Raised cabin vs flush deck

Discussion in 'Sailboats' started by gmat, Nov 16, 2013.

  1. gmat
    Joined: Nov 2013
    Posts: 14
    Likes: 1, Points: 0, Legacy Rep: 20
    Location: California

    gmat graham

    When you say extra windage, are we talking 10% or 50%. I am trying to understand the effect on boat speed of the extra windage.
     
  2. tom28571
    Joined: Dec 2001
    Posts: 2,474
    Likes: 117, Points: 63, Legacy Rep: 1728
    Location: Oriental, NC

    tom28571 Senior Member

    Probably well under than your 10% in all cases but it is too dependent on a particular design to say. I see the one design San Juan 21s where some are flush deck and some are trunk cabin boats racing against each other regularly with no rating penalty. There is bound to be some extra windage but it is apparently not enough to cause concern.
     
  3. PAR
    Joined: Nov 2003
    Posts: 19,126
    Likes: 498, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    I use to race with San Juans and the only time windage was really noticeable among the two types was in very light winds, naturally up wind was the place the extra windage hurt.
     
  4. dlblandjr
    Joined: Aug 2012
    Posts: 4
    Likes: 0, Points: 1, Legacy Rep: 10
    Location: Grafton ,Il.

    dlblandjr New Member

    Many thanks for the interesting thoughts posed herein, I am an old codger m'self, I had a old steel hull ketch of 43' unknown designer, built in kiwi 1940's I loved the look of that ship. However now that would be too much work for me to sail myself, so I've a little 26' sloop, which just happens to have a similar superstructure, if it could be called such, as the 20' er pictured above,. When I got it, I thought it rather queer looking, however, I have come to really enjoy the tuff little girl greatly! I would point out I was amazed at her wave taking ability, tremendous stability in the little girl! Sailing her on Lake Superior now, Good day all!
     
  5. capt vimes
    Joined: Apr 2009
    Posts: 388
    Likes: 14, Points: 18, Legacy Rep: 247
    Location: Austria

    capt vimes Senior Member

    wehn we are talking racing - in my eye the only situation were windage is of any concern - the flush decks have another big advantage:
    sheeting angle...
    see the images below - do you think those tight sheeting angles would be possible on a stepped deck?
     

    Attached Files:

  6. Skyak
    Joined: Jul 2012
    Posts: 1,462
    Likes: 145, Points: 63, Legacy Rep: 152
    Location: United States

    Skyak Senior Member

    I have not seen any mention of port placement and security yet. A flush high deck increases volume below, but eliminating ports cuts the perception of space, makes it less useful and less attractive.

    You might say that the same amount of port space could be added to the flush deck design but those ports are much more critical because they go deep under green water just putting the rail down, even before the mast tip hits. Moving ports 'down' to the topsides makes them critical and more expensive. Thus they are often minimized or even eliminated. Without horizontal views the space below becomes far less useful underway. I would also point out that seasickness can be severe enough that crew might not be safe above, and without views of the horizons below the seasickness will likely worsen below. A seagoing boat should have a safe refuge with views of the horizons.

    Personally I like flush decks from the mast forward and a nice pilothouse aft. The wimpy port lights in many production boat's raised cabins are not up to a full roll so...
     
  7. michael pierzga
    Joined: Dec 2008
    Posts: 4,862
    Likes: 116, Points: 0, Legacy Rep: 1180
    Location: spain

    michael pierzga Senior Member



    Gee...tight sheeting angles work fine on cabin tops....just put a track down. Deck sweeper tp52 headsails arent suitable for normal boats.

    And with flush teak foredecks ..they may look cool ...but you need studded golf shoes to work on them


    http://[​IMG] subir imagenes gratis
     
  8. foxy
    Joined: Aug 2009
    Posts: 25
    Likes: 1, Points: 0, Legacy Rep: 20
    Location: Florida

    foxy Junior Member

    A lot of the examples shown are flush deck, but not raised deck like the CAL example. The flush deck is feasible when you have heavy displacement and the sole can be well below DWL or when the boat gets big enough that the freeboard is not excessive in relation to the length of the boat.

    The raised deck works well with a center cockpit design such the Morgan Out Island series where it runs the full length of the boat. It somewhat masks the higher freeboard that the boat actually has.

    The raised deck also works on smaller boats as a way to mask higher freeboard and gain space below. A drawback not mentioned is that boats with high bows and raised decks tend to sail around a lot at anchor. They also tend to be harder to control under power in windy conditions such as when you are trying to pick up a mooring or come into a slip.
     
  9. michael pierzga
    Joined: Dec 2008
    Posts: 4,862
    Likes: 116, Points: 0, Legacy Rep: 1180
    Location: spain

    michael pierzga Senior Member

    Esthetically tall topsides look...well...tall !


    And since raising the deck to cabin top level doesnt create any extra headroom down below i find it not desirable.

    Some small boats benefit, but in general i dont like them.

    I f your thinking of a raised deck sail boat do some sketches of deck layouts and whatnot to be sure you are going in a doable direction.
     
  10. gmat
    Joined: Nov 2013
    Posts: 14
    Likes: 1, Points: 0, Legacy Rep: 20
    Location: California

    gmat graham

    If we put the ports up near where the side meets the deck (so at the same height they would be in the cabin design, but now on the sides), we address this issue to some extent.

    However, having said that, how waterproof are such ports? And does the hull material make a difference (fiberglass for example probably flexes more, breaking seals ...).

    I am trying to understand the trade-off in having ports in the hull sides but high up (since it's a flush/raised flush deck).
     
  11. michael pierzga
    Joined: Dec 2008
    Posts: 4,862
    Likes: 116, Points: 0, Legacy Rep: 1180
    Location: spain

    michael pierzga Senior Member

    You wont have a problen with ports....recess them deep into the topsides to prevent docking damage.

    Put a pad lock on them to prevent unauthorized opening by guests. Sailing with open ports ruins your day...

    A recessed port in the topside directly under the lifeline gate is a very nice detail. The recess give a good toehold when boarding from. dingy or alongside the dock..

    Inside the boat portholes must have curtains to block sun.
     
  12. dlblandjr
    Joined: Aug 2012
    Posts: 4
    Likes: 0, Points: 1, Legacy Rep: 10
    Location: Grafton ,Il.

    dlblandjr New Member

    ahoy Foxy, Try makin up a small riding sail, like the size of a tiny spitfire, only flown "backwards" if ye will, from the back stay.
    Good improvement on my boat to report, eh mate?
     
  13. michael pierzga
    Joined: Dec 2008
    Posts: 4,862
    Likes: 116, Points: 0, Legacy Rep: 1180
    Location: spain

    michael pierzga Senior Member

    To pick up a mooring, swing the stern into the wind directly downwind of the bouy ,then back into the bouy...you will have precise control and visabilty of the bouy at all times..

    Only boats without motor need to sail bow first into the bouy
     
  14. Milehog
    Joined: Aug 2006
    Posts: 571
    Likes: 121, Points: 43, Legacy Rep: 215
    Location: NW

    Milehog Clever Quip

    Michael, have you considered writing a tips and tricks book?
    You could name it... wait... wait... Tippy Tricks?!
     

  15. foxy
    Joined: Aug 2009
    Posts: 25
    Likes: 1, Points: 0, Legacy Rep: 20
    Location: Florida

    foxy Junior Member

    And then what? Do you stay moored by the stern or drag everything to the bow? Easier to pick the ball up at the bow in the first place.
     
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.