This sentence is incomplete. To complete it, we need to know what Jacob did. Here are some possibilities:

* Jacob took along a compass and grid pattern map when he went hiking in the woods.

* Jacob took along a compass and grid pattern map when he went on a treasure hunt.

* Jacob took along a compass and grid pattern map when he explored the abandoned mine.

To get a complete sentence, you need to tell us what Jacob did after taking the compass and map.