What is your normal cruising speed?

[Vince_nj1]

I thought it would be fun to collect some statistics on what speed everyone likes to cruise. Assume optimal conditions, inland waterways, light traffic. After answering the survey, please answer the following:

Boat year/model (ex. 2006 320 Sundancer)
Boat beam (ex. 11.5)
Configuration (ex. Twin 6.2, 320 hp V-Drives - Inboard)
Displacement (ex. 14,000 lbs)
Fuel type: (ex. Gas)
Estimated fuel mileage at that speed (ex. .9mpg)

 

[Vince_nj1]

Help/
Argh.. I screwed up I need to edit the answers. 2nd one down should say 28 to 30..How do I do that?

 

[timinfla2]

I cruise at about 3500 RPM, giving me about 30.5 MPH. I've not found any data from the factory or anything that lists the most efficient cruise, but watching my fuel flow, it seems to be about the sweet spot.

-T

 

[tawcat]

Boat year/model 2005 320 Sundancer
Boat beam 11.5
Configuration Twin 6.2, 320 hp V-Drives - Inboard
Displacement 14,000 lbs
Fuel type: Gas
Estimated fuel mileage at 20 knots, I'm guessing about 1 mpg

 

[timinfla2]

Boat year/model 2005 320 Sundancer
Boat beam 11.5
Configuration Twin 6.2, 320 hp V-Drives - Inboard
Displacement 14,000 lbs
Fuel type: Gas
Estimated fuel mileage at that speed I'm guessing about 1 mpg

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

-T

 

[quality time]

I voted 20-22 knots
Boat year/model: 2001 380 Sundancer
Boat beam: 13'
Configuration: Twin 3126 CATS (V-Drives)
Displacement: 21,000 lbs
Fuel type: Diesel
Estimated fuel mileage: not what it should be...

Vince - you do realize that some people don't know the difference between knots and MPH.:lol:

 

[VinceR]

SEA RAY 340​

2001​

PERFORMANCE​

“WILD RICE”​

TWIN 454 MPI​

​

Speeds by GPS
Fuel Flows by computer connected to engines.

RANGE IS 215 GALLONS

RPM MPH GPH MPG RANGE

700 3.9 2.0 1.95 419

1000 6.0 3.6 1.66 358

1200 6.8 4.4 1.55 333

1500 7.9 7.0 1.13 242

2000 12.4

2500 18.6

3000 16.9 24.0 .70 150

3200 20.5 26.6 .77 164

3400 24.1 30.6 .79 168

3500 25.0 31.0 .80 172

3600 26.4 33.4 .79 170

3800 28.0 34.8 .80 172

4000 29.5 38.0 .77 164

4300 32.6 47.6 .68 147

 

[trit21]

Voted 24-26 KNOTS
18 GPH
range is 130 S miles
equates to 1.5 MPG
using 85% of tank....85 gallons

Of course dependant on seas, winds and load.

 

[VinceR]

Nautical mile
Do you wonder why they measure speed in knots.?I thought that it was a form of the term “nautical mile” that was shortened to “nauts” and then evolved
to knots. “Knot” so. Going back to the days of Pythagoras, a nautical mile was established as 6,080 feet. Using maritime navigational knowledge, a nautical mile was calculated as one minute of latitude at the equator. There are 360 degrees around a circle (the earth) and each degree equals 60
minutes of latitude. Sixty times 360 equals 21,000, which is the number of nautical miles around the equator (or any other great circle around the globe). Working backwards from the 21,000 you will reach the 6,080 feet in each minute of latitude (one nautical mile). It isn’t important to remember the technical definition of a nautical mile, or knot. It is only important to know the relationship to a land mile. In specific terms, the ratio of 6,080 to 5280 shows that one nautical mile is .87 land miles and one land mile is 1.15 nautical miles. As an old Captain once told me, if the speedometer is calibrated in knots, land miles are “just a little bit less. If it is calibrated in land miles, nautical miles are just a little bit more. I use a simple calculation of 10% as a good quick conversion. At 10 mph you are doing 11 knots. At 10 knots you are doing 9 MPH. At 30 MPH you are doing 27 knots, and at 30 knots you are doing 33 MPH. Getting back to the evolution of the term “Knot” as a measure of speed, this derivation took place in the early fifteen hundreds and is not from the word “nautical”. It actually means knots. Beginning in the 1500’s, vessel speed was calculated using a crude device called a chip log. It consisted of a light line with a weight at the end, and was tied in knots at regular intervals. It was used in conjunction with an hour glass. Do you remember the movie titled Captain and Commander? Russell Crowe was forever chasing or running from an enemy ship. In one chase scene you saw the pilot alongside Crowe with an hour glass and line in hand as he excitedly exclaimed: “We are gaining speed Sir”. The pilot was measuring his speed with his chip log.
The line had knots tied in it every 47 ft. 3 in.; it also had a weight at one end. It was tossed over the stern as the hour glass was inverted. You then counted the number of knots that were let out in the 28 seconds it took for the sand to empty through the glass. The number of knots that were released measured the ships speed in nautical miles per hour. This was a fairly accurate estimation and was based on sound mathematics. The proportion of the distance between knots (47 ft. 3 in.) to one nautical mile (6080 ft.) is .00078. That is the exact same as the proportion of 28 seconds (the time in the hour glass) to one hour (360 seconds).
So when the pilot called out “12 knots”, it was both the number of knots that had slipped out, as well as the boat speed in nautical miles. We have come a long way since the 1500’s in measuring boat speed. Our present day computers are a lot more accurate than the old chip log. Yet it is interesting that, to this day, we still measure boat speed in knots. While this discussion is more academically informative than practical, it does bring to mind the importance of watching our boat speed. There is often “stuff” floating out there that we need to avoid. Wakes can be harmful to passing boats. There are many boats at docks that can be damaged by a passing wake. Many docks themselves can be damaged by wake action. Out of courtesy to our fellow boaters, it is always important that we watch our speed and wake. My seawall was recently being repaired. I could not believe the passing gawkers that ran right next to my dock to see the construction. They threw wakes that eroded part of my yard away. I lost a good six feet of land and two palm trees from the wake action. When I would go out and signal for them to slow down, most did so. Others gave a finger salute and continued on their way, oblivious to the damage they were causing. Caution is the word of the day. Take care and watch your speed and wake out of consideration of others. Is that “knot” the golden rule?

 

[SEEG]

Nautical mile
Do you wonder why they measure speed in knots.?I thought that it was a form of the term “nautical mile” that was shortened to “nauts” and then evolved
to knots. “Knot” so. Going back to the days of Pythagoras, a nautical mile was established as 6,080 feet. Using maritime navigational knowledge, a nautical mile was calculated as one minute of latitude at the equator. There are 360 degrees around a circle (the earth) and each degree equals 60
minutes of latitude. Sixty times 360 equals 21,000, which is the number of nautical miles around the equator (or any other great circle around the globe). Working backwards from the 21,000 you will reach the 6,080 feet in each minute of latitude (one nautical mile). It isn’t important to remember the technical definition of a nautical mile, or knot. It is only important to know the relationship to a land mile. In specific terms, the ratio of 6,080 to 5280 shows that one nautical mile is .87 land miles and one land mile is 1.15 nautical miles. As an old Captain once told me, if the speedometer is calibrated in knots, land miles are “just a little bit less. If it is calibrated in land miles, nautical miles are just a little bit more. I use a simple calculation of 10% as a good quick conversion. At 10 mph you are doing 11 knots. At 10 knots you are doing 9 MPH. At 30 MPH you are doing 27 knots, and at 30 knots you are doing 33 MPH. Getting back to the evolution of the term “Knot” as a measure of speed, this derivation took place in the early fifteen hundreds and is not from the word “nautical”. It actually means knots. Beginning in the 1500’s, vessel speed was calculated using a crude device called a chip log. It consisted of a light line with a weight at the end, and was tied in knots at regular intervals. It was used in conjunction with an hour glass. Do you remember the movie titled Captain and Commander? Russell Crowe was forever chasing or running from an enemy ship. In one chase scene you saw the pilot alongside Crowe with an hour glass and line in hand as he excitedly exclaimed: “We are gaining speed Sir”. The pilot was measuring his speed with his chip log.
The line had knots tied in it every 47 ft. 3 in.; it also had a weight at one end. It was tossed over the stern as the hour glass was inverted. You then counted the number of knots that were let out in the 28 seconds it took for the sand to empty through the glass. The number of knots that were released measured the ships speed in nautical miles per hour. This was a fairly accurate estimation and was based on sound mathematics. The proportion of the distance between knots (47 ft. 3 in.) to one nautical mile (6080 ft.) is .00078. That is the exact same as the proportion of 28 seconds (the time in the hour glass) to one hour (360 seconds).
So when the pilot called out “12 knots”, it was both the number of knots that had slipped out, as well as the boat speed in nautical miles. We have come a long way since the 1500’s in measuring boat speed. Our present day computers are a lot more accurate than the old chip log. Yet it is interesting that, to this day, we still measure boat speed in knots. While this discussion is more academically informative than practical, it does bring to mind the importance of watching our boat speed. There is often “stuff” floating out there that we need to avoid. Wakes can be harmful to passing boats. There are many boats at docks that can be damaged by a passing wake. Many docks themselves can be damaged by wake action. Out of courtesy to our fellow boaters, it is always important that we watch our speed and wake. My seawall was recently being repaired. I could not believe the passing gawkers that ran right next to my dock to see the construction. They threw wakes that eroded part of my yard away. I lost a good six feet of land and two palm trees from the wake action. When I would go out and signal for them to slow down, most did so. Others gave a finger salute and continued on their way, oblivious to the damage they were causing. Caution is the word of the day. Take care and watch your speed and wake out of consideration of others. Is that “knot” the golden rule?

One of the more interesting pieces of info I learned on the internet. I knew the length of a nautical mile but the way speed was calculated is interesting. What's your source?

 

[dpvandy01]

2001 280 Sundancer
Boat beam 9.5'
Configuration Single 7.4L 454 BIII
Displacement 8000lbs
Fuel type: Gas
20 to 22 knts
Estimated fuel mileage at that speed 1 to 1.5 mpg

 

[Nehalennia]

2000 260DA with 5.7L-EFI (GAS) and 2007 BravoIII
3500 RPM's = 25.7Knots = 30MPH and 8.5 GPH
I'm very happy with this cruising speed and fuel burn rate.

 

[Sea No Evil]

Voted 24-26 KNOTS
Data is same as trit21
18 GPH
range is 130 S miles
equates to 1.5 MPG
using 85% of tank....85 gallons

I live on the Intracoastal in Flagler Beach and I amazed at the lack of courtesy on the waterway. This is a narrow part of the waterway and I love it because I get to sell all of the traffic up close. There are wetlands across from me so there is nothing to worry about from the boat traffic and I put in a new seawall a few years ago so I don't worry about wave action but there are a lot of small fishing boats, kyaks, etc. that I see almost swamped by large craft. The speed limit here is 25 but no one seems to pay attention to that and there is not enough law enforcement available to control the speeds. I am not complaining - just making an observation. Living here has made me a better boater - more considerate.

Nice poll - great history lesson.

Jerry

 

[Sundancer]

1989 300 DA
11 foot beam
Twin 350's with Alpha I's
Cruising at 3,200 rpm.
Miles Per Gallon? Gas is cheap who cares? I'd guess about 1 mpg.

 

[Four Suns]

I live on the Intracoastal in Flagler Beach and I amazed at the lack of courtesy on the waterway. This is a narrow part of the waterway and I love it because I get to sell all of the traffic up close. There are wetlands across from me so there is nothing to worry about from the boat traffic and I put in a new seawall a few years ago so I don't worry about wave action but there are a lot of small fishing boats, kyaks, etc. that I see almost swamped by large craft. The speed limit here is 25 but no one seems to pay attention to that and there is not enough law enforcement available to control the speeds. I am not complaining - just making an observation. Living here has made me a better boater - more considerate.

Nice poll - great history lesson.

Jerry

My boat going 14 knots throws a huge wake compared to going 26 knots... I would guess the wake at 14 knots is over 4 feet high.

 

[berth control]

1985 270 Sundancer
10' Beam - 8000 lbs displacement
Twin 170 Mercruisers; 170hp ea.; 4 cylinders :smt100

Minimum plane speed: 13-15 mph
Cruising speed: 25 mph @ 3200 rpm
Max speed: 34 mph @ 4200 rpm
Economy @ cruise: 1.5 gps miles per gallon
Max Range: 150 miles (based on 100 gallons of 125 gallon tank)

Good poll - it's interesting to see how other boats do on performance and economy from owners, not just guesses and magazine articles.

Quote from Jerry:

"I live on the Intracoastal in Flagler Beach and I amazed at the lack of courtesy on the waterway. This is a narrow part of the waterway and I love it because I get to sell all of the traffic up close. There are wetlands across from me so there is nothing to worry about from the boat traffic and I put in a new seawall a few years ago so I don't worry about wave action but there are a lot of small fishing boats, kyaks, etc. that I see almost swamped by large craft. The speed limit here is 25 but no one seems to pay attention to that and there is not enough law enforcement available to control the speeds. I am not complaining - just making an observation. Living here has made me a better boater - more considerate.

Nice poll - great history lesson.

Jerry "

I agree with you completely. :smt038
Here in Michigan the bigger boats come into the pier heads on plane and then throttle down just inside the entrance. This makes about the biggest wake possible and causes a real challenge for the smaller boats. I understand when they have to do this in adverse conditions to maintain control, but on a calm day with no current? My grandpa used to do this, he said it was the only way to come into a channel safely, but I have been almost sunk in a small bowrider from a guy doing this in front of me, and have seen others go through the same thing. Kind of my boating pet peeve. :smt013

 

[sbw1]

We do about 26 knots at 3500 RPM and get just shy of 1 MPG. Range at this speed is 205 miles.

 

[VinceR]

One of the major factors on fuel economy is weight. Once we have burned ½ tanks in the 340 our fuel economy increases. We hold 1350 pounds of fuel 280 pounds of water. So at half fuel and water we are 815 pounds lighter. We never carry full tanks just for short day or overnight trips. We also will slowdown at times to enjoy the scenery and being on the boat. At 7 mph we double our fuel mileage from 26 mph.

 

[VinceR]

Dan,

I do not remember where I found that piece on nautical miles. It was somewhere on the Internet.

 

[trit21]

Vincent, we understand that your mileage will vary depending on factors (all boats are pretty much the same way) but for those of us interested in purchasing a 340 maybe you can average it out. On a normal cruise, what do you average MPH, GPH, etc etc. Just so we have an idea, thanks.