Conference vicki::boats

    One thing you would have to look at is the HP/efficiency curve(s) of
    one vs. two engines.  i.e. two engines running in an efficient RPM/
    Hp range could use less fuel than one engine running its guts out at
    cruising speed.
    
    Jeff

  The importance of the reliability is directly related to where you intend to 
do your boating.  

  I don't know about you, but my luck would put me 20 miles off shore, hearing
about a storm rolling in and THEN have my "big" engine crap out on me.  Out
running the storm at 20-30 knots would put me in protected water within an
hour, plowing home with the 10hp kicker MIGHT get me home in 4 or 5 hours of
hell.

  Do not discount the added manuverability you gain from twin screws.  The 
damage caused by one blunder in strong current or wind where the ability
to spin your boat nearly in place offered by twin screws would have avoided
crashing into a rock, piling, or another boat quickly offsets the economy of
a single engine.

  It all depends on what you intend to do with the boat!!!

YPYMAYTYC  (YouPaysYourMoneyAndYouTakesYourChoice)

Al

A few other thoughts to add to the good ones so far:

1) In the larger size you mention, twins may provide higher HP than any 
   single you can buy (such as twin 200's, for instance.)  Who knows if 
   you need that much power, but you did term this your "ultimate" boat.

2) Twins with counter-rotating props, which all the better large engines 
   offer, eliminate any torque steer.

2) Hull design should affect engine choice.  For a deeper V hull, a single 
   (outboard) engine means either a lower transom opening which can more 
   easily collect a following sea, or adding a Sea-Drive or other entended 
   engine mount.  The latter's advantage is more planing surface and 
   working room within the boat, but disadvantages include expense and 
   it's a longer way back to a much more vulnerable position if you need 
   to work on an engine or prop. 

3) Deeper V hulls also may benefit from twin installations in reducing the 
   draft.  In Florida Bay and the Keys, people really care about that, but 
   it may not be important to a New Englander.  Still, they have to be 
   mounted close enough to the centerline that when on a plane -- riding
   on the hull steps for a modern V -- both props are biting solid water,
   even in turns.  I heard about an owner-butchered installation in Florida 
   that looked impressive, but he couldn't get onto a fast plane because
   the props from his wide-mounted 175's lifted high enough to grab air
   under the hull.  I saw the telltale original transom holes as it sat in 
   the marina.

J.

    Maneuverability alone is not a good enough arguement for a second
    engine; engine and drive setup is what, $5k plus?  A bow thruster,
    which can be had for as little as 1K makes a lot more sense, weighs
    less, takes up less space, requires no extra fuel capacity, and is more
    maneuverable to boot.  
    
    I'd spend the money on better maintenance of the single engine, radar,
    maybe an autopilot, GPS unit, etc.
    
    I must say, though, that there is something about the allure of
    twins...
    
    Carl

    A bow thruster puts the bow where you want it. It does nothing for the
    stern. Twin engines put the stern where you want it. Of course you can
    buy a stern thruster also, but I vote for twins. A lot of big
    motoryachts with twins have bow thrusters as well. Besides, I like the
    feel of a nice set of Morse controls, those "joy stick" controls for
    bow thrusters feel like you are playing a video game.

    Single Versus Twins --
    
    A little late, but a nice note -- I've only had twins on my boats and
    wouldn't trade them for the world  -  I've seen boaters showboating
    with bow thrusters and - yeah their nice, but a thruster won't gt U
    back to port.
    
    I run on the Great Lakes and have been in situations where one of my
    engines has puked -- Matter o'fact, last year I puked the port one
    while underway at speed on the Detroit River -- With a 7 Knot current
    and slugs of other boats around, going from one to none wouldn't have
    been an alltime happy experience.
    
    A twin screw boat is a dream to maneuver in close quarters.  I have a
    42 that handles beautifully in tight docking situations -- I won't even
    let dock hands touch the boat until she's completely stopped, lest they
    screw up my docking maneuver.
    
    If you want security, great handling, and overall general performance,
    twins do it better.
    
    Of course there are downsides --
    
    Double trouble
    Double costs
    Fuel Costs
    
    BUT how many times have U blown a docking maneuver in front of a crowd?
    Generally won't happen with a twofer!
    
    Regards,
    
    Cap'n Ahab