Traxxas Spartan with chine walk? Anyone?

[traeside]

Okay I am sorry I am new and just kidding. I did read everything I could find on how to fix the obvious chine walk issue with the Spartan. What I did not see anyone mention forgive me if I missed it but one of the things that I know can cause chine walk at least in real boats is slop in the rudder or steering cables. I got a slightly used Spartan 3 days ago and the first thing I noticed was that there was a lot of play in the rudder system. I replaced the rudder pin with a bigger pin (.127) I have not hit the water with it yet but I already ordered the second set of trim tabs and will install them before getting it out as well. I was just wondering if anyone had tried replacing the pin? or is going to make little to no difference with the amount of flex in the transom?
Sorry for one more thread on this.

[dana]

Keep in mind that what is true for full scale boats, doesn't exactly transfer to scaled down versions. Lessening rudder slop is always a good idea, but may not make a difference in chine walk. Trim tabs can help with the issue, but no guarantee

[traeside]

Dana,
Thanks for the reply. yes the more i read the more i see that there is no one fix and what may work today may not work tomorrow. i think you are going to get some sort if issues when you try to push the limits. i wonder what i could expect if i ran a similar setup in my old 40" Prater hull. When I say similar I mean the Seawing 180 and leopard 4092 that I plan on ending up with after I do what most everyone else seems to do with the stock setup

[Fluid]

Deep vee monos chine walk because they are trying to balance on the point of the keel. Anything which upsets the balance will initiate chine walk, including waves, rudder drag on one side, etc. One cure is to lower the hull into the water so that it is not trying to balance on the sharp edge of the keel. This can slow the boat down a bit but adds stability. Raise the strut a bit at a time and eventually you'll fine the sweet spot where you have good speed without chine walk. Moving the CG can sometimes help, as can putting the packs as far out by the chines as possible. Trim tabs seldom do much since they are out of the water when the boat is up on the keel....unless they are mounted close to the keel. Most are not.





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[traeside]

Thanks Fluid,
Yes the second set mounts very close to the keel. Like you say I will have to play with the CG and the inner tabs tell I can get it close. For now I have not even had it in the water. I see a lot of people having trouble on 6S with the stock setup I have separated the cooling system and board out the rudder pick up, and exit fitting. As long as I don’t go to big on my prop or try to go WOT for the full pack I should be able to at least make some trial runs to check temps right?

Side note I am using a transom mounted pickup for the motor system does it matter what side I put it on? I have only built a few boats but have always mounted it on the right side as close to the keel as possible when looking from the rear.
Thanks again for helping out a newbie

[Fluid]

One of the worst things you can do is run your boat extensively at part throttle. This is very hard on the ESC and is one cause of ESC failure with some setups. Better to prop down and run at full throttle, or limit the part throttle running to less than a minute - but even that can heat up the controller.




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[traeside]

wow okay that is good to know. you just saved me at least one ECS thanks
all of my brushless experience is from the air world this will be my first water setup

[dag-nabit]

You have already received good advice, just a couple things to expand on what has already been said.

I would suggest mounting your transom water pick up on the port side of the boat (left side looking at rear of boat) since the rudder is already offset to the right, mounting the pick up to left may help counter the rudder offset.

Trim tabs are not really meant to provide a ride pad for stability, their intended function is to provide control over the attitude of th hull (how it rides in the water) by either lifting the stern and forcing the bow lower which puts more hull in the water (trim tabs adjusted downward for this), or, setting the trim tabs higher (upward adjustment) which will allow the sten to run lower in the water and allow the bow to rise.

With the bow lower and more hull in the water you will usually notice more stability on a vee hull, but you do sacrifice some speed because more hull contacting the water surface results in more drag.

With the bow higher, the boat will ride more on the rear pad of the hull and with less hull contacting the water there is less drag, and ultimately the opportunity for more speed. But with less hull in the water the boat is more likely to chine walk or "get loose" on you.

Trim tabs are extremely effective on boats that don't have much room inside and provide limited flexibility for changing battery positions. My experience with the spartan is that the long battery trays provide the opportunity for a wide range of battery positioning, and that battery position has a greater effect on the attitude of the hull than the trim tabs.

The goal is to find the setup (battery placement, strut angle, trim tab position) that provides the best balance of speed and stability.

I would suggest starting with trim tabs and strut angle at neutral and experiment with battery placement first to determine the best battery position. If you are using different brands/sizes of batteries that weigh noticably different amounts, you may need to determine slightly different positions for each battery type.

Then use trim tab and strut adjustments to fine tune the ride. (as suggested above many of us have found a slightly positive (up) strut angle works well. The owners manual explains how to adjust strut angle and the limits on how far to go.

If you get the bow riding too low (battery position making center of gravity too far forward, trim tabs too much down trim, or strut angle in negative (down) position) you may notice better stability under normal running, but there are downsides. Loss of speed, added load on electrical components, and the boat may tend to nose in or "torpedo" if it catches air coming over a wave.

If you get the bow riding too high you will notice great speed, but the drawbacks are; less stability, boat getting loose, and more chance of blow over.

I don't think anyone has managed to fully control the chine walk on the spartan, but with some patience you can dial it in to provide a stable enough ride to be fun to run.

Kevin

BTW I thought the rudder was a bit flimsy and may be contributing to the chin walk, so I added an extra bracket on the left side of th mout to stiffen it up. The extra bracket definitely firmed up the mount, but did nothing to help chine walk.

[traeside]

Dag-Nabit
Thank you for all the great advise, it all makes perfect sense. I am hesitant to say that the plan is to try to run 6S on her as I am sure I will draw fire from people that have smoked the stock ESC. My original plan was to run 2 of Heli batteries in parallel but 2 time 6S 5000 was just going to be too much weight so I ordered 2 3S 5000 40C. I was like most people are advising planning on putting then in the forward most position with tabs at -1 and drive 0 then move them back tell I can feel her get loose. If I get too far back I go with your advice and give the strut +1. I ordered and a Prather 220 and then got worried that might be too much and ordered the 215.
Thanks again for all the help

PS: I would love to see a shot of your extra bracket

[dag-nabit]

I run 2x5s 5000 MAH batts in parallel on one of my Spartans. The heavier batteries are in some ways a bonus helping to stabilize things a bit. I usually run these batteries 1/2 to 2/3 of the way rearward in the battery tray.

I think you were wise to drop back to the 215 on the stock electrics, the 220 would increase the load too much on a system already marginal on 6s. The octura x442 is also good on the stock setup.

Here is a couple threads outlining my two seasons with the spartan. Unfortunately this season has not panned out well for rc boating. Between the weather and being too darn busy I have only managed 3-4 runs total on the spartan. Maybe things will quiet down in the fall and I can get some good days in before freeze up.

The first link has pics of the extra rudder bracket.

http://forums.offshoreelectrics.com/...Spartan-Season
http://forums.offshoreelectrics.com/...lly+got+to+run

[traeside]

okay i have finished reading the first season. i like your placment on the pickup. question did you have to put it that low to keep it in the water at speed? it looks to be almost 1/2 down.

[dag-nabit]

I set it there using the WAG method, I've always has good flow so never bothered to try raising it to see if it would still work.

Also I'm not sure how it looks based on the angle of the photo, but it is probably only about 1/4" or so below the bottom of the hull.

Kevin

[traeside]

I am on page 3 of season 2 and I am getting a bit discouraged. I am seeing AMP readings far beyond the stock esc. I ordered an upgraded shaft from Kinetic but I have no idea if it will hold up. I am now thinking I should have gone 5S.

[dag-nabit]

Remember that ESC's are rated for continuous amp draw, plus a burst rating.

The stock ESC is rated for 80 AMP continuous, 300 AMP peak (I find the peak rating hard to believe)

Bottom line though, the stock ESC is marginally sized for running 6S. The number of fried ESC's on 6S is a testament to that.

Kevin

[FE-Speedboats]

Elimination of Traxxas Spartan Chine-Walking - Video

Hi Traeside;
I found a video on Youtube of a guy who states he totally eliminated chine-walking in his Spartan. Here is the VIDEO. I have not tried this mod myself so I can't verify this, but it may be worth a try. Note that the mod'd strut he's using also helped with this mod.
He's got lots of other nice mods on his boat which he describes in full detail so even if you just take a look at his mods it'll be worth a watch.

Graham