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R E K

"To avoid a collision on the water with another boat, look at the other boat and the land behind it. Pick out a tall fixed object on the land behind the boat. From one spot on your boat, watch the other boat's movement relative to that fixed object. If after a minute or two of watching, the other boat does not move relative to that fixed object, you can conclude you're on a collision course with that boat."

From Defensive Boating, by Ken Taylor (Excerpted from Small Boat Journal-July, 1990)

A graphic showing a sailboat on a potential collision course with another sailboat at sail, behind is a lighthouse on land.
A second set of 2 graphics shows two  scenarios with a sailboat positioned differentely in relation to the light house.

The first graphic reads: approaching boat will pass ahead.

The second graphic reads: approaching boat will pass astern.
8 comments
Marieke

@rek

the lighthouse 🥹

also the sailing. gosh, I’m looking forward to being on the water again this summer

[DATA EXPUNGED]
Jaxom Kaplan

@rek Interesting. I learned it with "from a spot on the boat, locate the other boat relative to *a fixed detail on _your_ boat* "> no change = collision course.
I find it easier, as you don't need background view.

R E K

@jaxom_kaplan yea i've used both, on open waters cant rly use land as a reference :>

Nicolas Bouilleaud

@rek @joachim C’est le principal truc dont je me souviens de mon permis bateau :) Ça marche aussi en regardant l’angle par rapport à *son propre bateau*: si l’autre est à un azimut qui ne change pas (par exemple, “à 2h”) alors qu’on est en mouvement, c’est qu’on est sur une trajectoire de collision.

Autre détail amusant: ça marche aussi en voiture ou à vélo.

Bleyddyn

@rek “Constant bearing, closing range,” is how my grandfather phrased it.

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