Are deathwatch Marines on "loan" to the Deathwatch? Will they ever (should they live long enough) go back to their chapter? Or are they in the Deathwatch for life?

They're basically on loan. I forget how long it is, something like a decade, I think, but I'm not entirely sure.

It is mentioned in the book that once a DW marine reaches /buys out the last rank of DW advances his tour is over and he is returned to his home chapter.

I think it can be anywhere from 2-10 years, or more in special circumstances.

Thanks guys.

I was going to play a Dark Angel who has encountered the Fallen before he was told about them. So they sent him off to the Deathwatch to "watch" him and contemplate bringing him into the inner fold or not. If he dies in the Deathwatch they have an answer, if he does not, and he returns(which is why i was asking) then they might find him worthy.

How do you guys deal with "down time" in your deathwatch games?

While waiting for a ship to take us on mission warp currents make the ship take longer to get to us - what would a marine do in the meantime (besides pray and train) especially if there are no true "space marine" facilitiys on this planet?

How do you guys deal with "down time" in your deathwatch games?

With any game I run I allow some meandering time during downtime, if the players want it. This allows them the chance to work on, or start a project that their character is interested in, an excuse to start studying for the next advances they want to take, etc.. Other times: "Several weeks/months have passed since mission X, what have you been doing?" With the expectation that the players will quickly fill in the gaps and to help them flesh out their characters.

While waiting for a ship to take us on mission warp currents make the ship take longer to get to us - what would a marine do in the meantime (besides pray and train) especially if there are no true "space marine" facilitiys on this planet?

Without proper training facilities I would imagine the marines would improvise some. They might co-opt a lesser used cargo hold and turn it into an improvised obstacle coarse. They may a section of the ship and start running boarding actions and room clearing techniques. They might find a librum, if one is on the ship, or they may indulge in any vices they may have. I could see a Space Wolf setting up a still or a Storm Warden finding some place to gamble away the night. They might even get bored enough to go looking for trouble in the deep holds of the ship they are on.

I think we may have found a front runner to the age old question of:

Q: What is worse than a bored Kinder?

A: A bored Space Marine.