I have to admit it I have ACTUALLY tipped over a 3.5 ZODIAC CADET SIB (during my youth years was 15 then) with a 9.9 Johnson on it.
The story, near Cape Sounion was just 300-400 mtrs away from the beach, wind strong force 6, month August, quite a chop, sib went over cause I was being stupid with it and was trying to impress a girlfriend I had on the boat at the time, no life jackets just swim suits, no flares or anything else (OK I know is bad but this is how things work/ed in Greece). Only a pare of oars
SIB will not come up when we tried at first, but tried harder and because I was lifting the side that was caching the wind and the girl was leaning on the engine the boat came up.
By that time were a mile and bit away from the shore. No flares on the boat or anything like that, engine wouldn't start as it had flouded with salt water and had seased. Stood up and waved and luckaly some people saw us and came out with their boat. Saved the SIB that I still have (and is made out of PVC!!). We were not in danger at any one time as we both are/were very good swimmers it was just the thought that I'd lose the boat and someone else will find it. This is why I didn't let it go!
It was difficult with a small boat I think that it will be impossible with a larger RIB. So better sink it and claim the insurance