Loping, not porpoising BassCat

[CarkyF]

Since there are a few guys on Ultimate Bass that are not on the BCB owners board, I would like to share this from the owners board in hopes that it may help another owner down the road.

The link and the text of the original message will be provided for those that want to read the whole thread.

http://basscatowners.yuku.com/topic/21714/Loping-not-porpoising-PII-Suggestions-are-welcome#.T-r2WdK69IE

Noticed last summer that my 2011 PII wants to porpoise at full throttle intermittently.  It seems conditions have to be 'right' for this to occur.
Here is a summary of when it happens:
1.  Fishing alone in water temps>85 degrees and air temps > 90 degrees.
2.  Happens at full throttle; trimming down or up really does not seem to have an impact on the porpoising one way or another.
3.  This is more noticeable when the surface is calm; have not really noticed this with any type of chop on the water.
4.  Last summer, the jack plate was set with the inner and outer plates flush running a 25 Tempest Plus.  I raised the jackplate 1/4 of an inch a month ago to see if top end picked up.  With the plate flush, the porpoise seems to have a 'longer' area of travel vertically--kind of like a longer sine wave.  With the plate up 1/4", it seems to have a shorter area of travel, but it seems to be more frequently--kind of like a shortening sine wave if anyone is a math person.

BCB, Phil Addison, Chris Hagler, Rick V, and others that don't provide a name were kind of enough to offer their insight on the owners board at BCB. 

Bottom line is the prop is losing its bite at high speeds.  Personally, I have never heard of or experienced 'loping' in 20 years of running high performance boats, but I am grateful to have the resources available to keep learning.

The solution(s) are to drop the engine on the jack plate to give the prop more bite or try another prop.  For now, I am going to drop the engine and see how much top end is lost.

Hope this helps someone else.

[18x2]

Good thread and thanks for sharing.  I think your problem will be within the prop since Tempests are not the best prop out of the box. 

[BlackCat]

I run a 26 Trophy on mine. I had my prop tuned by Ronnie Gilbert. Mine did the same thing so we loward the jack plate and it stoped buy lost almost 2 MPH. Problem was the tips of the blades weren't grabbing enough. Ronnie did some more tip work and it stopped. Raised jackplate back up and got me speed back.

Running about 71.5 loaded down and 73.5 to 74 on a light load!

[Flyswatter]

So adding cup solved it.  My first thought would have been to lower the motor which you did.  Seems you are ahead of the curve with some prop modification.  Great numbers for this time of year too. 

Carky,  Thanks for bringing that info to UB.  BassCat support knows no boundaries.   Here's to ya!