T&T: 3160 Cat Diesels and Repowering 20 Ton Boat
red...@travel-net.com
the ones we may look at. Cat diesels have a good reputation. Should one
expect 10,000 to 15,000 hours bfore rebuild if looked after. 800 houor
routine would probably be a top end overhaul. During survey have a leak
down test and compression test done. Opinions?
Repowering - replace with lower power diesels with newer technology or
rebuild, the 210 HP out of these Cats apparently can take the boat to 15
knots, hardly up on plane but drinking a lot of gas. Taking a boat this
size past 8-9 knots is not fuel efficient in any way. Opinions?
TIA
Ernest Nash
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Arild Jensen
> From: Ernest Nash
> Looking for information/opinions regarding 3160 Cat diesels,
>
> rebuild, the 210 HP out of these Cats apparently can take the boat to 15
> knots, hardly up on plane but drinking a lot of gas. Taking a boat this
> size past 8-9 knots is not fuel efficient in any way. Opinions?
REPLY
In light of current and forseeable fuel pricing, the topic of how much power
is really needed to move a given boat hull is going to get a lot more
attention.
Does it make any sense to have twice as much horse power installed than what
is required to drive the hull at an economical hull speed?
I'm not talking about having some reserve to deal with contrary head winds
and maybe a bit of opposing water current.
I'm talking about the habit by marketing people to use numbers and the
bigger the better. A trend which often leads to ridiculous horse power
ratings far beyond what can reasonably be used on that boat.
Naval architects have reliable formulas backed up with tank testing that
show exactly how much power is required to move a given hull at a specified
speed. In the case of a true full displacement hull, we know exactly how
fast that hull can move at maximum speed.
A number of listees have mentioned they seldom if ever run at maximum
throttle because of the excessive fuel burn that produces. Evidently these
boats were built with oversized engines.
Engines that can be delivered in varying HP sizes have much longer life
expectancy in the lower power range than when maximum power is extracted.
Seems to me the whole boating industry is due for a reality check when it
comes to determining engine horse power for a given hull size. Trawlers in
particular do not benefit from over powering the boat. They simply dig
bigger holes in the water and tend to empty the owner's wallet faster.
What say the list members?
Arild
Pascal Gademer
8V71Ns. top speed is 14kts, 15kts maybe on a good day burning.. i don't
even know !
i always run around 9kts in deep water... (more like 8 to 8.5 in shallow
biscayne bay) at about 1450 rpm, whihc is fast enough to keep temperatures
where they need to be. If i ever repower, I'll look into smaller
engines...no point in keeping 7000lbs of iron on board...
pascal
miami, fl
70 hatteras 53my
live helmcam www.sandbarhopper.com/#cam
red...@travel-net.com
Wholeheartedly agree with your premise. I would estimate that it takes no
more than 100 HP to move this boat through the water at 8 knots, a 48 Ft
Gulf Commander. I would further submit that a single 120 HP diesel engine
would be more than sufficient. A more contrary position would be concern
about tides, narrows and such on the west coast; however, there are owners
out there with low powered boats taking these issues in stride and
travelling accordingly. I would also say that a 20 ton boat with twin
3160 cats @ 210 HP does dig a fair hole when using full power, but being a
semi-displacement hull the hole is not as big. However, in support of the
overpowering industry that appears to be prevalent, gas was much cheaper
back in the late sixties, early seventees.
Another issue, slightly off topic is finding an older boat, say '70s
vintage with a sizeable BW tank (grey water soon to be uppon us).
Saying all this, is it better to repower with less horsepower, considering
the possibility of changing transmissions and other anciliaries, or just
rebuilding the same and cruising accordingly?
Ernest
On Mon, 21 May 2007 11:17:18 -0700, "Arild Jensen" <el...@telus.net>
wrote :
red...@travel-net.com
Have always enjoyed reading your posts. One check mark for repowering
with smaller, lighter engines, most likely way more fuel efficient as well.
Ernest
On Mon, 21 May 2007 14:55:37 -0400, "Pascal Gademer"
<pas...@sandbarhopper.com> wrote :
> while my boat isn't a trawler, it will not get on plane with its 325hp
> 8V71Ns. top speed is 14kts, 15kts maybe on a good day burning.. i don't
> even know !
>
> i always run around 9kts in deep water... (more like 8 to 8.5 in shallow
> biscayne bay) at about 1450 rpm, whihc is fast enough to keep
temperatures
> where they need to be. If i ever repower, I'll look into smaller
> engines...no point in keeping 7000lbs of iron on board...
>
> pascal
> miami, fl
> 70 hatteras 53my
> live helmcam www.sandbarhopper.com/#cam
>
> ----- Original Message -----
> From: "Arild Jensen" <el...@telus.net>
Ron Rogers
assume that the hull is like that of a Grand Banks "trawler" and is a
"semi-planning" hull. GBs come with ridiculous (to me) horsepower options.
In the old days, fuel was cheaper and those who bought these boats were not
fuel price sensitive. Many remain that way and like the option of going
fast - inefficient or not. Just look at the wakes they leave.
However, I now see this type of boat offered with smaller engines. Buying
low rev engines of lesser power enhances fuel economy and resale value -
IMHO. GPH is a function of hull, propeller, and engine efficiency.
Therefore, the first thing I would do is determine the largest propeller
that can properly fit in the given space and then work out the proper HP and
reduction gear. OR, as a cost savings measure determine which smaller
engines are compatible with your existing transmissions.
Ron Rogers
Arild Jensen
> From: Ernest
> Saying all this, is it better to repower with less horsepower,
> considering the possibility of changing transmissions and other
anciliaries, or just
> rebuilding the same and cruising accordingly?
REPLY
If the existing transmission cannot bolt up to a smaller engine, there will
probably still be a resale value to offset getting a gearbox to match. As
another poster said, such a repower will definitely enhance resale value.
Selecting an engine that can drive the hull at full displacement speed with
a 20% reserve should be less expensive.
Concerning other anciliaries; they would be larger than required but this
should not be a detriment.
Cheers
Graham Pugh
hp turbo charged engine, I couldn't agree more with Arild's opinion. The
only time I ever had the engine up to WAT was when I bought and sold the
trawler during sea trials. This semi displacement hull would have been
perfectly happy with a very much smaller engine probably half the size, but
many of this popular model were sold with very much larger engines than
mine.
I've just returned from a trip to UK where I had rented a Peugeot 307 1.4
litre. This comfortable mid sized car by British standards had plenty of
power
and averaged 6.5/ litres per 100 km or about 36 miles per US gal.
None of our three US made cars average anything like that fuel consumption
:-)
Graham Pugh
Kando 11
Kingston, ON
Pascal Gademer
wants a tiny car with a 1.4 litre engine, US manufacturers in europe
already sell decently sized cars and SUVs with fuel economy 30 to 40% higher
than those they sell to US consumers.
so it's kind of funny when we hear all this talk about ethanol is going to
save us and how mileage must go up by 10 % 5 or 8 years from now when we
coudl do much better, almost immediately, without sacrificing size, safety
and comfort if emmission standards where relaxed jsut a little.
it's called... DIESEL ! check out the european Chevy or Ford web sites...
30 to 40% better mileage than equivalent US models...
pascal
miami, fl
----- Original Message -----
From: "Graham Pugh" <graha...@earthlink.net>
> I've just returned from a trip to UK where I had rented a Peugeot 307 1.4
> litre. This comfortable mid sized car by British standards had plenty of
> power
> and averaged 6.5/ litres per 100 km or about 36 miles per US gal.
> None of our three US made cars average anything like that fuel consumption
> :-)
Alec McLocklin (amclockl)
fuel prices going to the roof, a local yacht broker is telling me that
all of the potential buyers through his office in the last month would
jump at a large sport fish with smaller engines. Its all about space
with efficiency now.
Alec