rigger pulling to the right ?

[Marty Davis]

I understand pivoting on the fin dynamics and C/G positioning to fin relationship
** But there is a HUGE difference in a 6# .21 rigger and a 12# gas rigger in Centrifugal force applied to the fin holding the boat while cornering :huh:

Scott:

I understand that there is a big difference in weight. The fin for the heavier boats must be thicker, and anchored well into the sponson. 2 8/32 bolts work fine for a 12+ lb Twin.

Not sure I understand what you are trying to say..... Are you saying that you must have a brace for the fin???? If so, I don't agree with you on that. Depends on the efficiency of the fin and how well the boat pivots.

People keep telling me that it is impossible for there not to be a big spray off the fin. I can tell you that there is hardly ANY spray off of my turn fins even on my 67 boat. When you ge the fin shape, location in relation to the dynamic CG, depth, etc, there won't be much spray at all. People just don't make the effort to refine their boat to that point.

Marty Davis

 

[Rokieboater]

I understand pivoting on the fin dynamics and C/G positioning to fin relationship
** But there is a HUGE difference in a 6# .21 rigger and a 12# gas rigger in Centrifugal force applied to the fin holding the boat while cornering :huh:

Scott:

I understand that there is a big difference in weight. The fin for the heavier boats must be thicker, and anchored well into the sponson. 2 8/32 bolts work fine for a 12+ lb Twin.

Not sure I understand what you are trying to say..... Are you saying that you must have a brace for the fin???? If so, I don't agree with you on that. Depends on the efficiency of the fin and how well the boat pivots.

People keep telling me that it is impossible for there not to be a big spray off the fin. I can tell you that there is hardly ANY spray off of my turn fins even on my 67 boat. When you ge the fin shape, location in relation to the dynamic CG, depth, etc, there won't be much spray at all. People just don't make the effort to refine their boat to that point.

Marty Davis

Got any pics to help us out????

Robert Holland

 

[speakerboy]

Wow ... its been a while since thios post went balistic .. some good info on turnfins here. . in the netherlands the ice is melting and the boats are ready tu run ..

last sunday i took out the rigger for a spin .. i did made some changes , there is a new motor in there , its the same M&D cast motor but now with some extra power , thanx to matthew who built a cutom motor for me . i have to handle with more than 7.5 hp now at 19000 rpm .. point is i need to play with pipes now .. i have a great pipe but it will not bring the motor over 17500 , but that does not change the handling of the boat (not now atleast ) .

i also changed the pushrods of the carb , its stronger and more sollid now .

i took off the AB turnfin and used a belt sander to take of the sharp leading edge , and reshaped the fin back to 45 degrees and sharpened her again .. looked good .

on the water !

the AB fin is turning amzingly good it hangs real good in the turns but i cant run straight . over 80 mph and i am doing a full 180 turn in less than 300 feet . i tryed to do some Saw passwes and ended up with 86 mph , i have to start in the left upper corner of the lake and ended up at the left lower corner .. (running towards me ) . i tryed all kinds of adjustments on that fin but it wont track straight .

than i mounted the Virgina craftman fin on her again .. i must say that its running a tat slower with that fin . ended up with 84 mph but still not tracking straight .. its better than the AB fin , but not straight . it does have even more grip in the turns and seems to be the best oval racing fin on this boat ..

i have 2 sets of sponsons comming for this boat .. i will work wit ha set of sponons to get it working on the AB fin . i might concidering the tow in option with this fin ..

the other set will function for SAW only and will get a very small carbon fiber fin ..

in the future i will test a new pipe for this boat .. i believe with the right setup it must be capable of 90 mph .. i am getting there. .

(did i mentioned i am addicted to riggers ? )

jeroen

 

[Rigged]

7.5hp M&D Cast? Stroker bottom end?

Have you tried shimming the fin yet Jeroen? That made all the difference in the world with my Rigger. Ill sacrifice the little bit of speed with mine to keep it going straight.

 

[Tom Foley]

Wow ... its been a while since thios post went balistic .. some good info on turnfins here. . in the netherlands the ice is melting and the boats are ready tu run ..
last sunday i took out the rigger for a spin .. i did made some changes , there is a new motor in there , its the same M&D cast motor but now with some extra power , thanx to matthew who built a cutom motor for me . i have to handle with more than 7.5 hp now at 19000 rpm .. point is i need to play with pipes now .. i have a great pipe but it will not bring the motor over 17500 , but that does not change the handling of the boat (not now atleast ) .

i also changed the pushrods of the carb , its stronger and more sollid now .

i took off the AB turnfin and used a belt sander to take of the sharp leading edge , and reshaped the fin back to 45 degrees and sharpened her again .. looked good .

on the water !

the AB fin is turning amzingly good it hangs real good in the turns but i cant run straight . over 80 mph and i am doing a full 180 turn in less than 300 feet . i tryed to do some Saw passwes and ended up with 86 mph , i have to start in the left upper corner of the lake and ended up at the left lower corner .. (running towards me ) . i tryed all kinds of adjustments on that fin but it wont track straight .

than i mounted the Virgina craftman fin on her again .. i must say that its running a tat slower with that fin . ended up with 84 mph but still not tracking straight .. its better than the AB fin , but not straight . it does have even more grip in the turns and seems to be the best oval racing fin on this boat ..

i have 2 sets of sponsons comming for this boat .. i will work wit ha set of sponons to get it working on the AB fin . i might concidering the tow in option with this fin ..

the other set will function for SAW only and will get a very small carbon fiber fin ..

in the future i will test a new pipe for this boat .. i believe with the right setup it must be capable of 90 mph .. i am getting there. .

(did i mentioned i am addicted to riggers ? )

jeroen

Just for the heck of it ..toe in the right sponson a lot more than it is now for testing purposes and observe the change . I would almost bet it makes it better .

 

[speakerboy]

HAHAHA ok ok , i will toe in the sponsors o see what effect it has !

motor is a normal M&D cast motor .. matthew did some extra to it to get this boat over 90 mph ..

Jeroen

 

[Camman]

WOW!!

What thread!!!!

I had been looking for information on turn fin placement for my Gas rigger build on other forums. Thought I would stroll over here & see what I could dig up. Man! did I ever find a bone LOL

Very good thread fellas & I would like to thank all of you for sharing the information.

Mike

 

[Tom Foley]

HAHAHA ok ok , i will toe in the sponsors o see what effect it has !
motor is a normal M&D cast motor .. matthew did some extra to it to get this boat over 90 mph ..

Jeroen

Just kind of curious what kind of prop pitch and RPM you are getting to put you over 90 MPH while pulling really bad to the right like it is ?

Also, maybe I missed it, but is there any toe - in on the right sponson now ?

 

[impba3548]

Jeron, You have a pm...............

mike sr

 

[speakerboy]

Tom ...

i never touched 90 .. 85.6 mph was the best i got .. its a 2716/3 blade with bended ears , to get the cone a bit lower . rpm was 17200 .

boat has NO toe-in !

Jeroen

 

[Tom Foley]

.

boat has NO toe-in !

Jeroen

There's your answer right there .

 

[speakerboy]

he Tom ..

thanx for your answer .

i will leave this set of sponsons and booms intact like they are now . they are lined up for heat racing perfect etc etc .

i will have 2 sets of new sponons comming and one of the set i will toe in ! the other set i will use to raise the AOA , to adjust it a bit more for SAW .. right now the AOA is about 3 to 4 degrees and i think i should go to 6 ore 7 .

for your info .. running this boat with a 2716/2 blade , i have less speed (about 75 mph) and less propwalk ore pulling to the right .. i can run straight without a problem .. for heat racing more than enough ..!

Jeroen

 

[Jerry Muro]

Okay i am new to the rigger sence but here is where I am getting confused when you mention angle of attack. In my reading of all articles angle of attack is which the boat runs in relation to the water. Positive /negative or/ 0 . Then there is sponson angles where the sponsons are adjusted by means of shims under the booms? When you say you are running 3.6 degrees or 6 degrees AOA is that sponson angles? I am working on setting up a gas rigger and I am setting up my sponson angles to 3.6 degrees in the front and the rears at 1.8 degrees as per the designer? I am using a smart digital angle finder to set the angles. I am setting this up with boat upside down and leveled then I adjusting sponsons to the desirded angle.Is this correct or am I understanding something different?? Is it 3.6 degrees the boat is running to the water? I am so confused please help me understand this. Thank You Jerry

 

[Camman]

Jerry

I have been there bud.

This is the best thread I have found on the subject

Read it all & all should be clear

http://www.jrcbd.com/showthread.php?t=5343...igger+build+101

 

[Tom Foley]

he Tom ..
thanx for your answer .

i will leave this set of sponsons and booms intact like they are now . they are lined up for heat racing perfect etc etc .

i will have 2 sets of new sponons comming and one of the set i will toe in ! the other set i will use to raise the AOA , to adjust it a bit more for SAW .. right now the AOA is about 3 to 4 degrees and i think i should go to 6 ore 7 .

for your info .. running this boat with a 2716/2 blade , i have less speed (about 75 mph) and less propwalk ore pulling to the right .. i can run straight without a problem .. for heat racing more than enough ..!

Jeroen

Whatever you want to do , but how can it be setup for heat racing if you cant drive it ?? I'v' messed with a bunch of hydros and right sponson toe in will help to steer the boat left to counteract prop walk ..all you have to do is drill two holes . Again I respect your build and it is fast but the handling chacteristics you decribe are friggin crazy !

boat below has 1 /8 " toe in as measured over the length of the sponson to the tub with a stainless rule for a straight edge .

boat goes straight with little input .

 

[speakerboy]

Tom .. i will work on the Toe -in thing ...

my boat is only pulling when i go faster than 75 mph ... below that speed i can run a perfect oval setup ... if i run a wide lane in oval i can go faster and work with the pulling , but going real fast and try to get a high nr i need to go straight . right ?> over 75 it will not go straight ..

thanx for the input !

Jeroen

 

[Tom Foley]

LOL ...Life begins over 80 ...... LOL

 

[impba3548]

LOL ...Life begins over 80 ...... LOL

Right on Tom!!!

 

[Nigtmare]

Hey Jeroen, I don't understand why you don't want to try the toe

in method. It was mentioned many times by different people.

You have tried every other thing twice, and nothing has fixed your

problem. By having the right sponson toed in , not only will

your boat track straight at any speed but also it will go a lot

faster. Your prop torque has a tendency to pull to the right,

the turn fin will push the boat to the left. The two forces against

each other will lift the hull up which should increase your speed. <_<

It is a very easy fix and it will only take one extra hole in your

boom tube. Why not give it a try?

Nick

Try to run 1/16" toe in on the right sponson Nick

 

[speakerboy]

Nick .... and others ...

thanx so much for your reply .. you are right i am going to .. i have some sets of sponsons comming in and i will work with them in a toe in setup ...

the reason why i did NOT worked with a toe -in option is becouse the designer of this boat told me in this post to try other things first and wait with a toe in as a last option ...

let me promise you , that IF the pulling is much less than before after i did that Toe in trick , i will buy drinks for any one who responded on this post ..ok ? ?

Jeroen