Ok. I read on FTL forum somebody managed his saves with a tool, so I thought there was a mod.
The game would be much more easy if there was a save/load feature...: 100% success for sure, instead of 10%.

It's not a mod that is handled like the other ones that adds ship/graphics/gameplay mechanics... i guess is just some kind of script that runs in the background and copy the .SAV file from time to time.

Someone wrote a save game application for "Uplink" back in the days too. It simply made backups of the game's own temporary save files which you could copy paste back into the game folder to go back in time. Uplink was a longer game than FTL so it made a bit more sense to have the feature (losing 5 hours into the game because of a simple mistake is never fun), but just like FTL, the reason Uplink was so intense and exciting was because getting caught could very well be a permanent game over.

This is where the extra scrap comes in. You can buy the power and you can buy the drone parts if you really need them (personally, I rarely do, because it is a fairly common resourse, and it will last you a long time if you use it sparingly). And frankly, what ship (safe for for Engi B) does only have 2 Engis ? You can board almost any ship if you have at least 3 crewmembers (all you need the third one for is either to pilot the ship or aim the weapons. I guess it is possible to board if you only have 2 crewmembers with a certain setup).
So do I. Why do you find it so hard to believe? You get 15-25 scrap per combat encounter in the first 2 sectors (less in the first, more in the second), If you get 20 encounters, it will easily put you in the 300-400 range. And Long Range Scanners help you choose nodes with ships in them, ensuring the source of income.

I just had short 3 games with this ship. In the first one I had collected just enough in the first sector to buy myself a teleporter and by the end of 2nd sector I had 2nd level cloak, 2nd level teleporter, 2nd level oxygen, 3rd level weapons, Ion Cannon, 2 extra power, and 230 scrap in the bank (30+75+30+25+25+20*2+230-50 for selling the Titanium augment=400 total). In the second game I managed to buy the Pre-Ignifier, Pike Beam, 2nd level oxygen, 2nd level cloak, 4th level weapons, 3 extra power and had 30 scrap left in the bank (120+60+25+30+25+35+20*2+25*1+30-50=340 total). I don't remember the numbers for the third game, but they were close. All of this was bought, not found through special events. Since the ship does not need much in terms of upgrades to run, it can build a huge scrap reserve, which buys you awesome stuff you find in stores. And stores are anything but rare in this game.

This is not the matter of challenge, this is a matter of being able to make decisions whether to wait a bit for something better to show up, or to stop waiting and make do with what you have. A teleporter is always a solid investment, whether you have the crew to pull it off or not, but a lot of them are more situational. It seems to me that this is where you are making mistakes.

Did I mention that The Nesasio starts with those? Did you know that they allow you to pursuit allied ships lost in nebulaes and rescue their crew, providing you with free crewmembers? That ship is more suited for boarding than a Mantis Cruiser! :P

Ok, so here is a quick guide to piloting The Nesasio.

1) Learn to use your strenghts, that is, the cloak system. Many players make the mistake of using it only to evade enemy projectiles. This may work for other ships that have shields to rely upon and therefore only need to avoid missiles, but with the Nesasio you do not want to be hit at all - and enemies often fire their weapons out of sync, allowing you to dodge one, but not the other. Which is why you use the cloak as a poor man's Pre-Ignifier, cloaking immediately at the beginning of combat to charge your weapons and then proceeding to take out enemy's weapons system in one swipe. 2nd level cloak is the first upgrade you buy.
On the other hand, if the enemy has weapons that fire simultanously, it might be a good idea to wait for their salvo before cloaking. That should give you even more time to decimate their weapons.
2) Cloaking is also a good way to temporize, when you wait for enemy to run out of oxygen (if you do not have a teleporter and cannot disable their weapons in fear of blowing up their ship), or when you really need to repair one of your systems, or when you are praying for the FTL to charge faster so you could split.
3) Your starting weapons charge fast (10-11 seconds, respectively), even faster with someone manning the station. 2nd level cloak lasts 10 seconds, which, essentialy, gives you a free shot, and you might get a second shot in before the enemy fires their first. The meaner weapons they are packing, the more probable is that they won't get to fire them. Your dual laser is the fastest of the two weapons. Do not hesitate to fire it out of sync with the beam if it will prevent you from being hit.
It takes time for your laser projectiles to hit their target. The beam fires instantly. Fire the laser a second before the beam charges. This often means a difference between disabling enemy's weapons or getting hit yourself.
4) Always man your weapons station until the enemy's is down. Your cloak and weapons are more important than oxygen.
5) 4 points in engines give you a solid 30% evade chance when you man the cockpit and the engine room. Never - as in ever - leave the cockpit until your opponent can no longer harm you. Remember to reroot the energy to the engines when you are being shot at. Chances are, between this, pre-emptive strikes via cloaking, and Titanium Casing, you are going to be relatively unhurt.
6) Your starting equipment will last you the first couple of sectors easily, but you will need something more substantial from the third sector and on. Start looking for shops early, and try to keep a good amount of scrap in reserves. Choose nodes with ships in them, and you should amass lots of scrap in no time.
Titanium Casing is not only a good starting augment, but also an extra 50 scrap, should you find something that you really need.
7) Explore nebulaes. They allow you to spend more time in the sector, which directly translates into extra scraps. Besides, they have some interesting events that might give you something special if you have good sensors - which you do.
8) Upgrade wisely. You don't need your engines when you are cloaked (unless you are dodging, in which case you don't need them for long anyway), or when the enemy's weapons are disabled, so you can safely do without upgrading the reactor by juggling the power. You can power Engines4, Oxygen2, Medbay2, Cloak2, Teleporter2. Drones2, Weapons3 with 10 power bars and never notice a difference. In fact, encounters within an Ion Storm in the first two sectors can be safely done with only 5 power bars availabe (Weapons2, Cloak2, the last one switches between Engines/Oxygen/Teleporter when needed).
You will need Cloak2 and Weapon3 to protect yourself from stray shots. The rest depends on many factors, such as the galaxy chart, what you find in shops, who is on your crew list, etc.
9) Get a teleporter. It helps tremendously with scrap collection. It also has a good overall synergy with the ship. When you disable the enemy's weapons, you want them to stay down, so you send the boarding crew to prevent repairs. Once the weapons are down, you might want to send everyone in, including the pilot. Even better If the ship you fight has a teleporter of their own - wait for them to board you, engage them, cloak when they are nearly dead so that they could not escape, then take their ship which only has a few crewmembers left.
If you don't mind spending extra time, make sure to level up your crew by dismantling as much systems as possible while the enemy crew is still alive. Be careful not to blow up the ship, though.
10) Contrary to the popular belief, shields are not a priority, firepower is. You don't need shields if the opposition has nothing to hit you with. You can safely ignore getting shields until the third sector, or even the fifth sector if you really know what you are doing. I'll take Pre-Ignifier over Shields any time, but an extra weapon with an Automatic Pre-Loaded will serve just as well.
That said, you don't need that much firepower. Dual Laser, Burst Laser 1-2 and a beam weapon will carry you through the game, including the final boss.
11) If you happen to engage in combat with a ship with some attacking drones, cloak immediately and prioritize taking out their drone systems. Drones fire faster than weapons, and thus are more dangerous. Even better if you can target both the drone and weapon systems. Remember that offensive drones require 2 power to run, and you do not need to destroy the system completely to shut them down. More often than not, if the enemy only has one drone, it does not get off more than two shots. By the time you start encountering 2 drones, you should have means to deal with them. If, for some reason, you do not, Engines4+ (to power FTL at double+ speed) and Cloak3 (to temporize) are your best bet.
12) Avoid Zoltan ships if you can help it. They are doable, but are far more trouble than they are worth.

This should get you through the first 4-5 sectors. By then you should acquire all other systems and the ship plays exactly the same as any other.

Neville, thanks for all that info.

Any general tricks for the other ships if you still have time?

Sure.

Please understand, though, that these alone won't win you the game. The most crucial advice had already been given, it's up to you to make it work.

General Tips and Tricks, in no particular order:
1) Do not be afraid to switch off your oxygen to power other systems. Don't forget to turn it back on when needed.
One of the tricks that I personally prefer to use is upgrading my oxygen system to 2nd level when I need an extra power bar. It allows me to switch the oxygen off for a long period of time, essentially freeing up the power. The oxygen can be refilled in a matter of seconds, sparing both my real and in-game time. And the upgrade protects the system from a stray shot or those special events that shut it down.
2) While taking enemy's shields out with a missile to pounce them with lasers may be a good strategy for the first few sectors, later on enemies tend to have a decent evade chance. By then it is often beneficial to target the helm first and ensure that all your other shots hit.
3) With most of the 'normal' ships that rely on conventional strategy (that is, Kestrel, Torus and Osprey), you want shields to be your first upgrade, possibly in the very first sector. It makes you immune to beam weapons and to most of the lasers, as enemies tend to fire out of sync. After these you rarely get hit until the end of the 2nd sector, if at all. Missiles still hurt, but they rarely get to fire more than once.
4) If you have a teleporter and a team of boarders, micromanaging them can do wonders. Running around the enemy ship prevents its crew from manning the stations. If you split your boarders, you can often force the pilot out of the cockpit, which drastically lowers (or completely negates) enemy's evade. When your boarders are nearly dead, instead of sending them home you can try sending a new wave in. Let the newcomers engage the enemy crew in melee and then let your wounded crew join the fight from a safe distance. Note than you can choose who gets to melee whom by choosing the right order for your crew to enter the room.
People in FTL can't fight unless they fully enter the room. By constantly leaving the room as the enemy crew is entering, you can fool around indefinitely and keep them occupied, while, for example, you wait for the teleporter to charge again or while the rest of your crew reduce the ship into scrap heap. The possibilities for abuse are so vast, it almost feels cheap. But hey, whatever works. :)
Watch out for enemy cloak or door control systems, though. These have claimed more lives than alien spiders, and that's no mean feat.
5) Engines are important. You want them at level 4 by the end of sector 2 (they are dirt cheap), and you want them maxed out by the end game. I hear people complaining about the final boss being too difficult all the time, and when I ask them for screenshots, I often find that they stopped upgrading their engines at level 4-5. Ouch.
For me, it is better to have shields at level 6 and engines at 8 than the other way around. Of course, it is MUCH better to have them both maxed out. :)
6) You probably already know this, but you can board automated scouts, even though they do not have air. All you need is level 2 teleporter. Those ships usually have some insane evade, so every little bit helps.
7) An upgraded medbay allows you to get the best results out of some dangerous encounters, such as the madman, the station with an unknown decease and several others, which otherwise often result in death of one of your crewmembers. Still not a priority upgrade unless you have a teleporter.
8) Scrap recovery arm is an incredibly useful augment. In all of my runs I had only 2 ships that maxed out on every possible system, and one of them was an Osprey that had bought 2 of these during the course of the game.
The repairing arm is not one of my favorites for the same reason. I prefer not to be hit at all.
9) I hope that by now you can deal with any number of boarders by venting the oxygen and guiding them to medbay. Still you might want to send one of your men to engage them in combat, to stop them from damaging your systems (and possibly, your hull) while the air gets thinner.
Switching the oxygen off helps to drain the rooms faster. Having oxygen system at level 2 makes this stratery much less risky. With this, I am not in a rush to upgrade the door system.
10) Remember that you (usually) only pay for drone activation once per encounter. Once they are active, you can switch them on and off as you like. Power the defensive drone when you need to avoid missiles and then switch the power to other systems.
If you are low on drone parts, try to measure possibe benefits from their use. A drone part costs 8 scrap, and a hull point costs from 2 to 3 scrap to repair. It is generally not efficient to use a defensive drone against an enemy that has a single Leto/Artemis missile launcher, unless you fear that it can get off more than 2 shots or your overall hull integrity is not at its best.
11) The bombs are quite effective as bypassing enemy defenses and damaging enemy systems and personnel. They also tend to leave the hull intact, which helps when you are actively boarding and need to shut down a system without blowing up the ship. Still they take a long time to recharge, which means their overall effectiveness is pretty balansed.
12) Weapons that breach the hull or start fires can be a great asset to you. They prevent the system from being repaired AND manned. Moreover, enemy crew tends to avoid fires whenever they can. Setting a system on fire and teleporting in some Rocks is a great way to start a fight.
13) Have no fear of the rebel fleet. They are just ships, after all. They are one threat level higher than the rest of the ships in the sector, but it is only one level. The tactics that have carried you through the sector will work on them, too. If you have a choice of jumping to the next sector or lingering for a bit longer with a possible risk of getting in a scuffle with enemy fleet, weight the pros and cons and choose accordingly. 50 scrap from 2 extra encounters is usually more than enough to cover repair costs, if it even comes to that.
14) In all situations, keep your calm. More often than not those 'OMG what am I supposed to do with this?!' ships tend to be the ones that deal a few damage points more than the average before going down, and nothing else.

That is all I can think of from the top of my head. There are probably other bits and pieces of advice, but I can't remember them right now.

If you want my opinion, Kestrel is the easiest ship to win the game with, followed closely by Osprey and Nesasio. I find Torus to be too reliant on finding an extra weapon to be successful as often as these 3, and too time-consuming to play, as it lacks in ways of dealing hull damage.

Thanks a lot again. I knew some of that and applied it (often or not), had ideas from some of the others but never really applied them, and didn't know of some more others.

How about thanking nevill for his tremendous work he put into these posts trying to help you in the form of "Thanks, using your tips I can now win despite bad luck" or at least a "Thanks, I still cant win, but I see now how it would be consistently possible even without luck".

You came all this way to flame some more? Really?

How about I give you a big fat fuck YOU, "jamotide"?

A big fat FUCK you, jamotide.

That will be all.

Well at least you proved me right in the little arguement I had with jonesy89, that being helpful to you is pointless.

Troll Jamotide is right: Somebody who, like him, has always good luck, will always win.

Lol yep, I'm just 100% lucky with zero skill, I also got banned from the lottery because I always win.

So...any (lack of) luck yet?

Come on, Dr.Z, people put alot of work into this thread to help you, don't let it be in vain!

Helpful? Perhaps this is some new use of the term "helpful" of which I am unaware, but what exactly about "How about thanking nevill for his tremendous work he put into these posts trying to help you in the form of "Thanks, using your tips I can now win despite bad luck" or at least a "Thanks, I still cant win, but I see now how it would be consistently possible even without luck"" constitutes helpfulness? All I see is a post that contributes nothing to the conversation except veiled contempt and insult. To those who have responded with constructive advice, Zoidberg has been nothing but civil; all you have proven is that people do not take kindly to being flamed.

And with that, I regretfully inform you that this post is the last bit of food that I shall toss under the bridge you have chosen for yourself (something I think a good many of people on this forum would be well served to emulate), and I hope that it lasts you long enough to give you time to reflect on your actions.

Yeah exactly, I was refering to the people un this thread more optimistic than me. He should reward them with something more substantial than mere civility. Because that was the idea of this thread, I quote the opening post:

" If it's true and the tactics are logic, I'll make amends. "