at the beginning of this season, I definitely felt dawnbreaker was harder to heal than s1. and although o haven’t played rsham since cata, i have been pretty much always played healers.
for the first boss on the boat, just make sure you rotate your healing output cooldowns around the arrow heal absorb thing & dispel that thing ASAP. this part was super hard for me as a washed up healer, but getting CD rotations down has essentially nullified the mechanic.
2nd boss is almost purely mechanical. don’t get hit by the orb & aim the orb down the path. again, rotate healing output cooldowns around the boss’ AOE/your teammates getting grazed by the orb.
third boss I think is insanely easy and you shouldn’t ever have trouble with it