Thanks for all the thoughtful replies. I remained at anchor for a day off beautiful Dog Island and took the advice to pull the water hose off the exhaust elbow to look for salt obstruction. Found none. Then left Monday, motoring back to home port, bashing into a 15 kt Easterly wind/3 ft waves. Steam was still there in amounts I think were more than normal. Then a series of failures occurred in rapid sequence, only one of which was related to the steam. I'm still sorting it all out but here's what happened and what I think the causes might be. First, engine heat alarm came on and I immediately shut down, went forward and dropped anchor. Lucky to be in relative calm water about 17ft and good weather.
Pulled eng cover to fine belt shredded, in pieces all over the place. The belt was new and top of the line. Replaced belt, but pretty sure the belt went due to the heavy load on new 80amp Balmar Alt.. I reprogrammed the voltage reg to take 35% off the load in "Belt Saver" mode. Cranked up and proceeded. Next, GPS lost fix, soon after engine overheat siren came on again, followed by another immediate shut down, another anchor drop and lots of good salty sailor language. New lady friend aboard remained amazingly cool, calm and not critical. Promoted her to boson, then dove below to find the issue. Belt in fine shape, no blockage in raw water intake. Decided to sail back to nearest port with repair facility and found that engine would run at 1200 without overheat. Limped into a slip at repair yard at midnight. Tense, tired, hungry and beer deprived. Next day disassembled raw water side of cooling system to find a half a cup of dissintergrated pieces of previous raw water pump empeller packed into heat exchanger. Fact is when that empeller was destroyed (see earlier post about running engine with water intake closed) I had the latent good sense to remove the heat exchanger and look for such at that time. These pieces must have been lodged up stream somewhere to elude that earlier search. Cleaned out the exchanger and every hose in the system. Put it all back together and came home, yesterday running 9 hours at about 2200, at which I'm guessing cause the darn Tach went out as well. No more overheat, and very little steam, but some. More later on what caused the GPS to lose fix and the tack to quit. If you want it. But I think its related to the alternator's heavy load.
Damn I love sailing!

Thanks for the links Stu. Actually, I think I read most of those last year when I was redoing my system adding the 80amp Balmar and external ASR-5 regulator. I just had not used the belt saver function until I shredded that belt underway. (I thought it would just happen to others, not me) So, after getting the boat home and letting the (belt?) dust settle, I continued my sleuthing. I had two other anomalies to explain; why the GPS fix was lost and then came back on its own and what was wrong with the tach (dead, no needle movement). Had a eureka! moment when I discovered the red power wire in the Balmar supplied harness from the regulator to the alternator had vibrated off right at the terminal and hanging loose. Spliced the wire onto a new ring terminal, hooked it back up and voila! I have my tack back. I'm not sure when in the earlier trip that wire broke but I now think that it was early, and so my 71% depleted house back got even more depleted. To a point where the GPS ant detected insufficient power and shut itself off. It worked great the next day after we spent the night on the power chord and charger. All is solved but only now need to verify that my alternator is still OK.
And to think, that I used to think that the most important skill I needed to own one of these boats was actual sailing expertise!! Good thing I like it!

As I'm often reminded, my spelling is not the best. Cord, chord, potato, potaito.