I can not find an exact picture, but this is the best I could do. Instead of the swivel base mounting on the floor it mounts on the starboard gunnel back by the tiller post.
The Mainsheet attaches to a becket on the swivel, runs up to a double block mounted towards the end of the boom, down to a single block mounted on the gunnel on the port side, back up to the boom, and finally back to and through the jaws on the cam cleat.
The whole thing makes like an inverted V. No traveler is used.
Note; The harken photo is not exactly how it is set up, but should give you the idea.
As mentioned it's an attachment point for your mainsheet, which typically is arranged in a block-and-tackle (not in the picture) to get a mechanical advantage. The pair of dark gray plastic cams at the top forms a cam cleat: if you pull a line through it towards the flat side, it will open, but if you apply tension in the other direction, the cams will close down and pinch the line.
Do you have a picture of the outboard end of your boom? That's the other attachment point for the mainsheet.
12-17-2008 09:08 PM
That is your mainsheet block, but on the Cal21 (I have been on) its not located on the cockpit floor, its actually on the cockpit gunnel close to the transom.
12-17-2008 07:24 PM
Looks to be missing a block but should bolt to the floor off the cockpit. Its for your main sheet.
12-17-2008 07:11 PM
Guess this part?
I purchased a Cal21 with this part. Any ideas what this could be and how it works? Thanks in advance.