Yes it is. I got it from here:
https://www.marineoutfitters.ca/index.cfm?category=10427%7C11795&product=54069231&code=BIBTI believe it is also available directly. The name is 'Bed It butyl tape'.
https://shop.marinehowto.com/products/bed-it-tapeIt was actually fun to use.
I would read
https://marinehowto.com/bed-it-tape/ on the correct approach. I was unable to counter sink the holes, because the holes are huge and probably only an oil drilling rig has a bit that size, and the wires for the pedestal also run through the guard.
That being said I plugged the hole with butyl, and after the guard was placed on the deck again covering the holes, I added about a 1/4" around the tubing at the deck level, so that when the plate comes down it sealed the tube to plate gap. Hopefully that makes sense! Sorry I didn't take photos as I was under the gun weather wise.
Also, the how to mentions to repeat tightening over time as it will compress out slowly. This is true. I tightened 3 times over 30 minutes until I got no movement from the screws.
NOTE: They are screws not bolts so don't over torque. I used cordless drill and set the clutch on 3 and worked my way up until I was getting reasonable torque. It wouldn't take much to strip the hole.
NOTE NOTE: For me I had 4 screws, port and starboard, from the other side (under cockpit area, where steering quadrant is) of the aft berth wood panel holding the panel on. I had to reach through and blindly unscrew them. The bottom 3-4 screws on the inside of the aft berth were not the only screws holding it in place.
Took me a while to figure this out!
I have to do this same repair. Is that butyl you used?