After talking to several other boat owners at my marina, I decided to implement a fresh water flush of the raw (salt) water system. Actually was very easy. Too bad I didn't do this all along -- it probably would have prevented several of the problems I've had to deal with over the years.
The system is simple enough. There's a bronze tee connecting the raw water seacock and thru-hull to the strainer. (Picture 1.) Fortunately, the tee is arranged so the strainer is on the "side" and the seacock is attached to the "straight" part. There's a bronze cap at the top of the tee. With the seacock closed, I simply remove the bronze cap and then attach a rubber hose that feeds into a bucket of fresh water. (Picture 2.) A garden hose is used to fill the bucket with fresh water. Now start the engine and run several buckets full of water through the engine. Remove the hose and reinstall the bronze cap.
Note, in the pictures, the sink cabinet door was removed for other projects. It is not necessary to do that for this task.
Final note, the bronze tee described above is also a good arrangement if you have problems with kelp or other things tending to clog the thru-hull. Just remove the cap and jam a stick down though the open seacock to push the offending item out of the way. Once water starts gushing in, remove the stick and close the sea-cock and then put the bronze cap back.
Nice job, makes winterizing with antifreeze easier too.
mark, i did something similiar, but i used a 3 way bronze ball valve directly in line so i don't need to disconnect the hose. it is positioned above the raw water strainer. in the spring and fall i pull the handle to the other position, remove a cap and screw the water hose into the valve, hose into the bucket, fire her up and flush with fresh water or antifreeze in the fall. just another method...jeff