Wilddoug
New Member
Looking at purchasing a 2001 400 Sedan Bridge, with twin cat 3126 350 hp. Plan to travel long distance and will need to have good range, what is bow speed of this craft that will offer best fuel efficiency?
What is 2001 400 sedan bridge Bow Speed?
- Thread starter Wilddoug
- Start date
- Oct 6, 2006
- 12,153
- Boat Info
- 1996 450DA
- Engines
- 3116 Caterpillars
Most efficient cruise can only be determined after you load your boat, top off the fuel and water, then figure out what speed she runs at 100 rpm intervals. When you do that, we can give you the fuel burn at each interval so you can then compute your miles/lkilometers per gal/liter. THere is so much variability in how these hulls perform under different loads that a guess at a 400DB hull speed will be nearly useless.
SR400DB
Active Member
- Mar 18, 2008
- 975
- Boat Info
- 2003 400DB, Simrad NSS12, 6100i, Furuno Navtex, KVH M3 Harbormaster Mark II
- Engines
- Cummins 6 CTA'S 8.3 417 BHP.
My boat has different engines, so it may be moot. At 8.8 knots fully loaded I burn between 3.6 and 3.9 gallons per hour. During my recent 900 mile trip, we got very familiar with the most efficient speed.
BillG72340
Member
The most efficient speed for maximum range will be at idle and around 5kts. We spend a lot of time at 1000rpms at 7-7.2kts burning about 2.5 gph when conditions permit. My best cruise is at 2400 between 19-21kts depending on load. FWIW.
Alex F
Well-Known Member
- Nov 14, 2006
- 9,166
- Boat Info
- 2005 420DB with AB 11 DLX Tender, Raymarine Electronics (2x12" MFDs) with Vesper AIS
- Engines
- Cummins 450Cs, 9KW Onan Generator, 40HP Yamaha for tender.
100% correct.
According to boattest.com my range at 600RPMs is almost 1500NM. As soon as you touch the throttles you're going to use more fuel, regardless how much speed you gain. But, most important thing you need to keep in mind that your hull speed is about 7.4kts. You should easily get there at 900-1,000RPMs (with no current and mild wind, and seas). At this point you shouldn't push the throttles any further, b/c you only going to loose efficiency (burn more fuel for very little speed gain). This approach will allow you most of the distance.
Fast cruise speed is a totally different story and without feature like SmartCraft it takes some time to figure your sweet spot. I found in my boat that she's more efficient (in terms of MPG) when I push her a bit harder rather than conservative. Your boat is similar (stern heavy), so I would expect you find similar behavior. As noted above, 2400RPMs is what I also think would put you closer to the sweet spot. Going along with Frank's theory of 100RPMs interval, I would run at 2400RPMs and see if you can adjust the trim tabs to get max speed. Then, I would drop down to 2300RPMs and see the difference. Then, test with around 2450RPMs (I'm not sure if 2500 is recommended RPM for these engines).
From my personal experience I've tested from 2000RPMs to 2400RPMs. The gain was more than 6kts in exchange for 300-400RPMs.
Good luck.
