Tidal Current Charts

jcmannone · #1 12-13-2002

Hello,

I am new to this site. I did a members search before posting this question.

On a sailnet.com webpage, Jim Sexton wrote an article entitled "Using Tidal Current Tables" (Jul 31, 2000). He speaks about Tidal Current Charts available on-line or in print. A nice graphic for Long Island Sound is in his article. (http://www.sailnet.com/collections/seamanship/index.cfm?articleID=sexton0059)

I cannot find a link or any information on this product. It seems to belong to Sailnet since it has its registered mark on the software generated map.

I have e-mailed Sailnet a couple of times within the last 3 weeks and have tried to call them several times after leaving message with them. They simply refuse to respond. It has been frustrating.

Can anybody help me? I would like to have a chart generated for Charles River at Boston harbor during Spring high tides. I am doing some research on Paul Revere''s crossing from Boston to Charlestown (April 18, 1775).

Thank you so much in advance,
John

tsenator · #2 12-13-2002

If I were you I would buy The Eldridge Tide Book. I beleive it has the tide charts for Boston Harbor. I know it has new york Harbor and Long Island sound. Ore you could purchase their software that will give you anything you might want. Take a look here http://www.tideware.com/frameld.htm . It has 50 NOAA/NOS digital vector shoreline maps of the United States East Coast and the Gulf of Mexico. I think their tide current software is free ?

Also try going here http://scilib.ucsd.edu/sio/tide/

It has lots of sites with tide info.

jcmannone · #3 12-13-2002

Hi tsenator,

I have tried to use Tide Water Player (Eldridge) but it doesn''t seem to support my platform (Macintosh G4 under OS X or 9).

The links are helpful. I know most of them already. My only real hope was MacTide 1.3.3 since it allegedly calculates currents too. I can''t seem to download it (my curser just churns with a notation of "setting passive mode". I terminated the attempt after 40 minutes. As I was writing this, I got an undeliverable from the software originator at MIT- I guess he''s gone.

Back to the drawing board.

John

tsenator · #4 12-13-2002

Hmmm......try finding a friend with a Windows/PC platform and run it again.

Though I''m not sure the Eldridge software will run for 1775. If you got the tides that day and just a current chart relative to tides for Boston Harbor(like NY Harbor and LI Sound) then it would be easy to figure out.

In fact I never get a new Eldridge for the current charts, I just laminated an old one and figured it out relative to the Tides (i.e. current "x" hours before or after hi-lo tide) . It really never changes.

jcmannone · #5 12-13-2002

Hi,

I had the same thought. Find someone with a PC who will download the software and run it for me.

You are almost certainly correct. The software will not go back to 1775. But that''s OK. All I need are the tidal currents for the Charles River, Charlestown, MA for a typical year in April, 3 days after its full moon. This will be close enough.

When I say current charts, I am talking about the the speed and direction of surface tidal currents associated with the incoming tide. I have good tide times data.

Thanks,
John

jcmannone · #6 12-14-2002

The online software WWW Tdie and Current Predictor has helped me somewhat. Current speed is not available for most locations, but I was able to get data at Boston Light. The good thing, though, is that you can get tabulated or graphical output for any time between 1970 and 2025 AD. You are not limited to the present day analysis like the other sites give you.

It looks like the seasonal max flood is around 1.5 kts. Do you think I can get a good estimate of the current speed between 1775 Boston and Charlestown from simple geometry? If I assume same depths, and compare the mouth of the river at Boston harbor (width D) with the size with the necked-down area (width d), then conservation of mass should give me a good guess. Then neglecting changes in salinity, v = 1.5kts x D/d. From old maps, I estimate D/d to be 8/5. This give 2.4 kts ceter channel speed. From a mariner''s practical experience, does this make sense? Or did I over(under) compensate?

Finally, though I have data I can work with, I still want a chart with the current depicted on it like the one that appears in the article mentioned at the befinning of this thread.

Thanks
John

jcmannone · #7 12-19-2002

Hello everybody,

Well, with the help of maineharbor.com, I found a source that displays tidal currents on a chart. This is a PC-only Nobeltec software- Visual Navigation Suite with a separate Advanced Weather Overlay (I run a Mac, plus the software is expensive).

It will generate present and future data only. I am interested in April 16, 2003 Boston Harbor data. Unfortunately, they won’t run it for me.

Is there anybody with this software who could do me a big favor and generate such a chart for me? It is for a lecture series detailing the astronomical impact on historically significant events, like Revere’s crossing of the Charles April 18, 1775.

Thank you so much,
John

kirie396 · #8 02-05-2003

I was loaned a beautiful, old NOAA LISound current chart book last summer, which is the (much better) source of the common Eldridge current charts. My local store never heard of it but I find it for sale through Maps Unlimited at www.wae.com/px/newcom/nautprod.htm .

jcmannone · #9 02-07-2003

Thanks for the link.

Here is the info I found on it, in case someone else was interested. Now I can only hope I can get the Boston Harbor chart- I think I''ve heard they stopped making that one. Maybe they''ll have used ones, too. I''ll call Saturday or Monday.

Maps Unlimited
State University, AK
800 510-2123
$12 + 6.50 S&H

Tidal Current Charts

These charts graphically represent tidal currents in selected bays and harbors of the United States. Each series consists of a set of 12 or 13 charts that depict, by means of arrows and figures, the direction and speed of the tidal current for equal intervals of the tidal cycle.

Boston Harbor
Charleston Harbor, S.C.
Delaware Bay and River Atlas
Long Island and Block Island Sounds
Narragansett Bay
Narragansett Bay to Nantucket Sound
Puget Sound, Northern Part
Puget Sound, Southern Part
Tampa Bay
Upper Chesapeake Bay

JCM