide reasonable lateral control if both lines run to a single reelwinch. How many thousands are you budgeting for this feature and how many hundreds of pounds? Lots of ancillary considerations such as wiring and gallows and custom mast staying. I thought it funny that the photo had a topmast schooner in the background. They "just" lower their topmasts. A dumb old counterballance is really hard to beat. Even I haven't managed to break gravity yet. The counterweight could be stored elsewhere when cruising. Maybe five 100# lead blocks that can double as kellet weights and trim ballast. If you have about seven feet to the pivot, 500# would help out quite a bit.
     
  12. TeddyDiver
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    TeddyDiver Gollywobbler

    Looks there's no shrouds at all... just what we could call (again my bad in english) violin shrouds and a pair of back stays. It's possible to change that rigging to conventional shrouds and running backstays without much complication..
     
  13. keysdisease
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    keysdisease Senior Member

    You are right re the bad seamanship, but the owner over rode my recommendation to lower all the way. I went along because we only had a couple of hundred yards to go in that configuration in a dead calm canal. My bad, lesson learned, doesn't mean something like another boats wake couldn't happen while lowering to someone else.

    That by the way was when I decided to jump ship. I had gone along with the new owner as I had experience and had made the Okeechobbee Waterway trip before. He had bought the boat in the Tampa bay area and we were taking it back to Miami. He knew everything and was really getting on my nerves telling me all of it. When we got to Stuart we ordered a Pizza delivered to where we docked and I offered the delivery guy $50 to drive me home to Miami. Was home that night. :)

    Steve




     
  14. whitepointer23

    whitepointer23 Previous Member

    cat, have a look through some of the trailer sailer forums, they have a lot of good advice on mast raising and lowering systems . i am sure you could scale up a ts system to suit your boat.
     

  15. waikikin
    Joined: Jan 2006
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    waikikin Senior Member

    This is pretty much the system to go for i reckon, same as on my seawind cat, on that I use temporary shrouds to the diamond spreaders & also temporary stays to the boom end, a cradle that attaches to the seagull striker might be good too
     
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