How to check my swing keel is working?

[seeSimon]

6 x 6 fence posts, or railway sleepers are good, and can be readily cut to useful length with a chainsaw. Not too heavy, unless waterlogged. Not too expensive, compared to "boat props"...

 

[langstonelayabout]

If your boat is sat on mud, grass, etc. then you could dig a slot in the ground about 2'6" deep; enough to lower the keel into.

Make sure you fill it in afterwards...