TX18 centre of gravity

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jacquesmm
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Re: TX18 centre of gravity

Post by jacquesmm »

A little bit behind the console is correct, it put its at 18" behind C but the TX18 is not a classic planing hull.
In a standard planing hull, I will put the CG between 40 and 45% of the DWL, forward of the transom. Closer to the transom for fast hulls, further forward for moderate planing speeds. The idea is to put the LCG over the center of planing lift.

The TX18 is not a normal planing hull, it also has lift from the "air cushion" under the hull however, that air cushion moves as the boat accelerates. It is also more sensitive to engine trim than other hulls. It is an experimental boat that does not obeys the same rules and you may have to be ready to move things around.
To put the LCG 18" behind C is my best guess.
That is about where the empty hull LCG is.
The weights must include all weights: motor, bracket if any, tanks, batteries, crew etc.
Jacques Mertens - Designer
http://boatbuildercentral.com

Vundu
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Re: TX18 centre of gravity

Post by Vundu »

Thank you all for your help and input.

Before flipping the hull onto the trailer I placed a fulcrum under where station 'C' would sit and balanced the trailer prior to placing the hull on it. Interestingly enough the empty hull shell balanced near perfectly over station C when placed on the trailer.

My intention is to move the fulcrum back as advised by Jacques, re balance the trailer without hull, then continue the build on the trailer. This way I can periodically check the COG as the build progresses and move components around as needed to ensure the COG is correct.

TomW1
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Re: TX18 centre of gravity

Post by TomW1 »

Yep, the empty hull would balance at about C, but since there is more weight with the wood for the motor well bulkhead and more weight from the stringers aft it will move it back as Jacques notes. Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

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