My heavy (11,000lb) moderately deep-V, high-powered 26' boat is hardly a
trawler, but it does 3-3.5 nmpg if I cruise at 6.5 knots rather than 18
(which it will do on plane, at 1.75 nmpg). I have been cruising at 6.5
for several years and many thousands of NM, recording mileage
calculations at every fill-up.
The engine is a 1997 all-electronic turbocharged, aftercooled, and
supercharged 3.6 liter 260 hp Volvo KAD44 with duo-prop I/O. It
currently has 3100 hours, and runs like a top.
The 40-series engines started many years ago with basically the same
block but much less technology - no turbo (I think), no aftercooler, no
supercharger, and only about 160 hp. They then grew step by step to
have much higher horsepower and all those gizmos (toward the end of the
series even electronic controls). The last of the series was the next
one after mine, the 282hp KAD300.
If I understand correctly the (specific fuel consumption) stats provided
by Volvo wizards:
The stats I've seen show that newer models generally achieved better
efficiency than the previous ones. Not by huge amounts, but better.
My guess would be that with a modern engine chosen appropriately you
would achieve at least as good results.
Richard Cook
New Moon (Bounty 257, Volvo KAD44P-EDC-DP)
Larry H wrote:
I have a 1978 Puget Trawler 37 (Taiwan built) with a single Ford Lehman 120
hp.
On last summer's trip from Seattle to SE Alaska I ran at 1600 rpm achieving
7 knots and burned 2.0 gallons per hour for a mpg of 3.5 Nautical MPG(US
gallons).
The Lehman is an older design, all mechanically injected engine. Are there
any newer engines that can achieve the same economy?
My heavy (11,000lb) moderately deep-V, high-powered 26' boat is hardly a
trawler, but it does 3-3.5 nmpg if I cruise at 6.5 knots rather than 18
(which it will do on plane, at 1.75 nmpg). I have been cruising at 6.5
for several years and many thousands of NM, recording mileage
calculations at every fill-up.
The engine is a 1997 all-electronic turbocharged, aftercooled, and
supercharged 3.6 liter 260 hp Volvo KAD44 with duo-prop I/O. It
currently has 3100 hours, and runs like a top.
The 40-series engines started many years ago with basically the same
block but much less technology - no turbo (I think), no aftercooler, no
supercharger, and only about 160 hp. They then grew step by step to
have much higher horsepower and all those gizmos (toward the end of the
series even electronic controls). The last of the series was the next
one after mine, the 282hp KAD300.
If I understand correctly the (specific fuel consumption) stats provided
by Volvo wizards:
The stats I've seen show that newer models generally achieved better
efficiency than the previous ones. Not by huge amounts, but better.
My guess would be that with a modern engine chosen appropriately you
would achieve at least as good results.
Richard Cook
New Moon (Bounty 257, Volvo KAD44P-EDC-DP)
Larry H wrote:
> I have a 1978 Puget Trawler 37 (Taiwan built) with a single Ford Lehman 120
> hp.
>
> On last summer's trip from Seattle to SE Alaska I ran at 1600 rpm achieving
> 7 knots and burned 2.0 gallons per hour for a mpg of 3.5 Nautical MPG(US
> gallons).
>
> The Lehman is an older design, all mechanically injected engine. Are there
> any newer engines that can achieve the same economy?
