JAE 67/84 build up

[Jeff Lutz]

View attachment 278493
So how wide is to wide???????
I am going to cut the tubes to start at 27" inside to inside on the sponsons.
I can change it at will any time and try different spreads and off set set ups.
Can do it by just moving the clamps at the pond as I test.
Will also try different turn fins.

It does get the turnfin drag way out there. But you will know if it tracks well soon. In race water it can make the boat rock right to left more sometimes with reaction to waves/rough water.

 

[dwilfong]

How many have tried off setting the sponsons from one side to the other?
If so what did you see from doing this?
Also with the turn fin that far out there with all that leverage can you use less fin?

 

[dr gary turner]

I run 24” also on 101JAE AND TWINS

There is probably an ideal ratio between the after plane length and spread of sponsons

Spread/AP

 

[dr gary turner]

The left non turn fin, 1” wider
I think it helps keep the turn fin in the water

 

[dwilfong]

at 32" out side {27" inside} is the same as the after plane on this boat.
Also the turn fin to drive dog strait line measurement is 27".

 

[John Beardslee]

Doc, I’m going to 2” offset on my single 90 with the non turn fin side out wider. Hoping to reduce the amount of toe in on the fin sponson for good tracking.
Thanks John

 

[dwilfong]

So if the left sponson is out more it will have more leverage to use the drag.
So at some point it should balance the right sponson fin drag?
Wonder how much it will take?
Will try and find out with this fully adjustable set up.
Would be nice to have a strait rudder and a double sided sharp turn fin with no toe in.
Just not sure how it will react to race water.

 

[brad nichols]

The 90-101 boat is 24" to the outside of the sponsons. No toe-in and tub is on center.

Brad

 

[dwilfong]

This is 26 out side and 21 inside.
I think I will start here.

 

[dwilfong]

Sunday morning in the sunlight...........
Engine time.........

 

[dwilfong]

this is where the Novarossies get sucked in....LOL

Almost done with the eng mods.
Just have to make the water cap.
the carb comes to the same size as a .530 round carb.
The spray bar is .100

 

[dr gary turner]

Doc, I’m going to 2” offset on my single 90 with the non turn fin side out wider. Hoping to reduce the amount of toe in on the fin sponson for good tracking.
Thanks John

Very little toe in is required if the turn fin is sharpened properly

 

[dr gary turner]

So if the left sponson is out more it will have more leverage to use the drag.
So at some point it should balance the right sponson fin drag?
Wonder how much it will take?
Will try and find out with this fully adjustable set up.
Would be nice to have a strait rudder and a double sided sharp turn fin with no toe in.
Just not sure how it will react to race water.

The most effective way is have more AOA in the RT sponson than the left ie RT 5 deg LT 4.5

Thus the LT SPONSON pulls to the Lt

 

[dr gary turner]

Running my JAE 101 to day

 

[David Ashcroft]

View attachment 278536 View attachment 278537
this is where the Novarossies get sucked in....LOL
View attachment 278538
Almost done with the eng mods.
Just have to make the water cap.
the carb comes to the same size as a .530 round carb.
The spray bar is .100

What bowl cc you machine?
What Band width and angle?

 

[dr gary turner]

Let’s try it again

 

[dr gary turner]

Can’t get it to post, sorry

 

[dwilfong]

What bowl cc you machine?
What Band width and angle?

The cc are .65 with a 195 deg ex set at .010 clearance is 9.2 CR
The squash angle is 3 deg and .225 wide giving a 55 MPS/ MSV at 28000 RPM's

 

[John Beardslee]

Very little toe in is required if the turn fin is sharpened properly

You are correct Doc, that and the thinner the better.

 

[dwilfong]

Cooling head is all but done and the cowl is fitted.
Will paint the cowl and the wood on the sponsons next.