BTW Roy,
Re your post #5207 "Can't see the Americans abandoning Nuclear subs in favour of these."
You forget the Operational Requirement!
Sweden has no desire to play World Policeman like the USA.
Their main requirement is defence against the Russian Baltic Fleet not world cruises with a nuclear deterrent.
Cheers, Doug😎

Hi Roy,
Scarcely hundreds!
I make it around 130, although it is highly questionable how many of the Russian subs are actually operational.🙄

Re Swedish subs-
Actually their diesel electric Gotland class (3 boats) has been happily operating Stirling Motors for nearly 30 years. The successor is already being built, 2 for Sweden and 3 for Poland, also using Stirling Motors from the Kockums yard.
Sure they are not going to win any speed competitions running on the Stirlings alone. But that's not the point.😉
When submerged the Gotlands can make 20 knots running the electric motors off batteries. Or tootle around at 5 to 6 knots on the Stirling motors driving a 75kW generator.
Alternately the Stirlings are used to recharge the batteries without the need to surface. Thus 'EXTENDING' the underwater endurance from a few days to a few weeks. And that is the key to this question!!
It asks about 'EXTENDED' operation NOT unlimited as per nuclear power.
Nuclear powered propulsion has never been designated AIP as it has never been dependent on air in the first place.
As for as acoustic stealth goes, the weak point of nuclear systems has always been the pumps in the essential cooling water circulation.
Sorry Roy but no cigar this time😉
Cheers, Doug😎

https://en.wikipedia.org/wiki/Gotland-class_submarine

There are several hundred nuclear subs in the world, USA 66 and Russia 30 China 12. Of course if Russia does decide to attack Europe, non-political hot air may save us all yet!
The UK has survived over 2000 Russian incursions and attacks over the last year or so. The threat is there, if it happens they will run out of people to fight and money, as I doubt China will support them as their war is an Industrial one. They need American and European infra structure intact as countries that buy Chinese goods. Russia has only gas and oil and much of that is sanctioned.

It is an interesting scenario but rather dangerous. Oops sorry about the political side!
Roy

The heat source is diesel fuel and liquid oxygen. That seems neither one thing or the other. If they travel much distance from home port they could run out of LOX. They really only work in home waters.
Can't see the Americans abandoning Nuclear subs in favour of these.
Roy

I was one of them that chose the Sterling Engine because I thought there were to few nuclear subs and way more normal subs, plus it was a way too easy and obvious answer. However after I got it right. I was surprised, so I did some research and came across this.
https://www.saab.com/newsroom/stories/2015/march/the-secret-to-the-worlds-most-silent-submarine

Hi Fireboat yesterday's answer was'problematic', apparently their are 6 newly commissioned boats. They are for use in the seas around Europe, with 2 more expected around 2031.
Roy

I also picked the wrong answer with the submarine question along with 23 others 😂😂. Only 10 clever members got it correct..👍.
I was quite sure that we have had this question before and the answer was Nuclear??. 🤔🤔😕.

Today's 5th December question was one that took a full TV documentary to try to explain with no final conclusions. This I remembered from when I was very young 🎂🍦
, and it's a mystery that's stuck in my mind ever since 😊..

Thank you guys - I answered D, and was very surprised to be told I was wrong. Nuclear is almost totally silent, except for some of the attachments, but any engine will have a sound profile that modern acoustics can pick up.

I agree with Ron. And how in Heavens name (being polite) do you run a Stirling cycle engine in a submarine? What heat source?

I chose answer D which is correct. Sorry but the answer to the question should be changed to D not C🤔😬😬

I have been thinking about the longest number of words being the answer. It seems AI thinks the same (7 letters) but the clearly right answer is D with only 6 letters. But then is AI trying to set a trap with a double bluff?

Roy

Well I went for answer D as I asumed it would be the most obvious in this day and age in modern submarines also, while maintaining minimal acoustic signature and avoiding the need for frequent snorkelling.
And I got it wrong!!??.

I have since Googled the question, which I wouldn't normally do. and Google says that this is the correct answer. And why. Google A.I. also says answer D is correct. So why did we get it wrong?????????
Our answers should be corrected.

This is Google's Answer,

The correct option is D. Nuclear propulsion using pressurised water reactors.
Explanation
Nuclear propulsion provides virtually unlimited submerged endurance, limited only by crew provisions, because the reactor does not require access to atmospheric oxygen for power generation.
Submarines with nuclear propulsion can operate for months without surfacing or snorkeling, which is a critical aspect of maintaining stealth by avoiding visual or radar detection at the surface.
While air-independent propulsion (AIP) systems (Option C) also enhance submerged endurance for non-nuclear submarines, they typically only extend it to a few weeks, not the practically unlimited duration of nuclear power.

I read somewhere that Nuclear subs used the spare heat from the reactor to power auxiliary generators, which were Stirling engines. No exhaust no pollution and safe.
Roy

How do you produce enough heat for a Stirling engine underwater? Really didn't understand why that's the answer

Oh dear! Where does AI get the answers from? One of the Scandanavian countries experimented with Stirling engines in submarines and then gave up as they did not have enough power.

For local water very quiet subs the diesel one has proved to be an excellent alternative to Nuclear propulsion.

I think the question needs setting up again.
Roy

The answer is wrong as it did not non nucular subs, only non nucucar subs use
air propolsion🤔
Philuk👍

Hi, Boatshed, I also do the same and seal as many of the bow compartments as I can, but just in case there's a leak 😩, I fill them as much as possible with lightweight polystyrene.😊. Should make the boats bomb proof/unsinkable 😀,from someone who hasn't read the SOLAS manual 😕😃😣.

On todays question,
I had gone for answer C, as I would do this even on my wooden model boaats,
As I think this makes sense just to be safe.

Well I got that wrong. I read it as, what was the alternative to D2 standard. I knew from last time that D2 was the new standard so the alternative must have been the older water exchange D1. 🙄

Deja something or other🤔

Another repeat I think.

The ballast water management question is a repeat revision one, so easy to get correct 🤗.

The Beaufort question, I had to take a "slightly educated " guess 🤔 and got the confetti again.☺☺.

Rear Admiral Sir Francis has breezed in😁and graced us with his presence before!

😎

Coincidentally, right now, and especially for tomorrow, I've been monitoring the wind situation (force in knots and direction) in the area between Ostia and Fiumicino on the Roman coast.
For us, the service is provided by the Italian Air Force, which, among other things, issues the official Meteomar bulletin every six hours and covers the entire Mediterranean.
The Beaufort scale is the same worldwide, but definitions vary. I had to consult the internet to see that the English use the term "brezza" [breeze] (with different adjectives: light, gentle, moderate, fresh, strong) from levels 1 to 6, while in Italian, the term "brezza" [breeze] is used for levels 2 and 3.
For the last degree, the twelfth, the term corresponds to "hurricane," "ouragan," or "uragano" in English, French, and Italian.

Beaufort Scale is applicable on land as well as at sea...

I didn't know the correct answer, as my result proves!

Thats interesting why should everyone know the answer even not interested in sailing ?
Philuk👍

Everyone should get that one right even if no knowledge of seafaring

I have posted pictures of this type of tug, nearly all South African harbour tugs use this type of propulsion.

Again a repeat

The answer was within the question....😎

Did not have a clue, picked what looked right and was the longest and most detailed.😁

Everyone knows that the Portuguese Ferdinand Magellan named the new ocean the Pacific because it seemed calm and tranquil compared to the Atlantic.
He didn't have time to change his mind. Not everyone knows that Magellan never completed the voyage around the world (which was absolutely not the mission's initial goal).
Part of his multinational crew completed it only aboard one ship, the Victoria. Besides Commander Juan Elcano (the Spaniard who eventually took command), very few men returned, including the Italian Antonio Pigafetta (a native of Vicenza in the Veneto region), who had the great merit of recounting everything in writing.
We know it all thanks to him.
Despite being taught in school, despite being shown documentaries or, lately, TV series (very well done), I am still captivated by this fascinating and incredible story.
Recently, I enjoyed one of the best historical reconstructions of the entire expedition I've ever seen or heard, on YouTube.
The authors and the presenter of the channel, in addition to the notions and the story, which I already knew, were so good at making me identify with the anxieties, indecision, and suffering of the crew who had to face storms, calms, hunger, thirst, battles with various natives, but above all scurvy (a vitamin C deficiency disease completely unknown at the time).

Magellan himself named it “Mar Pacífico” (the Peaceful Sea).
😎

Could you be more specific in what you want?
Roy

Can it be more pacific 😀

AI has lent us a helping hand today.
It has come down to a very simple, elementary-level question.

Really 1520 talk about antcient history
Philuk👍

Once again answer with longest answer is the right one 😂
Philuk👍

Hi Steve, I agree with you; studying new topics is always a good thing (perhaps stimulated by something like an exam or a simple quiz without consequences).
However, today, it was enough to reason and use the logic and common sense of a good father.
Many rules follow a natural rationale that's easy to understand, accept, and agree with.
Other rules are highly technical or conventional and simply need to be memorized.
Today, the other three answers would have been rules that weren't in line with SOLAS's objectives.
Well done, Steve.

That was a good guess, but then reading the answers that made the most sense.

Hi, Phil, I remember this one from quite a while ago, but I always read the answers many times and gradually eliminate the ones that seems to be unlikely 😊.
So today we are back to the SOLAS regulations again which I found quite easy after downloading and studying the manual months ago😀.

The answer was the only one to mention surf like they alway say answrr is in the question thats why i read it twice and not jump in
Philuk👍

Lew, reading with a wide range of interests goes a long way. Life experiences help as well. Anyone who has surfed should know the answer today

I am amazed at the nautical knowledge of the people that answer these questions. Their internet skills are outstanding.
Lew

I remembered this one as I thought the answer should have been "The Beach Boys" 😁. It also looks like I missed yesterdays question. How I do not know..🤔

If you got this wrong keep trying as you will keep getting it

Good lord! I have reached the lofty height of numero uno for the first time ever with a lucky guess! It will be all down hill from now on...

Surf Beat question is a "revision" one asked a long time ago 😊.

Edw, mine was a lucky guess I think.