Why?
Some considerations:Why do you feel you have to move the mast? Is there any collapse of the compression post structure or main bulkhead? Has the deck deteriorated? Is there evidence the mast was ever moved to the wrong place before?The boat was designed as it came from the factory, fully safe and functional. There are reasons why it appears to be the way it is. Be sure you FULLY understand them before altering basic design parameters, especially because of fear or a 'feeling' it is 'somehow wrong'. (Can you tell I've heard this before?)I realise many engineer types can over-analyse some things. The reality is that the H-25 is a 4000-lb boat with 250 sq ft of sail using 1/8" wire shrouds and 'chainplates' that are nothing more than bent stainless-steel sheet metal held down with a couple of 1/4-20 bolts per side. This represents a realtively small boat for which most engineering arrangements are already probably overkill. You may safely assume that there is insufficient stress on the rig, and therefore insufficient compression on the mast, to wreak any serious damage to support structures under the deck if it's simply left as designed.Of course problems due to age, neglect, abuse, and modifications by owners not fully understanding yacht design and construction are another issue entirely.BTW I own a 1974 H-25, and the centre of my mast step is, of course, also 2-3 inches forward of the main bulkhead. I am replacing the mast compression post with a 3-pc one of sitka spruce-- but this is due to age and a little rot in the sole structure, not because the original compression structure was badly designed. Also I have discovered a little softness in the main deck beam but it is not enough to worry about and I will simply dry it out, saturate it in epoxy, and re-bed the SS mast tabernacle using 5200 against the deck and epoxy down the blind bolt holes. That'll fix it.Remember the guy that designed your boat has been called one of the true art-and-engineering geniuses of late-20th-C yacht design and I wouldn't mess-- AM NOT messing-- with anything he meant to be right. Trust me. I know better.(Then again, if you want to induce even more weather helm and create a whole new set of structural issues to deal with, by all means ignore this advice.)JC 2