Uh-huh...I can practically see British troop transports running the gauntlet all the way down the European coast, with Axis airpower, surface units and submarines being based and active (read: pounding the crap out of the transports/convoys/whatever) the whole effing way...
Yeh, TTL it would probably look like that, seeing the Axis never make a mistake & the Allies never get anything right. IRL, not so much. Finding convoys is harder than it sounds from the histories, even with air &
B-Dienst cracking the convoy cypher. Don't forget, only 7%

of ships in convoy were sunk. Recall, too, the TORCH convoy got across
completely undetected. TTL, it might be detected enroute, but you can bet there'd be a fight, & it wouldn't all go the Axis way. You might imagine Coral Sea; the U.S. TF commander, unlike Inouye, wouldn't turn back.
I would also expect that the allies would use resources to mine the enterance to the ReD Sea using submarine and or a fast Minelayer.
Good idea, in theory. Do you know how wide the Strait of Hormuz is? (--edit--oops, wrong ocean.) Mining the approaches to Alex, Tobruk, Haifa, & Dakar (for a start) would work. Also, positioning subs at Hormuz, Gib, & the Molucca Strait. TTL, we might see the USN boats sent to Europe deployed there, instead, & actually accomplishing something. We might also see the Oz-based USN boats being more successful, operating in the Indian Ocean, rather than under Japanese air in DEI/SWPA & turning in mostly dry patrols. I'd rather see them pulled back to Pearl to destroy Japan's merchant marine, but I expect the "Germany first" will be even stronger, here. Enough to get Brit warnings & fix the Mk6 exploder problems before
September '43,


maybe...?
Sea mines of that era were either contact mines (very difficult to use in deeper waters, for obvious reasons)...
They were of moored or floating varieties, don't forget. Bottom-moored contact mines, even in 300m water, wouldn't be useless, & the whole Red Sea (especially the harbor approaches & chokepoints, the vulnerable spots) aren't uniformly that deep.
The closing of the Bab al Mandab would thus be only temporary, I believe.
That's why you
renew minefields.

And lay
new ones.

Or, seeing Britain's success fooling the Germans with phony docs, fake ones: charts with marked minefields where there actually
aren't any...
... mines with magnetic fuses.
A minor point: they aren't actually fuses, they're exploders... (OK, I'm being picky.

)
It would also appear Winston's pipedreams of invading Italy or Yugoslavia will be put paid, thankfully.
Ops across the Pacific & Indian Ocean against Burma, Thailand, Madagascar, Iran, & the Red Sea (
via Kenya/Uganda thru the Sudan, or
via Ethiopia) look the best options. India, Oz, South Africa, & Kenya can still act as staging bases, & the longer trip length is made up for by the Pacific (still, & likely for the duration) being pretty much a U.S. lake. I don't feature Germany or Japan having the capability to seriously threaten that without ASB-level production increases.
Also, even with american help, it took them two years to gather, train and equip this one division that was sent to Europe... now imagine what will happen when the US has no spare instructors and equipment.
That was also when the situation wasn't nearly so dire as TTL. I daresay Brazil could produce weaps/gear under licence from the U.S. as readily as Italy can... Or Canada. Or Oz.
[When Manstein had discovered that the British had penetrated the German Enigma communication network back in September the Abwer had conducted a brutal self review. What they found was disturbing across the board but one of the most serious revalations was that the British had turned every single agent sent to the home islands under Operation Double Cross. Admiral Canarais planned a retaliatory operation to let the British know what he thought of their games.
And they detect this how, exactly?
And, yet again, more miraculous performances by the Germans & incompetence by the Allies...
...With only 28 destroyers in the Atlantic fleet...
By my math, that's enough to guarantee around 20000 ships safe passage. (Presuming Blackett's OR boys don't persuade RN to enlarge convoys even more. And presuming USN will bother to listen to Nelles & RCN; IIRC, Andrews wouldn't OTL, & lost merchies because of it.) Those surface raiders can't be everywhere. (Oh, wait, TTL I guess they can...

) And the Brits don't need to read Enigma to use traffic analysis & HF/DF to track U-boats & raiders; breaking the callsign cypher (not in Enigma, so don't even suggest it) & using air & sub patrols to monitor sorties works nicely, too. Thus, it's possible to avoid most (not all, but most) hostile contacts. And convoys are much harder to find than you appear to think.