G. Finlay 1/16th scale Hydro

[billf1973]

56828
Hello,
I am having a hard time getting my hydroplane to run correctly. It is powerd by a 3300kv, Esc is a seaking 90amp, Prop is a 1.34x2.06, and a 2s 3300mAh 30c lipo. The boat wants to go, but when full throttle is applied the front of the boat dives down. I have lowered the stuffing box about a 1/4in since it was level with transom. Still get the same result. Any help would be Great.

Thanks,
Bill

[Diegoboy]

can you post a transom pic?

[billf1973]

Diegoboy,
Here are a few pics of the transom.

Thanks,
Bill

568295683056831

[Diegoboy]

How much strut angle is there + or - ? Where's the center of gravity? and What size prop is that?

[billf1973]

Not sure of angle. I know it is about 1/4 inch between stuffing box and bottom of hull. CoG is up in front of motor where lipo goes, and its a 35mm prop.

[Diegoboy]

Can you take a profile picture of the transom please?

[billf1973]

That is 1/4 inches down at transom.

[Diegoboy]

http://www.modelpowerboat.com/images/attitude/strut01.jpg



Strut angle: A strut has a positive angle when the prop shaft points upwards, far from the water surface. In this situation, the transom is pressed down. A negative angle occurs when the prop shaft points down, towards the water surface, raising the transom. If you imagine the boat supported on a transverse shaft that goes exactly through the CG, it's easy understand that, when the transom is lowered the bow goes up, reducing the wet area. The contrary occurs with a negative angle for the strut. Although apparently we could use the strut angle to correct any incorrect attitude, the truth is that the neutral angle is the ideal, just a few degrees off are allowed to adjust the wet area. If more than 2 degrees are necessary, something else should be wrong.

[billf1973]

May be more then 1/4in.
568325683356834

[Diegoboy]

Does she run a solid prop shaft?
That seems to be too much negative angle

[billf1973]

No its a flex shaft .130

[Diegoboy]

Level that prop angle first.

[Heath M]

Try setting ur strut the same depth as the sponsons with about 1 degree of negative angle. Also straighten the rudder to 90 degrees, it's got way to much negative angle.

[billf1973]

When I first set the the strut it was level with the bottom of the hull(touching the hull). After running it for the first time I knew the prop needed more down angle. Moved the prop down and tried it again, same results.

[billf1973]

I will be changing rudder angle and prop shaft soon. Thanks guys!

[U1Racing]

i knew that the strut angle was it just fro reading your original post, keep us posted on how it works out!!

[electric]

Not sure how much experince you have, but as I read through the thread no one mentioned whether you had hit the throttle hard and held it. A lot of hydro's tend to bury the nose on take off, but if you hold the throttle down they come out of the nose dive and go. You probably know this, but just in case you have never run a hydro before I thought I would throw that into the conversation. The other method is to kind of toss it in the water going forward as much as possible and then hit the throttle.

[U1Racing]

i knew this, but i have a scale Karelsen hull hydro and it did the same thing, i know what your talking about though, notice in the first post he said: "at full throttle". just to throw that out there

[JimClark]

Where is the CG located when you are running?

[billf1973]

Ok guys,

I think the problem is solved. The strut is down more added a better prop and KABOOM, it took off like a bat out of hell! Need to seal hatch better got some water in there today. When finished I will upload video.
Thanks for All your Help!

[Heath M]

no probs, glad it got sorted out and ur happy :)

[billf1973]

Hey Guys,
Here is a video taken today.


L4WYLB_35-I

[Jesse J]

Sounds like it isn't quite letting loose, did you hit full throttle? What prop were you using in the vid? That thing should be ripping!

[billf1973]

Have a big prop on now its a x438 and that was only 1/2 to 3/4 throttle. Going to change prop to a smaller one.

[Jesse J]

I have a y535 I had s/b for me specifically for the one I had (that was my first FE build ever). If you want it let me know, it's in the for sale pileon it's way to the swap shop.

[billf1973]

This is my first scratch build also....How much did you want for the y535?

[billf1973]

I have learned over the past few years that brushless boats need at least a 4 pole motor. There was a 2 pole motor in this boat.