Custom/Hybrid I need some thoughts on my sponsons-tubies

[leedesigns148]

Im building a custom 89 300sx with an 750ss motor in it. I just fabed up these. I am wondering what you guys think of them and how ya think it will handle?

 

[227]

Good try for a first timer, however they need to be shaped exactly the opposite of how you have them. In other words the blunt edge needs to be up front to improve volume and stability and the tapered edge needs to be towards the rear for alloowing smoother turning transition and better water release. Think tear drop

 

[leedesigns148]

Thanks for the info. Im going to reshape them tomorrow. Wide up front and thin in the rear. How wide should they be. There 1.5" now?

 

[227]

1.5 is fine. just taper the rear more

 

[Wes K]

John (227) is probably the best person you can listen to in regards to making your own tubbies.. he makes his own for his boats and they are always great looking and also perform better than any aftermarket tubbie!

 

[dbattersby20]

the entire ski should become like a tear shape. I want to make my own tubbies as well and i was looking at the aftermarket skis, even though it's part of the hull some of the skis from what ive seen have bulges on the side that look like tubbies and they often go almost all the way to the back. Also, at the thickest part for probably like 14 -16 inches about 12 inches from the front of the ski there is a small channel at the bottom of the tubbies. Kinda hard to explain. ill see if i can make a section on CAD later that might better explain it and people can give their opinions on that... or at least find a good pic

 

[dbattersby20]

correct me if im wrong...

 

[kevbo]

Im building a custom 89 300sx with an 750ss motor in it. I just fabed up these. I am wondering what you guys think of them and how ya think it will handle? View attachment 174590View attachment 174591View attachment 174592View attachment 174593View attachment 174593View attachment 174594View attachment 174595View attachment 174596View attachment 174597View attachment 174598

First you must ask what you want from your tubbies. The way they are pictured will add lift and lateral stability with a little suck down while carving. The small aft radius will reduce their effectiveness compared to a larger radius fair. Chop the rear edge off square and you will get only lift and stability which would be good if you are just trying to stay upright in rough conditions. Most riders want their tubbies to help initiate and hold a turn at higher speeds, that is what common shapes do. The only negative is that they also make the hull want to hunt from edge to edge when going straight. Mounting them higher can eliminate this. Remember that water forms a powerful boundry layer that will try to follow any smooth rounded shape.