Viper Chinewalk

I have always wanted a hydrostream, and recently purchased a 78 viper with 76 135hp Evinrude.  Was propped poorly.  Got a 26" cleaver with the engine raised about 2" mounted directly to the transom and now run a scary chine-walking 62 at 5200 rpm.  There is more but I can't seem to steer out the chine walk.  The engine does have a skeg-guard which seems straight axially, but tilted towards the starboard side at the bottom.  I trimmed off the goofy wing on the bottom of it, squeezed the crossection down for less hydrodynamic drag and to tighten it nicely on the 1.3" of real skeg remaining.  I plan to but a new skeg on it, and possible contour it for torque steer, but there does not to be much torque steer until I get the engine trimmed way up beyond any real running trim.  Therefore I plan to use a normal replacement skeg.  Any input here?

I am now playing with weight distribution.  Winter is coming and I want to get a feel for what will work with battery / fuel tanks (2 x 6 gallon) placement.  Interior is nothing but a plastic drivers seat, which will become a 4 seater by spring.

Chine walk is the big issue.  Any tips to reduce chine walk in the Viper? 

I will recontour the hull this winter if necessary, but I was thinking a small trim-tab type damper at the chine if the skeg and weight distribution have little effect.

There is a small chunk in the starboard side of the pad (.25" deep from the side, 1.0" long positioned about 2" in front of the transom step) which has a nice rounded shape.   I doubt this has much influence on the walk. 

Some pictures attached. 

Regards,
Jerry Wagner

 

Jerry,

Chine walk is caused by the boat getting up on the pad and the nut behind the wheel not correcting it. It is not a bad thing. If your boat didn’t walk it would be slow. If your steering is tight you just need to learn the necessary corrections with the steering to control the walk. That is your number one priority. All the other things may improve it but the only way to control the walk is by your input.

Randy

 

 

Please submit whatever questions you have to IHRTechTalk@yahoo.com.  All questions and answers selected will be displayed on this page as they come in.  Note: though all boaters are welcome, priority may be given to I.H.R. members.  Randy can not be held responsible for any advice given.  Though his information and expertise is second to none, he has no control over what you do with your boat.  It is up to you to boat safely and act responsibly, and his advice is only to be used as a guidance for your high performance boat/motor of which you are the one responsible for the risks involved.

Thanks,
Mark C.

 

[ Home l About I.H.R. l History l Models l Registry l Members' Pictures l Feature Article l Tech Talk ]
[ Literature l Events l Top Guns l Guest Boat l Classifieds l Video Gallery l Racing Corner ]
[ Prop Slippage Program l Animated Videos l Screen Savers l HIN Decoder l Links l Contact Mark ]