Whitewater and rivers

Strainer (tree in the water)

Also: strainer, logjam, deadwood

Fallen trees and branches in the water act like a sieve: water flows through, boats and people get stuck. They are among the most common deadly hazards.

In English such an obstacle is called a strainer. The Paddleways definition: an obstacle such as branches that can trap objects. On small, gentle rivers in particular, trees are treacherous because you only see them too late after a bend.

• move to the other side of the river or land early
• better to portage than squeeze through
• as a swimmer, swim away actively; if necessary, go head first and climb over it hard, not under it

Sources and further reading

• Paddleways: Whitewater Glossary

Research as of 13 Nov 2026. We have marked manufacturer information as such.