Mast cap modification?

Discussion in 'Multihulls' started by SpiritWolf15x, Oct 29, 2012.

  1. SpiritWolf15x
    Joined: Apr 2010
    Posts: 194
    Likes: 1, Points: 18, Legacy Rep: 15
    Location: Vancouver, Canada

    SpiritWolf15x Senior Member

    Hey everyone, the mast I currently have on my 16' tri is a slightly modified Nacra 5.2 mast, with the old style main halyard system (pulled down from the front, over the top of the mast). I'm wanting to change it over to a system similar to the one I have on my Tornado (pulled down the inside of the mast from the bottom), I am also wanting to ad in a mast head fore sail halyard, I've a mast head (25') hoisted reacher I'm dying to try out. The current cap acts as a solid lid across the top of the mast and does not currently allow for halyards to be rerouted through it.

    I know I'll have to ad slots at the bottom of the mast for the blocks and cleats but does anyone have a simple mast cap design that will work? Can I get away with simply cutting out holes for the halyards in the existing cap or will I have to have a new one fabricated?

    Thanks,

    Wolf
     

    Attached Files:

    Last edited: Oct 29, 2012
  2. bruceb
    Joined: Nov 2008
    Posts: 1,204
    Likes: 38, Points: 48, Legacy Rep: 214
    Location: atlanta,ga

    bruceb Senior Member

    Cat mast

    Spirit, Most "beach cats" use a main halyard that runs back down in the luff slot to keep from compromising the water tight mast. It really makes a difference when (not if) you have to right the boat. There are mast caps that have a small sheave at the rear that can be made to fit your section.
    I haven't seen a current Tornado in years so I don't know how they do it. The local F-18s/ Nacra 20s use several different systems, some in and some out, I think-I will photograph them and post later this week. They are really fast with their reachers, you should love it:D B
     
  3. SpiritWolf15x
    Joined: Apr 2010
    Posts: 194
    Likes: 1, Points: 18, Legacy Rep: 15
    Location: Vancouver, Canada

    SpiritWolf15x Senior Member

    That is what I'm hoping for, there is a certain yellow catamaran who's transom I am aiming for, the reacher would help in that regard. Not that she isn't fast as is, I've had her up to 18knots, she can however... Be MUCH faster. :D
     
  4. bruceb
    Joined: Nov 2008
    Posts: 1,204
    Likes: 38, Points: 48, Legacy Rep: 214
    Location: atlanta,ga

    bruceb Senior Member

    soon

    We are having a "wind event":( for the next couple of days, when it is over, I will get the pics. The F-18s are fast- faster than my Buc off the wind in most conditions, and I am not slow. Very impressive. B
     
  5. SpiritWolf15x
    Joined: Apr 2010
    Posts: 194
    Likes: 1, Points: 18, Legacy Rep: 15
    Location: Vancouver, Canada

    SpiritWolf15x Senior Member

    I'm wondering if I can't get away with something similar to this set up and simply reroute my existing spinnaker halyard.

    Also, Bruce and anyone else on the Atlantic seaboard, PLEASE be safe.
     

    Attached Files:

  6. bruceb
    Joined: Nov 2008
    Posts: 1,204
    Likes: 38, Points: 48, Legacy Rep: 214
    Location: atlanta,ga

    bruceb Senior Member

    more masthead

    Thanks Spirit, at least I am inland and we are just getting wind.
    Keep any thing you build LIGHT! At the masthead, it really matters. The lake pics will have to wait, but I had these in my mast pile. One of these or something like them plus a hanger on the mast front would certainly work. You can cut slots near the top without hurting the strength of the mast. B
     

    Attached Files:

  7. SpiritWolf15x
    Joined: Apr 2010
    Posts: 194
    Likes: 1, Points: 18, Legacy Rep: 15
    Location: Vancouver, Canada

    SpiritWolf15x Senior Member

    Here is what I've come up with... Please excuse the crudeness of the materials used.

    The blue line is the existing main halyard which will be staying the same, all bolt on two aluminum bars onto the mast cap and add a third pulley wheel. Rerouting the spinnaker halyard through a new box pulley over the wheel down to a block and back up to a shackle giving me a three or so to one purchase.

    I figure something this simple will cut down on build time and maintenance.

    What do all of you think?

    -Wolf
     

    Attached Files:

  8. bruceb
    Joined: Nov 2008
    Posts: 1,204
    Likes: 38, Points: 48, Legacy Rep: 214
    Location: atlanta,ga

    bruceb Senior Member

    halyards

    Spirit, that is a two to one system, but it should be plenty if you can route everything properly. That 45% angle where the halyard exits the mast would not be good, most halyards lead almost straight down after they exit the masthead. Is your reacher so tall (long on the luff) that you have to go all the way to the top of the mast? Many spinnaker halyards exit the mast and then go down to a floating block on a bridle a few inches to a few feet down the mast. It allows a better lead to the side of the mast, about the same as the bail on a masthead unit. If it really is that tall (I understand- go big or go home:rolleyes:), a forward bail like is on the masthead you showed is about the only answer, as the lead block usually needs to be able to float side to side. Also, are you planing on dropping the reacher or rolling it, and what kind of system? B
     
  9. SpiritWolf15x
    Joined: Apr 2010
    Posts: 194
    Likes: 1, Points: 18, Legacy Rep: 15
    Location: Vancouver, Canada

    SpiritWolf15x Senior Member

    It is a furling reacher on a 3ft beyond the bows bowsprit that hoists normally from the spinnaker halyard on my Tornado which is "about" 25ft off the main beam. My tri's mast is 25ft long and is supported about 1.5ft above the bow deck height. I figured if I lengthen my tri's existing 2.5ft bowsprit it'd "probably" fit.

    If the 45° wont work I think I can drill a rope hole into the cap plate, add a third pulley into the existing channel and have it 90° out to the new pulley then down to the block for the head of the sail then back up to the shackle for the 2:1 purchase. (Red lines)
     

    Attached Files:

  10. SpiritWolf15x
    Joined: Apr 2010
    Posts: 194
    Likes: 1, Points: 18, Legacy Rep: 15
    Location: Vancouver, Canada

    SpiritWolf15x Senior Member

    If I go the simple (cheap) route and simply bolt a block to the top front of the mast and feed a good beefy (tensile strength) halyard through it will it be enough to hold the sail? Do I "need" the 2:1 set up or will a 1:1 system work just as well?
     
  11. cyclone
    Joined: Jun 2012
    Posts: 15
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Trenton, Maine

    cyclone Junior Member

  12. SpiritWolf15x
    Joined: Apr 2010
    Posts: 194
    Likes: 1, Points: 18, Legacy Rep: 15
    Location: Vancouver, Canada

    SpiritWolf15x Senior Member

    That is an interesting mast.
     

  13. bruceb
    Joined: Nov 2008
    Posts: 1,204
    Likes: 38, Points: 48, Legacy Rep: 214
    Location: atlanta,ga

    bruceb Senior Member

    more mast tops

    Spirit, here are a few more cat masts set up for reachers. None of them are masthead halyards, but the same system will work, I use a similar set up on my 24 with a 600 sq foot chute. They all use a small single dyneema type halyard with a loop at the bottom end that is then tensioned with various tackle and hook systems. All light and low tech. At the top, they exit thru a small block or are external from the hounds up, and then lead down to a block attached to a loop around the mast. Again, light and simple. B
     

    Attached Files:

Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.