Help Me! Please!

[skyword]

Need some advice on what to try next to smooth out the porpoising!
Stock motor
Stock esc
2x 7.4 30c 5300 mah Gens Ace lipo's
Prather 220 prop.
Kintec offset rudder.
CG is curently at 9 1/4 from Transom. (End of sponson not the overhang)
Prop depth - centerline of prop shaft is even with bottom of sponsons.

I have tried prop depths higher and lower by 1/8 incements up to 3/16ths with not much diff.
Have tried CG at 9 and 8 3/4 with no difference other than 9 and less seems more pronounced and acts like it could blow over.
It will run at 3/4 throttle smoothly but WOT constant bounce. It will stop in a wide open if you have it in a slight turn. 10 degrees maybe!
Don't realy want to run it in a circle all the time! I do enough of that myself!
Any ideas or other things to try would be much apreciated!
I'm enjoying this boat but the wawawawa is anoying. A guy showed up at the pond with a BJ 26 and it ran smooth. He did barrel roll it once though! Luckily landed bottom down and kept going! My MG and his BJ were dead even but if I could tune out that porpoising I think my MG would be faster! Less anoying for sure!
Thanks in advance for any help.
I know there are threads devoted to this! I've read most of them!

[Make-a-Wake]

I'm in the same boat(LOL)..................my Mystic runs like crap at every setting................hopefully someone will chime in.

[dana]

try raising the strut all the way up?

[Diesel6401]

What helped me with my MG was getting rid of any and all excess lift. I ran a prop with a low pitch. When the prop has lift it forces the transom up to much and then it hit the steps and start loading and unloading "bouncing". Next I got rid of the wedge on the very bottom of the rudder, I rounded it and rounded the lower leading edge of the rudder. The best combo I had with that boat (before I sold it) was the PB1800 the kintec v2 offset and a grim 40x52/3. That worked excellent for me. The packs where hanging back around 9" cg or so I forget and I forget the strut depth. Getting rid of the excess lift is what def helped mine though, and constant tuning. A nice 90 on the last step may also help as well.

Sent from my T-Mobile G2 using Tapatalk

[jasoncyclone]

Have you tried changing the angle of the strut? Is it neutral right now? If you can get some pics from the side of the hull looking at your strut we might be able to help. I see tons of people with this same issue but it seems that no one changes the angle of the strut. Moving the strut up and down are only 1 of the adjustment that can be made with the strut!!!

[dana]

I agree with diesel, try a different prop for starters. Sometimes a change in prop will change how the boat rides

[skyword]

Thanks for the replies everyone!
Jasoncyclone -I have tried to get the prop to point down but am afraid of kinking or bending the stuffing tube.
Dana- I have not tried the strut all the way up but have considered it. I'm thinking it my cavitate to much but if it hooks up and helps the bounce then it would be worth it to me!
I do have a x642 waiting at my LHS to pick up when I can make it over there! I will need to S&B it myself! Is Berylium really as hazardous as they say? Or only in California? Ha!
Diesel-I was wondering about the lift in the back caused by the prop! I read where some create more than others. The x642 has a little less pitch than the P220 I think.
Thanks again to all for the help! Will try to post pics!
JJ

[dana]

Make the bottom of the strut 3/16 higher than bottom of sponsons. X642 has some lift, 1.6 octura props inherently have that character. Try an m445 or m440. I like m props on cats. They work well. 1.4 series octura have very little lift opposed to 1.6...

[Make-a-Wake]

Yeah, as Dana pointed out, the 642 is a medium lift prop as opposed to the x4 series which is low lift. The 642 being a 1.6 pitch also has more pitch than the Prathers which are roughly 1.5.

[joker rc]

mine skips a little only in straight line ,then seems to smooth out as it reaches top speed .if i turn even the smallest amount it runs dead flat , i am hoping its just the hull ride pads ,after i fill them will see ,

[joker rc]

well i tweaked the strut and tested it today ,no more bounce , running dead flat , move your strut till its level with your ride pads ,then tweak it down at the back a little ,few degrees . like this photo shows the top of the strut you can see how much angle i put on it ,. last photo show what it was set at ,level before a tweaked it
739837398873984

[jasoncyclone]

Thanks for the pictures Joker... That was what I was talking about with the strut angle.

[skyhighdiver]

Also try moving up to 2 14.8 packs the boat likes the extra weight smoothes her put and you almost double your run time

[joker rc]

yeah i just purchased some 4500mah 5s zippys 45c they will settle it down 650 grams each .over my 2s zippys 308 grams each . more top speed ,less WOT 9000mah long run times .it seems the 42x55 prop was not pushing the motor temp up to much mine needs more prop on 4s . or 5s
5s will be interesting , and a x642 might be better on 4s ,or m445 like your running ,

[skyword]

I decided to angle mine down but had a hard time getting it to move. My stuffing tube is a little long I think! I added a 3/32 gasket between the transom and the strut mount and this gave me a little extra room to get an angle on the strut. Hope this will get the bounce out of my boat as well. Won't be able to test for a few days.
Thanks to all for the replies and help!7409374094

[jasoncyclone]

Hey Skyword, you may have a little to much angle on the strut. If your boat does not get up to speed try taking a little less angle on strut. But you have the idea!

[joker rc]

yeah after testing 3xset lipos though it yesterday i jasoncyclone is right ,,, i found it to much angle moved it back almost level ,plus i had gopro mounted , still bounce in straight line ,but seems to smooth out just as i run out of water , lol need bigger pond , first test i did in choppy water was hard to tell as mine ,only bounces a little ,
i be testing heaver 4s4p 4500 5s packs next weekend , see if that settles it down . then i am going to fix the hull ride pads ,

[jasoncyclone]

I think smoothing the rides pads will also help settle the boat and make it more predictable to drive. I blueprinted my ride pads and installed the offset rudder and it runs like a dream!! I just balanced my geico at 32% from transom then kept adjusting the strut till she ran on rails....

[Darin Jordan]

I think smoothing the rides pads will also help settle the boat and make it more predictable to drive. I blueprinted my ride pads and installed the offset rudder and it runs like a dream!! I just balanced my geico at 32% from transom then kept adjusting the strut till she ran on rails....

I agree with this.

I just recently prepped a Mystic for a local club member and it's pretty amazing how "off" some of the hull bottoms can be. They seem to have a common trait, in that the ride surfaces touch at the very back, and up toward the front of the flats, and have a gentle arc upward in-between.

It takes some very careful block sanding at the backs and at the fronts, a little at a time, so get them in the "zone"... On my original Miss Geico, which I'm RE-Blueprinting right now (this is the boat I used to establish the initial 2-Lap NAMBA TT record with, prior to this re-work), was like out of shape even after blueprinting the first time. I think the earlier hulls were pulled from the molds a little "green"...

I have had to add 2-layers of glass on the inside of the back ride-pad surfaces because I had to sand so far down the material was getting thin. In hind-sight, it may have been easier to fill the pads instead. Either way, I think what needs to be done is to get the ride surfaces FLAT from the transom forward, where they are sitting on the setup table and touching evenly for at least the first 9-10" or so... and to have the rid-pads FLAT, fore-aft and side-side. Sharp trailing edges are a must as well.

It's a bit of work, but the results seem to be worth it.

[Old Sloppy]

I notice your prop is a 2 blade. and is set much too deep from what I see in the pix.

in the past I have owned a Drifter (24" with x632 prop) and a Drifter L (36" with x640 prop) that ran very well indeed with 2 blade props and high rpm's.

I prefer a 3 blade on my present Cat(s) and raise the prop shaft accordingly.

My Cat hops and runs too loose) with a 2 blade prop, a 3 blade prop "glues it down tight" to the water's surface.

Shortening the stuffing tube isn't that hard, I remove the strut leaving the tube still attached to the hull. then dremel cut the tube and reinstall the strut, this way the motor alignment is undisturbed.

Harry
from Atlanta

[joker rc]

at lest once there done ,ride pads that is , you eliminate them as a cause of the bounce , then its just a matter of fine tuning SG hardware ect . mine are pretty bad need filling,, its worth it though , if you can find the time .

[skyword]

Ran the other day with the prop strut angled slightly down and the shaft level with the ride pads as seen in my previous post.
The wind was blowing steady at maybe 15mph and the water had a solid 2 to 3 in chop. (Pond is out in the middle of miles of flat farm fields)
When I was running into the wind the porpoising was the same. (consistant when at 3/4 throttle and above.
When running with the wind the hull was dead flat and looked great!
My Question is this: Could the tunnel be compressing to much air and liftingI the back out of the water? When running with the wind it was essentialy catching less and not creating as much?
I know these are pretty deep thoughts but it was obvious there was a big difference into or with the wind.
When the wind did settle down the porpoising was still there both directions but when it was blowing and choppy it ran great with the wind!
Reply if you want, if not I understand!
JJ

[jasoncyclone]

When you are running into the wind you are getting much for lift on the bow "under the tunnel" of your boat causing the chop. When running with the wind you have less lift causing less bounce. The bounce is caused by the front of the boat lifting then not having the power to keep the bow up thus droping the nose then repeating the same over and over. You need to run your hull in normal wind conditions for your area then adjust the strut negetive or positive angle to get the boat to ride smooth. Hope this makes sense???

[benjijames]

77951

Hello, I would like to know If I have to stick with glue the 2 metal parts that I have circled in red on the picture.
This two parts always tend to separate themselves especially when I raise the drive. Last time it has even broken the flex shaft.
Thanks for helping.

[egneg]

It needs to have the weight of the lipos a bit forward. I had the same problem until I moved the lipos forward 3/4". Now it it runs flat and really moves out. I use a X642 that has been detongued.

[joker rc]

77951

Hello, I would like to know If I have to stick with glue the 2 metal parts that I have circled in red on the picture.
This two parts always tend to separate themselves especially when I raise the drive. Last time it has even broken the flex shaft.
Thanks for helping.


you have to much angle on that strut it will make it run wet , move the strut back to neutral .and 1/8 of a inch up above the ride pads ,some sealer will fix the join you show leaking water up the stuffing tube ?