Carbon Fiber Mast Modification

Discussion in 'Sailboats' started by Beezer, Oct 10, 2014.

  1. Beezer
    Joined: Mar 2014
    Posts: 34
    Likes: 15, Points: 8, Legacy Rep: 10
    Location: Naptown

    Beezer Junior Member

    Hi Folks,

    Question please for anyone who would like to chime in. I have a boat without a mast. 37 foot Ranger early generation IOR boat (early 70s vintage). I have a lead on a carbon fiber mast that is the identical Hall extrusion used on a J120 and J130, and came off a Tripp 41 that was wrecked. Keel stepped on both boats, masthead rig on both boats. The carbon mast is 61 feet and the original Ranger rig (Tall rig) is around 54 feet overall. Question is how do I get the round peg into the metaphorical square hole.

    Obviously buying a new mast is preferable, but that is not in the cards.

    I have been in contact with Hall and they gave me the details on the original mast including the section, which is as follows.

    Tripp 41
    P = 49.87'; ISP = 56.50' 202C section
    Triple spreader rig and all spreaders have 15 degree sweep
    Carbon bolt rope mainsail track
    Mast jack system with lifting bar, bricks, STP hydraulic pump
    Total overall length is 61'
    Diameter is 8 5/8" by 4 13/16"

    Ranger 37
    P= 42.83 ISP = 48.4

    My problem/question are as follows:

    1) The rig is used on a J130 with much more total sail area (955.88 vs 628.8 for the ranger). So I am guessing (dangerous) that the mast is more than strong enough for my boat, even without the triple spreaders. Is this a bad/foolish assumption?

    2) my old IOR boat uses inline spreaders and this mast has swept back spreaders attached with spreader bars. Is there a way to convert from swept to inline spreaders without changing spreader bases or monkeying with the attachment points? Could I swap the swept spreader bar for a straight spreader bar easily? If I swap spreader bars can the original spreaders me adjusted to fit the new angle (these tings are not cheap).

    3) Can I leave the triple spreaders rig or is it necessary to mimic the original single spreader rig. Triple would just be that much stronger, but is there some other design aspect I am missing?

    3) If spreaders could be dealt with, I still have almost 8 feet of extra mast up top. IF I cut, where do I cut? Up top or down low? Down low means moving all the boom attachments and halyard cutouts etc, but as I would be cutting 8 feet off, all the old holes would essentially be gone and I would be attaching things to relatively undisturbed carbon fiber. Cutting it up top means I would either have to attach a new masthead box(if there is one, or are they typically built in)? It would seem cutting the bottom makes the most sense here.

    And yes, this all sounds a bit crazy to me too, but I am trying to feel things out here before consulting a NA and formally moving forward. Section size is 8 5/8" by 4 13/16 "

    Thanks everyone.

  2. gggGuest
    Joined: Feb 2005
    Posts: 864
    Likes: 38, Points: 28, Legacy Rep: 76
    Location: UK

    gggGuest ...

    Unless you know exactly what you are doing I would counsel against changing the various anchor points, shroud, halyard etc, with the possible exception of the top and bottom. Depending on how the mast is put together there may well be local special treatment.
  3. messabout
    Joined: Jan 2006
    Posts: 3,332
    Likes: 470, Points: 83, Legacy Rep: 1279
    Location: Lakeland Fl USA

    messabout Senior Member

    I presume that you have the sails from the Ranger. Those sails, if they were good ones, would have been cut to marry well with the Ranger mast. The bend characteristics of the CF mast will likely differ from the Ranger mast. If so, you may need to have the sails re-cut to match the characteristics of the CF mast. Just one more cost factor that rears its' ugly head.
  4. Beezer
    Joined: Mar 2014
    Posts: 34
    Likes: 15, Points: 8, Legacy Rep: 10
    Location: Naptown

    Beezer Junior Member

    I posted this Q elsewhere and it seems that the stress areas are strengthened by hall So it looks like a no go for that mast as I would need to change spreader locations and boom base. Good news (or not) is that I have no sails so it is a fairly blank slate.

    Thanks for the reply
  5. bpw
    Joined: May 2012
    Posts: 291
    Likes: 5, Points: 18, Legacy Rep: 34
    Location: Cruising

    bpw Senior Member

    Any chance the new mast is light enough you could leave it full length? Maybe go to a fractional rig?

    The rig loading is related to righting moment, not sail area so you should look into that.

    Where is the spar located? if it won't work for you I may have an interest...

  6. gonzo
    Joined: Aug 2002
    Posts: 16,576
    Likes: 1,560, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    Modifying the spreader bases would be the easiest way to reuse the mast. The problem may be at the gooseneck, because after you cut the base of the mast, it will need to be repositioned. That may require some structural reinforcement on the mast. Unless the mast is free or really cheap, there are plenty of aluminum masts you can have for not too much money. Where are you located?
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.