What is your normal cruising speed?

[Vince_nj1]

Half tank fuel, Full tank of water, full fridge and coolers!

1992 Sea Ray 350 EB
Beam 11'5"
Displacement 11,500 lbs probably closer to 12,500 lbs
Twin 7.4 L 330 hp
Bravo II IO

2200-2400 rpm
20 - 22 knots
Estimate milage 1.25 - 1.5 GPM

Am I reading this correctly? Your able to stay on plane at 2200 RPMs with I/O's with THAT boat?..

 

[Daniel P Thomas]

Boat runs well on plane at 2000 rpm.
Running 17.5 x 23 inch props.
I have had boat up to 41 MPH, GPS, with clean fresh bottom paint in spring.
Loves the fuel dock at those speeds though!!
Sea Ray Spec with this configuration lists 44 MPH at 4600 RPM

Run with Auto Trim Tabs on all of the time.

2500 RPM I am at 25 MPH and just loafing along.

 

[NorCal Boater]

Boat year/model (1989 340da)
Boat beam (11' 11")
Configuration (twin 7.4L, 340hp V-Drives - Inboard)
Displacement ( 13,000 lbs)
Fuel type: (Gas)
Estimated fuel mileage at that speed (.7-.9 mpg)

 

[tawcat]

Estimated mileage at what speed? I didn't see the actual speed that you posted...

-T

Sorry, I corrected my post!

 

[timinfla2]

Cool - I'm a bit jealous at all these folks seeing 1MPG at cruising speed - I wonder if my smartcraft data is wacked or if I'm just unlucky, LOL.

 

[fc3]

Sterndrives are a bit more efficient. But what they save in efficiency, you get back in repair and maintenance costs, especially on salt water. Been there, done that, ain't going back.

Best regards,
Frank

 

[osd9]

what's so different between a stern drive unit and a zeus/IPS unit hanging in the water all season long?

 

[quality time]

I Voted 20-22 knots.....

Boat year/model 2003 410DA
Boat beam 13' 10"
Configuration Twin CAT 3126-TA 350HP V-Drive
Displacement spec sheet...22,500...real world..24,500+++
Fuel type: Diesel
RPMs at that speed 2250-2350 RPMs (I added this row)
Estimated fuel mileage at that speed. according to the books 18-20 GPH.....accroding to a seasons 'average'.....1.1sMPG




Aaron, I'm surprised that your cruise is the same as mine! What RPMs do you normally run and what HP are your CATs?

Dom,
My engines are 350HP also, I run around 2350 since I am turning about 2750 on the top end. My props are going out in a week to hopefully fix this.

The part that I don't like to talk about is the 27 GPH and .8 that the Flo-scans are reading...

 

[VinceR]

what's so different between a stern drive unit and a zeus/IPS unit hanging in the water all season long?

Very good question.

 

[LADY G 290]

On our 1994 290 DA w/Twin 4.3's I cruise at 30 MPH which is right at 4000 RPM the way I am propped. This is at 3600 feet above sea level and the mpg is always 1.25 to 1.55.
This speed is verified with my GPS.

 

[Turtlesboat]

what's so different between a stern drive unit and a zeus/IPS unit hanging in the water all season long?

10 times the cost if you knock off a zeus drive. I was on a cruisers 43' with ips drives. They were leaking at the boot, at the show. Other than being more forward and being able to move them independently, I don't really see a maint. benefit.

 

[Alex F]

I usually cruise with about 3/4 load of fuel, water and all other supplies with 4 people. I cruise at 3650-3750RPM @ 22-24knts or 25-27MPH in normal seas conditions. This seams to be the sweet spot for my boat.

Boat year/model: 2004 Sea Ray 320DA
Boat beam: 11.5
Configuration: Twin 5.7 350MAGs MPIs, 300 hp V-Drives - Inboard
Displacement: 13,200 lbs (dry weight based on specs), realistically 14,500 lbs + with all the load.
Fuel type: Gas
Estimated fuel mileage at that speed 0.8-0.9mpg.

 

[fc3]

what's so different between a stern drive unit and a zeus/IPS unit hanging in the water all season long?

The IPS drive housing is nibral. The propellors are also nibral. Nibral is very noble in salt water; therefore, it does not corrode easily. It's also very hard. Sterndrives are aluminum, which is not noble in salt water. It's soft and corrodes easily. There are multiple bellows, boots, and seals on a sterndrive boat. The seals on an IPS drive are simple and protected. They're designed to last over 10 years. The transmission and clutches are outside the boat in the sterndrive where there's limited space but inside the hull on IPS. Therefore IPS works great with big diesel power, not so for sterndrives. It's easy to check the integrity of the oil on an IPS drive, not easy on a sterndrive.

IMHO, Zeus is unproven and therefore, based upon Merc's past performance with new products, a piece of crap.

Best regards,
Frank

 

[Larry]

Half tank fuel, Full tank of water, full fridge and coolers!

1992 Sea Ray 350 EB
Beam 11'5"
Displacement 11,500 lbs probably closer to 12,500 lbs
Twin 7.4 L 330 hp
Bravo II IO

2200-2400 rpm
20 - 22 knots
Estimate milage 1.25 - 1.5 GPM

Are you sure about these numbers? I am very aware of the advatages (hydrodynamicly) of the stern drives on your boat compared to my inboards but I just don't think these big blocks are developing enough torque at these RPM to sustain plane. What is your WOT RPM?
My boat is lighter with more HP and I can run my "tuned" props (17 X 17 3/4) @ 3100 RPM I am doing 24kts @0.95 MPG. If your millage is "Gallons Per Mile" (your abreviation?) your fuel burn is dramaticly higher then mine, are you sure your not over proped?

Don't get me wrong I would love to have gas motors that can cruise a 6 ton boat @22kts. only turning 2400 RPM.

 

[Air O'Nautical]

1995 Searay 400EC
Beam 13ft
Twin Merc 7.4 inboard straight shafts
Displacement: 18000+fuel,gear=20k
Fuel: gas
Cruise:18kt@3000rpm,24kts@3500rpm
WOT:29-30kts@4200-4400rpm. Just to check the props
Fuel burn: I dont want to know......:smt101

 

[Daniel P Thomas]

Larry
Sorry
Should have been 1.25 - 1.5 Miles per Gallon
Per Sea Ray Spec:
IO T-7.4L
PHP 300
CHP 330
Bravo 2
Ratio 2.00:1
Prop 17.5 X 23
WOT RPM 4600
WOT Speed 41-44 mph
I have had boat running 41 mph on GPS and Speedo

Usually run 2200 - 2500 rpm all day long with a short burst up for 10 min or so
Friends with similar sized boats are amazed at the speed of this thing
It just jumps up on plane
Very different from my 1989 340EC with straight drives
Almost 10 mph more and 1/3 less fuel burn!

Love to see gas below $2.00 here!!!!

 

[Larry]

Larry
Sorry
Should have been 1.25 - 1.5 Miles per Gallon
Per Sea Ray Spec:
IO T-7.4L
PHP 300
CHP 330
Bravo 2
Ratio 2.00:1
Prop 17.5 X 23
WOT RPM 4600
WOT Speed 41-44 mph
I have had boat running 41 mph on GPS and Speedo

Usually run 2200 - 2500 rpm all day long with a short burst up for 10 min or so
Friends with similar sized boats are amazed at the speed of this thing
It just jumps up on plane
Very different from my 1989 340EC with straight drives
Almost 10 mph more and 1/3 less fuel burn!

Love to see gas below $2.00 here!!!!

I gues I never realy saw specs on a larger cruiser like yours that had I/O's. Your performance then is amazing, sorry if It sounded like I was doubting you.

 

[Daniel P Thomas]

Not at all Larry
It kind of shocked me coming from the old 1989 340 EC
Especially the difference in fuel burn.

I like to just loaf along at around 19 to 22 mph most of the time.
But if and whenever we get a flat Lake Michigan down at the South End, it is kind of fun to blow by some of the smaller cruisers.

The additional picture above is on our last run across the lake 2006 season end.
I was running about 31 mph next to my buddies 32 Tiara
He was maxed out at about 33 when I nailed it.
He got on the vhf and couldn't believe how mine seemed to jump out of the water and take off. My GPS was reading 40+ as we hit the Calumet River.

 

[Daniel P Thomas]

deleted

 

[Vince_nj1]

I am also very impressed with those numbers. I guess the combination of stern drives with a bridge that moves the center of gravity forward is the reason.