PLL,
I hate to throw cold water on the ship sighting by de Anza's guide, but there is no mention of this in the original diary, copied below, so I suggest that it is just a "story" created by some investor-hunter with a sharp imagination. Doi you have another credible source?

By the way, the actual name was "Anza", not "de Anza", currently widely accepted all over CA.
Bob
Sunday March 6.–To add to our ills, in the morning we learned that our guide had fled, leaving us his poor weapons as signs at the place where he had slept. For this reason, and for the lack of water which we were suffering, I sent six men with a corporal to look for the watering place which our runaway guide had said was nearby. The corporal bore appropriate instructions in case he should find heathen there or in any other place and to report to me whether or not he had found the water.
At two in the afternoon I set forth with all our train toward the west-northwest over the trail of the six explorers. When I had gone about three leagues two soldiers met me and reported for the corporal that they had found a good watering place in the middle of the sierra and near it a heathen Indian boy.
Guided by these two soldiers we arrived at nightfall at the place where the water was, distant from the preceding one a little more than four leagues. Immediately the corporal, who was here, told me that soon after he had seized the Indian boy mentioned an older Indian came down with great timidity and gave him to understand that the boy was his son, and that he should be given up to him. To this the corporal replied that they must not run away, because he would do them no harm, but in spite of this they insisted on leaving, which they were permitted to do after they had been regaled, in keeping with my orders, for I have always impressed upon the minds of all the soldiers with me that they must not use force upon any heathen, even in minor matters, except in cases of extreme necessity, in order that we may not acquire a bad name at first sight.
This watering place I gave the name of Santo Thomás. [Footnote 98] Besides five small springs of bitter water which are here, there is one of very sweet and clear water, and there is also some grass but of bad quality. It is situated in a sierra which we infer must be one of those which form the California chain.–From Tubac to Santo Thomas, 192 leagues.