Harwich to Ramsgate - best time to leave?

[Rafiki]

OK, I have Roger's book but unless I spend a LONG time working put alternatives it doesn't seem to to give a simple answer to my obvious question --" What is the best time to leave Harwich for Ramsgate relative to HW at Harwich ( or Dover for that matter), assuming average speed through the water of 5Kts"

Intended route is via Sunk and Fisherman's Gat ( 'Route 28'). Date is 7th June, HW Harwich is 02:00 and 14:24 UT, Spring(ish) tides. I really don't want to leave earlier than 4 am UT but would also prefer to get to Ramsgate by 15:00 UT.

Maybe the theory is that you are generally crossing the tidal flow, and therefore direction not critical and the only part that really matters to avoid a foul tide is N Foreland to Ramsgate, which of course is difficult as the tide there is N flowing from about 13:30 UT

Any suggestions or do I just leave as early as possible?

Andrew

 

[tillergirl]

I have tried for over an hour to post a thread and have had to retype it again and again as the response gets deleted just before posted – 6 times now! There is something wrong with my machine… again, but only with the Forum. It seemed to be cured last week but it’s going wrong again.
So I am typing this on Word and then will attempt to paste it on the thread.
What I said was:
“It doesn’t matter what time you start!
That is a bit glib so I best explain. Route 28 is the unique route in the Estuary. It is the only route that cannot beat the tide! The route is 39.90nm. If it was on a lake at 5knts it would take 7hrs 58 minutes to complete the route. But in the Estuary the best time is 8 hrs: i.e. the best it can do is to avoid negative tide. Actually what happens is that where there is a benefit, there is also elsewhere a hindering tide and at best they cancel each other. This is because there is a tide effect from the North Sea and also the Channel but the tides don’t work together in that part of the Estuary.
Why did I say it doesn’t matter what time you start? Well, because the slowest passage would take 8hrs 35 minutes – a mere 35 minutes difference. So the impulse for social navigation might be strong: for 35 minutes I would tend to prefer to have a good night’s sleep!
By the way if Neaps, the best time would be 7hrs 55 minutes, so not much difference.
As another ‘by the way’, going North is quite different. The same route would only take 6hrs 51 minutes which because the two tides do work together that way.
Seriously about the start time. I would still tend to opt for the quicker durations which at 8hrs are between -4.30 to -4.15 Sheerness. Sheerness on 7th June is 0400 and 1616 BST. They benefit from the final sectors including down past North Foreland – which is very sensible. Indeed there is a nice wide window of good times for the final sector between the start times but that all coincides with the worse durations. But that would be for a later arrival than you want.
I have been doing a lot of development work over the winter to answer the question you have asked: ‘what is the best time to leave?’. The development work is, umm quite large. To provide that question for each of the routes, north or south, springs or neaps, 3, 4, 5, 6, or 7 kts, I have had to find the answer to over 1.3 million questions. I have cracked the maths but I have a knacksack of 40mb of figures that I now need to convert this into an app. That is really difficult.
Andrew I suggest you pm me an email and I can send you something cut out of my development work. I think you might find it interesting, even useful.

 

[tillergirl]

Phew. Managed to post the above. But took three times to post this.

 

[John 32i]

Thanks Roger, I have the book too but additional information is always a bonus :encouragement:

 

[MikeBz]

Using NavigationPLANNER, Landguard -> N Gunfleet -> SW Sunk -> Fisherman's -> Ramsgate gives this:

Harwich to Ramsgate
Time - Elapsed time -- Arrival time
0:00 08 hours 14 mins 08:14 Friday, June 07, 2019
1:00 08 hours 30 mins 09:30 Friday, June 07, 2019
2:00 08 hours 59 mins 10:59 Friday, June 07, 2019
3:00 09 hours 30 mins 12:30 Friday, June 07, 2019
4:00 09 hours 32 mins 13:32 Friday, June 07, 2019
5:00 09 hours 34 mins 14:34 Friday, June 07, 2019
6:00 09 hours 33 mins 15:33 Friday, June 07, 2019
7:00 09 hours 12 mins 16:12 Friday, June 07, 2019
8:00 09 hours 13 mins 17:13 Friday, June 07, 2019
9:00 08 hours 31 mins 17:31 Friday, June 07, 2019
10:00 08 hours 33 mins 18:33 Friday, June 07, 2019
11:00 08 hours 23 mins 19:23 Friday, June 07, 2019
12:00 08 hours 14 mins 20:14 Friday, June 07, 2019
13:00 08 hours 22 mins 21:22 Friday, June 07, 2019
14:00 08 hours 47 mins 22:47 Friday, June 07, 2019
15:00 09 hours 21 mins 00:21 Saturday, June 08, 2019
16:00 09 hours 33 mins 01:33 Saturday, June 08, 2019
17:00 09 hours 26 mins 02:26 Saturday, June 08, 2019
18:00 09 hours 27 mins 03:27 Saturday, June 08, 2019
19:00 09 hours 14 mins 04:14 Saturday, June 08, 2019
20:00 09 hours 06 mins 05:06 Saturday, June 08, 2019
21:00 08 hours 56 mins 05:56 Saturday, June 08, 2019
22:00 08 hours 43 mins 06:43 Saturday, June 08, 2019
23:00 08 hours 20 mins 07:20 Saturday, June 08, 2019


As luck would have it the least unsociable time to leave (5am) which gets you there before 15:00 gives you the maximum length voyage for the day...

I assume the software uses UTC/BST sensibly, but it's not mentioned anywhere.

 

[MikeBz]

Hmm, so while I was doing that Roger posted - his times are quite different to those given by software - I would trust his I think!

Edit.. ah, my route is 43.6 nm vs. Roger's 39.9. I don't have the book in front of me to compare.

 

[johnalison]

From Titchmarsh we don't have a completely free choice and I usually leave as soon as we can after LW. This takes us over the Little Sunk with even more than the minimum 3.5m and up to Foulger's Gat with the tide.

 

[tillergirl]

Hmm, so while I was doing that Roger posted - his times are quite different to those given by software - I would trust his I think!

Edit.. ah, my route is 43.6 nm vs. Roger's 39.9. I don't have the book in front of me to compare.

It's via the Little Sunk rather than the SW Sunk. We noted a couple of yachts did the SW Sunk from the north that day we did the survey. I am currently under orders (from SWMBO) so I'll respond later in the day (or I won't be able to respond at all!).

 

[Rafiki]

Thanks all -- so the answer is that if you are using Route 28 elapsed time varies very little with when you leave. Roger has separately provided me with an insight into his development work which will help identify the optimum time for departures and colour code the sectors to indicate strength of tidal flow.

 

[debenbar]

I usually aim to be off Long sand head at low water and then carry a fair tide to Ramsgate.

 

[pvb]

I leave at HW Dover +1 to +3.

 

[jimi]

I'd be aiming to avoid adverse tide on the last bit to Ramsgate. Tide flows hard there