# half angle of entrance

Discussion in 'Boat Design' started by Adarsh Edakkote, Dec 19, 2015.

1. Joined: Dec 2015
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Location: India

Hello friends,

Can anybody give me the exact meaning of half angle of entrance.
I believe half angle of entrance is directly proportional to block coefficient of ships.

I need angle of entrance to calculate the resistance of my barge,i am using holtrop method.Please advise.
Regds,

2. Joined: Apr 2015
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Location: Berlin, Germany

### HeimfriedSenior Member

You will find the answer here:
http://www.ittcwiki.org/doku.php/structured_dictionary:shipgeometry#waterline
and here:
http://www.ittcwiki.org/doku.php/structured_dictionary:shipgeometry#block_coefficient

There is in general no proportionality, because very different shapes of hulls (with very different half angles of entrance) may have the same block coefficient.
If you consider only very similar hull forms, you will naturally find a decreasing half angle of entrance causes a decreasing block coefficient.

3. Joined: Nov 2003
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### PARYacht Designer/Builder

The half entry angle is a bit of an arbitrary measurement, used for comparative purposes. As mentioned it has little to do with specific hull forms, though some "generalities" can be gathered with much observation of this angle (in conjunction with figures). This requires a database of similar designs and only offers a modest average of what's been previously used and no justification for any specific range of angles.

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