I thought it was patched to v2+ but I can't research Magnetic Navigation until after I research a Lobsterman Navigator.

Any thoughts?

In V2 you should be able to just research it if you have recovered it from a downed or landed USO, perhaps that is your problem?

option 2 upgrade to openxcom it fixes alot of these bugs.

The TFTD GOG version is 2.1, so in theory the research bugs should be fixed. Anyway, The Lobsterman one was solved in 2.0 patch with a workaroud.

From the ufopaedia site:

[i]Unpatched
A Lobsterman Navigator is needed to research Magnetic Navigation

Ion Armour is not required for Magnetic Ion Armour. All the technologies you need for Magnetic Ion Armour are Plastic Aqua Armour, Ion Beam Accelerators and Magnetic Navigation.

v2
Magnetic Navigation can be researched as soon as one is in storage. The lobsterman navigator is NOT required.

Ion Armour is required for Magnetic Ion Armour. Magnetic Ion Armour now just requires Magnetic Navigation and Ion Armour.

Yes, in other words, the v2 patch makes it easier to get Mag. Ion Armour. However, it also means that winning the game hinges on your ability to obtain a live Deep One terrorist AND researching it in the right order.

If you patch your game and reload a campaign created before the patch, you might face a few research problems. It's not that common, but you might find that you'll have some trouble with researching the more advanced armour via the V2 method. There should be no problems if you haven't even started on the Ion Armour or Mag Ion Armour yet. It's mostly for campaigns where you're already half-way through researching the armour.

v2.1
Only difference from v2 (per StrategyCore) is that the MC Reader bug is fixed: it can be researched even if you didn't have a sample when MC Lab was complete. Note that TFTD CE is v2 and does not include this fix.[/i]

GOG sell not recent versions and only DOS - but as i remember it for Xcom1. TFTD is up-to-date(?) - but you must start it not from GOG's link\Galaxy but from Terror From the Deep_patched.exe (latest Win version executable).

If the info is accurate GoG Galaxy advises TFTD is version 2.1 according with the version number under extras/offline installer.

Anyway I tested it, to be in the safe side, loading my savegame from the original GOG DOS where I can not research Magnetic navigation. I loaded the savegame under OpenXCOM where the bugs are really fixed and I am able to research Magnetic Navigation but not under the DOS version.

So, no matter which version is advised under GOG, in the vanilla GOG DOS version apparently the bugs are not fixed.

Not tested the windows executable under the GOG folder because it is incompatible with Windows 10 from my side. I am unable to launch it

Greetings.

I just started playing, and for sure the bug of losing the equipment of the first part in two part missions is presents.

People from GOG. Could you look at it? I mean, you were able to add cloud saves to it. Getting the patched version on the package instead of the original buggy one, should be a breeze compared to that.

GOG staff often do not read game-specific forums. If you need GOG to make a change, you should file a support ticket with them.

The GOG DOS version is not v2.1. You can download the v2.1 patch from the internet and apply it though. This fixed the bugs for me.

It isn't relevant what version GOG ships, as OpenXcom renders all this version faffery moot.

Better im start with that one supposed to be at the end.
... But im not say here for OpenXCom this one are bad. it is good remake. I say it should be examined how accurate TftD supported in current versions. Again, this time - GOG bring up-to-date (windows native exe from about '05) version for the game, without need of using separate installer or disc images from GOG (or 3rd party sources or remakes) (hided in game folder, same exe for Xc1 was missing here). If OP here ask, he probably(?) do care what files included even if there is remake.
..... Not relevant at all?

Well, at some point yes. Definitely yes for Xcom1, cause GOG didnt provide latest version alternative. But sharing same engine require a bit more work from OpenXcom devs. When i last time try it, OXC almost just start to support TftD and use non-original battle maps scale (higher than XC1 less than XC2).
Or it be something else... hmm... Not matter. Such remakes never be 100% original gameplay experience: 50% for improvements, 50% for for non-improved differences (new AI). It is something devs should be interested to achieve, and since open-source someone enough interested to exam code for such details as how it be in TftD if now they share same engine. For open-source it is sometimes take decade to fix something implemented 10 y. ago.

It is not so accurate answer like 'who cares what is come with the game, if there is OpenXCom'. Obviously there is old bugs, and there is new ones. Thats axiom. You choose between them.
So first you better get vanilla game in most full\up-to-date form. For such releases GOG sadly not a best source usually.

If you need more examples of that theoretically thing (mean: obvious), i cant provide enough for OXC (and it is about old time when TftD just added, im not play it after), but can provide for Theme Hospital CorsixTH. Good one example, not all features still implemented, existed implemented in few very last versions, there is issue with them (new feature for random earthquakes implemented before campaign-scenarios based, now both are included and calculated by default and you need tweak this or you get too much earthquakes in campaign). Also good example of native Windows exe which one not available on GOG like for most DOS and ScummVM releases here. Like X-com 1 here too.

Another good example is Warzone 2100. It have many issues for decade. Some 10yars bugs never be fixed. Some new features broke original and some version even remove old unit controls system features (while it is readded, there is a chance they not work properly). New bugs (auto-rapair-turret not repair automatically). And new contributors who not interesting or just cant fix what need to, so they bring campaign balance changes. Which ones by devs word supposed to stay original with all changes to MP only (and never be like that, Wz2100 always share balance).

So OpenXCom is have general issue - new AI. Which one can be better or not. It is just differ. Xc1->Xc2 engine original improvements not be respected first TftD support been added. Few implemented as improvements for Xc1 already, but that require review how it in fact applied to Xc2 now. it took time for such projects. Sometimes literally decades.

All that irrelevant. But there is ppl who still try to argue with that, with that im not wrote here. Original is original. Remake is remake (official or not). They never be same, what is obvious, so obvious = give differ experience = they should both be played. Remake wont give you original exp, original obviously not have new remake experience.
Sometimes that bring more issues when new contributors not even respect original experience at all, which one broke core ideas - current versions of Wz2100 campaign. When OpenXCom or CorsixTH is good remakes (for CorsixTH even with missing features), this one more like bad remake for campaign, even if close eyes on many else technical issues. Sadly, it be better during v.2.2.2 times. ...

Yes, I'm perfectly aware of the nature of source ports and how they're imperfect due to the nature of the beast. I'm absolutely aware of how OpenTTD doesn't include the original AI because it's a bunch of black box code.

At the end of the day, I'd rather not struggle with getting multiple executables to work in harmony in an emulated DOS. I'd rather a game actually be easy when I select easy, rather than having to hunt down 40 aliens per map. There are advantages or disadvantages, sure. But OpenXcom pointedly, has been feature complete for a long while. It isn't something like OpenApoc where they're in the early stages of recreating assets. It is closer to OpenTTD or OpenRCT2 in terms of completion.

How OXC could look worse than original? It use exactly same graphic (probably globe is only difference as I change how shading work because in original game was bugged), same with sound, only difference with sound could be what sound card you use but this could be fix by downloading music pack that have have modern sound files created based on specific sound card.