I was able to find the 1848-1854 Huwelijksbijlagen for Den Helder in the FamilySearch Catalog: https://www.familysearch.org/search/catalog/280682?availability=Family%20History%20Library
Scroll down and you will see the films near the bottom of the page, after the Tienjarigetafels, geboorten and Huwelijken.
Sorry for my late reply. Thank you for helping me out. Best regards, Maud