What's behind this mast plate

[n4hhm]

1981 H 27. Small plate at base of mast. Looks like it might be associated with the pulleys in the mast. I removed the screw but the plate would not separate from the mast.
Appreciate your help.

Henry

 

[rufus1138]

looks like access to the sheave bolt without stepping the mast, odd, makes me wonder why it was done.

 

[DianaOfBurlington]

Behind the mast plate

That is probably the plate welded to the butt end of the sheave axle-- take out the screw, bang it through from the other side, and the sheaves will fall into the mast. Most mastmakers after the '70s provide sheave pins with this plate as a feature. Earlier ones have cotter pins/rings on either side.

This sheave pin should be inspected and re-lubed in white lithium grease every three years or so. Replace the little screw with a new one (and bed with removable threadlocker). Remember to follow the pin through with a temporary replacement (use the pin you drive the sheave pin out with) to avoid losing the internal sheaves. Yours look like they are accessible down here; but the same arrangement is probably at the top of the mast as well. I have worked with very experienced riggers who have made this mistake!

 

[Leroy McMillan]

yes ... the axle for the sheaves is welded to the plate. tape a piece of twine to the sheave and rotate it 360 degrees and tie a constricting knot around the sheave so you don't loose them. The above post is spot on.

 

[DianaOfBurlington]

Another thing--

In addition to what I wrote above, be wary of aluminum corrosion behind the plate on this sheave pin. My patented, frugal trick is to lay white electrical tape on the face of anything stainless before installing it to the spar-- you can trim it with a (sharp) X-Acto knife and make a very good gasket to insulate against bimetallic corrosion. Lithium lube doesn't hold up in this sort of application; and why buy anything more than a $1.99 roll of tape to do this equally well?