[Toller]

This is a 12' Petrel. There is a screw with two plastic washers on it in the gooseneck. I thought maybe it was to lock the gooseneck in position on the mast, but when I put a knob on it nothing happens.
I am thinking something is missing.

Any idea what this is for,and what is missing?

 

[CaptainForce]

Does your gooseneck slide freely up and down in the track? It appears from the photo that the tightening of a knob on this bolt would hold the gooseneck in place, while loosening could allow a dwonhaul adjustment. Am I correct that the tab in the sailtrack under this bolt is contiguous with the metal band around the gooseneck that the vertical pin of the gooseneck pivots within? I do notice that they are the same color.

 

[svHyLyte]

... It appears from the photo that the tightening of a knob on this bolt would hold the gooseneck in place, while loosening could allow a dwonhaul (sic) adjustment. ...

Correct...almost. It allows the adjustment of the positioning of the goose neck. There is no fitting allowing for a down-haul although one could be added. A Cunningham would be more effective for adjusting luff tension however.

 

[Toller]

Does your gooseneck slide freely up and down in the track? It appears from the photo that the tightening of a knob on this bolt would hold the gooseneck in place, while loosening could allow a dwonhaul adjustment. Am I correct that the tab in the sailtrack under this bolt is contiguous with the metal band around the gooseneck that the vertical pin of the gooseneck pivots within? I do notice that they are the same color.

The tab is one piece with the metal band.
And yes, the gooseneck sides up and down freely.

I thought the knob might hold it in place (and I can't imagine what else it could be), but putting a knob on and tightening it does nothing at all. That is what makes me think a piece is missing. Maybe a U shaped piece that fits under the knob, with the two arms pressing against the mast?

 

[svHyLyte]

The tab is one piece with the metal band.
And yes, the gooseneck sides up and down freely.

I thought the knob might hold it in place (and I can't imagine what else it could be), but putting a knob on and tightening it does nothing at all. That is what makes me think a piece is missing. Maybe a U shaped piece that fits under the knob, with the two arms pressing against the mast?

I believe that the threaded rod projecting from the tab within the slot once had a knob affixed to the end with which one screwed the rod through the tab and into the slot until the inner end-face of the pin came into contact with the inner face of the slot, locking the goose neck in place. If so, there may be slight indentations on the inside facing of the slot that could be observed in good light. The rubber grommets would have prevented the stop pin from being over tightened and distorting the slot.

FWIW...

 

[Toller]

Assuming something was missing, I tried to guess what it was, and make the attached. (I made the knob yesterday, just try to find a 10-32 knob!) I had to remove the washers as they don't fit my piece, but some the right size might make adjusting it easier.

It seems to work, though the faces that contact the mast need to have a radius put on them.

Am I on the right track?

 

[sailor6783]

replace your washers and use a wing nut, raise your mainsail to the top of the mast track then pull down on your boom end at the mast and tighten the wingnut.

 

[deniseO30]

It could also be an attachment point for block (pulley) as some booms have a line to pull it down and tension the main sail, but what you did is all you need to lock the boom .