In praise of outboard-powered cats
Quoted with permission from a private email from Lloyd Kubis
kubisl@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
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@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
Lloyd raises several very valid points regarding the benefits of outboards.
But giving up about a third in fuel economy/range is a very stiff price to
pay for those benefits.
In addition, outboards don't provide a reasonable option for adding
engine-powered accessories such as high-output alternators and hydraulics.
Some of the issues Lloyd raises with fixed shaft props are addressed by
running with outdrives.
As usual, a "series of compromises"...
Bob Deering
Juneau, Alaska
From my experience, a difference of a third is a little high for the large new
computer controlled outboards!! I'd put it more in the low 20's!
Out drives I see around here are a big problem!! The boat designers and
builders like them as they are easy to install but the users get to hate them
as most require major expensive annual overhauls ( in warm salt water).Alaska
may not have a barnacle problem but a good deal of the world does and then
one's perspective changes. One has to always consider the impact of the
cruising area and it's inherent conditions, there is no single solution for
all!!
Secondly most outdrives still cannot get the prop clear of the water!!
Just my view from boating in tropical waters!!!
Cheers!
Lloyd
----- Original Message -----
From: Robert Deering
To: 'Power Catamaran List'
Sent: Tuesday, April 22, 2008 11:25 AM
Subject: Re: [PCW] In praise of outboard-powered cats
Lloyd raises several very valid points regarding the benefits of outboards.
But giving up about a third in fuel economy/range is a very stiff price to
pay for those benefits.
In addition, outboards don't provide a reasonable option for adding
engine-powered accessories such as high-output alternators and hydraulics.
Some of the issues Lloyd raises with fixed shaft props are addressed by
running with outdrives.
As usual, a "series of compromises"...
Bob Deering
Juneau, Alaska
Power-Catamaran Mailing List
I am reminded of the quote in PowerBoat Reports
quite a few years back describing outdrive power
as being the worst of all means of moving a boat!
HUGE hole (or holes) at the stern of the hull, large
amounts of easily corroded metal permanently
in the water, among other things.
** D C "Mac" Macdonald **
- m/v Another Adventure *
** '95 Carver 355 ACMY ** - Grand Lake - Oklahoma *
** USPS & AGLCA (#217) ** - K2GKK -- USAF/retired *
Date: Mon, 21 Apr 2008 17:25:40 -0800
From: deering@ak.net
To: power-catamaran@lists.samurai.com
Subject: Re: [PCW] In praise of outboard-powered cats
Lloyd raises several very valid points regarding the benefits of outboards.
But giving up about a third in fuel economy/range is a very stiff price to
pay for those benefits.
In addition, outboards don't provide a reasonable option for adding
engine-powered accessories such as high-output alternators and hydraulics.
Some of the issues Lloyd raises with fixed shaft props are addressed by
running with outdrives.
As usual, a "series of compromises"...
Bob Deering
Juneau, Alaska
Well, opinions...everyone has them.
Lately I have been able to compare outboards against inboard outdrive
motors fitted our Aventure 32, we offer both.
outboards are easy to maintain, powerful when eventually you have the
correct
prop configuration, speed versus fuel.
Petrol is not quite the answer and it is still heavy on fuel when we compare
to the inboard diesel outdrive, very economical by half, less maintenance
and in the water the boat with outdrives looks more attractive, I think.
Tim aventure power catamaran
----- Original Message -----
From: "Robert Deering" deering@ak.net
To: "'Power Catamaran List'" power-catamaran@lists.samurai.com
Sent: Tuesday, April 22, 2008 3:25 AM
Subject: Re: [PCW] In praise of outboard-powered cats
Lloyd raises several very valid points regarding the benefits of
outboards.
But giving up about a third in fuel economy/range is a very stiff price to
pay for those benefits.
In addition, outboards don't provide a reasonable option for adding
engine-powered accessories such as high-output alternators and hydraulics.
Some of the issues Lloyd raises with fixed shaft props are addressed by
running with outdrives.
As usual, a "series of compromises"...
Bob Deering
Juneau, Alaska
Power-Catamaran Mailing List