No winged keel
In his excellent book, 'All This And Sailing Too', Olin Stephens criticized modern yacht designers for employing what he considered race-only design features to cruising-only boats. (By 'cruising-only' I include modest club racing.) From his context it is very clear he meant the winged keel. I don't think OS ever drew a winged keel unless it was for a race-only boat. The drawbacks, including structural vulnerability, far outweigh the benefits the average cruising sailor would notice or even get even theoretically.
We Cherubini-boat owners are privileged to have very well-designed, well-built and reliable boats conceived in a time of sailing history when decent, well-rounded seaworthiness was to the fore. Later boats (oh, let me see... can you say BENETEAU?) attempted to entice 'performance-minded' buyers (read that: hyper-competitive guys in their 40s and 50s thinking they're still going out for sophomore football) by offering racy-looking boats that are not really fast, comfortable, easy to handle or fit for serious offshore work. The plumb bow dives through waves rather than riding over them. (Who thought of that?) The lack of tumblehome makes for wet side decks. The winged keel, remember, places the same amount of 'lift' to the other side as it does to the good side. It negates itself. At least a straight fin keel does so less so.
The REAL reason for the winged keel on a Beneteau is to provide more weight down low, since the depth of the fin itself is so little, owing to the depth of the hull's 'canoe-body' being so deep, owing to the need to have three double berths, two heads with separate showers, and air-conditioning on a 38-foot boat while still making it theoretically shallow enough (under 5 ft) for the Bahama Bank, which is where most of these boats end up chartering.
And you couldn't possibly fasten a homemade wing to the bottom of the keel without serious structural fiberglass or metal work to make it strong enough to stay on with the forces that are likely from even mild sailing. I suspect that you'd haul the boat at the end of the season and find you'd lost it an untold time ago-- and never missed it or even noticed it'd been there in the first place.
A better idea on your 33, especially because it's shoal draft, is to straighten the after end of the keel with a vertical trailing edge. We did this on our Raider, which used a variation of the H33 deep-draft keel. My dad made a 'cuff' of fiberglass, like a slightly-open manila folder, using a Formica mold, about 42" long, about 8" wide, and just wide enough at the open end to wedge onto the back of the keel, which was angled aft at towards the bottom. As on Peterson's 'Gambare' of 1977 the vertical trailing edge improves straight-line performance and avoids the accumulation of weird tip vortices coming off a pointed bottom corner. We applied it with sheet-metal screws and Bondo on Wednesday, faired it and painted it on Thursday, launched Friday and raced Saturday. Those were the days. (Oh; and we won.)
The cuff did work; the boat seemed to come about more quickly. But it should have been augmented with an intensive underbody redesign including getting rid of the vestigal 'skeg' between the rudder and keel on the R33 which slowed down water passing side-to-side in slow turns and in driving to weather. My H25 appears to be the direct predecessor of the R33 in that the same skeg is much more pronounced. My dad always said he should have eliminated it completely on the R33 (Gambare didn't have it either; but the Raider was designed first!).
