Tide Clocks

[DaveS]

With a birthday coming up in about three weeks time, I will no doubt be asked if there is anything that I would like as a pressy.

My son just gave me a bottle of Scotch for 'fathers day', so well sorted there , don't need any new fishing gear, and have got plenty of socks

Something for the boat perhaps?

Having been buying a steady stream of 'bits & bobs' for the boat, since we bought it last August, she has pretty much got everything I need now.

However, browsing the chandlers websites for ideas, I came across a nice little (4.5") Brass cased Tide Clock:

I thought this might be a useful gadget (gimmick?) to have onboard, for planning our trips around the Broads, to run with the tide whenever practical to do so (fuel economy ), clearance under bridges (e.g. St Olaves and Beccles old road bridge)), and journeys through Yarmouth.

So, do any of you guys have them, and if so, are they useful or just a gimmick?.

BTW, it certainly pays to 'shop around', as my local chandlers, and chandlers in Norfolk, are asking £54 to £56 for Plastimo clock shown in the picture, whereas at TCS Chandlery, its £35

Dave

[Antares_9]

So, do any of you guys have them, and if so, are they useful or just a gimmick?. Dave

Yes, yes, and no.

I also have a tide graph on my watch, when I can be bothered to wear it, all information is useful Dave and if the means of getting it is via a "shiny bit" then even better.

[DaveS]

I think we all like a few 'shiny bits' onboard David, even if its only because they look nice, or 'tiddly' as they say in the Navy

I keep a tin of Brasso onboard to keep the 'ship's bell' shiny. I didn't buy that one, it came with the boat

I think I'll drop the hint about the tide clock

Set it to Gt Yarmouth tide time, and then its just matter of applying the corrections, for wherever we happen to be on the Broads.

Dave

[jimbo]

How do these work then?? Is it a case of setting the Low Tide say every morning and then using it as an at a glance reference, or do they actually keep up with the daily changes somehow?

[Antares_9]

You set them to next high water when you board Jim, some you rotate the bezel to next high water and the clock keeps the time as usual then you read off the tide state (or rater predicted tide state) from the bezel.

[jimbo]

Cool! Sounds like another gizmo to add to the BGCM's list

[Happy Jax 3]

Hi Dave

I have one of these on HJ2. As you say I have set it to Gt Yarmouth yacht station and add correction to were I am on the broads. I use it all the time, even when mooring up to work out tidal stream. As a back up I have one on my mariners watch, as with you David when I can be bothered to wear it. I have also just down loaded a Tide App to my new Ipod touch.

I guess, as with many of us boaters we just like gadgets.

[Guest]

They are set to give a dial revolution every 12 hours and 25 minutes, half a Lunar Day, to keep pace with the Moon's gravitational pull on the Tides.

The trouble is these simple analogue clocks cannot compensate for the variations caused by the Sun's influence during the 29 day Spring/Neap cycle. They can therefore be as much as one hour "out" during the Lunar Month.

[Guest]

If you can catch up with Lord Paul he was selling dashboard size ones for £20 last season, he may have some left, mine looks great mounted on my dashboard! I will find out how useful it is in a few weeks time : :

[DaveS]

How do these work then???

From Wikipedia:

Tide clocks keep an approximation of the average time between high lunar tides: 12 hours 25 minutes per revolution. As the precise average time between high lunar tides is actually half of a lunar day, or 12 hours 25 minutes 14 seconds, tide clocks gain about 15 minutes per month and must be reset periodically

Or, in keeping with what Strowager said:

Tides are caused mainly by the moons gravitational pull on the ocean.The time it takes the moon to reappear at the same place in the sky each day is 24 hours and 50 minutes . Most areas in the world have two high tides and two low tides a day, so the tide clock has been specially designed to rotate twice each lunar day (every 12 hours and 25 minutes) giving you a quick and easy indication of high and low water. The Quartz tide clock will always stay synchronized to the moon.

There are other influences on sea levels that effect exact tide times. Therefore the tide clock should only ever be used as a guide, and is not intended for navigational use

The suns own gravitational pull, when lined up with the moon (full moon and new moon) creates higher and lower tides. This can alter tide times by up to an hour.

Changing atmospheric pressure.

Strong on-shore and off-shore winds.

Changing volume of river flows.

Dave

[Guest]

It's the "dependable" inaccuracy between the Spring/Neap cycle that put me off using mine.

The fact that they are up to an hour out during every two week period makes them far less useful.

I found (for the Broads) that my old "Hamilton's Tide Calculator" is far more useful. A simple cardboard disk affair. I just set it by my watch once a day when cruising, and it tells me tide states around the Broads system at a glance, for that day.

[Antares_9]

They really only one piece of information in the chain but used properly are quite adequate. Obviously on rivers like the Thames and those that are part of the broads system there are many other factors that can and do affect predictions. The animated tidal graph on my plotters is the thing I use most and have found it to be accurate in practise.

[DaveS]

There you go , I just happened to mention to Mrs S that I'd like a brass tide-clock for the boat, and she said "why not have that for your birthday"

I have seen one that I rather like said I, "why don't you go ahead and order it" she said. Ok said I, and no sooner was it said it was done

Dave

[marshman]

Trouble is on the broads they don't really work. Or do they? Because of the river flows, normally the ebb flows for longer and the flood for rather less. Certainly up here on the Northern Rivers I always tend to use 5 hrs of flood and 7 of ebb!!!

So that b*****S that up then if i am right!!!!!

[DaveS]

Well, Colin (Happy Jax II) seems to find his useful, and I guess I'll find out in due course if it works for me.

In any case, it will look nice on the boat

My plan, as with Colin, is to set it to HW at Yarmouth, and just add the correction for wherever on the Broads I happen to be.

Dave