The causeway is at that angle because of a solar alignment which has nothing to do with boats..
Although it should make for an interesting read in its entirety, the central part of this post [grahamhancock.com] deals with the Solar☆Vessel in context of the Causeways at Giza:
Likewise, ref. my webpage: Astronomical alignments of Giza
(Linked topics at bottom of page also tackle the issue of the SunDisc -- carried by SolarBoat -- respective of the horizon and Causeway alignments, in conjunction with astronomical phenomena incurred during its journey)