[PCW] In praise of outboard-powered cats

[Suzanne & Lloyd Kubis]

One other benefit of the outboards I forgot to mention was the fact one can
shut down one of the engines and raise it out of the water to eliminate the
drag, to save fuel which is an important consideration these days!! I do this
often as I have a 45 minute trip up and down the river we live on to reach the
Pacific! The river is speed restricted so it is pointless to run with boat
engines, even at near idle. Shutting the one down saves over a third of the
fuel consumption even when running the remaining one at higher RPM to maintain
the same speed! Being an outboard, manoeuvrability is still the an issue like
on fixed props!

This is a technique used by many of the locals on longer passages as well!!

Hope this helps in the debate!!

Cheers!
Lloyd
40 ft Ozzy Cat
KaBitta
  ----- Original Message -----
  From: Georgs Kolesnikovs
  To: Power Catamaran List
  Sent: Tuesday, April 22, 2008 5:25 AM
  Subject: [PCW] In praise of outboard-powered cats


  >Quoted with permission from a private email from Lloyd Kubis
  ><kubisl at iprimus.com.au>, a Listee Down Under:

  I have a Honda 3+ Kw unit and it's a little honey!! It starts with
  the turn of a key,is vibrationless, light to carry for two, very
  quiet even quieter than the smaller 2Kw units that Honda offers and
  it handles short overloads well! Also runs a long time on its own
  tank when in the economy mode. I was going to plumb it into my boat's
  fuel tanks but haven't bothered as it runs long enough for us!!

  On my Cat it powers two Crusair airconditioners, one a 5KBtu and a
  16.5KBtu unit, a 40A charger plus misc power points without any
  strain, even when both aircons decide to start up at the same time!!
  Actually a 2Kw Honda will easily power up a 5KBtu aircon and run it!!
  It may even do the 16.5K unit but not both, particularly if both
  start up at the same time!!

  Having owned a couple of 40 ft Powercats, one having a pair
  of 6cyl Yanmar diesels and the other a pair of 6 cyl Suzuki 250's on
  them, I have watched the various opinions on gas outboards vs diesel
  inboards with some amusement.   In my opinion, the debate has missed
  a number of differences that in practice matter much more than the
  ones being speculated on!!

  Initially, I too spurned gas outboards but then I discovered that
  most of the locals here in Australia on the Gold
  Coast, overwhelmingly preferred outboards on their Cats!!

  Having owned the diesel powered Cat first, I quickly discovered the
  problems of owning and operating diesels on smaller Cats.

  Even though the engine access on my 40 ft production built Cat was
  much better than most around here, it still presented serious
  service issues because by default having a Cat hull means limited
  side access to the engine. The narrower the hull the worse it gets!

  Guess what -- the Yanmar's coolant pump access was on the bottom side
  of the engine. Checking or replacing the cooling water impeller
  was near impossible as it meant disassembly of a good deal of the
  front of the engine, usually worth a day or so and a lot of
  unbelievable language emanating from the hold!! Even simple things
  like belt adjustment and oil filter changes resulted in a major
  effort. I know of one local Cat design where the front of the diesel
  is only accessible by crawling over it from the back and using the
  Braille method of adjusting/fixing things on the front of the engine!
  Try this out on the ocean with a hot engine!!!

  Secondly, here in OZ, barnacles seem to grow overnight on anything
  left in the water! My fixed props were always getting fouled,
  reducing the power and causing vibration on the boat. Yes I know
  there are all sorts of magic potions one can put on the props to
  prevent this growth, tried most of them!! All wasted money as they
  all lost effectiveness in a short while due to either wear or running
  on sand bars, which everyone does here eventually!! Many were useless
  as well!!

  I also discovered that the problem of using gas on boats is overrated
  as most pleasure craft are gasoline powered.   Locally just this past
  week we had diesel powered commercial trawler with 6000 L of fuel on
  board burn and sink as a result of an engine room fire. With the
  thousands of boats in the area, mostly gasoline powered,  I can't
  remember another fire in last few years. Certainly no CO mishaps!

  My major reason for buying the outboard powered boat was the prop
  issue and the fact I could raise them clear of the water. Secondly,
  as we have a lot of thin water around here it was possible to reduce
  the draft and also to get off the bars more easily.

  But there were many other benefits that we discovered along the way
  -- the most obvious immediately was how quiet and vibrationless the
  outboard powered boat was, particularly near idle! Many times I had
  to look at the RPM gauge to determine if the engines were running as
  I could not hear them from the helm position! Even at full throttle
  it was much quieter and vibrationless!!

  Manoeuvring was much better  and more responsive with the outboards,
  which is one reason why the local fisherman prefer outboards
  particularly when crossing the bar!

  Servicing as expected was a breeze and less costly! Mechanics were
  not a problem to find as there was good choice!! Has anyone noticed
  how mechanics suddenly become too busy when they find out that one
  has a diesel  powered cat??? I think I was often put on the bottom of
  the list as being "too hard"!!

  There was no diesel fuel bug and polishing to worry about!! No
  barnacles to clean out of the heat exchangers as on the diesels!! I
  could trim the boat easily with outboards to adjust for any load
  differences.

  One negative was the use of control cables on my long Cat!! Although
  more positive perhaps and probably good on shorter boats, I'd stay
  away from them on longer boats as they are difficult to
  operate. Fortunately Suzuki has solved this now as they have built-in
  electronic controls on their higher powered engines ~~ a bit too late
  for my engines!!

  Cheers!
  Lloyd

  KaBitta
  40ft OzzyCat
  _______________________________________________
  Power-Catamaran Mailing List