Where do you find the captain that gives cut on fire red?

You can find the Captain who gives you the Cut HM in FireRed on Cinnabar Island.

Here's how to get it:

1. Beat the gym leader: First, you need to defeat Blaine, the Fire-type Gym Leader on Cinnabar Island.

2. Head to the northeast: After defeating Blaine, head northeast from the gym.

3. Look for the boat: You'll find the Captain standing by a boat just north of the Pokémon Mansion.

4. Talk to him: Talk to the Captain, and he'll give you the Cut HM, which allows you to use the move to clear paths blocked by trees.

Important Note: You can also find another captain in Vermilion City, but he is a fisherman. He won't have the Cut HM for you.