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Hello Ted, Thanks for your kind reply. The fact that you noticed something was 'off', already makes you part of a select minority. Ever since I started looking into these matters I have been surprised by how few people even notice that real-world observations don't match the model which is suggested in schoolbooks and most other popular sources. I also grew up inland myself. I studied aerospace engineering at Delft University but decided to become an airline pilot nevertheless. Only when I took up sailing, some 20 years ago, did I notice, like you did, that there was no correlation between the moon being overhead (which never really happens at 52 North latitude anyway) and the high tide. I started asking around and reading whatever material I could find. To no avail. It still amazes me today that this is a subject about which you need to know what the answer is before you can find appropriate sources. Yet, very few people (I estimate somewhere around 1% of those who believe they understand the ocean tides) can give you correct answers. Most just repeat the popular explanation and have been satisfied with vague reasoning to explain away the inconsistencies. I am proud to say that I figured it out for myself. Applying the physical principles I learned in Delft I started theorizing about how forces could be applied to ocean water to create a tidal rise. It was quickly obvious to me that the popular 'the moon's gravitational attraction pulls the water upwards' could never be made to work. I came up with a more logical hypothesis which could be made to work. Only afterwards did I find out that I had stumbled upon the exact mechanism which is believed to be the cause of the tides by oceanographers and earth scientists. But I am rather proud to say that I discovered it for myself. Pity that it had already been discovered (over 100 years ago), otherwise I would really have been a pioneer. The Nobel Prize would have looked great on my mantelpiece. But I'm amazed at how few people are aware of it, although it is common knowledge to every student of physical oceanography around the world. Of course it doesn't really help that even many respected scientist, like astrophysicist Neil DeGrasse Tyson are unaware and actually reinforce the popular, yet incorrect, explanation. The problem appears to be that many astrophysicists understand tidal forces very well, from an astronomical point of view, but are unaware of their own lack of understanding of the appropriate hydrodynamics of the oceans. In that respect a simpleton, like yours truly, has a distinct advantage. Nowadays I can easily point people towards the appropriate sources and papers (the material on the NOAA website is a treasure trove, for instance). But hardly anyone listens because, at first glance, they believe this explanation to be some hare-brained private theory, like flat-earth. It was actually much easier to figure out your whereabouts. I did indeed wonder, from your question, where you were. Because the same phase difference can also occur at many locations around the North Sea or, for that matter, in most of the other seas and oceans around the globe. But is really was as simple as clicking on your profile and seeing the video about the geese. Kind regards, Garret

Thank you, Garret,@@TribusMontibus. What a wonderful learning journey you took. Maybe tell Neil DeGrasse Tyson. I've been trying to get Quirks and Quarks to answer my question; now I'll send your link to them.

@@TedHopk Hello Ted, in my experience people like NdGT are difficult to reach. I used to be a flight instructor and one of my former students became head of training for Extra Vehicular Activities at NASA. He has trained many astronauts and has met many well known people like Elon Musk and NdGT. He tells me that when he first met NdGT, Neil asked himm 'how many astrophysicists do you know who can do the moonwalk' and proceeded to do the moonwalk. My friend says he found Neil to be a very nice person. But even through him, I doubt I could reach Neil. But, what's more, I expect to get the same reaction I get from many other respected people. When confronted with something which surprises them this much, they will typically assume that this is some hare brained little theory, dreamt up by a small group of conspiracy theory minded skeptics.

I suppose so, Garret,@@TribusMontibus. I sent your blink to Q&Q along with the PBS link and will keep my fingers crossed that Bob MacDonald will get in touch with you. Bob lives in Victoria and I suggested to him that he actually go to his waterfront when the Moon is on Victoria's meridian and check the tide.

@@TedHopk Hello Ted, Ah, Victoria! That's typically our planning alternate when we fly to Vancouver. Supposing that all runways are suddenly blocked at YVR we plan to divert to YYJ or, if the Victoria weather is bad or the airport otherwise blocked, to Abbotsford or Seattle. In fact, I'll be in Vancouver this coming weekend. I'm not sure if Bob ever makes his way out to the Vancouver Harbour Flight Center, where the seaplanes go up and down with the tides. But it's within a stone's throw of our hotel and I'll be happy to point out the apparent time discrepancy to him. Kind regards, Garret p.s. We don't have Q&Q where I live but, some years ago, I picked up Q&Q's book 'Guide to Space' from a book store. I like the light hearted approach. It's a fun way to teach things without getting stuffy.

Hello, No, you aren't missing anything. You are totally correct, if you are referring to 'the lateral point' (the point 90 degrees from the sublunar point). Here the net acceleration for a mass, due to the gravitational influence of the moon points slightly away from the moon due to the angle you refer to. The actual 'neutral point' where the resultant acceleration points straight downward is slightly forward of the lateral point. Mind you, what I am really adding (subtracting) are vectors of acceleration, not really forces. A mass in space may have an absolute acceleration due to a certain gravitational attraction from a mass (in this case; the moon). But when you are trying to figure out the net influence of that attraction in an environment, you need to correct for the acceleration of that environment (in this case; the earth underneath) due to the same gravitational attraction. That's what the tides are all about. That's also where many people fail a real understanding, because they remain fixed on absolute attractions and forces rather than the comparison. Another caution; don't lose sight of the comparative dimensions. The average Earth-Moon distance is measured in hundreds of thousands of kilometers while Earth's radius is measured in only thousands. The angles we are talking about are incredibly small in magnitude. I'm on vacation in the French Alps (riding my bike up hills which are a bit too steep for me) right now so I don't have my laptop with me. But I could look up in my spreadsheet where the neutral point is and just how small the angles are. Typically you have to read it two or three times before realizing how small such numbers are. Many draw the tidal force envelope as symmetrical. But as you correctly deduce, that isn't correct. It isn't exactly, longitudinally, symmetrical. But many an 'explainer' is already so happy that he/she can get people to understand why 'the far side' also experiences tidal forces which raise the water that he/she takes this tiny, negligible asymmetry for granted. Kind regards

Thanks for the fast answer! But I actually didn't mean the point that is 90° from the sublunar point. I mean the point that is on the surface of the earth and is the same distance away from the moon as you show it in your video. Should be around 80-85° (?), marked by the dashed line in 4:40 . Also wanted to say that your video is superb! :D Just one more question: Why vectors of acceleration and not forces? Sure you can explain the tides with comparisons of the accelerations. But the reference point (the centre of earth) doesn't fall into the moon. The centripetal/centrifugal force is counterbalancing the gravitational attraction of the centre of earth to the moon. Therefore we can speak of forces (?) Or is it because F=m*a ? Because we can't apply a particular force to a single point on a planet, due to not knowing what the mass of a single point is? But even if that's the case, one could just "measure" the forces of a grain of sand in different locations giving a broad estimate of the envelope now made up of forcevectors.

Hello again, To be honest, the geometry of the vectors, within the range you are talking about, gets complicated. It is no longer a matter of trigonometry with fixed values of the vectors which are involved. They change with every next iteration as a varying position-to-moon distance requires a recalculation of the 'local' acceleration vector. This becomes an exercise in differential equations which would have made my head spin during my student days. Either way, when I wrote my spreadsheet, that wasn't the problem I was trying to solve. So the spreadsheet isn't especially suited to finding that exact answer. But I can tell you that you are off by a significant amount, in your estimate. The spreadsheet does allow me to fumble around with the numbers a bit. This shows the 'neutral point' to be in the vicinity of 89.1299 degrees away from the sublunar point. My answer to your second question is a lot easier. There are very good, practical reasons for comparing accelerations rather than forces. The aim is to find out what effect the moon's gravitational attraction has on any given mass in any given position on or within the earth. The earth moves roughly like a huge blob through space. The deformations of the planet and variations of various masses, on and within, are insignificant within our context. Therefore you can easily calculate the acceleration vector, for the entire earth, due to the moon's gravitational attraction. Mind you, this certainly doesn't mean that the earth is getting closer to the moon. But the moon is constantly pulling the earth away from the elliptical orbit which the earth would have described around the sun if the moon hadn't been there. In the end it's really the Earth-Moon barycenter which describes the orbit around the sun. This means that you end up with an acceleration vector which is the same for any position on or within the earth. It would, at this stage, be rather meaningless to use forces anyway because the magnitude of the gravitational force on the entire earth isn't useful for any local comparison. But it's most important to realize that, for tidal purposes, you need to compare the gravitational influence on a local mass to the gravitational influence on the entire environment (the earth). By comparing both (the vector addition) you are left with a net acceleration which can be added up for local masses (using F=m*a) to get meaningful results. Kind regards

@@TribusMontibus thanks again! :) Yeah the 85° were just eyeballed from the schematics from your video, were the distances of moon and earth were changed to visualize the stark contrast of the vectors. And with the fact that I should bear in mind that the scales of the radius and the distance from earth to moon are magnitudes away from each other, as you state in your previous comment, I should have realised that it should be really close to 90° . Loved also the explanation for the use of vectors of acceleration instead of forcevectors. Thanks for clarifying!

@@TribusMontibus hello again! After some thought I tried to calculate the tangential force that pushes the water and came up with my own formula. I checked my results with the values of your video and they matched (hurray!) . I came back to ask you if you know a much more simple formula for these forces. I calculated them over many steps with long terms and tried to find a simple version on the Internet, but couldn't find any. Do you know any? Even if it is really oversimplified, I would love to see it.

But the guns are 0.5 calibers too short to be a heavy battleship, even though the armour could out-stun a gazelle at 30000 yards and its left screw was counter rotating even though the tips had yet to be painted yellow by the time it underwent sea trials....

Hello, Although you make some valid points, I stand by my viewpoint. If there are parallels with age-of-sail frigates, they have come about through coincidence and development. They were never the justification for designating modern frigates as 'frigates' (apart from the USN post WW2 frigates, until they too took the wrong turn). Besides, reasoning like that, you'd have to call modern destroyers cruisers or even ships-of-the-line. In my opinion the historical justification doesn't hold up. Kind regards from Montreal

@@TribusMontibus Didn't expect a reply so thanks for that. I think that's a pretty USN and RN-centric view of things though. It's not like all navies in the entire world decided to designate their ships frigates because the RN did it, you even showed an example of classifications not lining up with the Dutch Tromp class because of differing classification schemes, and there are other examples like the Danish navy classifying Hunt class escort destroyers as frigates. You might be right that the classification makes little sense in the USN and RN but it's a pretty broad and sweeping statement to declare that this means it must be the case in literally every navy in the world. Also you are wrong to say that the Frigate class died out completely in the late 19th century, several remained in active use such as the Niels Juel screw frigates up until the early 1900s even if they were in the end relegated to being barrack ships. In the Danish navy therefore there's only a fairly small gap with no active frigates from 1910-1945 which also happened to be a period where the Danish navy just saw a lot of cuts and only operated a few coastal defense ships. Both before and after this period frigates would make up the main force of the Danish navy and take on the exact same missions, though with the modern frigates being much more capable. This would seem like a pretty clear example of at least one navy having clear continuity in the role of the frigate. This is further evidenced by the first indigenous frigate of the Danish navy, the Peder Skram class, being already very large and heavily armed (even if that did only fire on innocent vacation homes) with a respectable top speed. Also I don't see how this leads to calling modern destroyers cruisers or ships-of-the-line. They have no similarities in mission whatsoever. Destroyers can be defined in their role as escorts for capital ships, modern destroyers are still doing that as they're intended to escort carriers. Being more capable doesn't change their basic mission, if ship classes can't become more capable over time then no class can last longer than 30 years at most. Cruisers were ships meant primarily for long range patrol duty in colonial empires, with enough armor and armament to engage anything they'd come across and also participate in major battles, and ships-of-the-line were meant as the primary surface combatant in a battle line and not really anything else except maybe coastal bombardment. The USN doesn't even have an AShM in service right now so categorically their destroyers cannot be seen as equivalents of ships mainly meant for direct combat with enemy ships, and even in navies that do have AShMs on their destroyers they are still clearly meant primarily to protect carriers while said carriers provide the majority of the striking capability. Also the name ship-of-the-line kinda implies there being a line of battle which isn't a thing anymore.

@@hedgehog3180 Hello, I'll have to get back on that (much) later. In an hour I'm supposed to go fly to Europe and saturday morning I'll be starting in a 2000km endurance gravel bike race, following which, I leave for the Middle East. So I'm going to be a bit busy. Your last message happened to catch me while I was having a cup of coffee during the last quiet moments I'll have for a few weeks. Kind regards

Goedemorgen, Ik zie je punt. Eerlijk gezegd heb ik ook ernstig overwogen om de Holland klasse specifiek te vernoemen, zeker omdat dit zou illustreren hoe verwarrend de categorisatie wordt indien je ook nog eens 'onderzeebootjagers' beschouwt omdat de KM zich daar specifiek op toelegde. Ik heb besloten om dat niet te doen omdat, wanneer je even niet goed oplet, bij kijkers verwarring zou kunnen ontstaan dat je het dan had over een soort 'destroyer escort'. Ik hoef jou niet uit te leggen dat de Holland klasse verre van die categorie af stond. Dus dan had ik ook nog het principe van een 'submarine destroyer' moeten introduceren in een video die al gevaarlijk lang werd. Dus heb ik me voornamelijk gehouden bij de 'meest in het oog springende' USN en RN klassen. Ook uit die landen krijg ik (terechte) vragen waarom ik andere belangwekkende klassen niet heb vernoemd. Over toepassing van Hollands vernuft op marineschepen die internationale wortels hebben zou je alleen al tien video's kunnen vullen. Maar eerlijk gezegd ben ik bang dat mijn kennis daarover anecdotaal en te oppervlakkig is om het echt goed recht te doen. Ik probeer geen video's te maken omwille van het video's maken. Wanneer ik er een maak hoop ik dat het iets nuttigs zegt. Ik overweeg nog om er een te maken over de Slag in de Javazee, omdat ik daarover informatie/inzichten heb die je niet terugvindt in boeken (zelfs niet in de uitgaven van de laatste jaren). Maar dat onderzoek heb ik nog niet tevredenstellend afgerond om er al een sluitend, goedlopend verhaal van te kunnen maken. Gezin, werk en andere hobby's nemen op dit moment veel tijd in beslag. Eigenlijk had ik ook niet verwacht dat deze video een miljoen kijkers zou trekken. Ik heb hem redelijk snel, als 'tussendoortje', gemaakt. Ik zou er waarschijnlijk meer zorg aan hebben besteed (en beter geluid) als ik dit had geweten. Met vriendelijke groet (nu even vanuit Montreal), Geert

You clearly haven't understood the video at all. That's exactly the point of the video! There is no generally accepted definition. It's not my video which is 'all over the map'., the (mis-) use of the words 'frigate' and 'corvette' is. Maybe you ought to pay more attention to content, before commenting like that.

@@TribusMontibus Yes, you are correct, I missed that point (and only made it just past the WWII portion). However, you reference back to points you made previously that contradict yourself or at least are inconsistent. The title and the narration seem to be building (erroneously) to a conclusion, which, _I guess,_ is not your intention at all. Thanks for the response, though (to my not so complimentary comment).

@@georgehugh3455 Hello George, No problem. I understand that20 minutes is quite a long haul to sit through. The video was made for people who have always wondered about 'what exactly makes a frigate a frigate'. There really is no definitive answer to that (even though my video's title might suggest there is). But I attempt to take viewers through the f* up in naval history, with some questionably motivated decisions, which led to the confusion. My true answers are somewhere towards the end of the video. 'A frigate is a frigate because the owner decided to call it a frigate' and 'corvette or frigate, it's still a wasrship'. Kind regards, Garret