To Jeff H
As a rough approximation, you can measure from the bootstripe (water line stripe) to the bottom of the keel in the folded up position. This is only a rough approximation of the board up depth. To refine this you can use a carpenter''s level and take measurements to both sides and down to the lowest edge of the keel with the swing keel in the up position. Then with the boat in the water you can take a rough measurement of the position of boot stripe relative to the actual waterline to refine things further.(Of course, you need to be standing on something other than the boat when you try to sight the actual waterline.)Also don''t forget to check if your rudder hangs below the depth of the Centerboard.
To figure the board down depth is a bit harder. Most times there is a little mark or discoloration on the top of the keel, where the swing keel where the keel abrades at the where the top of the drop keel aligns with the hull in the full down position. If you don''t have one then you can dive under the boat with a pencil and make a mark alng the bottom of the hull on the top of the keel with the keel down. With the boat out of the water you can then measure down to the bottom of the hull from the waterline and measure perpendicular to the pencil or abrasion line on the keel to the lowest point of the keel and add the two together to find yoru approximate draft.