4m keel2

2008: Internal structure of the keel. Top parts of the two carbon tubes are mounted into the bottom of the hull. Two stainles steel rods on either side of the two carbon tubes are also used to hold the keel to the hull. Lead ingots are assumed to be below the bottom bulkhead.

The keel was made in the summer of 2008. During remote testing during the fall of 2012 it was decided that the keel produced enough lift but not enough dynamic stability.

4m keel1

2008: The external structure of the hull is made of wood and the front half and leading edge are covered in carbon fibre.

Current ProblemEdit

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Inside of 2012 Keel, Lead plates and Foam

The current problem with the boat is that it heels too much under heavy winds. Possible fix includes adding weight to the keel to make it heavier. The first solution is drill a hole near the top of each compartment and to fill the compartment with lead balls. Smaller balls can then be added to fill the gaps between the larger ones to achieve the highest packing density.

Another option would be to remove an entire side of the keel between two bulkeads and to cast a solid piece of lead to fit into the compartment.

2013 Solution ProcessEdit

In February 2013, the Keel was deassembled all except for the 2 carbon tubings. The design for the new keel is stated below:

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Feb 2013, Carbon tubes of keel


Shape the keel by using SS plates and alternating each with a foam layer in the desired naca foil shape. The specs for this are:

NACA 32 

Span: 120cm as by the carbon tubing length (though bulb will be later added to the base)

Chord: 32cm

Plates: 316 Steel (SS), 1/8" thickness each, 11 plates total (will probably use 8 and have extra)

Foam: Insulation foam (blue currently, but prefer to have the stiffer purple of pink foam), 6" each section (have three 2" foams together).  The foam was sanded to the proper shape, then coated in Bondo to add strength, and fill in deformations.  It was then fiberglassed twice, sanded and painted along with part of the hull with antifouling paint.

Keel BulbEdit

The keel bulb is approximately 200 lb and made from Lead scraps and old keel bulbs that were melted down in a pot using a hot plate at 550ºC. This was a slow process, and once melted the was poured into a concrete mold.The mold was hand made and not perfect. It should also be noted that there wa not enough lead to fill the entire mold, mixed in with the lead were impurities, iron scraps most likely. The poor shape of the bulb was improved with bondo, and then sanded.  


The bulb was attached with two threaded half inch steel rods which run through the keel tubes.  There is a stainless steel plate on top of the keel box with nuts and washers that support the rods.  There are stainless steel nuts and washers underneath the keel bulb ass well. To keel the bulb from moving around the keel M3 5200 marine sealant was used between the bottom of the keel and the top of the bulb. This was then covered in bondo to improve the shape.  Everything was painted.

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