Same deal. It actually rides better all the way up but scrubs MPH. I also gain 100 RPM with the diverter all the way up.

That would be the pump leaving the water. Or cavitation as I call it.

Do you know where the COG is?

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Chris didn't do any machining to the impeller side of the bowl he only machined the exit side. However the previous owner of the bowl shortened it before I bought it to build pressure.

I am not sure what you a referring to but the suction was machined. Here's a picture of the wear ring being line bored.

(Attachment Link)

sorry, thats what i was referring to....thanks.  dunno why i said bowl....

Do you have access to a full droop?

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Those pictures are with a full droop. I went to a place droop thinking it would help and it didn't.

Those pictures are with a full droop. I went to a place droop thinking it would help and it didn't.

Can you borrow am HTP straight?

I feel your problem is upstream, would love to measure some stuff.

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There are really only three causes for a porpoise condition.

Trim angle to high causing the too much bow lift for the available thrust to support.

A rocker  (aka convex) in the bottom of the rear if the hull, this does not give enough surface for the pump to push against. This can include disturbances before the pump and on the intake of the pump itself

Incorrect weight distribution for the set up. Try moving stuff around a little.

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My understanding is that the Southwind's just have to much lift. The center most strakes end half way through the intake and all the strakes are large.

The super hillbilly fix would be to put a small kick on the outside strakes, I think 5/16" X 2" long would be more than enough. You could use Bondo as an experiment.

GT

Inner most strake.





Intake

Do the outer strakes go all the way to the transom?

I would wedge them. Your pump is leaving the water looking at the far away teeny tiny cell phone video... LMAO

GT

Yes they do go all the way to the transom.

It sounds stupid. but I would take a little Bondo and put a couple of little wedges on the very back of the strakes on the outside. Probably two inches long and no larger than about 5/16" think at the back, tapered. It will not cost you any speed at all. It may even improve speed if you can get it to settle down. 

Is there anything weird in front of the pump intake?


GT

No nothing weird that I can think of.

I could tell you what we did to our Southy, but then I would have to have you killed...LOL

We have a 1978 with a Small block, extensive bottom changes, does a little over 60 with a small block Chevy, shooting for 70 MPH, I have the impeller out and we are making some carburetor changes tomorrow. What I really want to do is put some headers on it, but the grey guy wont let me... 

But seriously, there was a weird bump in front of the intake at the keel line, no idea what was being done, it was similar to a spoon. But wider and shorter than what I have seen in the past. Our ride plate is right at 3° up and has a full droop with a race nozzle and butt bucket. We used a flat shoe, but the intake is at 3°.

The bottom is speed coated to about 7' forward, but that should not really change the handling characteristics. Buy a quart of Bondo and try it, worst case scenario is you sand it back off....

Bet it fixes it...

GT

Have you/can you put a straight edge across the keel and see where everything is?  Like the height of the loader ramps, the difference in ejection of the shoe relative to the keel, how straight the keel is in front of the intake.

Looking at this picture, it looks as though it has that odd hump before the intake.

And is that ice cream on the loader? Lmao.

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Have you/can you put a straight edge across the keel and see where everything is?  Like the height of the loader ramps, the difference in ejection of the shoe relative to the keel, how straight the keel is in front of the intake.

Looking at this picture, it looks as though it has that odd hump before the intake.

And is that ice cream on the loader? Lmao.

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If I have time before I leave I will try to put a straight edge to it, otherwise I will do it next time I make it up. The hump/bump isn't really there any longer. No, it's a rats nest...no just crap from the river water. lol