Prop walk & mixture control

[marktrish]

I have an old Pinkert 90 size rigger that prop walks pretty good. Seems like I have to dial in alot of left rudder trim to keep it going straight. I was wondering if anyone might have some ideas to help that problem. Also I'm thinking of running a third channel mixture control on it. Who makes them and where can I get a good one. I run a Picco 90 hydro in it. Thanks...Mark

 

[Don Ferrette]

I have an old Pinkert 90 size rigger that prop walks pretty good. Seems like I have to dial in alot of left rudder trim to keep it going straight. I was wondering if anyone might have some ideas to help that problem. Also I'm thinking of running a third channel mixture control on it. Who makes them and where can I get a good one. I run a Picco 90 hydro in it. Thanks...Mark

Hey Mark before you blame the prop take a quick look at your turn fin, make sure it's parallel with the tub looking down from above boat. As for remote mixture controls look at this-

https://www.intlwaters.com/gallery/displayimage...m=33&pos=16

 

[marktrish]

It is Don. I just checked it. Any other ideas? As far as the mixture control goes...that looks like a nice unit. Can you give me some more info on it? Mark

 

[Don Ferrette]

It is Don. I just checked it. Any other ideas? As far as the mixture control goes...that looks like a nice unit. Can you give me some more info on it? Mark

The base is from me @ $22 & it uses the OS in flight 3rd channel needle assembly-

http://www2.towerhobbies.com/cgi-bin/wti00...I=LXCN51&P=

Make sure your prop is sharp & thinned as a dull thick bladed prop will cause propwalk big time. Lay a straight edge along the right side of the rudder blade, it should be just about parallel to the tub. it will look like you have left dialed in but this is where you want to be.

 

[Doug Ashby]

I have an old Pinkert 90 size rigger that prop walks pretty good. Seems like I have to dial in alot of left rudder trim to keep it going straight. I was wondering if anyone might have some ideas to help that problem. Also I'm thinking of running a third channel mixture control on it. Who makes them and where can I get a good one. I run a Picco 90 hydro in it. Thanks...Mark

That's the fuel mixture control that I was talking about. I'll send you pics of my set-up sometime this weekend. I need batteries for my camera...

 

[jimv]

I have an old Pinkert 90 size rigger that prop walks pretty good. Seems like I have to dial in alot of left rudder trim to keep it going straight. I was wondering if anyone might have some ideas to help that problem. Also I'm thinking of running a third channel mixture control on it. Who makes them and where can I get a good one. I run a Picco 90 hydro in it. Thanks...Mark

That's the fuel mixture control that I was talking about. I'll send you pics of my set-up sometime this weekend. I need batteries for my camera...

For the prop walk issue, is you trun fin a flat one or does it have a bend / cup in it? Make or find a flat fin. Put that on, make sure it is paralell with the hull. It will at least not lift or pull down. It's easier to check the ride that way. Once the ride is correct, then go to a cupped fin.

Does the boat have a water pickup on the sponson? Where is the rudder placed?

Using an angled offset strut of a few degrees is something that is done to correct some of the torque effects. Also angle of attack can cause boats to do some strange things.

Bottom line, there are a lot of things to do. Get the boat running attitude right first, then work the details.

 

[marktrish]

The turn fin is cupped. The water pick up is on the back side of the left sponson. The bottom of the pick up is about a half inch below the water line. The rudder is on the extreme right side of the transom. The strut is offset a few degrees. The angle of the strut is just about 0 degrees. The prop is an ABC 65x110...balanced and sharpened. The boat rides very flat on the water...very stable. Whenever it comes out of the water it always lands flat. Sticks like glue in the turns. I'm happy with the performance of the boat...just would like to see if I can get some of the left rudder trim out of it. Mark

 

[jimv]

The turn fin is cupped. The water pick up is on the back side of the left sponson. The bottom of the pick up is about a half inch below the water line. The rudder is on the extreme right side of the transom. The strut is offset a few degrees. The angle of the strut is just about 0 degrees. The prop is an ABC 65x110...balanced and sharpened. The boat rides very flat on the water...very stable. Whenever it comes out of the water it always lands flat. Sticks like glue in the turns. I'm happy with the performance of the boat...just would like to see if I can get some of the left rudder trim out of it. Mark

The two things I'd do first is to remove the pickup from the sponson, get a new rudder with a water pickup and get a flat turn fin. See how it goes with that. Once the boat is not puuling right, go back to a cupped fin.

Have you looked to see if the sponsons are at the same depth and angle of attack? Is everything square and true on the hull? You can try different depth of rudders to see what's optimum.

You did metion that the boat seems to run flat. How about, how loose it is? Sometimes flat and stable is a little too tight to the water and you wind up with some drag pulling one way or the other. Different prop or strut depth / angle?

 

[Don Ferrette]

The two things I'd do first is to remove the pickup from the sponson, get a new rudder with a water pickup and get a flat turn fin. See how it goes with that. Once the boat is not puuling right, go back to a cupped fin.

I would not remove the water pick up yet until improvements in the pulling right are obtained. Right now the drag of a water pickup on the left sponson will create a pull to that side so removing it now will only add to the problem. I agree with using a rudder with water pickup instead of on the back of the sponson, just not yet. Something else to check is that the leading edge of the turn fin is sharpened & tapered on the outside edge only, the inside edge that faces the tub should be totally flat from front to back. If it isn't this can induce alot of right pull.

 

[jimv]

The two things I'd do first is to remove the pickup from the sponson, get a new rudder with a water pickup and get a flat turn fin. See how it goes with that. Once the boat is not puuling right, go back to a cupped fin.

I would not remove the water pick up yet until improvements in the pulling right are obtained. Right now the drag of a water pickup on the left sponson will create a pull to that side so removing it now will only add to the problem. I agree with using a rudder with water pickup instead of on the back of the sponson, just not yet. Something else to check is that the leading edge of the turn fin is sharpened & tapered on the outside edge only, the inside edge that faces the tub should be totally flat from front to back. If it isn't this can induce alot of right pull.

Yup Don, good ideas.

 

[marktrish]

Checked the hull and sponsons. Everything is square. As far as running flat goes...it doesn't seem to drag through the water. It dances around pretty good but it stays flat. I do have a water pick up rudder on it...but the reason I went to the sponson pick up is there is to much rudder deflection to keep the boat straight so I wasn't getting much water to the engine. The water inlet on the rudder is on the right side. Speaking of the rudder...it's right at 4 inches below the transom...3 inches below the rear sponsons. Yes Don the turn fin is tapered on the outside edge only. But I did notice that the turn fin has a small twist in it. Never noticed that before. At speed that might be the problem. Mark

 

[Mike Hughes]

Sometimes it is hard to see a twist in a hydro fin. Your best bet is to take a 3' piece of angle aluminum and clamp it to the blade and measure off of centerline of tub. You will need to reclamp it at different depths to see the twist. 1/4" increments should do the trick. Make sure the length of the angle stays parallel with the ride of the boat.

Mike

 

[Don Ferrette]

But I did notice that the turn fin has a small twist in it. Never noticed that before.

I'd definitely start there.

 

[Chris Wood]

one little secret that i learned about 3 yrs ago.

MAKE SURE YOUR RUDDER IS PERECTLY STRAIGHT UP AND DOWN. If you transom has some angle on it and the bracket is mounted to a slightly angled transom. loosen the bracket bolts, take some shim stock and shim the top of the bracket till the rudder is 90 degrees to the water ( or a flat surface ) .. that helped a pulling problem i had and it fix one other key thing as well.

chris

 

[marktrish]

Thanks for the suggestions guys. I realize that it's an older boat and I'm sure the design is outdated...but I would like to see how well I can get it to run. Once again...thank you. Mark