MJM Yachts LLC 40z, Owner'S Manual

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Chapter 9 Finishes, Equipment, and Appliances MJM 40z Owner’s Guide page 41
14. In addition to aft and midship supports in
locations seen on the previous page, support
the boat under the bow, forward of any straps.
15. Leaving side and aft pilothouse curtains in
place best protects the boat interior.
16. Lock companionway door. Advise driver and
receiving yard on the combination.
9.8 F
UEL
C
ONSUMPTION
The data in the adjacent chart was obtained in
Jan-Feb 2009 from three separate runs in three
separate locations: Boston Harbor, near Captiva
FL, and near Miami during the Boat Show. Volvo-
Penta technicians conducted two of the runs.
Displacement
Assuming similar hull designs, fuel
efficiency is a function of the power-to-weight
ratios. Less weight equals less fuel for a given HP.
Dry and empty weight of the boat was 16,000 lbs.
Each run was made with the boat at approximately
21,000 lbs. that included approximately 3/4 full
tanks, 1400 lbs. of cruising gear and 2-4 people.
Propulsion System
Test runs were done on 40z
#1 powered with an IPS 500 propulsion system
consisting of twin D6 370 HP diesel engines and
stern drives.
Range of Efficient Operation
Nautical miles per
gallon remain fairly constant from 9 to 27 knots.
Cruising Speed
Volvo Penta suggests that in
suitable conditions, 10% below open throttle
(about 3200 RPM at 30 knots) is optimum cruising
speed. The data below would indicate that 2900-
3000 RPM at 28-knots would be more efficient.
Sour Spot
The 40z seems to have a huge “Sweet
Spot” and one small “Sour Spot” at about 1700
rpm at just over 10 knots where the most power is
applied to overcome resistance before the boat
achieves a plane. Notice that the boat is no more
efficient at that point than at 30 knots.
When underway fuel may run back in
the tank where the fuel level sensor is located. It
may then indicate more fuel than is actually there;
it’s wise to fill up when you get down to 1/3 tank.
FUEL EFFICIENCY RANGE TIME
RPM GPH KTS NMPG NMRANGE
Secs
*
600 0.6 4.8 7.6 2392
1000 2.3 6.7 3.0 937
1200 3.5 7.6 2.2 684
1300 3.9 8.0 2.1 646
1400 4.7 8.2 1.8 555
1500 6.8 9.3 1.4 428
1600 7.8 9.5 1.2 384
1700 9.5 10.0 1.1 333 2.5*
1800 9.7 13.1 1.4 425
1900 10.6 14.3 1.3 425
2000 12.7 15.1 1.2 374
2200 14.8 17.9 1.2 380
2400 17.6 20.9 1.2 374 5.3*
2600 20.5 24.0 1.2 370
2800 22.9 26.9 1.2 370
3000 26.4 30.0 1.1 357 9.5*
3200 30.5 32.8 1.1 339
3400 35.7 36.1 1.0 319
3500 38.5 37.7 1.0 308
*Seconds required to reach the indicated speed.
Volvo technicians said, “ This is a Ferrari! ” as I
mashed the throttles forward to hit 20 knots in 5.3
seconds from a standstill. No wonder, that’s on a
par with some “
thunder ” boats and about what it
takes a Mercedes SL550 to hit 60 mph (52 knots).
…R.I.J.