Swing Keel Additional Ballast
I decided to add ballast to the keel because I wanted to make the boat a little more stiffer. My Ballast & Heeling analysis had provided me insight as to the effect of additional weight on the keel. I needed to consider that too much weight added to the keel could cause an overload of the keel winch or the pivot bushings. I figured that adding 50 lbs. would give improved performance without adding too much stress on the keel system and its components.
I contemplated several options of adding weight, such as a 'bulb' or a 'wing' at the end of the keel. One of my key concerns was any adverse effect on drag when the keel was in its raised position. The keel is usually in its raised postion when motoring or sailing in shallow water. I finally came up with the solution of just making the keel a little bit longer. I was planning on using lead, and 50 pounds of lead would add only about 4 inches in length to the keel. This looked like a good way to go - the boat would draw 4" more when the keel is lowered, while having virtually no adverse effect when the keel is raised.
I needed to fabricated a piece of lead that had the same profile as the existing keel, and could be secured to the end of the keel. One of the nice things about lead is its melting temperature; a cool 450 degrees. This meant that I could cast a 50 lb. piece of lead myself, avoiding the cost of a foundry/machine shop. I had learned of a simple sand casting method, where you make a mockup of the desired piece out of styrofoam. The styrofoam piece is then embedded in sand, and 'voila' a simple sand cast.
Casting metal is a bit dangerous, so I would not recommend this to the inexperienced.
Pictured below is the styrofoam 'plug' and the resulting lead casting.
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| Styrofoam plug | Lead casting - leading edge | Lead casting - trailing edge |
This piece fit nicely into the contour at the end of the keel. The rough surface of the sand cast was excellent for epoxy adhesion. I epoxied it to the end of the keel and then covered the entire keel with fiberglass. At this point it was time to finish the keel (on to next page) or (back to previous page)