Tips on Dagger Board Trunk Construction?

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

  1. AndrewK
    Joined: Mar 2007
    Posts: 475
    Likes: 33, Points: 28, Legacy Rep: 344
    Location: Australia

    AndrewK Senior Member

    Regarding the discussion of suitability of styrofoam for the spacer, yes the common 22kg/m3 can be used and will not crush.
    But I would only use this if making a split case, one side at a time. The reason is that you can not drape it over the leading edge like the spacers I mentioned or the wound rope. You would end up with lots of wrinkles and possibly crimps over the leading edge.

    Making the case in halves and joining is not a problem, this is how production cases are made. You use two male moulds to produce each half, but the laminate at the solid leading and trailing edge is kept to a minimum initially. You add the bulk of it after the halves are glued together.
  2. Tigawave
    Joined: Sep 2007
    Posts: 39
    Likes: 2, Points: 0, Legacy Rep: 12
    Location: Buckland

    Tigawave Junior Member

    I'd like to offer an alternative view seeing as Thordon has been replaced by a more advanced bearing composite in some applications.

    I feel manufacturers such as Thordon use the elastomeric properties of their bearing material as a benefit when it may not help at all. If you have a material that gives under pressure whatever mechanical system you have designed will flex more as the bearing pad gives. To transmit forces you don't want rubber, you want a rigid structure. A foil is designed as a precision part which you don't want to twist and bend. There are materials which have as good or better bearing properties with regards to friction, load distortion and thermal change and these are rigid non melting, they also now have surface chemistry and surface properties to resist marine growth.

    So if you build a lifting dagger board do you really want it to flex, bend or move in its mount? You spend a fortune getting a super rigid carbon foil so you need the fixings to be as rigid as you can get.

    One of the latest materials comes out of Perth it's called Maritex and is used on some high profile applications such as latest (military) submarine dive plane designs as well as yachts like Baltic Yachts panamax in the lifting drive pods. It will exceed the performance of an elastomeric material when under high load in pretty much all cases.

    Do some research and see where current technology is.
    1 person likes this.

  3. CatBuilder

    CatBuilder Previous Member

    Phil, what did you use as a spacer between the plug and trunk? Also, could you pm me regarding a build of trunks for my boards? This is wasting too much time for me...
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.