lengthening a rigger hull

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Michael Costanzo

Well-Known Member
Joined
Jan 7, 2009
Messages
1,953
if you were to per say try and make a .80 size hull handle the power of a bigger motor,would you be able to make it longer and the stance a little wider? what i am getting at is,would you make the tub longer in the front,middle or rear and how would you compensate as to not screw up the CG? all food for thought.thanks for sharing.
 
Last edited by a moderator:
Try using an extended strut and brackets to see if it helps. The motor could change the CG. For the amount of time to try and lengthen the tub, build a new one. Add the length in the middle and this will allow you to move the motor to adjust the CG.

Brad
 
Try using an extended strut and brackets to see if it helps. The motor could change the CG. For the amount of time to try and lengthen the tub, build a new one. Add the length in the middle and this will allow you to move the motor to adjust the CG.

Brad
hi brad,yes i thought about the longer strut.OK so if i build a new tub where about do you set the CG? sorry i am a kit builder not a scratch builder.
 
Michael measure the after plane length of the current boat and then measure from the trailing edge of the front sponson to the center of the engine. Take the measurement to the center of the engine and divide by the total after plane length. This will give you the percentage the engine sits back in the after plane. Now add the additional length you desire to the after plane length and divide by the percentage to give you the distance the engine should sit back from the trailing edge of the front sponson on the new tub length.

For example if the after plane is 10 inches and the engine sits back 3 inches this would give an engine center point of 30%. Now stretch the after plane to 13 inches and multiply by 30% and you get 3.9 inches to the center of the engine.

That's the easiest way for me to figure it out. Hope it helps.

Dave
 
Michael measure the after plane length of the current boat and then measure from the trailing edge of the front sponson to the center of the engine. Take the measurement to the center of the engine and divide by the total after plane length. This will give you the percentage the engine sits back in the after plane. Now add the additional length you desire to the after plane length and divide by the percentage to give you the distance the engine should sit back from the trailing edge of the front sponson on the new tub length.

For example if the after plane is 10 inches and the engine sits back 3 inches this would give an engine center point of 30%. Now stretch the after plane to 13 inches and multiply by 30% and you get 3.9 inches to the center of the engine.

That's the easiest way for me to figure it out. Hope it helps.

Dave
dave, thank you for that very clear explanation. sorry after all these years i need to ask what is the after plane? is this the tub? also what happens to the turn fin mounting position? thanks,mike.
 
Last edited by a moderator:
The after plane is from the trailing edge of the front sponsons to the end of the strut or the drive dog. You will also need to move the turn fin back as well. I would start with the distance the engine moved and mirror it.
 
The after plane is from the trailing edge of the front sponsons to the end of the strut or the drive dog. You will also need to move the turn fin back as well. I would start with the distance the engine moved and mirror it.
sounds great.thank you for the help,mike.
 
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