OPC Quandry

[Randy]

I have been running My new OPC doing changes as we go. I am running a 9L with a Y636 prop. The strangest thing is going on, every thing is fine until the boats airs out then the left sponson starts to lift like it is torturing out of the water. The sponson is straight and sharp in the rear so I think it is the motor/prop combination. Any ideas?

 

[forresterace]

Randy

If I might be so bold as to suggest - there a huge number of OPC tunnel experts on this board, but not necessarily on this forum (FE). Why don't you try posting this same question on the Outboard forum. My guess is that you will be inundated with opinions no matter what its motive power. ;D

 

[Grimracer]

Doug is right...were here for you man.

Its the deadrise.

Grim

 

[Randy Naylor]

Well the whole boat is out of the water, only the last 2 or 3 inches is left in, the dead rise is 8 inches foward.

How about the out drive being tweek to the right on the bottom about 3 degrees? I was sitting eating breakfast when I saw it.

 

[Grimracer]

Randy

If the deadrise is less then...say 8 deg.. the boat can hop out of the water dew to tork.. This can happen when running or launching the boat.

Keep in mind that shallow deadrise is fast in a straight line but can be a hand full to tune and to get around a corner.

Good luck.

Grim

 

[Kris Flynn]

Hey Randy, does this mean you are testing your new 'Hooters' Tunnel?

Sent you mail to address listed in your profile on here...

Kris

 

[Randy Naylor]

Kris Yes I am testing and modfying the mold as I go.

Grim, explane dead rise so I know that we are talking oranges to oranges. I have always felt the dead rise is the curved portion of the sponson bottom. To find the deg. draw a line from the tip back to the start of the curve and that is the deg. of the deadrise. Am I wrong?

 

[Slideblues]

Randy, what you just described is rocker, deadrise is "One" in this pic:

Gene

The V2 had a little tail wag cornering, and if the left sponson lifted aired out, that was the last warning, and Poof!!!

 

[Randy Naylor]

Thank you for the picture and the Info . I allways call #1 diheadril. I do not think I spelled it right but it was the best I could do.

 

[Slideblues]

Here is how Mikie described it in another post

Question was whats the difference between dihedral and deadrise in tunnel hulls:

I really dont know if I spelled it right either?? :-

 

[Jack Garcia]

Randy,

If the prop is pretty high there's a possibiity that your boat is prop walking. Try lowering the motor by 1/16" increments to see if it will quit.

Good luck :-

 

[Randy Naylor]

I only do one change at a time and this time I squared up the out drive with the bottom of the ride pads looking from the rear. I took it ot the pond and it worked great!!!! It is fixed! Now the fun can begin. ;D

 

[Randy Naylor]

well I think I learned a little I have allways was not sure what deadrise was but then being mostly a hydro and mono man I never questioned it. It is good for things to go wrong and learn from mistakes. My old Pops use to say "That when you do not make any mistakes, you are not doing anything any more or dead." In 30 days He will have been gone for a year, Boy do I miss him.

 

[TomMoorehouse]

mike made some real nice explanitory pictures.... go here to see:

http://www.intlwaters.com/articles/tunnelterms.php

tom

 

[CySlyde]

sorry replied in wrong post