Conference unifix::sailing

Plumb bows innovative? Seems to me I've seen drawings and pictures of
19th century pilot boats and fishing trawlers with plumb bows (and full
keels of course). 

  I've sailed a '110', which is a small keelboat with a plumb bow.
I would guess that the main reason for a plumb bow is racing rules based
on LOA rather than LWL.  (Lenght Over-All and Lenght Water-Line).  The
BOC race is a good example.  Most BOC boats have plumb bows.

  Is it possible that pictures of BOC boats will help sell this
'innovation'?

    In traditional boats, plumb bows are associated with wet boats.
    This is because there is usually little flare with a plumb bow,
    because it requires extreme bends in the planking to build the flare.
    This should not be an issue with fibreglass boats. But I would be
    interested to see just what the shape of those bows are. If the
    have a strong flare, they may have rather funny waterplane shapes
    when heeled. I suspect the main reason for plumb bows is (as stated)
    racing rules, a desire to get maximum interior volume on limited
    length (LOA is critical in Europe due to slip and dockage fees),
    and simple product differentiation.
    
    Ross Faneuf
    

    I tend to agree with .2
    
    Within a fixed length (such as certain racing classes with LOA limits
    and little else), one way of maximizing theoretical hull speed is
    to eliminate the bow and stern overhangs. Whether that translates
    to a safe, comfortable cruising design is sometimes questionable.

    My speculation:
        
    While a plumb bow would give you room to move girth further forward
    with the same underwater shape (and add interior volume) I wonder
    how a boat like this would react sailing into waves.  I suspect
    it would be more likely to drive thru waves and put a lot more water
    on deck than a similar hull with a sloped bow (where bouyancy increases
    as a wave attempts to submerge the bow, lifting the bow). On the
    other hand it would probably hobbyhorse less.

    
    Walt

    There are some more contemporary designs with plumb (or near plumb)
    bows than the 110.  I'm familiar with the Evelyn 26 which is a morc
    racing oriented design.  Max waterline is clearly the overriding
    design goal with this boat and its performance reflects it.  Very
    fast for its size, despite the standing headroom and generous beam.
    Almost as big inside as the C&C26 but much faster.  I"ve been aboard
    in 20+ knots and the deck stays nice and dry.  Lots of freeboard
    so you're above the waves but you do hobbyhorse.  However, there
    may be one drawback.  Every time I sail by the boat on its mooring,
    someone on board my own boat mutters "Man is that ugly".  

Re: .3 & .4 -  I think you're both correct in your surmisings.  Though my 
meager yacht design background hardly qualifies me to enhance Ross' reply, 
I do know that most modern plumb stem designs should be sailed quite 
upright in order to gain their potential speed advantage.  The waterline
planes at larger angles of heel begin to look strange (and perform poorly.)
If those who like to work to keep their boats level -- changing sails &
shifting weight constantly -- this may be an exciting design trend!

The BOC boats have plumb stems mostly to maximize LWL for the class they
are in, and thus speed in displacement mode.  That they may influence
recreational boat design based upon some new idea of what "fast" should
look like without clear consideration of seaworthiness is discouraging. 
(They also round the deck edges to reduce wind resistance!)  But
predictable...look at all the funny-looking IOR bumps and squeezes on
recreational boats 10-15 years ago! 

Unless the plumb-stemmed boat is very light and has a low pitching moment,
doesn't it seem to suggest a wetter boat than one with flared bow and
overhang? 

John.