Salty Dogs - Map question

edsr · 12-20-2002, 10:44 AM

O.K. so I look at the SST map and there are Lat. and Long. numbers. What is the distance between long. 124'00' and 124'30''? and what is the distance between 44'00'' and 44'30''? I am trying to get a rough idea about the mileage so that I can plot a Tuna interception route.
edsr

Miss B Haven · 12-20-2002, 10:55 AM

edsr- Lat is easy - 1 deg = 60 nautical miles (so 1 min = 1 nautical mile). Long depends on what Lat you're at though. I believe up here (at ~45 lat) it's about 45 miles from 1 deg of long to the next (2/3 of what it is at the equator)! Maybe someone else has a better number! Easiest way is to put to two points in your GPS (your not going TUNA fishing without one are you?) and let the GPS give you a distance between the points.
You can do it on a chart with dividers as well. :smile:

[ 12-20-2002, 07:41 PM: Message edited by: Miss B Haven ]

Scaup · 12-20-2002, 12:38 PM

Here's a web site that will convert distances between two lat/long coordinates into miles:

http://jan.ucc.nau.edu/~cvm/latlongdist.html#formats

Mark Mc · 12-20-2002, 12:41 PM

Hi edsr; just to piggyback onto what Miss B said:

When you're just talking east & west, or north & south, it's pretty straight forward. The other courses are trickier.

For e x w, the distance between each minute of longitude is equal to the cosin of the number of degrees lattitude for that location.
So let's say we're talking about a fishing spot at about 45 degrees N. Put 45 into your calculator and hit the cosin (COS) button. Answer is 0.707. So one minute to the west is 0.707 nautical miles. Since there are 60 minutes in one degree, there are (60 x 0.707) 42.4 n miles per degree. At the equator, it is zero degrees lattitude. Cosin of zero is one, or one mile per minute east or west.

For the more "diagonal" courses, there is a great website that will figure this out:

distance calculator

On the water, as Miss B said, use your GPS, or learn how to do it with dividers. The latter method is a little tricky unless you just want a rough estimate. It involves figuring the n/s and e/w components separately, creating a triangle with the two known legs, and solving for the third side of the triangle.

Miss B Haven · 12-20-2002, 06:49 PM

Good links guys. Very fast and easy, I'll be putting that in my favorites!

Delta between 124W and 125W (at 46 degN) is 48 statute miles or 41 nautical miles. :grin:

edsr · 12-21-2002, 04:24 PM

Thanks guys,
I knew there must be some way to calculate and not have to use Kentucky Windage to get close.

Miss B
No I wouldn't thnk of going tuna hunting without a GPS or two. What would be a good machine for an open boat, i.e. , waterproof shock resistant EASY TO READ, as in big letters and user friendly. I don't need all the bells and whistles just a solid machine that is reliable. Oh, did I mention that it shouldn't break my piggy bank? Am hoping to get VHF, Fish/depth finder and GPS in the next few months, work the bugs out and be ready to catch the fever. Would appreciate your experience with any of the above electronics, including where to buy. Things that have worked well. Learning from experience is very expensive, especially 20 mi. out in big blue.
Best regards
edsr

Miss B Haven · 12-21-2002, 06:47 PM

edsr - I don't have an open boat, so I can't give you a recommendation for such. I will however let you know that if you are talking about permanent fixed mount equipment, I would recommend Furuno.
Good service and the big thing is they have buttons and knobs to do all major controls. I have Raytheon on my current boat and there are way to many layers of soft keys and menus to go through to control normal functions. Furuno is much more user friendly!
I have owned both and prefer the Furuno because of that. Quality on both is good. If you want handheld, I'm not experianced. Lots of other folks here who can give you an opinion. Good luck, happy shopping!

Mark Mc · 12-21-2002, 07:22 PM

Hi edsr, as Miss B infers, Furuno is THE top brand. Raytheon is a close second. Your timing is perfect: Furuno just came out with the GP 32, which is WAAS enabled (I think it stands for wide area augmentation system). For a while, everyone was on the DGPS bandwagon. But our government did us a favor and stopped scrambling the signal on the extra satellites. So differential (the 'D") doesn't give you much extra over the standard system anymore. But this WAAS is supposed to get you within a few meters accuracy (vs 40 or 50 meters for "regular").
I got a quote from Consumers Marine Electronics (800-332-2628) of $325. for the Furuno GP 32. This is a fantastic buy, for what you get with WAAS, compared to what people are still paying for the GP 30 & 31. Check it out at the Furuno website:

web page

corrirod · 12-21-2002, 10:26 PM

With the number of satellites I can track on the coast I get within 12 ft. accuracy (according to the reading on the GPS) on my regular GPS now that the government turned off the error. About the worst I get is 21ft.

I don't know about anyone else but that's close enough for me! I've marked buoys in the fog before and man is it scary just how accurate it is. It takes some tests like that to really get confidence in your electronics. That goes the same for radar. You really have to believe in what it tells you and learn how to decipher it correctly.

I also carry an old Eagle/Lowrance handheld GPS and it's surpisingly more accurate, at least from a zoomed in 1/10th mile plot.

Edsr, I'm not sure which unit would work best for your particular boat but one key feature to have on a GPS is a numeric keypad. Nothing sucks worse then having to scroll thru the alphanumeric sequence to enter coordinates or names. With a keypad you can type them in instantly. For instance if I'm fishing and someone wants to read me coordinates over the radio, I don't have to find a pen/paper, I just hit "new waypoint" and start typing in the coordinates. Or if you're cruising and you want to enter general waypoints as a way to keep your heading, you can do that while you're driving vs. stopping and spending 5 minutes trying to get 1 coordinate in let alone several waypoints in a row. The other features to look for are the "Light List" and a tide predictions. Preprogrammed light lists are handy for cruising in unknown waters. They're not 100% accurate because buoys/lights move but they're a good reference. The tide predictions function is priceless. No more wondering what the tides are in the area you are in. The GPS automatically knows where you are and picks the closest tide station predictions and BAM you're in the know. No more scrambling to find the tide table booklet and making all kinds of rediculous conversions to compensate for your area.

Sorry for the long post. Hope it helps.

edsr · 12-23-2002, 03:35 PM

corrirod, MissB, & MarkMc - many thanks for the info.
Corrirod, what brand and model are you refering to? I don't think that I have ever seen a Light-Tides mode on any, must have over looked that feature.

The Furuno sounds like a good deal, I thought they would cost more considering the brand name.

My boat is a 23' + dory that I have been testing and tuning for the last few months ,it has a center console and is an open boat at this time. A cuddy cabin could be added but I was anxious to get it into the water so quit building after the center console. That is why my asking questions about electronics for open boats. The hand held units are getting better all the time and many are waterproof.
The learning curve in electronics/ VHF/Depth-fish finders has gotten steep, especially with all the choices. It can be very expensive to make the wrong choice.
Really appreciate all your info, please keep it coming.

Wishing all of you and yours the very best of holidays and a hope for a healthy and propersous new year.

edsr