There are ferries from Belford to the ferry terminal on W 39th street just above the Lincoln Tunnel. NY Waterway runs busses from there around midtown. I'm not 100% sure, but Seastreak is taking over that ferry route next month, it looks like it still will go to 39th street, but not sure if you'd be able to utilize the busses since it will be operated by Seastreak instead of NY Waterway.

This is the schedule they will be running: https://seastreak.com/wp-content/uploads/2022/11/Master-Schedule-Pricing.pdf