rigger pulling to the right ?

[TomMoorehouse]

Hey Tom I do not think Jerone built a FF. I did build a FF gas rigger and I am having issues with pulling into the course as well. The water got hard around here before I could try what I did. I shimmed the strut 2 degrees to help. Are you saying that the design of the front sponson and rears have to much belly into them? Please explain as to rectify if this is the case. I haven't really had a lot of water time on the boat. It seemed to be okay in speed but as I said the handling issue reduced the speed. Any help will be greatly appreciated.

I'd be glad to share a new design with you to test out..... i still have to draw it.... then sounds like we have all winter to build them

ill aim for before christmas to have it done....

 

[John Finch]

I can only guess that a crabbing boat is slower because of the dynamics but I have never experimented with it. Imagine a boat where the prop drags the transom left and a turn fin that pushes the same boat left to keep in from turning into the course. The boat starts the straightaway in lane one and is in lane 6 by the end of the straightaway. That can't be as good as a boat starting in lane one and staying there.

 

[Rigged]

I can only guess that a crabbing boat is slower because of the dynamics but I have never experimented with it. Imagine a boat where the prop drags the transom left and a turn fin that pushes the same boat left to keep in from turning into the course. The boat starts the straightaway in lane one and is in lane 6 by the end of the straightaway. That can't be as good as a boat starting in lane one and staying there.

I do not experience this with mine... it drives straight down whatever lane i have it in, unless i dont come out of the turn with it straight to begin with.

Can you see anything wrong with the way it "drives" in this video?

http://rcuvideos.com/video/FireFighter-Gas-Rigger

btw dont take my post as being a smart a$$... im more so just trying to figure that theory out. Im the first to admit i know very little to nothing at all about riggers.

 

[John Finch]

I can only guess that a crabbing boat is slower because of the dynamics but I have never experimented with it. Imagine a boat where the prop drags the transom left and a turn fin that pushes the same boat left to keep in from turning into the course. The boat starts the straightaway in lane one and is in lane 6 by the end of the straightaway. That can't be as good as a boat starting in lane one and staying there.

I do not experience this with mine... it drives straight down whatever lane i have it in, unless i dont come out of the turn with it straight to begin with.

Can you see anything wrong with the way it "drives" in this video?

http://rcuvideos.com/video/FireFighter-Gas-Rigger

btw dont take my post as being a smart a$$... im more so just trying to figure that theory out. Im the first to admit i know very little to nothing at all about riggers.

Looks good! Makes me want to get my rigger out and go make some laps. We are all learning all the time. Every time I think I know something about how a boat works, the same principals don't work on the next boat. A rigger looks simple, but the more you experiment the more you realize that things change on almost every boat. For a while I was experimenting with a turnfin design that would lift the right sponson completely out of the water and ride like a hydrofoil. I had fun with that for a while. The cup, the placement forward or back of the cg, the rake of the trailing edge, the leading edge angle and cut, all makes a difference. You can get as deep as you want to go on every aspect of the turn fin, rudder, and boat design. This is what keeps it interesting.

 

[Jerry Muro]

Sounds good Tom please let me know when you are done drawing them. I'll wait to hear from you I have some free time on my hands now during the winter.

 

[speakerboy]

WOW .. this started out to be a real data base of info about a rigger pulling right .. cool !

ok here are some pics of my setup . all pics are from the fins mounted on the rigger the way i did run it last weekend ,

to fresh up some memory.s :

first 3 pics , the virginia craftman turnfin , its big fin on this boat but its great for heat racing , running onder 70 till 75 mph it does not pull that much , i can control it easy , runnin it with a 2716/2 blade the max speed is 74 mph and it tracks straight , with the 2716/3 prop i reach almost 85 mph now but over 80 its pulling to the right ., so bad i cant run a good oval couse .. here are the pics .

 

[speakerboy]

Now , second fin is a AB turnfin , i mounted that on a Carbon Fiber bracket , no flex , real strong . i made a mistake with this fin by sharpening it and took away the 45 degrees angle . the angle is now less and all sanded back to a sharp fin . the boat runs real fast with this fin aswell . top speed was over 87 mph , but i cant run straight .. in the turns it will lift out the right sponson about 1 inch high . and accelerated in the turns (what is real cool to see) it acts like a slingshot .. i think i found the error allready after reading your posts , but here are the pics to confirm that .

 

[speakerboy]

the last i did run was a kinda SAW turfin .. its a small carbon fiber fin i made my self , straight down , no angle .. very small .. running the rigger with this fin was kind of scary .. it could not turn very well . and i need about half the pond to make a 180 turn , therefor i could not rev the boat out like i wanted but in the small straightd it did run the boat was still pulling , it was very little but it was pulling to the right .

here are the pics :

 

[speakerboy]

if the boat is still pulling with that little turnfin ,i am in doubt if we are doing right blaming the fin for the pulling .. like some mentioned , we spin bigger props and i might have problems with just propwalk , i also have not such a big rudder blade to correct that propwalk ., its only 3 inch deep , messured from the rear sponson . lets see what you cracks has to say about the pics ..

thanx allready ,

Jeroen

 

[Tom v.d Brink]

jeroen,

the depth of your rudder might well be a problem as well. 3inch is a depth used for .45 size boats with 60mm propellors.

my rudder is about 3.75" from the bottom of the hull and on high pitch propellors i still have to be carefull not to go on the throttle to quick as it will pull.

 

[speakerboy]

Tom ,, thanx for your answer .. just to make clear , the blade is 3 3/4 inch under the hull . and 3 inch under the rear sponson . i think i did cut about 1/2 inch of hte blade when i bought it .. it looked awfull long than , but i will order another blade to check the diff ..

Jeroen

 

[Terry Keeley]

How about some pix of the rudder with a ruler next to it?

ps: unfortunately you ruined the effect of the CMD fin to keep the boat straight, it's probably too small though anyway...

 

[Tom Foley]

You could also try toeing in the right sponson as a unit on the front boom if you have not already tried that . The lifting with the AB fin is more likely caused by the fin having a positive angle up causing the sponson to "plane " on the fin . Sounds like you have her flying though !!

 

[Don Ferrette]

How thick is the rudder blade?? I found out the hard way a couple years back when I tried a dual pickup Speedmaster (.250" thick at trailing edge) on my SGX twin how badly it would make the boat pull right when you nailed the throttles. Switched to a CMDi blade that was almost .060" thinner and the problem went away. Just to prove it to myself I put the Speedmaster blade back on and the pulling right problem came right back. :blink:

 

[speakerboy]

Terry . here is a pic of the boat with the rudder in the length that it is right now .. draw a line under the rear sponsor .. than its 3 inch below that line ..

your right about the AB fin , it will turn but i killed the 45 degrees angle .. never though of that .. was stupid . i learned the hard way ..

Tom .. i think the lifting is from the fin . i am working on the fin now to get her in "line " maybe the fin is too small but it didnt look like it ..

The Designer , Tom van den Brink is not so happy about the toe -in .. so i will wait with that and use that as a last trick ..

Don . thanx for the heads up with the rudder .. the rudder is 3/16 inch wide at the trailing edge ( thats .250 right ?) the front is razor sharp .. is there a waterpickup in the AB rudderblade ? i might use that ..

Jeroen

 

[AndyBrown]

How about some pix of the rudder with a ruler next to it?
ps: unfortunately you ruined the effect of the CMD fin to keep the boat straight, it's probably too small though anyway...

Terry is correct about the fin. We run them just the way they are all shipped with kits.

The effect is not so small.

Some years ago Kently called me with a problem of his SG pulling.

I went down the list of things to check. He changed some things and tried again...still pulled.

We went over more details on the phone...still pulled.

Finally I said, send me the boat.

I took it to the pond...ran it...it pulled, BADLY. Kently had done a BEAUTIFUL job of radiusing and polishing the turn fin.

After trying a few things I took off the turnfin and installed a new stock unit. PRESTO!!!...problem fixed!!

Still may be that you need a longer rudder too.

 

[Rigged]

.250 is 1/4". 3/16 = .1875 to be exact. Thats fairly thin... the blade i run on my rigger is .122 at the trailing edge (Bob Austin "SAW" blade.. no pickup in it, i use a propblast), 1-1/4" wide and 3-1/4" under the rear sponson.

 

[Tom Foley]

How thick is the rudder blade?? I found out the hard way a couple years back when I tried a dual pickup Speedmaster (.250" thick at trailing edge) on my SGX twin how badly it would make the boat pull right when you nailed the throttles. Switched to a CMDi blade that was almost .060" thinner and the problem went away. Just to prove it to myself I put the Speedmaster blade back on and the pulling right problem came right back. :blink:

Whats required to put the AB blade on a speed master bracket ...i want to try this on mine as well .

 

[Don Ferrette]

How thick is the rudder blade?? I found out the hard way a couple years back when I tried a dual pickup Speedmaster (.250" thick at trailing edge) on my SGX twin how badly it would make the boat pull right when you nailed the throttles. Switched to a CMDi blade that was almost .060" thinner and the problem went away. Just to prove it to myself I put the Speedmaster blade back on and the pulling right problem came right back. :blink:

Whats required to put the AB blade on a speed master bracket ...i want to try this on mine as well .

Well I used to re-drill the CMDi blade to the Speedmaster pivot block. After some poking & prodding I got Andy to start making pivot blocks that adapt their blade to the Speedmaster bracket without re-drilling the blade. Just give them a call & tell Donna you want one. B)

 

[Terry Keeley]

Terry . here is a pic of the boat with the rudder in the length that it is right now .. draw a line under the rear sponsor .. than its 3 inch below that line .. your right about the AB fin , it will turn but i killed the 45 degrees angle .. never though of that .. was stupid . i learned the hard way ..

Tom .. i think the lifting is from the fin . i am working on the fin now to get her in "line " maybe the fin is too small but it didnt look like it ..

The Designer , Tom van den Brink is not so happy about the toe -in .. so i will wait with that and use that as a last trick ..

Don . thanx for the heads up with the rudder .. the rudder is 3/16 inch wide at the trailing edge ( thats .250 right ?) the front is razor sharp .. is there a waterpickup in the AB rudderblade ? i might use that ..

Jeroen

Yup, looks like it woulda been better full length...