I'm going to make holes in my mast!

Discussion in 'Multihulls' started by Meanz Beanz, Jun 16, 2007.

  1. Meanz Beanz
    Joined: Jun 2007
    Posts: 2,280
    Likes: 33, Points: 0, Legacy Rep: 585
    Location: Lower East ?

    Meanz Beanz Boom Doom Gloom Boom

    Not big ones! What I am doing is making my halyards internal. Three in total, main, jib and spinnaker. The boat is a Seawind 24 Cat, she seems to be over built in many respects, the main beam is big enough to support the mast without a dolphin striker and I think that the mast has the same sort of reserve strength, its a bit of a telegraph pole for a 24 footer. I want to know if there are any rules of thumb when cutting the holes for the halyard exit plates. The holes will end up around 120mm long and 12mm wide, obviously they will be toward the bottom of the mast and to the rear and I will not overlap them. Is there anything I should be giving special consideration? Or no go zones like near the boom goose neck maybe? :idea: Any words of wisdom?

    Beams and mast are Aluminium by the way :)

    Thanks
     
    1 person likes this.
  2. lazeyjack

    lazeyjack Guest

    not really, as long as you make the slot finish as smooth as possible, using a router in a jig is good, but drilling the ends and cutting beween the holes with saw is ok, and filing and sanding smooth , so as to lesson any risk of fractures starting
    and then stagger, the slots,
     
  3. alan white
    Joined: Mar 2007
    Posts: 3,731
    Likes: 121, Points: 0, Legacy Rep: 1404
    Location: maine

    alan white Senior Member

    Spose you lose any in-mast flotation you might have. Maybe there was none.
    Jib is probably 3/4, not 100%, and if so, you might save an exit plate (entrance for jib halyard) by running up to the crane and down inside (a small amount of wire will be exposed forward of the mast). This would be where the shroud tangs would be too, and so going up to the crane would be one less hole in a very stressed area.
    It is also very difficult to know exactly where to place the "entrance sheave" for the jib once the mast is down. It has to be lined up perfectly. If your rig is a 3/4 or 7/8 rig, and you do put an entrance plate/sheave on the forward face, it might pay to climb the mast when on the hard while the rig is still up and carefully mark the point of entry. This would be a good idea even if you relocate the jib halyard block at the head of the sail to run up to the crane.
    All this is assuming your forestay doesn't go all the way up.

    Alan
     
  4. Meanz Beanz
    Joined: Jun 2007
    Posts: 2,280
    Likes: 33, Points: 0, Legacy Rep: 585
    Location: Lower East ?

    Meanz Beanz Boom Doom Gloom Boom

    Thanks guys,

    No the mast offers no flotation at all and the jib halyard block is placed just below the forestay also its a rotating rig so this limits the opportunity to enter the mast higher, too many fittings in the way. I intend to take the entry point for the kite halyard up about a meter or so but not to the masthead, the boat is a 3/4 rig so mast head is almost 3m above the hounds with 10.6m of stick in all.

    I'm using some Ronstan exit plates LJack, they need rounded ends in the slot to fit but yes I agree no sharp corners, that just invites trouble at some point.

    Cheers
    MB
     
  5. waikikin
    Joined: Jan 2006
    Posts: 2,293
    Likes: 92, Points: 58, Legacy Rep: 871
    Location: Australia

    waikikin Senior Member

    Meanz Beanz, I wouldn't bother with the exit plates esp if all rope halyards as they'' deflect the halyard thru greater angle & often require a bigger(badder) hole than is needed, just smooth it up sweet as lazy said is most important other than that sounds like your going good with gooseneck avoidance & staggering, dont put them too low though as it restricts pumping the halyard up & sweet angles to cleat off ,also I usually just step into a bight of halyard for final tension. Regards from Jeff.:)
     
  6. Frosty

    Frosty Previous Member

    Im not a specialist on masts much but I once converted a keel step to deck.

    The reason I say this is because the mast had a foam core inside it at about 2 foot from the deck. This had failed and water was entering the boats bilges, ( reason for conversion)
    If yours has the same the mast would need to be removed to get this mess out.
     
  7. Meanz Beanz
    Joined: Jun 2007
    Posts: 2,280
    Likes: 33, Points: 0, Legacy Rep: 585
    Location: Lower East ?

    Meanz Beanz Boom Doom Gloom Boom

    Hi waikikin ,

    Yeah I might think about just making some slots, I'm going to paint the mast with 2 pak anyway so it would end up looking fine. I think your right that the slots would end up smaller than the holes required for Ronstan plates + cheaper too!

    Hey Frosty, the mast is down and clean at the moment, nothing like foam blocks etc only a couple of through bolts, don't forget shes a cat and the mast is stepped on a beam.

    I'm going to use all rope (spectra) halyards, it might cost a little more but I don't want to mess around with wire & wire rope splices etc.

    Cheers
    MB
     
  8. catsketcher
    Joined: Mar 2006
    Posts: 1,203
    Likes: 88, Points: 48, Legacy Rep: 790
    Location: Australia

    catsketcher Senior Member

    Slots sound wide

    Hello Meanz

    When I made my mast I was told by the Allyacht spars bloke to keep the slots as thin as possible. I listened to his advice because the man was John Sayer and he has designed and built a few good boats. I would think that 8mm spectra halyards would be fine for a Seawind and so you need about 9mm slots. When the slots are finished sand them and then get out the wet and dry and polish them with 1200 grit. Mine have gone about 10 000 miles and the halyards are still in great shape.

    have fun

    Phil Thompson
     
  9. Meanz Beanz
    Joined: Jun 2007
    Posts: 2,280
    Likes: 33, Points: 0, Legacy Rep: 585
    Location: Lower East ?

    Meanz Beanz Boom Doom Gloom Boom

    Hey Phil,

    Yes I was going for 8mm, a bit over strength but a reasonable compromise between $$$ and hand comfort. The 12mm slot was all about the Ronstan exit plates (approx), if I don't use them a 9mm slot would be fine I suppose.

    I like Sayers boats, I remember a concrete one in Sydney called the "Flying Footpath" racey looking thing for concrete and went quite well by all accounts, a real oddity :)

    How did you line the slots up? I was thinking of pulling a builders line on the outside of the mast down the path the halyards would follow. The slot would end up just off the vertical but it will minimise chaff, or did you just cut them vertical?

    Cheers
    MB
     
  10. catsketcher
    Joined: Mar 2006
    Posts: 1,203
    Likes: 88, Points: 48, Legacy Rep: 790
    Location: Australia

    catsketcher Senior Member

    Lining up slots

    I can't remember if I lined up my slots vertically or not. I did take care to make sure they lined up correctly for winches etc. Check and double check as the way halyards will lead to a pulley or winch will differ from straight down.

    I like the idea of builders string led outside the mast to give you the correct line. Easy and will do a good job. Put it through the blocks you will use at the mast base and tie it up top.

    cheers

    Phil
     
  11. Meanz Beanz
    Joined: Jun 2007
    Posts: 2,280
    Likes: 33, Points: 0, Legacy Rep: 585
    Location: Lower East ?

    Meanz Beanz Boom Doom Gloom Boom

    I'm going to put some rope clutches on the mast after the exit slots and then spring base turning blocks at the base of the mast. So the slots and clutches will be in a straight line and the blocks will have enough movement to handle any angle. That way I can haul the sails up while standing and then run the halyards on to a winch for tightening. I have to to it this way because the mast rotates so everything must terminate on the mast.
     

  12. Meanz Beanz
    Joined: Jun 2007
    Posts: 2,280
    Likes: 33, Points: 0, Legacy Rep: 585
    Location: Lower East ?

    Meanz Beanz Boom Doom Gloom Boom

    Mast is painted, back together and back in place. Halyards all run well and the setup is much neater that the original. The test sail ended up being in 22 knots of breeze and a good chop, wet wild and fast but it all held together well so it must be strong enough. While I was at it I have been playing with the rake on the mast. I now have it raked much further that most SW24's, she handles it well and it appears to have greatly improved upwind performance. It also has minimised some interesting lee helm issues off the breeze. I plan to add a dolphin striker soonish and that should help improve upwind performance and eliminate the rest of the downwind lee helm issue as it appears to be related to flex in the mast beam.

    Cheers
    MBz
     
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.