Tips on Dagger Board Trunk Construction?

Discussion in 'Boatbuilding' started by CatBuilder, Dec 21, 2011.

  1. CatBuilder

    CatBuilder Previous Member

    I plan to make my board trunks from foam/glass, since they are below the waterline and I don't want to have to re-do this in the future.

    It's time to put them in now, while the hull is upside down.

    Does anyone have links showing how these are constructed, with pictures and descriptions?

    My design shows everything, but I'm not 100% clear on the steps involved, the order of construction, or while glass goes inside or outside.

    Thanks
     
  2. Phil Locker
    Joined: Oct 2004
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    Phil Locker Junior Member

    If there is core involved, then both sides have to be 'glassed.

    If your daggerboard(s) have a simple rectangular cross section in the head, this is pretty easy construction. You're just building a box, possibly with a channel for control lines.

    If the board(s) are foil-shaped top to bottom, it can be best to use the daggerboard itself as a male mould to laminate the trunk over.

    I'm attaching an example of the latter, complete with control line channel.
    This one is solid laminate, no core. (actually we didn't use the daggerboard as a mould as it had a curved tip section... we cut a plug of the same foil section but rectangular planform).

    Phil
     

    Attached Files:

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  3. Yobarnacle
    Joined: Nov 2011
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    Yobarnacle Senior Member

    Attached Files:

  4. CatBuilder

    CatBuilder Previous Member

    Thanks guys. It's a good start. The trunks are indeed cored, so of course I'll be glassing both sides, but there is a big schedule of laminates (3 triaxial, 1 uni) down at the base of the trunk, aft.

    I'm not clear if those laminates go inside the trunk or outside. It's not clear to me on the plans. What would be most likely? (Sometimes, I have to give me designer a break)

    Do all larger dagger board cases have control line channels? That would make a lot of sense for my particular design. The designer doesn't make any mention of the control lines in my plans.

    The automatic dagger board retracting invention is pretty neat. But... my board is about 13ft long x 3' wide and goes in this hull, which is 8ft from deck to keel. I need to control these boards from the cockpit with uphaul and downhaul lines...

    [​IMG]
     
  5. Silver Raven
    Joined: Oct 2011
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    Silver Raven Senior Member

    G'day to everyone & the very best of festive seasons greetings to everyone.

    I've now been in this 'boats & things' field for over 50 + years, so that's where I'm copming from.

    Phil & Dave @ fastcomposites are really - up-there - Great products, informative & user friendly web site. Hay guys - you 2 are a credit to the marine industry - for sure. Good fortune in everything you continue to do. Caio, james
     
  6. Yobarnacle
    Joined: Nov 2011
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    Location: Mexico, Florida

    Yobarnacle Senior Member

    If the cat has a very wide beam, instead of dagger board cases, you could have hinged swing up boards that reposed horizontal athwartship under bridge deck. They're pulled down till they are verticle in the water and tight against inner hull. No hull perforation, no case to build. Can't jam
     
  7. CatBuilder

    CatBuilder Previous Member

    The cat does have a 25ft beam, but...

    I'm sorry... I may not have been specific enough and you're kind of new here, so you may not know my story. I'm not designing a boat. This is a Kurt Hughes design. I'm just building it.

    There are dagger boards with trunks at about the fore and aft midpoint. I am getting ready to build these trunks now because it will be easier to cut the hole in the bottom of the boat while the hull is still upside down (as pictured). I don't have much clearance between the keel and the floor of the shop once the hull is righted and in position to join with the other hull. Low ceiling out at the 25' mark. Easier to install the dagger board case now.

    The plans show some diagrams of the trunk, but it's sometimes hard to understand exactly what you are doing from the plans. For instance, the reinforcements shown are in a separate diagram, which doesn't show me if they are inside or outside. Their purpose, being low and most concentrated on the aft part of the trunk, is obviously as impact protection. I just don't know if they go inside or out.

    I also haven't been fortunate enough to own a catamaran with boards yet, so this is my first experience trying to figure out the best way to rig the boards so I can control them from the cockpit via winch.
     
  8. Yobarnacle
    Joined: Nov 2011
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    Yobarnacle Senior Member

    ambitious project. good luck
     
  9. tunnels

    tunnels Previous Member

    I dont believe you !! are you chinese ??

    If you have plans for your boat and are now asking how to make dagger
    board s holders !!!
    What the hell did you pay all that money to the designer for a set of drawings for ???thats his job !! thats what he is on this earth to do!! to work out where and how and why so all you have to do is follow simple instructions !!!
    Its a bit like painting pictures by numbers !!
    Or are you one of those people that just likes to looks at the plans says stufff this and then throws them in the corner and do your own thing ?? Later when you have the boat in the water and you wonder why it dosent sail like it surposed to !!!ummmmmmm!!.
    You must be related to the people that run this company where i work !! :confused::eek:
     
  10. CatBuilder

    CatBuilder Previous Member

    ...and you must be related to either a rock or some kind of plant life. You're the guy that yelled at me for using Raptor staples to hold my glass during vacuum infusion. Do you know anything at all, or do you just come on here to yell at people and pretend you know something more than polyester resin and chopper guns?

    You need to get back in the shop where you belong, dripping in cheap polyester resin. You obviously have zero people skills. What a tool.
     
  11. Charly
    Joined: Dec 2009
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    Charly Senior Member

    LOL!

    Hey Cat, fwiw, my plans show uni re-inforcement down low and outside the trunk, along with triax, with the zero deg running fore and aft also, along with a doubler at the hull, and with the assembled trunk sticking through the hole in the hull (as opposed to butting the inside of the hull) I don't think you could put too much reinforcement down there aft of the trunk. My plans call for lots of bog and biax.

    The control lines, are probably not to detailed on the plans because there are so many different ways of leading them, making each situation unique. I have about decided to rout mine through a hole inside the boat, way up high against the overhead and lead aft under the companionwayand tyrned out through the hull side to the helm station.
     
  12. CatBuilder

    CatBuilder Previous Member

    Thank you *very* much, Charly. Those details are exactly what I didn't have on my version of the plans. That (along with Phil's post) should give me enough extra info to figure these out. Hope the project is coming along well for you...
     
  13. Charly
    Joined: Dec 2009
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    Location: st simons island ga

    Charly Senior Member

    except I am wondering how to keep the leaks out where the lines exit the hull into the cockpit. (?) pvc pipe maybe?
     
  14. waikikin
    Joined: Jan 2006
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    waikikin Senior Member

    Catbuilder, typically dagger cases come back to a solid laminate at top & bottom- the core is left out for say 4-6" particularly at the bottom for where the tabbing/laminate to the hull & deck skin, also particularly at the bottom the core material is removed for a specific(from designer) margin around the cases interface thru the hull bottom & replaced with extra layers of fabric & the inside skin relaminated over the lot + 6" or more & some times a knee/gusset is also laminated in place or a convenient bulkhead. Some times the case is laminated in over the daggerboard with addition of packing material(such as corrugated cardboard & a realease film or coreflute or such for clearance) or even laminated strait onto the faired & painted dagger + wax & release agent- with this the trailing edge is not joined side to side & once the dagger is out this is spread some for clearance & the case extended slightly & then joined side to side. I read Kurts boats can incorporate some kind of crush/crash box- never seen one though. Some case are rectangular & use guides top & bottom(esp if you want to alter the board profile or "tune" toe in or such). Treat the interface of case to hull like a big skin fitting/thru hull(which it kind is) & "close out" the core.
     
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  15. waikikin
    Joined: Jan 2006
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    waikikin Senior Member


    with control line channels you might not need them with the "cut out" in your boards, they can also be in the board unless you want to be able to end for end them. If laminating them into the case its simply a matter of "adding" a sealed batten to laminate over- this can be held in place with a few dabs of hot melt glue then radiused in with "plasticine" from your composites supplier then waxed & release agent so they dont become a permanent! installation.
     
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