Tidal Differences, Height Differences, and Reference Station for MAINE'S OUTER COAST "Subordinate" Stations
MAINE, outer coast Time Diff. (Click for "How to interpret") Hgt. Diff. (Click for "How to interpret") Reference Station
Station ("subdordinate station") High Low High Low
Damariscotta River
  • East Boothbay
 -0 02 +0 01 *0.98 *0.98 Portland
  • Newcastle
+0 16 +0 25 *1.02 *1.02 Portland
Damariscove Harbor, Damariscove Island -0 09 -0 10 *0.97 *0.97 Portland
Boothbay Harbor -0 06 -0 08 *0.97 *0.97 Portland
Southport, Townsend Gut +0 01 +0 01 *0.98 *0.98 Portland

How to interpet "Time Difference" data:

  • To determine the time of high and low tide at any subordinate station listed in this table, add or subtract the hours and minutes from the time of high or low tide of the reference station (for these data, Portland, Maine).
  • A plus sign (+) indicates that the tide at the subordinate station occurs later than at the reference station (for these data, Portland, Maine) and the difference should be added;
  • A minus sign (-) indicates that it is earlier and should be subtracted.
  • To obtain the tide at a subordinate station on any date, apply the difference to the tide at the reference station (for these data, Portland, Maine)for that same date.
  • The results obtained by application of the time differences will be in local time for the subordinate station.

How to interpret "Height Difference" data:

  • The height of the tide is given in one of two ways:
    1. As height differences, where
      • A plus sign (+) indicates that the difference should be added to the height at the reference station (for these data, Portland, Maine); or
      • A minus sign (-) indicates that it should be subtracted.
    2. Or as ratios, indicated by an asterisk (*)
      • To obtain the height of tide at the subordinate station, the height of tide at the reference station (for these data, Portland, Maine) should be multiplied by the ratio listed.
      • The result is normally rounded to the nearest .1 foot.
  • For all of the examples shown above -- and for most stations -- use of a height difference (method #1) would give unsatisfactory predictions. Therefore, most stations use ratios (method #2) to predict tidal heights.
Example Tide Calculations
For Boothbay Harbor, Maine, the time and height adjustments listed in the tables are:
Time Difference (high) Time Difference (low) Height Difference (high) Height Difference (low)
-0 06 -0 08 *0.97 *0.97
and the reference station is Portland, Maine and the example date is Monday, July 20, 1998.
COLUMN 1 (data from Portland reference station)
  • 250am L, -.3 ft
  • 905am H, 9.3 ft
  • 302pm L, .3 ft
  • 922pm H, 10.7 ft
 COLUMN 2 (data from above for Boothbay Harbor)
  • -0 08
  • -0 06
  • -0 08
  • -0 06
 COLUMN 3 (data from above for Boothbay Harbor)
  • *0.97
  • *0.97
  • *0.97
  • *0.97
 COLUMN 4 (resulting predictions for Boothbay Harbor)
  • 242am L, -.3 ft
  • 859am H, 9.0 ft
  • 254pm L, .3 ft
  • 916pm H, 10.4 ft
"L" = low tide "H" = high tide     "L" = low tide "H" = high tide
If the times in column 1 are the tides for a day at Portland, column 2 are the time corrections and column 3 are the height corrections (in this case, high and low corrections are equal) for Boothbay Harbor, then column 4 will be the predicted tides at Boothbay Harbor.
Portland, Maine Tide Predictions (High "H" and Low "L" Waters)
July, 1998 Daylight Savings Time (from NOAA, National Ocean Service)
 
 
Day Time Ht. Time Ht. Time Ht. Time Ht.
1 W 509am H 8.8 1125am L 1.0 545pm H 8.8 1156pm L 1.5
2 Th 603am H 8.5 1215pm L 1.3 636pm H 8.8    
3 F 1252am L 1.6 659am H 8.2 106pm L 1.5 726pm H 8.8
4 Sa 147am L 1.5 755am H 8.1 156pm L 1.6 815pm H 9.0
5 Su 240am L 1.3 849am H 8.1 245pm L 1.6 903pm H 9.2
6 M 329am L 1.0 939am H 8.2 330pm L 1.5 947pm H 9.4
7 Tu 413am L .7 1024am H 8.4 414pm L 1.3 1029pm H 9.7
8 W 454am L .3 1106am H 8.7 455pm L 1.1 1109pm H 10.0
9 Th 534am L .0 1147am H 8.9 536pm L .8 1150pm H 10.3
10 F 613am L -.3 1228pm H 9.2 618pm L .6    
11 Sa 1231am H 10.5 654am L -.5 109pm H 9.4 702pm L .4
12 Su 115am H 10.6 737am L -.7 153pm H 9.7 749pm L .2
13 M 202am H 10.6 822am L -.8 239pm H 9.9 839pm L .1
14 Tu 251am H 10.5 910am L -.7 329pm H 10.0 933pm L .1
15 W 345am H 10.2 1002am L -.5 422pm H 10.1 1031pm L .1
16 Th 443am H 9.9 1056am L -.3 518pm H 10.2 1134pm L .1
17 F 545am H 9.6 1155am L .0 618pm H 10.3    
18 Sa 1239am L .0 652am H 9.3 1257pm L .2 720pm H 10.4
19 Su 146am L -.1 759am H 9.2 200pm L .3 822pm H 10.5
20 M 250am L -.3 905am H 9.3 302pm L .3 922pm H 10.7
21 Tu 350am L -.6 1005am H 9.4 400pm L .2 1018pm H 10.8
22 W 445am L -.8 1100am H 9.6 454pm L .2 1111pm H 10.9
23 Th 535am L -.9 1150am H 9.6 544pm L .1 1159pm H 10.9
24 F 622am L -.8 1237pm H 9.7 631pm L .2    
25 Sa 1245am H 10.7 707am L -.7 121pm H 9.6 717pm L .3
26 Su 129am H 10.4 749am L -.4 204pm H 9.5 801pm L .5
27 M 212am H 10.0 830am L -.1 245pm H 9.3 845pm L .8
28 Tu 255am H 9.6 911am L .3 327pm H 9.2 930pm L 1.0
29 W 339am H 9.2 953am L .7 410pm H 9.0 1017pm L 1.2
30 Th 426am H 8.8 1036am L 1.1 454pm H 8.9 1107pm L 1.4
31 F 516am H 8.4 1122am L 1.4 542pm H 8.8    

Click here to return to "Predict Tides at Your Favorite Coastal Spot"