Rigger Tub questions

[teddy dauphinee]

Ok you rigger experts I have questions for you.

Does the width of the tub matter while running in the water?

Why doesn't anyone make a tub rounded on the bottom?

Why doesn't anyone make the bottom of the tub come to a point?

Length.

What is the relavence of the length to the size of the motor?

Is shorter better or longer?

This is for heat racing not straight line racing.

 

[Mike Hughes]

Does the width of the tub matter while running in the water? The wider the tub, the more air can get under and cause lift and making the sponson dance or blow off all together.

Why doesn't anyone make a tub rounded on the bottom? Anything round on a rigger below the water line tends to drag the boat down. Bernouli therum.

Why doesn't anyone make the bottom of the tub come to a point? I would think it is because of building ease. Plus Bernouli therum.

Length.

What is the relavence of the length to the size of the motor? Larger motor = larger prop. Larger prop needs more tail weight to keep it in the water. Other wise, you will have a rigger turning right all the time because of the prop walk.

Is shorter better or longer? Longer than needed can add more tail weight than needed so a prop with more lift must be used to keep the back end up. Ideal thrust cone is staight out the back. Anything pointed up is wasting your power. Shorter than needed - see last answer. Prop walk insues.

This is for heat racing not straight line racing.

 

[teddy dauphinee]

What would the best length to use for a twin inline 52-60cc gas motor then?

Looking around 12-14 hp...around 18,000-20,000rpm....around 5-7 lbs for motor.