Echoes Of Heinlein III

Poul Anderson, The Boat Of A Million Years (London, 1991).

See here and here.

Seven immortals confer:

"None would have accepted a chairman, but one person had to take the initiative and [Hanno] was the senior." (p. 447)

Hanno asks:

"'...shall we continue our masquerade, using new masks?'" (ibid.)

With capital initials, "Senior" and "Masquerade" are important words for Robert Heinlein's Howard Families, bred for longevity:

the oldest member present at a Family meeting chairs;
the oldest member of the Families is the Senior;
the Masquerade involves changing identities and locations every few decades.

Difference: Howards survive mature but unaged well into their second century, then age and die quite quickly, with one exception - Woodrow Wilson Smith/Lazarus Long, the Senior, a mutant, lives indefinitely like Anderson's much smaller group of mutant immortals.

Regular correspondent Sean asked whether it is a flaw in Boat that the threat from Senator Moriarty is allowed to peter out. I did not think so although it is a fair question. All we can say is that Moriarty had started to investigate several of the immortals; however, knowing this, they slipped away into alternative identities and his investigators, including the FBI, were unable to keep track of them. As part of this "masquerade," the deaths of Hanno's older personae were faked.

Boat really does combine elements from all of Anderson's other works of fiction. We next see Hanno a long time later, exploring Jupiter from orbit with a robot craft that descends into the atmosphere. We recognize this scenario. What a mission for a Phoenician sailor!