I almost left the seacocks alone and was just planning on adding some lube and away I go.  Glad I did not.  I have now taken all of them out.  12 of them, plus one other through hull fitting.  The Seacocks are the original 30 year old all bronze seacocks and they are in good shape.  A little green, but that is just cosmetic.  A few had steel pipes attached to them and have filled with rust over the year.  WHO DOES THAT!  Put a STEEL pipe BELOW the water line on an intake valve?    I removed 10 seacocks today, 4 bolts each.  Of the 40 bolts, 20 could not be taken off.  Either the nuts were frozen, or the heads were so stripped I couldn't grab them. I HATE SLOT SCREWS  WHY ARE THEY EVEN STILL MADE!  I will NOT put them on my boat.
 They are counter sunk into the hull so there was not way to get them.  So I had to cut off 20 bolts....or the nuts....or both.  Getting the flange off the bottom was also a challenge.  I tried drilling them out from the bottom, but it was too easy to slip and drill into the fiber glass, so a drummel it was and about 15 cutting disks.  
              I finally used my metric set of wrenches...by jamming one into the opening to catch the 2 small bumps on the outside of the seacock.  Then with 2 large wrenches I was able to twist them off.  Well all but three.  One was stripped and needed to be cut off...2 still need to be done.  I got tired.

Most of the seacocks have great access.. except 2 (See picture).  Larger one is a cockpit drain (starboard side), with a tiny opening inside a cabinet above for access... by enlarging the hole above it , access will be adequate but not great.  The other one....I have no idea how anybody ever even touched it before.  I was only able to get to it because:   A. The engine was out.   B.  The bathroom sink was out.  AND C. the wall separating the bathroom and the engine room was out.   This seacock I will move.  I will put it above the shaft in the aft stateroom floor panel.  Nice easy access. 

Here is the Steel piece...looks sort of O.K. on the outside...inside is just rust.  Inside of seacock is covered with rust flakes.

This is how I was able to get all the 30 year old pieces separated.  This piece of pressure treated 2x12 has been sitting in my work shop for 10 years.....See I knew it would come in handy some day.

Coming soon:  A picture of them all cleaned up....plus the other three I haven't gotten out yet.