There are a couple of points of interest here which resonate with me, the first being the increase in sail area. Like Annie, I thought you might be getting a bit carried away with 48 sq m on an H28. I think the concept of being able to set more than the designed sail area in light airs, on the argument that the rig is easily reefed, is a good one, but there is a limit, a point of diminishing returns, and I suspect the limit is in mast height rather than sail area. In anything more than a light breeze you will only be able to carry what sail the boat will stand up to, so a faster boat is still going to overtake you. The burden of an extra metre of naked mast is going to be no help at all.
There was a bit of discussion recently on one of the threads, about mast weight and how the weight of the rig comes down as you reef etc etc and I am not totally convinced by that argument (yet) but Arne came up with an interesting point about a few extra kilos aloft being merely the equivalent (in terms of static heeling moment) of one person moving to leeward in the cockpit, which has tempted me now to add an extra 1 metre to the length of the mast I am making. I am airing my ignorance here in the hopes that more knowledgeable members will correct me if I am wrong, but I think ultimately you do still have to consider weight aloft, and in addition you need to consider windage and rotational inertia (ie pitching and rolling). I think Arne has developed a plan form to achieve high sail area for a given height of mast.
(On a practical level, from handling commercial fishing boats with and without even a relatively low mast, it is noticeable in a breeze how much a mast adds to the difficulty of stationing over gear, and handling in a confined space, while under power. And it is quite a sight to see a whole row of yachts tied up in a marina all heeling quite noticeably in a strong cross wind. I think windage might be the limiting factor on mast height, if it is not indeed weight aloft.)
I hated the idea of a tall mast, but now, rather than theorise, I am making my mast a metre longer than I previously dared, and thinking to put an extra lower panel in the sail. We’ll see what happens. The idea is to be able to easily shorten the mast and modify the sail if it proves to be too much. I’ve got the makings of a long enough spar and hate to cut it short until I am sure, and I do like the idea of having a bit of extra sail area in light conditions.
As I said, this might provoke a learned reply or two.
The other point of interest is the tapered aluminium street pole. They don’t seem to have been available in New Zealand and if you succeed in finding one I think it will be of great interest here. Dave W has researched the question of importing one, and may be able to give you some leads. At least three local boats that I know of, in your size range, are making hybrid masts based on a standard 6m length of tube 152.4mm OD and 5mm wall thickness. These tubes are available locally and Annie has proved one already on a 26’ Raven which is roughly comparable with your boat in terms of mast requirement. She made a wood top section and is doing it again for her SIBLIM design. I am making an aluminium/aluminium hybrid using the top half of a large tapered aluminium flagpole, and Marcus has done it with a custom-made glass/composite moulding which might be the shot for you, if you find you have no option but to make it in two parts and have no workshop facility. I’m in West Auckland and contact details are on the website here.
Your first priority must be going for a sail with David – lucky you.