rear sponsons on an outrigger- where & why

[Don Ferrette]

didnt hope to stomp on your post Don, the questions kinda pertain, my knowledge is small, just thinkin big..... mike

No problem at all Mike, this is exactly why I started it. BTW- the right rear is not useless, if the boat gets loose & brings up the left front, guess which rear you need to settle it down? Boats like the Eagles and others having fixed rears you need to rely far more heavily on tuning of the prop & strut, adjustable rear shoes are a big plus in my book. B)

 

[Tofastformellow]

Training wheels slow you down, but they keep you safe. How fast do you realllllly need to be to win?Not very.

I completly understand to be practicle a heat boat needs to be forgiving.

just talking theorys here.

Jason

 

[John Finch]

I think there are many sponson arrangements that work. It's sometimes easier to tell what doesn't work. Personaly I use one degree or less on the rears, but then you have to ask for how long a distance before you increase the angle as you go forward and how wide do they need to be. I built a boat 3 years ago I called the bat boat. It was a heat racing boat. I started out with 1 inch wide sponsons and kept cutting then narrower during the year. By mid year the sponsons were only 1/4 inch wide. They worked well at 1/4 inch wide. When I cut away the sponson, I cut the inside of the sponson so that the tunnel at the transom was wider each time I cut material off the sponsons. With a v967 prop it did not matter what sponsons were on the boat as far as getting thru the corners because the prop kept the rear of the boat up in the corners. What did happen when I took the sponsons completely off is the boat would rip the corners and the straightaway very smoothly, but if I let off the throttle down the straightaway the boat would blow off the water at about 95 mph because the rear would settle and put the boat at a positive angle of attack. Thus the blow off.

I will tell you that at this point in MY testing, that the well know boats like the crapshooter, sgx, roadrunner, all are best set up as per manufacturers directions. These guys have paid their dues and you reap the benefits.

 

[John Finch]

Training wheels slow you down, but they keep you safe. How fast do you realllllly need to be to win?Not very.

I completly understand to be practicle a heat boat needs to be forgiving.

just talking theorys here.

Jason

Jason,You are absolutely right. For record trials or just going faster than your buddy the theory can help you get an edge if you can adjust for more speed. I do not use sponsons for straightaway or oval trials. Just a center shoe. The training wheels are off!

 

[aaron alberico]

Jason,

as John said, sgx's crapshooter, roadrunner, tiapan are all good boats,

and have different theroies behind them on how and why they work,

i have run several diffenent boats over the years and built serveral of my own,

my opion rear sponson's are a must for heat racing,

as they help support the prop on launch,

help support the prop through the corners,

help stable the boat down when it becomes flighty.

and can help with down force at the rear[prop stay hooked up.

on my SAW 67\80 boat i added rear wings like sgx's for the down force at high speeds,

as i had a prop weight which was on the lighter side and at speeds of 100mph+ the prop

would brake loose, with the winglets this helped the prop stay hooked up.

the old saying there is more then 1 way to skin a cat,

great topic guy's keep it going

regards Aaron