Closing in pocket tunnel

Discussion in 'Fiberglass and Composite Boat Building' started by fjlegend, Oct 1, 2009.

  1. fjlegend
    Joined: Apr 2008
    Posts: 12
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: HotLanta

    fjlegend Junior Member

    I have a custom pocket tunnel that was added by a previous owner on my 20' center console. I would like to close it in as I think it is hurting more than helping.

    How should I go about closing this in? Here is a pic:

    [​IMG]

    Also do you think I will need to lower my motor? It is full down in the picture on a 6" bob's jackplate.
     
  2. gonzo
    Joined: Aug 2002
    Posts: 15,500
    Likes: 1,039, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    You'll have to lower the motor. The easiest thing would be to fill the cavity with foam and glass over.
     
  3. fjlegend
    Joined: Apr 2008
    Posts: 12
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: HotLanta

    fjlegend Junior Member

    I recall that the cavitation plate should be level with the keel. Since I have a setback I would think it could be a bit higher.

    Any thoughts are welcomed.


    kls
     
  4. Commuter Boats
    Joined: Oct 2006
    Posts: 177
    Likes: 12, Points: 18, Legacy Rep: 182
    Location: Southeast Alaska

    Commuter Boats Commuter Boats

    Rather than filled the tunnel you might try a propeller better designed to operate in the conditions yours is in, that aluminum propeller won't hold water very well.
    I would suggest a stainless steel propeller with thin blades and a lot of cup. You'll have to go to somebody more knowledgeable of the current propellers that are available but any good prop shop could help you.
     
  5. fjlegend
    Joined: Apr 2008
    Posts: 12
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: HotLanta

    fjlegend Junior Member

    The pic I posted is before I changed to a 4 blade trophy plus prop. The prop changed helped some but performance still is sketchy. Trim and jack plate have to be just right and it is very touchy. Then I added a Mantaray Cavitation plate that is designed just for tunnel hulls. This is not your average wing. It is huge and designed to keep water around the prop. Performance improved some but overheating became a problem mainly due to having change how I ran the motor. I don't have a pressure gauge so it was trial and error.

    Third option is to lengthen the trim ring on the transom by about 5" or as big as I can get away with. Not sure if I want to go this route as I think the tunnel is of poor design. Filling it in an being done with it seems easier.

    From my calculations I should have to lower the motor almost 8 inches. Seems like a bunch this amoutn would but my cav plate about 1.5" above the keel which is appropriate for the flatback design and 6" setback.

    I welcome further ideas on filling in the tunnel or modifications.


    Kevin
     
  6. Itchy&Scratchy
    Joined: Jul 2008
    Posts: 140
    Likes: 3, Points: 0, Legacy Rep: 117
    Location: Oxford & South Africa

    Itchy&Scratchy Senior Member

    I think you need to change your motor :mad: for a longshaft -looks like a shortshaft in the pic but difficult to tell.
    J
     

  7. fjlegend
    Joined: Apr 2008
    Posts: 12
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: HotLanta

    fjlegend Junior Member

    It is a 20" shaft. DF140TLK3

    Kevin


    The second last digit in the model
    designation refers to the boat transom
    height that the engine is designed to be
    installed on. Inspect the outboard to
    determine this code. The applicable
    transom height for some small motors is
    not indicated in the model designation as
    it is assumed to be short.
    S = 15”, L = 20”, X = 25”, XX = 30”
    Note: “G” or “Z” letters after the transom height
    designation indicates counter rotation.
    DF50TLX DF50TLX
    DF50TLX
     
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.