Rotating Mast Control and Daggerboard Uphaul

Discussion in 'Multihulls' started by SolGato, Feb 12, 2023.

  1. SolGato
    Joined: May 2019
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    Location: Kauai

    SolGato Senior Member

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    I’m trying to sort out the rigging of my rotating mast on my Trimaran. Unlike my last Trimaran, this one didn’t come with an owners manual. I can only go by photos I took when it was rigged by the last owner, and various photos of it dating back to its launch.

    Looking at old photos from previous owners (grainy and hard to make out) and newer from the last, I suspect there may be more to the system than perhaps the last few owners realized.

    See photos above for reference.

    The last few owners had the “spanner” attached to the boom only, but looking at older photos it looks as though the spanner was designed to handle rotation control of the mast, with a double 2:1 purchase running from the end of the spanner (behind mast) out and forward to a pair of pad eyes either side in front of the mast, with control lines then running aft to the cockpit which makes sense to me as a way to lock or induce rotation.

    Looking at photos of other setups, I have found examples where the spanner is only connected to the boom (usually lower with more
    pulling angle), others where the spanner is mounted to the mast closer to the deck and only rigged to the deck to control mast rotation, and then others that are connected both to the boom and to the deck to control the both boom and the mast.

    Based on the hardware mounted to the boom and to my deck, I believe the spanner was designed to attach to both.

    What’s strange when comparing photos of other setups, is that the spanner is mounted kind of high up to allow for a good pulling angle on the boom, and pretty high up off the deck compared to examples where the spanner is used to control the mast only.

    Also, since the spanner is bolted to the mast at a single pivot point either side, I would think when connected to the boom and the deck that the spanner would want to pivot and change angle. Perhaps that is what it is supposed to do? However if it pivoted downward too much, I believe it might interfere with the winches, and there is evidence of that in the close up photo of the mast off the boat. If you look closely, you can see evidence that the spanner has contacted the welded on winch mounting pad on the mast, leading me to be,I’ve that at some point it was rigged down to the deck.

    In the last two photos above, the blue lines and circles show where I believe the rotation control lines would have been attached. The pad eyes are well anchored and forward of the mast and far enough apart to allow for a perpendicular mast angle.

    I do know the previous owner broke the old spanner and had to have a new one made. He was only connecting it to the boom.

    Comparing photos, I can see that the new one was built to match the old and mounts in the same spot.

    Is the only purpose for the boom connection to act as a “fence” to keep the boom from swinging back and forth, and not as a way to control the boom with regard to vertical movement? If that’s the case, then I guess the angle of the purchase isn’t that important.

    This is my first boat bigger than a beach cat with a rotating mast, and I can see a reason for the spanner providing both functions, but I’m just not sure how it should be setup.

    Can anyone speak to how setups like this are supposed to work and be rigged? This boat was built and rigged in the early 90’s.


    Also while we are on the subject of rigging systems, check out this interesting contraption/system designed and fabricated by a previous owner somewhere along the line. I understand what it was designed to do, but am not sure why someone felt it was needed.

    Please refer to the two photos above for reference.

    Basically it is a hinged lever that is mounted to the deck behind the center board case with a hinge that pivots and pulls the board up the case to retract it to hull surface level by way of a control line led aft to the cockpit. This particular board deploys deep into the case, and this lever and line system works like a crane boom with a hoist at the end in that when the line is pulled, the board is lifted by the line using the sheaves mounted at the end of the lever as a pulling point, then when the board comes up to the surface of the deck, and all the free line has been pulled, the board and the lever become one and the final few feet of board are pulled up above deck level as the lever itself pivots as it is pulled up and back.

    It’s a really interesting design, and someone clearly put a lot of thought into it, however unfortunately it was not well fabricated and would need to be remade out of better/stronger materials which I may do if I can figure out the reason/advantage of having it in the first place.

    Originally the uphaul of the daggerboard would have been a traditional system consisting of a sheave mounted up and off the front of the mast aways.

    My one thought was perhaps this system was designed as a way to keep the board low and eliminate the original control line position in an effort to keep the area clear for tacking headsails, especially larger ones, since the control line can be kept much lower using the lever system.
    Last edited: Feb 12, 2023
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  2. revintage
    Joined: Nov 2016
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    revintage Senior Member

    My small contribution is to add a short Dyneema from the rotator end up to the gooseneck to hinder it from moving down(thin red line).

    Nothing wrong with the mast-boom system, as long as you have the mainsheet at an angle so that it pushes the boom forward when sheeting.

    In lighter wind a system that forces the mast to rotate with a pair of lines sideways/forward will surely work.

    If the rotator could be moved back from the diamond fitting to the widest part of the mast and the boom fittings moved more to rear on the boom, I think the rotator system might work better.

    As I am only used to smaller rigs below 25 sqm, I am not sure it my ideas work on larger?

    Curious, how long is the daggerboard and how deep is the daggerboard box? Do you ever sail with the board lifted?

    Skärmavbild 2023-02-13 kl. 11.03.53 fm.png
    Last edited: Feb 13, 2023
  3. John Perry
    Joined: Nov 2003
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    John Perry Senior Member

    Solgato - The extra line that Lars sugests should hold your mast spanner up and if that gives you the right mast rotation I would say that's all you need. However, I find that the rotating mast on our Farrier F32 trimaran does not rotate as far as I think it should do without some additional forcing of the rotation. To that end our F32, in common with many other Farrier trimarans, has a mast spanner that folds up to allow the mast to be lowered but otherwise sits just above the deck behind the mast and two tackles with tails led back to the cockpit act on this to force the mast to rotate. I could get a picture of the arrangement next time I visit the boat. I would say that I am thinking about altering the tackles that control the mast rotation on our boat to give even more purchase. I would also say that if you have a system like this it is easy to forget to change the mast rotation as you make a tack. If you do forget you will be sailing with the mast rotated the wrong way and that noticably slows the boat down - perhaps an indication that rotating masts really are a benefit. A rotating mast also makes it easier to hoist the mainsail without being closely head to wind. Whats not to like.
  4. SolGato
    Joined: May 2019
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    SolGato Senior Member

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    Thank you a John and Lars for your input and suggestions.

    Lars -(please refer to photos above) To answer your questions, the daggerboard is about 7’ long and drafts about 4.5’ when locked in the down position with about 2.5’ remaining in the case which puts the top of the board about 2.5’ down into the case from deck level. The case is very strong on this boat as it is tied into the forward main bulkhead which also ties into the sockets for the plug in beam arms. The rotator/spanner bracket is already mounted at the widest section of the mast profile but the photo may not have conveyed this.

    I have not yet sailed the boat.

    One of the only things I didn’t like about the daggerboard setup was that the downhaul was routed inside the cabin along side the daggerboard case. This meant that the control line had to run through the cabin across the seating area and out the companionway, then coiled up and stowed when not in use.

    Originally the line terminated outside one side of the case, passed through the wall, then ran up one side of the board through the boards built in block, then down the other side, through the other case wall side, up a glassed in drain/catch, then through a turn block and cam cleat mounted on the bulkhead and back to the cockpit.

    I changed the line routing as it exits the case so that it is led up a PVC tube along side the case to the deck surface where I mounted a turn block on the surface just outside the center of the slot where the downhaul control line turns out to the T-track where it can be routed back to the cockpit. The bottom of the PVC tube fits inside the old drain/catch, so any water entering from the deck surface or wicking down the line drains down the tube and into the case.

    Per your suggestion, I will plan to add a connection above and between the rotator/spanner and the mast to prevent it from rotating downward and it bringing the boom with it when mast rotation is locked or induced.

    John- Thanks for your input and offer. I am familiar with the Farrier setup, so no need to bother with photos. I don’t think I’ll have any problem getting full rotation based on how far out front and spaced apart the pad eyes are located and where I believe based on old grainy photos, the original rotation control lines would have been led. And I hear you on potential for forgetting to unlock the mast. I know some have damaged their sails. Fortunately my mast is a double diamond setup with short swept spreaders. I mention this because I think there may be a greater potential for sail damage with long single spreader setups.

    And just to clarify the different setups I’ve seen, here is a crude drawing of each.

    The first showing just a boom connection, the second showing a separate spanner for the boom and one mounted down low for mast rotation (like John mentioned), and the last is how I suspect the boat was originally setup and rigged, with the spanner connected to both the boom and the deck to perform both tasks.

    Last edited: Feb 14, 2023
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  5. revintage
    Joined: Nov 2016
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    revintage Senior Member

    Great, the arrangement you have done with the daggerboard, must be the way to go and also very neat. About the rotator you forgot one line;).

    PS Nice bird intarsia on the folded table in the cabin DS

    John, if you read this, please drop me a line about my AYRS membership.

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  6. SolGato
    Joined: May 2019
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    SolGato Senior Member

    Thanks Lars.

    Since I started this thread, I don’t mind clogging it up with photos.

    Here’s a better one of the table inlay.

    I modified the bunks so they both slide out to 3’ wide and built new support frames using Ipe which will continue darken over time to match the dark wood of the bird inlay and flooring.

    Still need to finish up the countertop and install the new sink and build some storage shelving and fill all the holes in from all the screws I removed that had been installed to route and hold down all the wiring that was exposed (now all hidden) on the walls and ceiling before freshening up the interior with a new coat of a brighter shade of white.

    I can’t stand exposed messy wiring, and the breaker box and VHF were previously mounted on the forward bulkhead so you had to enter the cabin to access them.

    Now all the main electrical components are located on the front side of the rear bulkhead reachable from the cockpit without having to leave the helm or the loss of visibility.

    Once the interior makeover is complete, I can focus the rest of my time and energy on “extra” exterior stuff before our mooring season starts in a few months.

    I have plans and ideas for other systems, but am going to spend the summer sailing it before I make final decisions on them.

    One of those is to decide on the best way to route all lines back to the cockpit and lock them off there since I sail single hand. I was hoping to find a trigger cleat that could be remotely triggered from the cockpit that would work well with the existing setup, but haven’t found anything yet and may have to make/modify my own. I thought about going with constrictors but they probably won’t hold up well and not everyone has had a positive experience with them. I like the idea of the variable clutching the offer, and the release line could be led aft easily enough, but they are too expensive to take a gamble on and would require more modification of the mast than I am willing to make for the sake of experimentation.

    The challenge of course as you probably know is how to handle leading lines aft without impeding rotation which would be easy enough if the mast was designed to do this from the start like modern setups.

  7. trip the light fandango
    Joined: Apr 2018
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    Location: Rhyll Phillip Island Victoria Australia

    trip the light fandango Senior Member

    Congrats on the new tri SolGato, please excuse my ignorance but what is it?, and if you could establish what the difference is between setting the mast for maximum flow and leaving it dead straight on a boat built for speed it would be very interesting, a comparison with the practicality/fun/ ability/ maintenance compared to your other smaller tri' experience would be very interesting , regards
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  8. SolGato
    Joined: May 2019
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    SolGato Senior Member

    Thanks Trip. It’s a 1990 Skip Johnson Seawing 24. OldMulti has covered the design in his thread.

    I wish I could say it is a “new” boat, but the sad truth is I have owned it for almost 3 years now and haven’t sailed it due to a move, Covid, and Mother Nature.

    But I have been making improvements and updates as it has sat in my yard these last few years and am on schedule for being able to enjoy a Summer of sailing this year.

  9. SolGato
    Joined: May 2019
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    Location: Kauai

    SolGato Senior Member

    Adding these photos of Solgato’s sail rig for another forum member to check out as I make final decisions on sail size and volume positioning before cutting down the sail and settling on the sprit and mast lengths.

    The first photo is the max size I can utilize and still maintain a strong tripod support while also keeping the lower sprit off the solar hardtop which is shown lowered into its wedge shaped “sailing” mode.

    I’m just looking to cruise, so I don’t want to overpower the boat, and I am hoping to get the sail volume and positioning in the ballpark with regard to balancing the boat and the CE.

    The whole rig will still be somewhat adjustable.

    The sail will primarily be used to putt around inside the Bay at sunset and for use the downwind journey around the island to the Napali Coast.

    Not looking to get wet or fly a hull by any means, so I’m leaning toward de-powering it by reducing the size and keeping the volume and power of the sail positioned behind the main front beam (as shown in second photo) in order to keep the bows from plowing during downwind tacks and the boat flatter.

    The whole rig can be raised or struck on the water, with the sprints and sail rolled up together and stowed along the top of one hull, and the A-frame mast swung down forward off the bow.

    Last edited: Feb 21, 2023
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