As we think ahead to Bigger Boat, one critical issue is draught - the depth of the keel below the waterline - and when, or indeed if, we'll be able to get in and out of our drying mud berth (which we're very happy with and would be loathe to give up)
So I sat down earlier and plugged the daytime high tides for 2016 into a spreadsheet and then used conditional formatting to highlight the tides which would give us access to the berth with our current 3' draught, with a draught of around 4'6 and again with a draught of 5'6 (which I reckon is the maximum we can realistically entertain)
This is based on our experience to date where we've found that we need a tide of 4.3m or better to comfortably get in and out of the berth with Erbas although we did scrape in last time with just 4.2m albeit leaving a groove in the mud with the starboard keel!
Here is the resulting table ...
2016 | ||||||||||||||||||||||
January | February | March | April | May | June | |||||||||||||||||
Fri 01 | 17:13 | 4.6 | Mon 01 | 17:55 | 4.3 | Tue 01 | 17:08 | 4.4 | Fri 01 | 18:25 | 4.2 | Sun 01 | 06:34 | 4.5 | Wed 01 | 08:47 | 4.8 | |||||
Sat 02 | 18:00 | 4.4 | Tue 02 | 06:18 | 4.3 | Wed 02 | 17:58 | 4.2 | Sat 02 | 07:02 | 4.2 | Mon 02 | 08:01 | 4.5 | Thu 02 | 09:58 | 5.0 | |||||
Sun 03 | 18:55 | 4.3 | Wed 03 | 07:27 | 4.1 | Thu 03 | 06:25 | 4.2 | Sun 03 | 08:40 | 4.4 | Tue 03 | 09:21 | 4.8 | Fri 03 | 11:00 | 5.3 | |||||
Mon 04 | 07:21 | 4.3 | Thu 04 | 08:47 | 4.2 | Fri 04 | 07:52 | 4.1 | Mon 04 | 09:57 | 4.7 | Wed 04 | 10:27 | 5.1 | Sat 04 | 11:55 | 5.4 | |||||
Tue 05 | 08:29 | 4.3 | Fri 05 | 10:00 | 4.4 | Sat 05 | 09:21 | 4.3 | Tue 05 | 10:58 | 5.1 | Thu 05 | 11:24 | 5.4 | Sun 05 | 12:48 | 5.5 | |||||
Wed 06 | 09:36 | 4.4 | Sat 06 | 11:00 | 4.7 | Sun 06 | 10:31 | 4.7 | Wed 06 | 11:51 | 5.4 | Fri 06 | 12:16 | 5.5 | Mon 06 | 13:35 | 5.6 | |||||
Thu 07 | 10:36 | 4.7 | Sun 07 | 11:52 | 5.0 | Mon 07 | 11:28 | 5.0 | Thu 07 | 12:40 | 5.6 | Sat 07 | 13:06 | 5.7 | Tue 07 | 14:08 | 5.5 | |||||
Fri 08 | 11:28 | 4.9 | Mon 08 | 12:40 | 5.3 | Tue 08 | 12:18 | 5.3 | Fri 08 | 13:28 | 5.7 | Sun 08 | 13:50 | 5.7 | Wed 08 | 15:01 | 5.4 | |||||
Sat 09 | 12:15 | 5.1 | Tue 09 | 13:26 | 5.5 | Wed 09 | 13:06 | 5.6 | Sat 09 | 14:08 | 5.7 | Mon 09 | 14:33 | 5.6 | Thu 09 | 15:42 | 5.3 | |||||
Sun 10 | 13:00 | 5.3 | Wed 10 | 14:06 | 5.7 | Thu 10 | 13:48 | 5.7 | Sun 10 | 14:50 | 5.6 | Tue 10 | 15:15 | 5.4 | Fri 10 | 16:25 | 5.0 | |||||
Mon 11 | 13:41 | 5.5 | Thu 11 | 14:47 | 5.7 | Fri 11 | 14:29 | 5.7 | Mon 11 | 15:33 | 5.4 | Wed 11 | 15:59 | 5.2 | Sat 11 | 17:11 | 4.8 | |||||
Tue 12 | 14:20 | 5.6 | Fri 12 | 15:28 | 5.6 | Sat 12 | 15:10 | 5.6 | Tue 12 | 16:16 | 5.1 | Thu 12 | 16:46 | 4.9 | Sun 12 | 18:00 | 4.6 | |||||
Wed 13 | 15:00 | 5.5 | Sat 13 | 16:09 | 5.3 | Sun 13 | 15:52 | 5.4 | Wed 13 | 17:04 | 4.8 | Fri 13 | 17:38 | 4.6 | Mon 13 | 06:35 | 4.5 | |||||
Thu 14 | 15:42 | 5.4 | Sun 14 | 16:54 | 5.1 | Mon 14 | 16:35 | 5.1 | Thu 14 | 18:01 | 4.5 | Sat 14 | 06:10 | 4.6 | Tue 14 | 07:38 | 4.4 | |||||
Fri 15 | 16:24 | 5.3 | Mon 15 | 17:44 | 4.8 | Tue 15 | 17:24 | 4.8 | Fri 15 | 06:36 | 4.6 | Sun 15 | 07:19 | 4.5 | Wed 15 | 08:46 | 4.5 | |||||
Sat 16 | 17:12 | 5.0 | Tue 16 | 06:04 | 4.9 | Wed 16 | 18:23 | 4.4 | Sat 16 | 08:00 | 4.5 | Mon 16 | 08:36 | 4.5 | Thu 16 | 09:49 | 4.6 | |||||
Sun 17 | 18:06 | 4.8 | Wed 17 | 07:17 | 4.6 | Thu 17 | 06:56 | 4.5 | Sun 17 | 09:22 | 4.6 | Tue 17 | 09:45 | 4.6 | Fri 17 | 10:44 | 4.7 | |||||
Mon 18 | 06:26 | 4.9 | Thu 18 | 08:49 | 4.5 | Fri 18 | 08:30 | 4.5 | Mon 18 | 10:28 | 4.8 | Wed 18 | 10:39 | 4.8 | Sat 18 | 11:30 | 4.9 | |||||
Tue 19 | 07:43 | 4.7 | Fri 19 | 10:09 | 4.7 | Sat 19 | 09:52 | 4.6 | Tue 19 | 11:18 | 4.9 | Thu 19 | 11:24 | 4.9 | Sun 19 | 12:12 | 5.0 | |||||
Wed 20 | 09:07 | 4.7 | Sat 20 | 11:14 | 4.9 | Sun 20 | 10:58 | 4.9 | Wed 20 | 12:00 | 5.0 | Fri 20 | 12:04 | 5.0 | Mon 20 | 12:52 | 5.1 | |||||
Thu 21 | 10:20 | 4.9 | Sun 21 | 12:06 | 5.1 | Mon 21 | 11:47 | 5.0 | Thu 21 | 12:36 | 5.1 | Sat 21 | 12:40 | 5.1 | Tue 21 | 13:30 | 5.2 | |||||
Fri 22 | 11:22 | 5.1 | Mon 22 | 12:50 | 5.2 | Tue 22 | 12:29 | 5.1 | Fri 22 | 13:10 | 5.1 | Sun 22 | 13:16 | 5.2 | Wed 22 | 14:06 | 5.3 | |||||
Sat 23 | 12:16 | 5.2 | Tue 23 | 13:27 | 5.2 | Wed 23 | 13:05 | 5.1 | Sat 23 | 13:40 | 5.2 | Mon 23 | 13:47 | 5.2 | Thu 23 | 14:41 | 5.3 | |||||
Sun 24 | 13:03 | 5.3 | Wed 24 | 13:59 | 5.2 | Thu 24 | 13:36 | 5.2 | Sun 24 | 14:08 | 5.2 | Tue 24 | 14:20 | 5.2 | Fri 24 | 15:18 | 5.2 | |||||
Mon 25 | 13:41 | 5.4 | Thu 25 | 14:30 | 5.2 | Fri 25 | 14:06 | 5.2 | Mon 25 | 14:38 | 5.1 | Wed 25 | 14:52 | 5.1 | Sat 25 | 15:55 | 5.1 | |||||
Tue 26 | 14:18 | 5.3 | Fri 26 | 15:01 | 5.1 | Sat 26 | 14:34 | 5.1 | Tue 26 | 15:08 | 5.0 | Thu 26 | 15:27 | 5.0 | Sun 26 | 16:37 | 5.0 | |||||
Wed 27 | 14:53 | 5.2 | Sat 27 | 15:29 | 5.0 | Sun 27 | 15:02 | 5.0 | Wed 27 | 15:41 | 4.9 | Fri 27 | 16:05 | 4.9 | Mon 27 | 17:24 | 5.0 | |||||
Thu 28 | 15:27 | 5.1 | Sun 28 | 15:58 | 4.8 | Mon 28 | 15:30 | 4.9 | Thu 28 | 16:17 | 4.7 | Sat 28 | 16:49 | 4.8 | Tue 28 | 18:19 | 4.9 | |||||
Fri 29 | 15:59 | 4.9 | Mon 29 | 16:30 | 4.6 | Tue 29 | 16:01 | 4.8 | Fri 29 | 17:02 | 4.5 | Sun 29 | 17:41 | 4.7 | Wed 29 | 06:59 | 4.8 | |||||
Sat 30 | 16:33 | 4.7 | Wed 30 | 16:37 | 4.6 | Sat 30 | 17:59 | 4.4 | Mon 30 | 06:14 | 4.7 | Thu 30 | 08:17 | 4.8 | ||||||||
Sun 31 | 17:10 | 4.5 | Thu 31 | 17:23 | 4.4 | Tue 31 | 07:29 | 4.7 | ||||||||||||||
July | August | September | October | November | December | |||||||||||||||||
Fri 01 | 09:33 | 4.9 | Mon 01 | 11:32 | 5.1 | Thu 01 | 12:54 | 5.4 | Sat 01 | 13:06 | 5.4 | Tue 01 | 13:38 | 5.4 | Thu 01 | 13:47 | 5.3 | |||||
Sat 02 | 10:42 | 5.1 | Tue 02 | 12:24 | 5.3 | Fri 02 | 13:31 | 5.5 | Sun 02 | 13:36 | 5.5 | Wed 02 | 14:08 | 5.4 | Fri 02 | 14:19 | 5.3 | |||||
Sun 03 | 11:40 | 5.2 | Wed 03 | 13:12 | 5.4 | Sat 03 | 14:03 | 5.5 | Mon 03 | 14:05 | 5.5 | Thu 03 | 14:38 | 5.3 | Sat 03 | 14:51 | 5.2 | |||||
Mon 04 | 12:35 | 5.4 | Thu 04 | 13:50 | 5.5 | Sun 04 | 14:34 | 5.5 | Tue 04 | 14:34 | 5.4 | Fri 04 | 15:09 | 5.1 | Sun 04 | 15:26 | 5.1 | |||||
Tue 05 | 13:23 | 5.5 | Fri 05 | 14:26 | 5.5 | Mon 05 | 15:03 | 5.4 | Wed 05 | 15:03 | 5.3 | Sat 05 | 15:42 | 5.0 | Mon 05 | 16:04 | 5.0 | |||||
Wed 06 | 14:05 | 5.5 | Sat 06 | 15:01 | 5.5 | Tue 06 | 15:33 | 5.2 | Thu 06 | 15:33 | 5.1 | Sun 06 | 16:19 | 4.8 | Tue 06 | 16:48 | 4.9 | |||||
Thu 07 | 14:45 | 5.5 | Sun 07 | 15:33 | 5.3 | Wed 07 | 16:04 | 5.0 | Fri 07 | 16:05 | 4.9 | Mon 07 | 17:04 | 4.7 | Wed 07 | 17:40 | 4.8 | |||||
Fri 08 | 15:24 | 5.4 | Mon 08 | 16:06 | 5.2 | Thu 08 | 16:37 | 4.8 | Sat 08 | 16:42 | 4.7 | Tue 08 | 18:03 | 4.5 | Thu 08 | 18:43 | 4.7 | |||||
Sat 09 | 16:02 | 5.2 | Tue 09 | 16:41 | 5.0 | Fri 09 | 17:18 | 4.5 | Sun 09 | 17:29 | 4.4 | Wed 09 | 06:34 | 4.4 | Fri 09 | 07:14 | 4.6 | |||||
Sun 10 | 16:40 | 5.0 | Wed 10 | 17:20 | 4.7 | Sat 10 | 18:13 | 4.3 | Mon 10 | 18:36 | 4.3 | Thu 10 | 07:59 | 4.5 | Sat 10 | 08:33 | 4.8 | |||||
Mon 11 | 17:21 | 4.8 | Thu 11 | 18:09 | 4.5 | Sun 11 | 06:50 | 4.2 | Tue 11 | 07:21 | 4.2 | Fri 11 | 09:16 | 4.8 | Sun 11 | 09:46 | 5.0 | |||||
Tue 12 | 18:08 | 4.6 | Fri 12 | 06:43 | 4.3 | Mon 12 | 08:17 | 4.2 | Wed 12 | 08:49 | 4.4 | Sat 12 | 10:20 | 5.1 | Mon 12 | 10:49 | 5.3 | |||||
Wed 13 | 06:40 | 4.4 | Sat 13 | 07:53 | 4.2 | Tue 13 | 09:36 | 4.5 | Thu 13 | 10:00 | 4.8 | Sun 13 | 11:16 | 5.5 | Tue 13 | 11:46 | 5.6 | |||||
Thu 14 | 07:42 | 4.3 | Sun 14 | 09:07 | 4.4 | Wed 14 | 10:41 | 4.8 | Fri 14 | 10:57 | 5.1 | Mon 14 | 12:07 | 5.7 | Wed 14 | 12:38 | 5.8 | |||||
Fri 15 | 08:49 | 4.4 | Mon 15 | 10:18 | 4.6 | Thu 15 | 11:33 | 5.1 | Sat 15 | 11:48 | 5.5 | Tue 15 | 12:57 | 5.9 | Thu 15 | 13:28 | 5.9 | |||||
Sat 16 | 09:57 | 4.5 | Tue 16 | 11:15 | 4.9 | Fri 16 | 12:20 | 5.4 | Sun 16 | 12:36 | 5.7 | Wed 16 | 13:42 | 6.0 | Fri 16 | 14:12 | 5.9 | |||||
Sun 17 | 10:54 | 4.8 | Wed 17 | 12:04 | 5.1 | Sat 17 | 13:06 | 5.7 | Mon 17 | 13:22 | 5.9 | Thu 17 | 14:26 | 6.0 | Sat 17 | 14:57 | 5.7 | |||||
Mon 18 | 11:45 | 5.0 | Thu 18 | 12:49 | 5.4 | Sun 18 | 13:45 | 5.8 | Tue 18 | 14:02 | 6.0 | Fri 18 | 15:10 | 5.8 | Sun 18 | 15:42 | 5.5 | |||||
Tue 19 | 12:30 | 5.1 | Fri 19 | 13:31 | 5.6 | Mon 19 | 14:24 | 5.9 | Wed 19 | 14:43 | 6.0 | Sat 19 | 15:55 | 5.5 | Mon 19 | 16:28 | 5.2 | |||||
Wed 20 | 13:13 | 5.3 | Sat 20 | 14:09 | 5.7 | Tue 20 | 15:03 | 5.9 | Thu 20 | 15:26 | 5.8 | Sun 20 | 16:47 | 5.1 | Tue 20 | 17:18 | 4.9 | |||||
Thu 21 | 13:51 | 5.0 | Sun 21 | 14:48 | 5.7 | Wed 21 | 15:43 | 5.7 | Fri 21 | 16:10 | 5.5 | Mon 21 | 17:45 | 4.8 | Wed 21 | 18:11 | 4.6 | |||||
Fri 22 | 14:28 | 5.5 | Mon 22 | 15:25 | 5.7 | Thu 22 | 16:26 | 5.5 | Sat 22 | 17:02 | 5.1 | Tue 22 | 18:51 | 4.7 | Thu 22 | 06:31 | 4.5 | |||||
Sat 23 | 15:05 | 5.5 | Tue 23 | 16:04 | 5.6 | Fri 23 | 17:16 | 5.1 | Sun 23 | 18:07 | 4.8 | Wed 23 | 07:23 | 4.5 | Fri 23 | 07:38 | 4.4 | |||||
Sun 24 | 15:43 | 5.4 | Wed 24 | 16:46 | 5.4 | Sat 24 | 18:23 | 4.8 | Mon 24 | 19:27 | 4.7 | Thu 24 | 08:40 | 4.5 | Sat 24 | 08:49 | 4.4 | |||||
Mon 25 | 16:22 | 5.3 | Thu 25 | 17:34 | 5.1 | Sun 25 | 19:50 | 4.7 | Tue 25 | 08:07 | 4.5 | Fri 25 | 09:46 | 4.7 | Sun 25 | 09:53 | 4.5 | |||||
Tue 26 | 17:05 | 5.2 | Fri 26 | 18:37 | 4.9 | Mon 26 | 08:39 | 4.5 | Wed 26 | 09:26 | 4.7 | Sat 26 | 10:39 | 4.9 | Mon 26 | 10:46 | 4.7 | |||||
Wed 27 | 17:56 | 5.1 | Sat 27 | 07:28 | 4.5 | Tue 27 | 09:58 | 4.8 | Thu 27 | 10:28 | 4.9 | Sun 27 | 11:24 | 5.0 | Tue 27 | 11:32 | 4.9 | |||||
Thu 28 | 06:35 | 4.8 | Sun 28 | 08:59 | 4.6 | Wed 28 | 10:59 | 5.0 | Fri 28 | 11:17 | 5.1 | Mon 28 | 12:03 | 5.1 | Wed 28 | 12:14 | 5.0 | |||||
Fri 29 | 07:50 | 4.7 | Mon 29 | 10:18 | 4.8 | Thu 29 | 11:48 | 5.2 | Sat 29 | 11:59 | 5.2 | Tue 29 | 12:39 | 5.2 | Thu 29 | 12:54 | 5.1 | |||||
Sat 30 | 09:14 | 4.7 | Tue 30 | 11:19 | 5.1 | Fri 30 | 12:30 | 5.3 | Sun 30 | 12:35 | 5.3 | Wed 30 | 13:15 | 5.3 | Fri 30 | 13:30 | 5.2 | |||||
Sun 31 | 10:29 | 4.9 | Wed 31 | 12:10 | 5.3 | Mon 31 | 13:08 | 5.4 | Sat 31 | 14:05 | 5.3 | |||||||||||
Highlighting bands are at 3'0", 4'6" and 5'6" draught and err on the side of caution |
The lightest blue is the 3' band and as you can see Erbas, or a boat with similar draught, is rarely neaped (unable to get in or out of the berth). Some months we wouldn't be neaped at all and at worse it's only for two or three days a month
Move up to around 4'6", the medium blue band, and we inevitably get neaped a lot more often. Twice a month and for periods of up to a week in fact. That's tolerable as we are rarely if ever inclined to go out for a sail on a whim. If we know we want to go out or come back during the period that we'd be neaped we can move off the berth onto the river pontoon or a spare mooring or do the same in reverse coming back
At 5'6" the scenario gets somewhat worse. It knocks a day off either side of on week where we can access the berth but it's the other window of access during the lower of the two tide cycles each month that really takes a hammering. There are times in the spring especially when we would be unable to get on or off for ten or eleven days at a time and then we'd only have a narrow window of opportunity
And this of course presupposes that the tides weren't suppressed by high atmospheric pressure etc. It is not unknown for the tides to be considerably lower than predicted
It could be managed but it isn't ideal so we really need to consider the draught of Bigger Boat closely and anything over 4'6" has to be so perfect in every other respect as to outweigh the drawbacks of being neaped for nearly a fortnight at a time (or worse)
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