Miles Per Hour or Nautical Miles Per Hour?

[IN2DEEP]

What do have your electronics set up to read?

MPH will make your boat appear to be faster to others when described using MPH :roll:

Your fuel economy will be greater when using MPH :roll:

However, speed over air and water is measured in knots, isn't it?

A knot, or nautical mile (6076 feet), is about 15% longer than a statute mile (5280). So, if you're traveling at a speed of 20 knots in a motor boat, you simply multiply 20 X 1.15 to get 23 mph. To go from mph to knots, multiply mph by about .87 to get knots.

Conversion table for
knots to miles per hour:
5 Knots = 5.8 MPH
10 Knots = 11.5 MPH
15 Knots = 17.3 MPH
20 Knots = 23.0 MPH
25 Knots = 28.8 MPH
30 Knots = 34.6 MPH
35 Knots = 40.3 MPH
40 Knots = 46.1 MPH
45 Knots = 51.8 MPH
50 Knots = 57.6 MPH



I'm set up to read knots

Please cast your vote!

[JETTYWOLF]

who would not have Knots?

I don't know anyone in a vehicle that would say, "Officer, I was only going 22 knot?"

DOH :razz:

[CanCanCase]

who would not have Knots?

I don't know anyone in a vehicle that would say, "Officer, I was only going 22 knot?"

DOH :razz:

I actually talked myself out of a speeding ticket in Alaska with that very line Dave! in a commercial fishing town is was plausible that I had been on the boat for so long I didn't know how to read the speedometer correctly!

I had another boat leading me once - we agreed we both cruised at 25... it wasn't until I almost ran over his transom that we realized he was talking MPH and I was talking knots!

-Case

[warthog5]

What do have your electronics set up to read?

MPH will make your boat appear to be faster to others when described using MPH :roll:

Your fuel economy will be greater when using MPH :roll:

I always set them to MPH and always clarify that my stuff IS set @ MPH...There is no confusion if you clarify and I don't have to refigure in my head. :)

[peterbo3]

Way back before GPS, I ran a trawler (shrimper) using radar & charts, plus a very early & expensive Furuno CRT colour sounder inside the Great Barrier Reef. Charts & nautical miles are good buddies, but I can use km & miles. Do it right with North up & knots or paddle a kayak slowly.

[welder]

Way to go Pete , You had to do the NORTH UP thing didn't you .
I run course up with my furuno , I know where north is , I want to see where I am going when I look up. The way I see it , I am running over the Chart the same way as the Bow is going.

Yeah , I know I'm weird .

[pjay9]

From the INTERNATIONAL MARITIME DICTIONARY:
KNOT. 1. A unit of speed. The term 'knot' means velocity in nautical miles per hour whether of a vessel or current. It is the measurement of a section of a (chip) log line usually 47 ft. and 3 inches long.

NAUTICAL MILE. The standard unit of measure for marine navigation and for work with the Mercator chart. The NM is 6080feet, being for practical purposes the length of one minute of arc of a meridian or of the equator.

So if you are talking with a seafarer you best be speaking in knots...also if any of you have ever done chart plotting it is the standard unit used for all worldwide examinations and navigation standards.

The issue with clarification is for dunderheads that just don't get it! When telling the USCG your are proceeding at 12 knots to a the location of a vessel in distress they can figure your arrival time and monitor progress on a chart whether it is paper or electronic. Listen to the weather stations, everything for mariners is in KNOTS...seastate is translated into knots...Radar 6 minute plots are done in knots...it goes on and on...SO USE KNOTS. IT IS THE STANDARD THAT PROFESSIONAL MARINERS FOLLOW WORLDWIDE and those young fellows that may have to save your butt one day!

KNOTS is the only method to use! Capt PJ

PS You may have realized by now that this is a question that got my back up some...sorry if I happen to offend anyone...you will get over it!

[welder]

10-roger PJ, I will go out tonight and change my chart plotter to knots for safety reasons . That and to cornfuse some of the guys I fish with.

But I'm still keeping COURSE UP on the screen.

[warthog5]

But I'm still keeping COURSE UP on the screen.

I may change mine thruout the day. Course UP for the run out and back in [depending on the screen I'm using] , but change to North UP when maneuvering on a wreck. But it's usually just left on North Up.

SO USE KNOTS. IT IS THE STANDARD THAT PROFESSIONAL MARINERS FOLLOW WORLDWIDE and those young fellows that may have to save your butt one day!

I have noticed on my Standard Horizon VHF w/ DSC that it displays Knots and there is no way to change that on the radio. Even with the chartplotter set to Statute Miles.

[Napa Mike]

For what it is worth, I checked my copy of Chapman's Piloting and Seamanship. Chapman says that you should use nautical miles and knots for distance and speed when on salt water. However, within the United States, you should use statute miles and MPH for distance and speed on freshwater bodies and along the intracoastal waterways.


Mike

[goatram]

I use MPH. I am not a Navy Boy nor did I grow up on the boat. I got to many things to remember as it is and another conversion trick is not necessary nor wanted. If you don't ask then You will fish in a different area than the one I described as being 31 miles due west

[IN2DEEP]

10-roger PJ, I will go out tonight and change my chart plotter to knots for safety reasons . That and to cornfuse some of the guys I fish with.

But I'm still keeping COURSE UP on the screen.

You do realize that your perceived, terrific MPG is going to be less than it's been. Right?
I'm a North up guy

[amfboats]

I was born and breed in Km/h, first motor bike was in MPH, and then all the boats I started selling we quoted speed in MPH and in more recent times we refer to speed in Nautical Miles. Chart work has always been Nautical Miles and so all of my GPS use is in Nautical Miles for distance.

To sum it up I still favour MPH in a boat but quote Nautical Miles, Kmh in a car and on a bike, but I am pretty much always using the whole lot.

[CTMD]

I think in knots, do calculations in metres/second and talk in MPH. The third only when dealing with small boats as 95% of the logs give speed in MPH and KPH.