Foil rudder construction: would it work?

[Urban Hermit]

Mulling over building a foil rudder and this came to mind:  Great Stuff (expanding foam) one side of the stock rudder.  Cut two or three half-foil shapes out of light metal. Imbed them into the foam and use them as contouring guides.  With foam shaved/sanded/cussed into shape, West System three or four layers of glass over it, half as many bent over the edges, and smooth, duplicate on the other side including the half-as-many layers over edges.  Paint or gelcoat. 

Thoughts?  More work than it's worth?  I found a Compac 16 foil rudder on line for $425 with the satisfaction/bragging rights of DYI.   

[MacGyver]

I made my own by making some wooden shaped foils and attached them to the rudder plate. Then I attached blue DOW sheet foam to the sides and used a sander to get it to match the foil shaped wood pieces.
Glued everything using West System, and made sure to use 40 grit on the aluminum to get a good enough bite. Aluminum can be tough to bond to, so after the foam was where I wanted it, I coated the whole thing with fiberglass and West System Epoxy, and at the top and bottom was some reinforcments of glass, with the top being a larger glue joint to the Aluminum to ensure it would last a long time and hold tight.
The blue foam is used in foundations, etc, may even be the pink kind too now, but mainly it is pretty well water proof. Great stuff is not, it actually holds water and acts like a sponge.

It was a cool project, I had videos of it, Ill have to see if I made a Youtube of that or not, maybe I can find the video and cut it up and post it otherwise.

Mac

[Urban Hermit]

Thankee, Sir.  I think you describe what I had in mind, in more detail than I described it.  And thank you for the comments about the foam.  Yes, Great Stuff does absorb water -- I hadn't thought of that.

[Cpy23ecl]

About 10 yrs ago I bought a couple trailer loads of used dow 2x8 1" thick blue foam boards salvaged from a building.  A few of those were water logged so some of the blue foam definitely can absorb water.