Deserted Dessert Island

PART I:
Annabel, Bonnie, Chuck, and Denise want to travel to a famous deserted dessert island (that's not a typo!). They need to travel across the Isle of Hot Chocolate to reach the island, so they rent a sugar-proof, rubber raft. Unfortunately, the recommended weight limit of the raft is 230 pounds.
Annabel weighs 100 pounds.
Bonnie weighs 140 pounds.
Chuck weighs 180 pounds.
Denise weighs 90 pounds.

How will they reach the island of sweets by only using the raft?

PART II:
Upon reaching the dessert island, Annabel, Bonnie, Chuck and Denise stuff themselves silly with cakes, pies, and bread pudding. Within a few days, they are the following weights:
Annabel weighs 110 pounds.
Bonnie weighs 145 pounds.
Chuck weighs 192 pounds.
Denise weighs 98 pounds.

All of them want to get back to the mainland using the raft. How much will they exceed the recommended weight limit of the raft if they cross the isle using the same method as in PART I?

See the solutions