You can accomplish the same thing without unstepping the mast. Loosen the shrouds so there is no compression load on the beam other than the wieght of the mast. Install the jack or adjustable compression post under the beam, tension as desired and measure deflection on the outside cabin top. Chances are you need the compression post as most older boats do. YMMV Tom #664 Fun Zone

:: My '69 S22 has brownish drops of water coming out of the
:: beam under the mast and inside the cabin. I am worried
:: that there is rot and have read the post on beam
:: replacement but first I am trying to devise a way of
:: determining if there is degradation in the function of
:: the beam without drilling exploratory holes. Here is my
:: thought:
::
:: Unstep the mast, attach a rigid beam between the two
:: chainplates about 2 feet above the mast mounting plate
:: and attached to the beam to the chainplates with chain
:: or cable. Put a car jack where the mast was, a bathroom
:: scale on top of that and enough wood blocks to make up
:: the rest of the distance to the beam. Force 300 pounds
:: with the car jack between the cabin top and the
:: installed beam and determine the amount of deflection in
:: the cabin top over the mast beam.
::
:: What do you all think about this? Any idea on the amount
:: of deflection I should measure?