Two rangers were called upon to assist in escorting a houseboat and two open bow motor boats to the marina from out on the lake.  
Upon arrival they found that the houseboat did not have a means of propulsion and one of the two vessels escorting the houseboat and providing the propulsion was not working.  As this rafted set of vessels were moved out an into the main channel of Francis Canyon the inoperable vessel began to take on water.  The vessel was cut loose from the houseboat and promptly sank stern first. 
 
Vessel was retrieved the next day and finding by the marine crew of a 4" hole for water on the exhaust manifold being opened.
Navajo Dam