Deep Vee chine walking question

[JPriami]

I have been modifiying one of the traxxas spartans. Leopard 4082 1500Kv, T-180 esc, S+B+P M645, Speedmaster dual pickup rudder, etc,

I am having issues with chine walking above 55mph.

It has been suggested that the strut & stuffing tube being mounted at the lowest possible point in the bottom of the Vee is causing the boat to become more unstable at higher speeds because its to hard for the boat to balance on the tip of the vee. And that moving it up about 1/8" will help. That makes sense.

The boat also seems to want to torque roll. I have shifted the weight in the boat so the port side is slightly heavier. This seems to help at lower to med speeds. But still when the boat gets up to WOT it will still turn and start to chine.

So I looked up some stuff and found a few websites saying that if you offset the strut to the right starboard side about 1/8" this will help counter torque roll in Vee hulls.

I just finished modifying & moving my stuffing tube and strut up about 1/8" and over a little less than 1/8"

But I am hearing conflicting info about moving the strut over to the starboard side. Can any one shed any light on this about moving the strut over to the right to help counter torque?

Thanks

 

[ids987]

Strut height and strut angle will also have a significant effect on torque roll.

The lower the strut is, and the more that the prop is angled down, the more torque roll you will get - in my experience at least. I believe that the strut angle makes more difference than the strut height in that respect, and also to ride attitude. The prop can also make a big difference.

I have used right side strut offset, and I believe that it helps to reduce roll - though I haven't done any controlled experiments to prove it.

Strut height adjustments seem to have variable effects on the ride attitude - depending on the boat / setup. I have at least one boat which will nose up more (and drag the transom more), as you push the strut deeper into the water - though conventional wisdom seems to say that it should do the opposite. I believe that is due to competing forces. The thrust of the prop will tend to lift the nose more - as you go deeper, but there are other factors - like lift from the strut / stinger (which will lift the transom), lift from the prop (lift from prop pitch will tend to lift the transom, lift from prop rake will lift the nose etc). Depends which lifting element wins......

 

[Michael Costanzo]

hi, i am not sure of what dia shaft you run, but i have found that by using a octura "skegged stut" helps with the chine walk.also very sharp props reduced the problem.mike.

 

[JPriami]

Thanks for the info guys. I've got a little bit to report about today's test. I'll post later when im on a pc. On my phone now.

 

[TimothyJones]

Does that boat come with trim tabs?. I looked it up and couldn't find a pic of the transom.

I might have some trim tab ideas if you have them.

Tim

 

[shoboat]

J,

X-442 propeller really sharp 58.6mph this past weekend.

You have a pretty big propeller on it or try a three blade.

Thanks,

Mark Sholund

 

[JPriami]

Hello Timothy,

Yes it does come with trim tabs. I have a pair of adjusters on it too. I have tried a little starboard trim down.

Heres is some clips of things I have written so far showing the history to this project.

The other day I thought I had the boat nearly dialed in.and ran the 58.9MPH with little chine walk issue. though a little lift on the starboard side was the trick.

I ran the thing again yesterday and it was chine walking and I think that was also keeping me from reaching max speed because it only pulled 56mph.

Only difference I can tell is the water conditions are playing a roll. The day it ran 58.9mph the water had a little chop to it. and yesterday at 56mph the water was pretty smooth. Im thinking is it possible that the water conditions helped it with not chine walking?

I tried adjusting the right starboard trim tab and it helped but didn't take it out.

After I got home and watched the videos it seems to be when the boat is spooling up rpms that it leans a little to the right starboard side. Then comes up on plane and then the chine walking starts. I cant seem to trim that out with the tabs. So I am thinking I will try shifting the weight a little more inside the hull. I already have been making it about 5oz heavier on the left port side placing my gps there. Now I had the idea to shift the batteries over just slightly but still in their trays. Just on their sides. I checked this in the bath tub to see if the weight does in fact make the boat a little heavier on the left port and it does. I just hope it helps counter the boat wanting to lean right.

The above helped a little but it would still start to chine walk at WOT.

So then it was addressed that perhaps the boats ride area is too small above 55mph and its trying to balance on the tip of the narrow Vee.And its too hard because the stock strut location was too low on the hull.

So I filled in the transom area with PC-7 epoxy and 24+ hours later I relocated the strut & stuffing tube up 1/8" from stock postion and over to the right about 1/8"

I tested that setup today.

The results were odd. At first it looked a little better, the boat leaned just a little then took off and chined very little to none. But I noticed the boat wasn't tracking straight. I hadn't touched the rudder trim proir to having it dialed in. so I adjusted it to make the boat go straight. That made things worse. The boat would roll over to the right if you gunned it hard even at low/medium speeds. Torque roll was back.

I feel the boat wasnt tracking straight because the pushing force of the prop wasnt centered on the middle of the hull.So tonight I moved the stuffing tube & strut back over to the center of the hull but left it up a little higher than the stock location.

suggestions welcome, Thanks

Justin

 

[JPriami]

Mark, what boat did you do that in? what setup?

 

[shoboat]

J,

It is a boat just like yours. It was not mine but a propeller

customers boat. He gained 10 MPH with just a propeller change.

Thanks,

Keep Testing,

Mark Sholund

 

[TimothyJones]

Mark is correct as a large prop will cause chine walk.This is where testing comes into play with props.

water conditions also play a role.

Back to the trim tabs.....

If you had inboard TT you could lower the inboard starboard tab.

Don't know if you could get another set in there without affecting the prop.

This is just me as If I built one..2 sets on each side with the outboards 1/8"-1/4" from the sides.

Chine walk is caused by uneven airflow,torque,large prop, a very loose running boat and horsepower.

Tim

J,

X-442 propeller really sharp 58.6mph this past weekend.

You have a pretty big propeller on it or try a three blade.

Thanks,

Mark Sholund

 

[JPriami]

I have tried a 215, 220, 42x59, graupner 42,45 & 47mm m445 & m645. The props that didn't push the boat over 50mph no chine. Getting near 55 it chines.

Mark do you know if that guy was running the stock motor and esc? Cause it's a 36/74 1600kv 2 pole in there stock.

 

[shoboat]

J,

I will find out more about his set up since he wants even more speed.

I am thinking of going to a ABC 1614/3 Chopper and see how it likes

the three bladed propeller. The Chopper should be able to get up into

the 60's or more if the RPM is available. The ride attitude of the boat

will be very important to how fast we will be able to go with the set up.

Thanks,

Mark Sholund

 

[Kevin Krogness]

You spoke of videos, get them up lets see what you got!!!!

 

[JPriami]

Just look up JPriami on YouTube got lots

Pomenis is my YouTube user channel name too.

 

[wayne middlemiss]

looked at the vids & my opinion is in this case mark is your answer using tuned props te get it there in the 60's .

the other has been sugested is to get another set of trim tabs mounting them closer to the strut between strut bracket an existing tabs.

its a trial an error thing as with any other boat setup....................nice boat by the way ........................

 

[David vanmaris]

Mount strut 1/8 to left ,keep prop sharp ,use a 0 degree angle on strut and experiment from there ,remember old school basics

 

[JPriami]

Thanks,

I have been ill lately (passing kidney stones for the first time) so I haven't done much work on the boat project here. Im going to try the final relocation of the strut. then if that doesnt work look into another set of tabs in between the strut and outer tabs. And try some other props.

 

[JPriami]

Mount strut 1/8 to left ,keep prop sharp ,use a 0 degree angle on strut and experiment from there ,remember old school basics

mount strut to the left on the transom if looking at it from the rear? Ive read you mount it to the right? I tried that. it made it worse.

 

[wayne middlemiss]

Mount strut 1/8 to left ,keep prop sharp ,use a 0 degree angle on strut and experiment from there ,remember old school basics

mount strut to the left on the transom if looking at it from the rear? Ive read you mount it to the right? I tried that. it made it worse.

yes looking at it from the rear is correct, tourqe reaction from prop will be reduced a considerable amount .

but you still nee to run the props that dont have a huge effect on the boat test test test tune tune tune bend bend tweaking here and there.

wayne.

 

[JPriami]

Now ive heard two different stories about offsetting the strut 1/8 ive heard set it off to the right and the left.

Read down this page it says offset to the right

rc boat hull attitude

and i read it here

deep vee setup

im not liking the internet anymore lol.