Ed,
Forward mast bend is not really out of column and will not impact the mast pumping one way or the other. The pumping has to do with the mast cross section shape and how the air flows over that shape, it's length and where the stays attach all working together to create a harmonic vibration. It is more pronounced when the broad shape of the mast is facing the wind, like what happens when you have the boat in a slip. The only way to prevent this is to detach the laminar flow of the wind over as much of the mast as possible. I have had great success with taking the spin pole toppling lift line and centering it up at the block on the mast and warping each end around the mast as many times as the length of the line will allow, crossing each line in an "X" pattern at the forward and aft section of the mast. The more the line wraps and hence the more crossing of the line the more you break up the laminar flow, the less pumping you will have. Just doing the lower portion of the mast is enough to break the harmonic range for our rig setup and stop the pumping.
Also, forward mast bend can be a good thing when you are trying to de-power the mainsail in heavy air. Mainsails are cut with a forward curve in the luff to provide part of the shape(draft) in the sail. When you hoist that sail on a straight mast this is what provides the belly/draft in the sail. When you bend the mast forward, the bend of the mast approximates the bend cut into the luff of the sail thus flattening the shape of the sail thus producing less power and heal. Forward mast bend is usually produced by increasing the back stay tension, but on mast head rig such as ours the forward lowers can be use as well. If you are interested in learning more about sail shape do a Google search on "book on sail shape" and you will have your winter reading list for years to come.
Paul
Forward mast bend is not really out of column and will not impact the mast pumping one way or the other. The pumping has to do with the mast cross section shape and how the air flows over that shape, it's length and where the stays attach all working together to create a harmonic vibration. It is more pronounced when the broad shape of the mast is facing the wind, like what happens when you have the boat in a slip. The only way to prevent this is to detach the laminar flow of the wind over as much of the mast as possible. I have had great success with taking the spin pole toppling lift line and centering it up at the block on the mast and warping each end around the mast as many times as the length of the line will allow, crossing each line in an "X" pattern at the forward and aft section of the mast. The more the line wraps and hence the more crossing of the line the more you break up the laminar flow, the less pumping you will have. Just doing the lower portion of the mast is enough to break the harmonic range for our rig setup and stop the pumping.
Also, forward mast bend can be a good thing when you are trying to de-power the mainsail in heavy air. Mainsails are cut with a forward curve in the luff to provide part of the shape(draft) in the sail. When you hoist that sail on a straight mast this is what provides the belly/draft in the sail. When you bend the mast forward, the bend of the mast approximates the bend cut into the luff of the sail thus flattening the shape of the sail thus producing less power and heal. Forward mast bend is usually produced by increasing the back stay tension, but on mast head rig such as ours the forward lowers can be use as well. If you are interested in learning more about sail shape do a Google search on "book on sail shape" and you will have your winter reading list for years to come.
Paul