Could it be "Survuve the Savage Sea" by Dugal Robertson?

Amazon's description: "After their 43-foot schooner was stove in by a pod of killer whales, the six members of the Robertson family spent 37 days adrift in the Pacific. With no maps, compass, or navigational instruments, and rations for only three days, they used every survival technique they could as they battled 20-foot waves, marauding sharks, thirst, starvation, and exhaustion.

From their site: "The true adventure story of the Robertson family's fight to survive for 38 days aboard their small dinghy in the Pacific ocean, battling storms, hunger, thirst, danger and death, after their yacht sank in sixty seconds following an attack by killer whales."

survivethesavagesea.com

Duggal also wrote a sea survival handbook based on their experiences called "Sea Survival, A Manual"