There will be no Roosevelt Island F Train service to and from Manhattan this weekend.
According to the MTA:

ELECTRICAL IMPROVEMENTS No F service at 21 St-Queensbridge, Roosevelt Island, Lexington Av/63 St and 57 St.

Q, R and free shuttle buses provide alternate service Weekend, 11:45 PM Fri to 5 AM Mon, Nov 17 – 20

F Trains run via the E in both directions between Roosevelt Av and 5 Av/53 St

Shuttle buses operate between Queens Plaza and Roosevelt Island, making a stop at 21 St-Queensbridge.

The Roosevelt Island Operating Corp ( RIOC ) adds:

No F train service from Friday, 11/17/17 at 11:45 PM to Monday, 11/20/17 at 5:00 AM.

MTA will run free shuttle buses which will operate between Roosevelt Island and Queens Plaza beginning Friday, 11/17/17 at 11:45 PM thru Monday, 11/20/17 at 5:00 AM.

Additionally, RIOC will provide shuttle buses from the Roosevelt Island Tram Plaza to the Manhattan Tram Plaza. The first shuttle bus will operate from Roosevelt Island, Saturday, 11/18/17 at 11:00 AM, last bus from Manhattan will be at 7:30 PM on 11/18/17. Sunday, 11/19/17, bus schedule will be the same as Saturday.

Q 102 will operate normal regular schedule.

At Queens Plaza you can get the R, E or re-routed F Train to Manhattan. I asked the MTA: I asked RIOC President Susan Rosenthal:

Do you know what the MTA free bus shuttle time schedule is during the weekend F Train service outage?

Also, just want to confirm that the Red Bus Shuttle is on the hour from Roosevelt Island and Half Hour from Manhattan. Is that correct?

Ms. Rosenthal replied:

The MTA bus schedule … will be on a continuous basis. Your statement re the Red Bus is confirmed.

Roosevelt Island will have ferry service and a single tram cabin operating too. The pretend Roosevelt Island subway station is for Netflix TV show Maniac currently filming here. UPDATE 11/18: UPDATE 8:40 PM:

Roosevelt Islander