How many goo canisters can I have on one ship?

[flightmaster]

Like the question says, how many can I put on my ship before they either start becoming ineffective or inefficient?

[Whackjob]

Eleventy-one.

#EDIT: Seriously, though, I'd say no more than four of the same environment.

[Kasuha]

That depends on what kind of ship it is and what you are going to do with it. If you plan to visit all Mun biomes with it and return to Kerbin, you can use at least as much as there are biomes.

If you just want to transmit results back via an antenna, one canister is enough.

[Geschosskopf]

4 recoveries of any type of experiment pretty much gather all the points for that experiment in a single situation (landed in / flying over a biome). And with transmitting getting nerfed in 0.23, recovery will probably be the preferred thing. So, any place you send something, put 4 of everything you have on it and never go there again.

[Stargate525]

It depends on the mission profile. If you're heading anywhere, you'll need three per sphere of influence (high over, near space, and landed). Anything with an atmosphere will need two more for 'high in atmosphere' and 'flying at.' Even if I'm planning on transmitting, most of my planetary probes have three; I've never been good at timing/managing the power constraints well enough to get all three with one instrument.

For anything else, I pack two. For symmetry.

[longhornchris]

In answer to your direct question - after 4 collects in most areas nets you as much as you are going to realistically get.

With that said, if you have enough power one is enough, although 2 for symmetry makes it clean. I generally only fly several if I'm doing a return mission - i.e. early on when I don't have solar panels or batteries an can't afford the power. My early suborbital and orbital craft usually have lots so I can get as much science returned as possible.