You can rush without scouts, rushing with scouts can get you shunned on MP. Scots can kill constructors but you need other ships to kill the enemy.

The first capital ship is free so get one of those. Afterwards, scuttle you capital ship factory because you won't need it for a while.

TEC should get a Marza with the Raze Planet ability. The Marza will kill enemy ships and buildings very quick. Use cobalts and scouts for back-up.

Advent should get Mothership because its colonise bonus is very good along with the Shield Regenability. Get scouts, but don't get disciples after the first 10 min because they are weak.

The Vasari should get an Evacuator, better known as the Space Egg with colonise and the Nano-Dissassembler ability which kills any ship very fast. Tech assailants, but do not use scouts to rush as Vasari! Use Vasari scouts to capture neutral extractors to boost your economy.

i agree with Darvin on scuttling the cap ship yard. the small amount of cash is no reason to do it. the only reason i would do it is to get the logistics slot back so you don't have to buy a rather pricey logistics development upgrade on the homeworld. if its a straight rush scenario you probably haven't come close to running out of logistics slots so i see no reason to scrap the yard.

in general, when I rush i start the game with the particular type of rush strategy in mind that i'm going for. there are different approaches to this.

1) fast expansion base rush. you'll need the colonizer cap ship (which is why the Vasari Jarrasul is the best ship possible for this rush plan) and you want to go find a nice juicy Terran world somewhere in between your homeworld and enemy homeworld. you'll probably still want to colonize your first resource asteroid but then go directly to the terran world, try to take out the siege frigs in the militia as fast as possible and then go colonize it and get your ship out for repairs. you'll enjoy a nice income bonus as the population grows. once you've got some repairs and a few escort frigates for your cap ship you can go back and finish off the militia. once tahts done you can set up a forward shipyard (one or two frig factories and two repair bays usually) and use that to launch a full frontal asault on your enemy's homeworld.

2) economic disruption rush. you'll want a siege oriented cap ship for this one. the Vulkoras Desolator (for Vasari) or Marza Dreadnaught (for TEC) are the best for this. alternatively you can use the Sova Carrier to Embargo instead of outright destroy. Advent are kinda screwed on cap ship choices for this one and might not be able to do this one succesfully. the plan here is to scout the map as fast as possible and send your cap ship directly to your opponent's first resource asteroid as soon as you find it. then you blow it up and retreat to a nearby system. play some cat and mouse with your cap so he can't hunt it down and destroy it easily and make sure you keep your scouting active. when he goes to colonize another planet or asteroid you blow that one up to. this can seriously slow down and potentially fatally cripple your opponent's economic development. it will also slow your own development down alot since you'll have to colonize using only frigates, which means its hard to grab more than lightly defended asteroids and ice/volcano worlds.

3)cap ship destroyer rush. you build your nastiest 1on1 combat cap ship and go destroy your enemies cap with it. this is straight forward but requires excellent scouting and in combat micro management skills to do properly or else you'll probably just trade cap ships instead of destroy his and get out with yours intact. best ship possible for this plan is the Advent Radiance. The Kortul Devastator (for Vasari) is very good at this too as is the Kol Battleship and Marza Dreadnaught (for TEC). its usually a good idea to accompany your battleship with a small escort to turn the tides. for TEC or Vasari the escort should definitely be Missile Frigates (about 8 assailants or 10-11 Javelis is about right). For Advent you can get your carrier at tech tier 2 so you might actually want to consider using 1 or 2 Aeria Drone Hosts (with Bomber Squadrons, since your target is the cap ship) as the escort.

in any of these rush strategies though you'll still need to be simultaneously developing your own economy at least a little bit. the fast expansion rush is a primary economic plan in its own right so its totally safe going into the midgame even if your push against enemy homeworld fails, you'll still be in a good position. the other two rushes are much riskier because they do sacrifice a significant amount of economic development on your part. if you fail you'll probably be way behind and will need to immediately switch into defensive mode so you don't get wiped out in the inevitable counter-attack. mostly though don't try to rush unless you're pretty sure you can pull it off. this is why good scouting is absolutely crucial for any rush strategy. you need to know exactly where your opponent's ships are and what he's working on at all times or else you can get blindsided and fail and lose the whole game.

THERE IS NO SUCH THIG AS RUSHING IN SINS.

THE GOAL IN SINS IS TO KILL YOUR ENEMY, IF YOU CAN DO IT FAST, THAT DOESENT MEAN YOU RUSHED, THAT MEANS THE PLAYER WHO GOT KILLED FAST IS RETARD.

Not true; not all rushes are for the win, often times you're attacking to hamper your enemy's expansion and economy, giving you a long-term edge.  This is true in almost every game, including those famous for brutal rushing.  If you play it right, you won't lose on the rush, but that doesn't mean your opponent can't use a rush successfully for other purposes.

Scuttling the capship factory is not for the cash but for the logistic slots. That way you don't need to pay for the expensive logistics upgrades so soon.