Passage Plan Advice from Chi to Gosport!

[Zagato]

Unless depth over Chi Bar is critical you could leave Chi on the last of the ebb, and enter Pompey on the early flood. Stay close to Hampshire, go through the gap in the submarine barrier, and you'll stay out of the stronger east-going that'll be further out towards the deeper water.

Thanks for that Ken, I tried going over the bar one hour after low tide when the post said 1m depth. Mine is 1.07, I didn't read my depth gauge going over as I was distracted at that moment by a VHF call but it must of been tight, maybe a couple of feet under.

Mines probably about the same draft as you old Twister.

Also went through the sub gap bang on a spring low tide with maybe 2' under me. The bit just North of the Winner post is where I bottle it on low tide, will try it one day though on a rising tide Good to now the limits

 

[Zagato]

Heres another! Good ere innit I feel like I am at school copying someone elses homework

CHICHESTER to BEMBRIDGE.

I'm good to enter Bembridge 3 hours before HT but I reckon if I leave Chi for Bembridge 3 hours before HT this Thursday I should be OK with fighting a 0.5-7 tide from Bembridge. Doesn't seem to be anyway of avoiding the tides this time. HT is roughly 2.30 at Bembridge on Thursday when it will hopefully be quieter on the visitors pontoon. The passage entrance to entrance should be about 2 hours...

I would leave 3 hours before high tide on the return leg as it looks the tides are in my favour on Friday.

 

[lustyd]

For planning you need to know the latest you can enter and work back. This weekend will be lower tides due to pressure so enter 30 mins before the maths would suggest, and your earliest time will be 30 mins later, although less important. Then take away your 2 hour trip time to see when you can leave at the latest and give some wiggle room.

Heres another! Good ere innit I feel like I am at school copying someone elses homework

CHICHESTER to BEMBRIDGE.

I'm good to enter Bembridge 3 hours before HT but I reckon if I leave Chi for Bembridge 3 hours before HT this Thursday I should be OK with fighting a 0.5-7 tide from Bembridge. Doesn't seem to be anyway of avoiding the tides this time. HT is roughly 2.30 at Bembridge on Thursday when it will hopefully be quieter on the visitors pontoon. The passage entrance to entrance should be about 2 hours...

I would leave 3 hours before high tide on the return leg as it looks the tides are in my favour on Friday.

 

[Twister_Ken]

Ken, perhaps you can explain what else happens at noon every day to change the tide times and heights so drastically? This has literally nothing to do with astronav although I will concede that you're a very clever little boy for knowing astronav (if indeed you do have a better grasp on that than on this...). Nothing happens at noon every day to change tide times and heights dramatically. Tides behave in a very predictable fashion (hence tide tables can be calculated years in advance). In round terms, tides vary in synch (but two days later) with the lunar cycle. Hence in one lunar cycle, you'll have two neap days, two spring days. The solar cycle of 365 days has nothing to do with this. Where the sun plays a part is in modifying SLIGHTLY the gravitational suck exerted by the moon, depending on the sun/moon alignment.

As for due west, every single day of the year the sun is in the west at 6pm. Indubitably, but not due west, except for two days of the year. This isn't something I made up it's a fact. The sun will be at 90 degrees west at 1800 UTC, 180degrees at 0000 UTC and 90 degrees east at 0600 UTC (in the land of the rising sun). Obviously, it's west at 1800, but not due west (except on two days of the year). That's just how the planet spins, and yes it's tilted by a couple of degrees - rather more than a couple, actually 23.5º, which gives a total apparent progression of the sun's angle to the earth of 47º between December's and June's solstices. Not inconsiderable. And why the sun is only due west at 1800h twice a year. Exactly which days of the year will depend on your latitude. but at the scale we're talking about the fact that it'd due west is the important bit.

Here's a thought. Next time you're on your boat on a sunny day, use your handbearing compass to take a bearing on the sun (or better, the horizon under it) at 1800. You might be surprised, but the odds are 365 to 2 that it won't be at 270ºT.

 

[Twister_Ken]

Another way to put it, which you ought to have picked up on your astronav course, is that it is always local noon at 1800 UTC at 90 degrees west, everywhere on the line.

Agreed. Physics 101. But only one point on that 090ºW line is DUE west of you.

 

[lustyd]

Agreed. Physics 101. But only one point on that 090ºW line is DUE west of you.

I didn't say due west of me, I said west of the planet and I was right. The tide doesn't give two hoots where I am, if the sun is in the west then it's pulling the water (all of the water) in a westerly direction and therefore the water will be moving faster in that direction than if it wasn't.

 

[Twister_Ken]

I didn't say due west of me, I said west of the planet and I was right. The tide doesn't give two hoots where I am, if the sun is in the west then it's pulling the water (all of the water) in a westerly direction and therefore the water will be moving faster in that direction than if it wasn't.

You said DUE west on several occasions.

And you don't seem to have grasped that the Sun has a minor involvement with tide, it's the position of the Moon that counts.

Anyway, I'm wasting no more keystrokes on this.

 

[Laundryman]

Dave, I'm so impressed with your navigational knowledge that as my 1st Officer ( seconded during September) I delegate calculation of the passage plan to Cherbourg, Channel Islands and back to you. As for our relationship to the Sun, I would like to see it shining while we're playing with the boat and have no problem with it being east in the morning, west in the evening and south for the rest of the day, just as long as I can see it. My 5knot average may not be as exhilarating as an Anderson 22 but then its always blowing a gale in one of those. Just a gentle force 4 would be nice if you could factor that in. No sextant on my boat thank you, I prefer binoculars. I've got a pair for each of us. You keep swotting up on the technical bits and absorbing all the advice from these sailing professors and that together with all my electronic gadgets, we may find our way to France ( or thereabouts). Alan

 

[Ru88ell]

... electronic gadgets, ... ( or thereabouts). Alan

Microwave? TV?

 

[lustyd]

Dave, I'm so impressed with your navigational knowledge that as my 1st Officer ( seconded during September) I delegate calculation of the passage plan to Cherbourg, Channel Islands and back to you. As for our relationship to the Sun, I would like to see it shining while we're playing with the boat and have no problem with it being east in the morning, west in the evening and south for the rest of the day, just as long as I can see it. My 5knot average may not be as exhilarating as an Anderson 22 but then its always blowing a gale in one of those. Just a gentle force 4 would be nice if you could factor that in. No sextant on my boat thank you, I prefer binoculars. I've got a pair for each of us. You keep swotting up on the technical bits and absorbing all the advice from these sailing professors and that together with all my electronic gadgets, we may find our way to France ( or thereabouts). Alan

Yes I think a F4 would be ideal, preferably not from the south I'm sure we'll manage without the sextant, according to Ken I wouldn't know how to use one anyway although I'm not aware of having met him so how he's so sure of that I have no idea I've had a look at the charts for Cherbourg and CIs and think I've worked out what the blue bits are so we'll be fine!