Survey ships are the only class of ships that the AI ship designer will consistently design ships with survey modules in mind. If you want some other kind of ship to be equipped with survey modules, you are going to have to build that design yourself.

Its been asked a few times for the ability for players to design their own class of ships, much like how rangers, troop transports, or survey ships are their own class.  For instance, a survey ship is medium hull with a survey module, with a number of other modules for range and speed (and maybe more sensor range). Right now, we don't have the means to design our own class of ships (short of modding them in).

Yes, you will need to research the techs for medium hulls and survey modules at the very minimum. Without them, the game won't design the survey ship.

I'm sorry. Did I misread your post? I've been reading a lot the past few days, so I might be a little tired. I know that I was trying to answer a question for someone just recently, who asked if they needed medium hulls and survey modules to get a survey ship.

Somebody check the (new Beta 4) mass value of the Survey Module.  I suspect it's huge, and no longer fits at all in a medium hull.

Hence the autodesigner tries to put a survey module in, fails, and then it fills up the empty capacity with Navigational Sensors instead.  Can anybody verify?  (Just select your ship, click Details, list all of the components, and manually add up their masses, cross-checking with your own Designer or XML files as needed to get the raw numbers.)

Peregrine, I think you nailed it, in which case this is a bug...??