Tidal heights changes caused by 18.61 years cycle of lunar 'wobbles'

[LittleSister]

You wouldn't want to be neaped for nearly 19 years, now, would you?

The research reported in this article focuses on its effects on mangrove trees, but mentions various quirks of tidal variation that might be of interest to other boating folk.

‘Wobbly’ moon probable cause of mass tree deaths in Australia, scientists say

 

[Daydream believer]

Yes! I can believe that . When there is a full moon, I notice that I have begun to wobble a lot more on the way home from the local, than I did a few years ago.

 

[Chiara’s slave]

Yes! I can believe that . When there is a full moon, I notice that I have begun to wobble a lot more on the way home from the local, than I did a few years ago.

Any noticeable hair growth, in unusual areas?

 

[Daydream believer]

Any noticeable hair growth, in unusual areas?

Palm of the hands

 

[AngusMcDoon]

‘Wobbly’ moon probable cause of mass tree deaths in Australia, scientists say

If it's cyclical and been happening for the past few billion years I expect that the mangroves will cope. The headline is a bit alarmist. However, I've seen pontoons perilously close to the top of their retaining poles. There really would be a bit of a kerfuffle if the pontoons broke loose en masse.

 

[Telstar26]

And it's the 2nd smallest tide of the year next Tue - round here (Pembrokeshire) anyway. The smallest was 10th March

 

[Juan Twothree]

However, I've seen pontoons perilously close to the top of their retaining poles. There really would be a bit of a kerfuffle if the pontoons broke loose en masse.

Just get all the moored boats to drop their anchors. Problem solved.

But the question is...... Which sort of anchor would be best?

 

[ProDave]

I notice next weeks neap tides are the smallest range I have seen in <16 years boating, so it usually means the corresponding springs will be larger.

 

[dunedin]

I notice next weeks neap tides are the smallest range I have seen in <16 years boating, so it usually means the corresponding springs will be larger.

I find the Tidal Coefficients, as used extensively in France and other places, are really helpful as a simple and objective summary of how big the tides are - eg here La Rochelle-Ville - September tide times - METEO CONSULT MARINE - Free 15-day Marine forecasts - METEO CONSULT MARINE

And yes next Monday, for HM funeral, we have one of the smallest tidal coefficients of just 24.

Howeve, I dont see any particularly big tides in September (none over 100) and just a single 101 coefficient on 10th October.

I somehow managed to go into Gulf de Morbihan for my first time at mid-tide on a super tide of over 110 coefficient. That was certainly high speed and no option to turn back, but otherwise was not a problem, But would not have liked to head outbound into any waves in a 100+ coefficient tide.

 

[AngusMcDoon]

I find the Tidal Coefficients, as used extensively in France and other places, are really helpful as a simple and objective summary of how big the tides are.

They have those at the start of the tides section in the Small Craft Almanac. Not a lot of people know that!

 

[The Q]

We've had flooding on the broads over the last few days due to spring tides on the 13th, and a Northerly wind.

 

[jdc]

...Howeve, I dont see any particularly big tides in September (none over 100) and just a single 101 coefficient on 10th October.

This is not correct I believe, 11th/12th was a big tide.

• Dimanche 11 septembre 2022 - coefficients 104 / 105

 

[dunedin]

This is not correct I believe, 11th/12th was a big tide.

• Dimanche 11 septembre 2022 - coefficients 104 / 105

Apologies, the source I was using only went forwards from now, not the full month. When I kept a boat at La Rochelle I studied this table, and expected a few at 112 or more in autumn and spring (when had to be prepared for all of the visitor berths to be firmly aground)

 

[dunedin]

They have those at the start of the tides section in the Small Craft Almanac. Not a lot of people know that!

Interesting. No I didn’t - but then I never buy a paper almanac as get all tides information using apps / web

 

[lustyd]

And all this before the extra resistance of "renewable" tidal power builds up and sends the moon off into space.

 

[Quiddle]

And all this before the extra resistance of "renewable" tidal power builds up and sends the moon off into space.

Is it not already in space?

 

[jdc]

And all this before the extra resistance of "renewable" tidal power builds up and sends the moon off into space.

I know it was a humorous comment, but I think energy dissipated by tides is supplied by slowing the earth's rotation, not from the moon's orbit.

 

[lustyd]

I know it was a humorous comment , but I think energy dissipated by tides is supplied by slowing the earth's rotation, not from the moons orbit.

Bit of both, technically. Either way it's not really renewable in the very long term and is fun to bring up with eco-warriors. Same with wind power, it's just that we've not yet seen the side effects from mass adoption as we have with fossil fuels. Hopefully this time we won't wait too long.

 

[jdc]

I don't agree about tidal power: every rock in the earth, every molecule of liquid water, your body and mine and 7 billion others, is suffering dissipative tidal forces, and has done since the dawn of time. The proportion one could possibly extract for electricity would have no extra effect at all - a big tidal barrage could possibly (albeit unlikely) reduce local tidal ranges a bit, but would have no impact on the earth's rotation.

Energy of rotation of the earth is around 2 x 10²⁹ Joules. Total electrical power used on the earth is 15 TW (1.5 x 10¹³ Watts).

0.0001% (1 millionth) of the energy of rotation of the earth is 2 x 10²³ Joules, so at 1.5 x 10¹³ Watts that's 1.3 x 10¹⁰ seconds, or 423 years before you'd taken a millionth out (1/423,000,000 or 2.4 x 10^-9 per year). In the scale of environmental disasters it doesn't figure.

Another way of looking at it is the natural slowing of the earth, due to all those dissipative tidal forces I mentioned earlier, is about 6 hours in the past 2740 years, or 6/24/365.24/2740 = 2.5 x 10^-7, more than 100x bigger.

<rant>I'm no eco warrior, but I am a numeracy warrior! Inability to do sums is just sloth - a moral failing - one that makes an innumerate person unfit for public office.</rant>

 

[Zagato]

WHAT?