Waterline

by **John Hickman** » Sun Jul 31, 2005 2:58 pm

Can somebody tell me.... is the waterline on an EC-12 parallel to the bottom of the keel?

by **Nautic12** » Sun Jul 31, 2005 9:17 pm

the manual for the ec12 gives a diagram for measuring the water line
this shows the keel resting on a horizontal surface,you then measure from this surface the prescribed distance up to the hull bow & stern,to mark off the water line. [8D]

by **PegLeg** » Sun Jul 31, 2005 9:27 pm

The answer is simply YES

by **RodCarr** » Mon Sep 19, 2005 8:57 pm

While the prototype line drawing from Charlie Morgan showed the design waterline to be parallel to the bottom of the keel, work by Larry Robinson and his crew found that the minimum drag configuration (MDC) for the fully ballasted hull was accomplished when the centerline of a straight-king plank deck was either horizontal or 1-degree bow up. Additional bow up trimming was observed to be useful as wind speeds improved, while a slight bow down from the MDC was preferable in light airs. How that relates to the geometric relationship with the keel bottom was not explored, since it was easier to access the deck of a floating hull than the bottom of the keel.

by **Carl** » Tue Sep 20, 2005 12:36 pm

The line drawing for building an EC-12 shows a dimension of 8 3/8 inches from the bow to the waterline on the centerline of he boat.
It shows 9 1/2 inches from the transom to the waterline centerline.
You can mark these points and then supporting the boat on a work bench level the 2 points in relation to the top of the work bench. Using a pencil mounted to a small stand you can trace the waterline as you slide the small stand. It works best with the deck of the boat facing down as the stand is shorter.

Carl

by **Larry Ludwig** » Wed Sep 21, 2005 12:33 am

Ballast your boat with the same weight as the rig (often called a pig) so that she sits the same and everything in place as it would be when sailing (battery, Rx, hatch cover etc.)

Fill up the bathtub (yes, EC-12's fit in the average household tub)and put in the material of your choice, ANYTHING will work.. soap, DIRT, oil, the dog...(Asta gets in without being asked) and then set your boat in the water and leave it alone for 10 minutes. When you come back, lift the boat out carefully and vertically and it will leave the most perfect waterline of soapscum, dirt, oil, Asta-fuzz.. whatever you used... on your boat. Set it in the cradle and get your pencil. Trace the line and Voila! instant perfect waterline.

You would think that lifting it out crooked would be a problem, but it is much easier than it sounds. Try it, you'll like it.

visit us at www.LudwigRCYachts.com

by **Capt. Flak** » Wed Sep 21, 2005 1:11 am

Don't forget to clean that soap scum of the tub before the wife sees it!

Joe Walter #24

by **MichaelJ2K** » Fri Sep 23, 2005 9:03 am

Back when we used to measure International A's, we used talcum powder in the tank. Worked pretty good![8D]

by **Gene Rosson** » Fri Sep 23, 2005 5:12 pm

Larry:
That's a real crafty method. It is so obvious that a lot of us had not thought of it. I'll use the method for sure. If you are forbidden to use the bath tub the test tank will work as well. Sawdust or wood flour might work well for this application too.

For those of you who are curious. The bathtub/tank is a fun place to experiment. You might wonder how water will flow around, behind, and ahead of a floating object, you want to explore boundry layers ,etc. Sprinkle some sawdust or black pepper on the water surface...Pull the floating object through the water and observe the motion of the particles. Use scale speeds or less. Be sure to observe the area ahead of the object. It's almost as if the water knew the boat was coming.

Just thought I'd mention this for the benefit of guys who have nothing to do.

Waterline

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