Police recover a body from Poole Harbour in Dorset and launch a murder investigation after a man goes missing from a sailing boat off the coast. According to reports, officers recover the body from the harbour area and arrest three men on suspicion of murder. The arrests follow the missing person report involving the sailing boat, which prompts an active police search and subsequent investigation. Authorities do not present additional details in the available reports about the identity of the man, the circumstances of the disappearance, or the cause of death, but the investigation is treated as a homicide case based on current police assessments. The case remains under investigation as officers continue their enquiries following the discovery and arrests. The reports agree on the core sequence: a missing man associated with a sailing boat, recovery of a body from Poole Harbour, and three arrests on suspicion of murder.