LCG in RIB

[Mat-C]

Can someone tell me where the LCG should be in a 30-odd foot RIB?
Max speed is in the vacinity of 40 knots.

Also, I realise that at rest the boat will trim so that CG and CB are in line vertically, but where would the LCB be located ideally? I mean, when you see a go-fast boat sitting in the water, they often lie with the transom quite low and bow quite high. Would the designer have drawn it like this? Or more likely it would have had the buttocks parrallel with the WL and the CG and CB not in line....

[jsh]

Mat-C

Here is a good discussion on the subject.
http://boatdesign.net/forums/showthread.php?t=12844&highlight=LCG+PLANING
john

[Mat-C]

Thanks JSH - most helpful
Do you know the answer to the 2nd part of my question?... Whether the boat would be modelled level or not?

[jsh]

Hey Matt:

For the go fast type: for sure buttocks are parallel to waterlines with some variation where these sections begin.

Looks to me the faster they are (of the type) the more extreme the trim is by the stern

Both centers move aft with speed and trim angles.

How much?

I am building a 22' Deep V and am almost in the water and am very interested to see if my data is accurate.

your question "modeled level" I think weights are generally estimated with half load with the centers 50%-60% aft of the Lwl (rule of thumb)

I am a student not a master

john