JAE21 FE pulling to the right

[John MacLean]

I've been searching this forum for possible answers to why my rigger is pulling to the right at high speed. This boat that was built from JAE21 G2 plans a buddy passed along to me last winter. Besides having to modify the tub to accomodate a 4s setup I also fabricated the turn fin as to the design plans. The tub and sponsons are flat and square.

I love the way the boat accelerates and rips through the curners but it really only runs straight at half throttle. When it accelerates to full throttle it pulls right even when holding full left rudder. I am new to riggers and to building but I run with a couple of guys who have been building since the 80's. I did use a jig and build board as recommended by the Zippkits manual. One of my buddies looked at my turn fin and observed slight twist in it so I repaced it with a new one I had the guys in the sheet metal shop at work make for me using a hydraulic brake to keep my bends parrallel. I made the second one out of stainless which I thought should take care of any flexing issues. The results were the same. Then, wanting to rule out the turn fin entirely, I purchased one form Zippkits and ran it this past weekend with not much change if any. The only adjustment that seemed to make any difference was adjusting the pushrod connection at the rudder and shimming the strut a little on the right side.

I have read posts that suggest a number of reasons for this issue from the tub being out of square to prop walk to rudder sharpness and length.

Here are my setup details

CG is at the 60/40 mark as determined by an electronic kitche scale.

Turnigy 3665 motor

Batteries - 2 2s Zippyflight

Servo--- Hitec HS485 (6Kg/cm 80 oz/inches)

The rudder length is 146 mm. (It extends 3,1/4 inches below the ski)

Prop --- 1450 modified from Zippkits.

I haven't found too much on this particular issue on any of the forums except this one. I'd rather isolate the problem and address it properly than continue stumbling around in the dark. . . We've looked at the hull, the turn fin. . . I've wondered whether the servo not being up to the task. . . . and finalyy whether i need to start over with the hull . . . hoping that it won't mean the latter.

Thanks

 

[David Murany]

Hey John,

My first suggestion would be to cut down the rudder. We run ours at 1 1/2 inches below the ski. Start at 2 or 2 1/4 because you cant put the material back on. Also another thing that I did was extend the wet point of the left sponson back an 1/8 of an inch. This helps it track straight at speed but will want to go a little left at slow speeds. Good luck with your testing.

Dave

 

[RodneyPierce]

Shimming the strut is OK. And MAKE SURE your turn fin is very sharp. Also make sure you rudder is very sharp, along with the prop. I also toe in my right front sponson about 1/16th of an inch.

 

[Robert Elder]

I know I had some pulling issues early on with mine, (don't remember which way) and Joe suggested that I toe in the sponson slightly. If I remember correctly, it was more important with the right sponson than the left. It corrected the issue for me and also made the boat less twitchy.

 

[Chilli]

I second shortening the rudder. I run mine at 2 inches below the ski. Also. it looks like your strut assembly has the potential for flexing though I don't know how that would affect handling. It may just be the picture but Is your strut sitting flat on the ski?? If so you have way too much negative angle in the strut. You want the nose of the strut toward the back of the ski so you can get the prop down. Then place the boat on a flat surface and make sure the strut is parallel to the surface.

 

[John MacLean]

Thanks for the input, guys. I will sharpen all components as suggested and shorten the rudder starting at 2-1/4 inches below the ski. Chilli, yes it is hard to tell from the pic but my strut is sitting right down on the ski. I made sure of that after seeing Joe Petro emphasize that several times in other threads.

As far as achieving the toe in thing on the right sponson or extending the trailing edge on the left sponson I am open to suggestions as to how to accomplish that. My boom tubes are fastened to the sponsons with 6-32 screws and nuts drilled through as recommended in the manual.

 

[RodneyPierce]

To toe in the right side sponson, remove the sponson, and cut 1/16th of an inch off the end of the RIGHT side of the FRONT boom tube. Then reassemble. Leave everything else alone. (so when you measure from tub side to sponson inner side, the right side front boom tube should be 1/16th shorter then all the rest). Then, redrill your hole and your good to go.

 

[Ron Zaker Jr]

Thanks for the input, guys. I will sharpen all components as suggested and shorten the rudder starting at 2-1/4 inches below the ski. Chilli, yes it is hard to tell from the pic but my strut is sitting right down on the ski. I made sure of that after seeing Joe Petro emphasize that several times in other threads.

As far as achieving the toe in thing on the right sponson or extending the trailing edge on the left sponson I am open to suggestions as to how to accomplish that. My boom tubes are fastened to the sponsons with 6-32 screws and nuts drilled through as recommended in the manual.

before cutting the rudder ,I would put in 3/32nd-1/8th toe in on right front. Too short of rudder MAY increase the right pull at speed..

 

[John MacLean]

OK, Ron. I will hold off on shortening the rudder and do the 1/8 toe-in and redrill on the boom tube . . . to secure it in the new location. Will do that tomorrow but won't get a chance to test it till the weekend. I read a post where one boater fastened his boom tubes to sponson tubes using electrical tape so he could make whatever adjustments he needed. Should I try that as a temporary measure before drilling another hole in the tube?

 

[Blackout]

A pain to do now, but what about mounting the rudder on the left side? I plan to do this on my JAE 45.... A long left rudder would only drag the boat to the left, which will only help straight line handling on a rigger.

 

[Ron Zaker Jr]

OK, Ron. I will hold off on shortening the rudder and do the 1/8 toe-in and redrill on the boom tube . . . to secure it in the new location. Will do that tomorrow but won't get a chance to test it till the weekend. I read a post where one boater fastened his boom tubes to sponson tubes using electrical tape so he could make whatever adjustments he needed. Should I try that as a temporary measure before drilling another hole in the tube?

Solid booms = clean boom with alky and tape tightly with radio box tape (leave room from the shoreline in case of release) TEST ONLY purposes.

Hollow booms = epoxy in plug,fill drilled hole, and re drill new location.

 

[John MacLean]

Thanks. . . I wondered how well the tape thing would work on the right sponson. I will fill the original hole and re-drill to achieve the toe-in recommended.

 

[John MacLean]

Hey Blackout. Thanks for the suggestion. Being a newbie I'm gonna stick with the conventional plan and try to resolve it that way first. I started in this hobby a couple of years ago with an sv27 and owning a full size mono I understand a little of the principles involved in getting it to run well on plane. The only thing I know about hydros is what I've read on the forums and picked up from talking to a couple of guys around here who by the way talekd me into building a kneeler and a JAE rigger this past winter. Now I'm just trying to get them running properly.Huge learning curve right now.

 

[RodneyPierce]

But once you get it running well, you will be bitten by the hydro bug. Just last year I said I would "never" own a rigger, as they did not do anything for me. Now look at me, built my first one this past winter, and cant get enough!

 

[John MacLean]

My experience has been the opposite. I wanted to own a JAE the first time I saw one run. I saw a nitro powered JAE12 just after I bought my first sv27 and I'd never seen anything run like that before. And then I watched a couple of races on the H1 Unlimited Air National Guard website and was completely hooked on hydros. Never thought I'd build anything like them until encouraged to do it last fall. The only thing standing between me and my next build (maybe a Whiplash) is deeper pockets. LOL. I want to see my kneeler (see avatar) and rigger runing reliably before I even look at another set of plans.

 

[Neil LaGarry]

I've built my share of Zippkits riggers over 15 and found. This-- build the sponsons in pair's. Keep CKing the angle of the ride pads.

If built loosen one set of boom clamps and move to opposite way of the pull. Launch and CK

IF already built. .Use a setup board ,set down the hull. Roll a round dowel/brass pipe under the front tips and read the numbers. They should match -read to REAR of ride ski. If they don't match, get the belt sander out & remove 1 wood ski and redo. If you only off 1/2 a degree add 1/32 ply to bottom of ski ,sand to right angle then seal.

 

[Jim Caldwell]

Do NOT cut the rudder on an electric boat (we are a lot heavier than a nitro boat) until you get the boat running straight by angling in the sponson.

 

[John MacLean]

Boom tube has been filled and prepped for new hole. Left the rudder length alone but sharpened it along with the turn fin and prop. Also checked the ride pads again for being flat. Made a minor correction to the ride pad on the left sponson. Inside edge (closest to tub) was just off the surface. Everything is flat on the table now. I will install the right boom tube tomorrow with the recommended toe-in and see what happens. Either way I will include a video of the test for follow up.

Looks like quite a bit of rain in the forecast for the weekend. Hoping to get it back in the water but might have to wait until Monday evening.

 

[Blackout]

Boom tube has been filled and prepped for new hole. Left the rudder length alone but sharpened it along with the turn fin and prop. Also checked the ride pads again for being flat. Made a minor correction to the ride pad on the left sponson. Inside edge (closest to tub) was just off the surface. Everything is flat on the table now. I will install the right boom tube tomorrow with the recommended toe-in and see what happens. Either way I will include a video of the test for follow up.

Looks like quite a bit of rain in the forecast for the weekend. Hoping to get it back in the water but might have to wait until Monday evening.

Good plan.

Do you know how fast you are going?

 

[Philmunsterman]

Sounds like your on the right track. I would remove the shims from the strut. Phil