If they were loose, must likely your transom is rotten
Uumm… That is not a proper repair. The entire transom undergone a lot of stress. The rotted areas around the keyhole are going to crack/fail.Yup your probably going to have to tighten them again,and again. I fixed a soft transom by removing the transom bolts and drilling down the center of the bolts and cross-drilling the area that would be inside transom. I then put zerk fittings on the ends of the bolts and used a grease gun to force resin into the rotted wood.
Uumm… That is not a proper repair. The entire transom undergone a lot of stress. The rotted areas around the keyhole are going to crack/fail.
Fixed, bolts through transom left loose after the mechanic had serviced it! ( yes,he removed engine for the service just before I took over ownership of the boat) Very difficult to access but eventually able to get to them with a cut off spanner without engine removal.