Center of Effort

[PaulP]

OK, all you techie guys, does anyone know the position of the center of effort of an EC12? any put one in a pool and pushed it around with a pencil?

How 'bout it Scott, have you pursued this dimension?

Paul P

[Ken S]

Are you looking for center of effort or center of lateral resistance?

Ken

[PaulP]

Ken
Looking for Center of Lateral Resistance. I can calculate the Center of Effort.

Center of lateral resistance is based on weight, position of that weight and the projected side area of the hull & rudder. It is a determinable figure, but not easily calculated.

Most get it by placing a hull in a calm body of water and pushing near the water line with a pencil till the point that the boat moves exactly sideways, not twisting.

I don't have access to a calm pool or I'd work on it

Paul

[bigfoot55]

Do you do that experiment with the rudder installed or not? I guess each boat could be slightly different depending on how waterline is reached by ballasting, up down or sideways. Are you looking for the bistance from the bow in general?
tp

[Ken S]

Paul, I'll give it a try in the hot tub this weekend.

For those interested in COE and CLR and their effect on each other heres a link with a simple explaination.

The rudder will be installed as I'm sure you'll want to know the CLR of the full hull and appendages.


http://www.myrc.org/Library/centeref.htm

Ken

[PaulP]

Ken,
Did we lose you in the hot tub?

Curious if you came up with anything

Paul P

[Ken S]

Almost Paul...but I had to come up for air.

I used a pre '95 Hickman Hull with a Brawner pour, the rudder was installed as it will have a direct effect on the CLR while sailing. The winch/servo board is aluminum and is 7 1/2 inches long mounted low directly on the ballast. That and one healthy assistant, aka babe were the only equipment used.

The water was calm...most of the time
The wind was blocked, as were prying eyes, so as not to effect the outcome of My attempts...err, the tests.

After many repeated attempts...I mean tests, the figure I came up with was <b><font color="red">32 5/8"</font id="red"></b>.

I'll do the tests with a '95 hull with and without a 350 gram weight on deck, as soon as I convince My assistant to come back for further attempts...I mean tests. I also will be doing an Ozmun hull with a long low pour. (Should be next week)

[yachtie]

After many repeated attempts...I mean tests, the figure I came up with was 32 5/8".

So is that a B or C cup??[:p][:p][B)]

Chris
NZL1 Longtack
NZL110 Swept Away NZL128 Ketch me if U Can