Wilko van den Bergh wrote:

IMNSHO the main problem is that many couples who think that they have a
good relationship, don't. Finding out on the river that you're not
communicating but talking to each other, that cooperation is something
else than a fight for domination, that it's better to have the most
experienced boater set the course instead of the most dominant one...
A lot can go wrong in a relationship, but tandem kayaking is a good way
of finding out how well a couple really gets along and brining out some
deeper lying problems.

Jesus, this is getting scary. Does anyone actually know of a married
couple that has gotten a divorce because of tandem paddling?

Or is "divorce boat" perhaps a metaphor?

Steve