This would work, provided we are certain he would make this trade with only around 300 beakers left to go. Though it would speed up his path towards feudalism, which would be a bigger problem than Speeding Cathy up.
I'm not necessarily enthusiastic about giving-away Machinery, either.
Cathy just had to be the "most hated AI" on the block, otherwise we could consider the following:
1. Sell Code of Laws <-> Cathy's 140 Gold
2. Self-tech Machinery to within 1 turn of completion
3. Self-tech Compass
4. Self-tech that last turn of Machinery
5. Trade Philosophy <-> Cathy's Calendar + whatever Gold she has made over the course of those turns
Of course, those 2 trades to Cathy will almost surely make 3 AIs give us -4 You Traded With Our Worst Enemy penalties.
Unfortunately, Vicky, Joao, and Isabella are all in conflicting Religions with Cathy and none of them have Open Borders with Cathy, so I don't really see those relationships improving over time.
What MIGHT help, though, is if one of those AIs gets angry enough at us for the Code of Laws <-> Cathy's Gold trade for us to become that AI's Worst Enemy, then we might not get the full -4 Traded With Our Worst Enemies penalty when we make the Philosophy trade.
There is also the chance that Joao will switch into Hereditary Rule, as he is one of three 3 AIs that have it as his Favourite Civic. I doubt that him switching would bring him up to Cautious from Annoyed immediately, but maybe after a 10 turn interval or a 20 turn interval he'd almost certainly be up to Cautious towards Cathy...
If we DO go with this approach (angering 3 AIs, but delaying Willem's Resarch on yucky-for-him-to-get Machinery plus then delaying him a bit on his way to Feudalism), then we would want to Demand Vicky's Gold BEFORE making a trade to Cathy, since Vicky would almost certainly no longer be Pleased with us after we traded Code of Laws <-> Cathy's Gold.
The decision does not need to be made immediately, of course, but the more turns that we wait, the less Gold that Cathy COULD have if she spends or trades it... and the less Gold that we get almost means the greater the Traded With Our Worst Enemy penalties will be.
We can't get a GP 2 turns before the end of the golden age unless we delay it. Fortunately the final GP is being used to bulb engineering. We can get our penultimate GP in time to bulb astro, then tech CS and revolt before the end of the GA.
As long as we also get Calendar by the second last turn of the Golden Age, Lightbulb Astronomy by the second last turn of the Golden Age, and, as you say, plan to research Civil Service on the second last turn of the Golden Age, then you are right.
Therefore, we do need to think "short term" in terms of the Calendar trade.
But, at least we know that we can launch the Golden Age on time (Turn 167), which means that we won't need to do any re-testing of the Golden Age timing.
I can't see how giving Ragnar mysticism will get him back into the tech trading game.
Well, it is my experience that AIs like Shaka and Ragnar will avoid self-teching Mysticism, but once they get it, they can quickly shoot up the Religious tech tree. It's hard to know exactly what goes on since the game does not inform you about AI-AI tech trades, but we know certain facts:
a) Ragnar is avoiding Mysticism
b) Ragnar is the dumbest AI so AIs are avoiding making trades with him
c) I claim that if Ragnar is given Mysticism, experience shows that he will quickly get up towards Hereditary Rule. What I don't know is if he would trade for the techs or self-tech them, but he would very likely do one or both of those things
d) Once Ragnar starts shooting-up the Religious tech path, given that he also knows Construction above-and-beyond most of the other AIs, he will very quickly no longer be the dumbest AI. When multiple AIs vie for the "dumbest AI" position, then NO AI ends up being the dumbest AI... I'm not 100% certain how the mechanic decides a new dumbest AI, but it could be that a tech differential of 2 techs, instead of just 1 tech, is required, which is why it usually takes a while for AI-AI tech trading to "settle down" and for a new "dumbest AI" to be declared by the AIs
e) Even if a new "dumbest AI" gets declared after a few rounds of AI-AI tech trading, then if that dumbest AI beats the second-dumbest AI to researching their next tech, then the whole AI-AI tech trading process starts up again in haste
f) That's generally how you get a run-away tech situation, because the lower half of the AIs will ignore WFYABTA penalties... what usually keeps things from getting out-of-hand is that the "dumbest AI" gets shunned (ignored) in tech trades... but if there is contention as to which AI is the "dumbest," then "no dumbest" will actually exist and a lot of trading happens with the lower-tiered AIs. Let's just say that it gets messy really quickly
What I suggest that you do is look for some old games that you have played that have Ragnar in them (Shaka seems to also work). Find a game where one of those two AIs does not have Mysticism. Then, play the game forwards for 30 turns without trading it to them. Preferably, set Espionage to them, so you can see what they do tech-wise.
Then, play again, but trade them Mysticism on the first turn.
If the Trireme-blocking plan really were to work (which I do not think that it will in all scenarios), we could simply trade Alphabet <-> Ragnar's Gold, since then he wouldn't be grabbing Meditation and/or Polytheism anytime soon and would remain the "dumbest AI" by a margin of a couple of techs. However, I don't see that Trireme-blocking plan covering all scenarios, so I think that we're going to be forced to either:
a) Follow the Gifting Alpahbet + increments of 10 Gold plan
OR
b) Bet that Ragnar is going towards Paris and then plan things out so that his Galleys will have to "walk around" Trireme 2 for 1 square on 1 turn, which would give Trireme 1 a chance to catch up enough to be able to attack on the following turn. Triremes 1, 2, and 3, as well as our Galley, would all attack... and then we'd be at the mercy of the random number generator not to repeat the previous scenario that we saw when attacking the Barb Galley
Do you know when we will get our first +1 open borders modifier with Cathy, and if it would make her pleased? We might be able to beg the required gold from her instead.
Open Borders positive Diplo modifiers come after 25 turns of having Opened the Borders. When did we decide to Open Borders with Cathy? During my last turnset, if I recall correctly. We should be able to hunt for that info in one of my reports.
If we attacked with triemes we would have a 1 in 3 chance of losing one or more of them.
Well, Ragnar's moves are not 100% predictable and therefore it is possible that the proposal on the table will require us to attack with Triremes, otherwise Ragnar will sail right past us.
I propose using the galley to transport the workers/warrior from the iron island to the hoses island. The workers can then chop the forest there, before heading back to hook up the iron(it will be pre-roaded) after the final warrior is built. The extra production we get from the chop in iron will allow us to hire scientists there to give us the few extra beakers we need. The galley could take care. The trieme in the area will be shifted to between the capital and gold in case a barb galley shows up there.
This stuff is really going to depend upon how we resolve the Ragnar issue. If we get 10 turns of Peace out of him, then sure... but if we go with a war plan, then we really need every single boat going west, as we do not have a fool-proof blocking plan and may have to engage Ragnar in battle depending upon how he moves his boats.
I also think that the golden age should go ahead as planned, and that we should make the currency-calendar trade to Cathy at the last moment, and trade for Ragnar's 50 gold if we can't beg for the gold from another source by the time we need it.
So, wait, let me get this straight:
You want to trade Currency to:
a) The AI that has The Temple of Artemis
AND
b) An AI that already has 5 Cities
AND
c) To an AI that will immediately be able to trade it around to every other AI, due to that tech's low Monopoly-threshold
I mean, if you want to get Calendar from Cathy ANYWAY, then we MIGHT AS WELL not worry too much about the You Traded with our Worst Enemy penalties, since we'll be getting them ANYWAY.
In that event, I would much rather give her the useless Code of Laws (which Vicky already has by the way) and Philosophy techs, plus getting her 140 Gold as part of the bargain.
The only question becomes then... how long ago did Joao learn Monarchy (i.e. how long do you think that he'll delay his revolt--if he has already delayed for several turns, then it may be a while before he revolts) and how likely is it that +1 or +2 (+2 coming after 10 turns after he revolts) will make him stop treating Cathy as his Worst Enemy?
In other words, I'd much rather see us making the Code of Laws <-> Cathy's Gold and Philosophy <-> Cathy's Calendar trades (two useless techs for her) than giving her Currency (an extremely useful tech for her that she could also immediately trade around as a useful tech for other AIs). The only question becomes: how long can we wait for Joao to possibly stop hating Cathy due to a Shared Civic bonus for a Civic that he hasn't even revolted into yet (even though he has the tech to do so--Monarchy--I just don't know how long ago he got that tech)?