If I hold a B/B2 visa while I am in the US and were offered a job on yachts, do I need to get out of the US and re-enter the country with my employer papers?

You may be able to change your status in the US. However, that will depend on the type of work visa you qualify for. The job may be difficult to get a work visa for. I would need to know about the job, salary and company. Feel free to contact me anytime: harun@ksvisalaw.com. 858-874-0711