Impeller Balancing

No. That looks ridiculous, like a series of ever-increasing overcorrections. Shave them all off and start from scratch, or order a factory-authorized renewal part.

Thank you for your reply, the story is deeper than just the balancing,the short version -(happy to tell the long if interested) 2 new Castoldi TD340HC water jets were installed in a new 13mtr commercial fishing boat from new vibration and cavitation was present, Castoldi insist could not be their jet units, spent a year chasing ghosts until I removed the impellers discovered the balancing, impeller blade profiles all different (see photo), and cutlass bearing shaft not central (20 thou inch run out) Castoldi insisted this would not cause the problem and refused to repair, advice from my engineer was to correct blades and shaft alignment. this removed the vibration and reduced the cavitation.

I have since removed the jets and replaced with a different brand problem gone.Guess you are wondering where this is leading - I am in dispute with castoldi they refuse any claim and state what I did (correcting machining) was unnecessary. I am looking for independent opinions if these anomalies would cause vibration / cavitation. not sure if I can post a video but have a clip of the impeller in the lathe.

regards

Butchnz

Well I think an expert on impellers could certainly go into more detail about why the profile of the blades needs to be similar....I find it hard to believe the company disputes this after looking at all the evidence....I guess if you keep making noise long enough, and in the right places, you might get some results....I always like to go straight to the top if I'm having a problem with lower level employees, I would call the president of the company, but I would make sure I had all my ducks in a row first, including a chronological timeline of events including documentation, from purchase to decommission...I would also bring a lawyer on board to discuss strategy....

I assure you I have been to the top (Castoldi himself) they blame the boat hull and insist their jets are made to the highest standard the machining is within acceptable standards and would have nothing to do with the problem, we are now looking at legal action, I have owned / operated commercial water jets for past 30 years, I am no engineer but I fail to see how such workmanship could be acceptable. any leads to an impeller expert would be appreciated. thanks

Your response is a good example of why anonymous posters should be BANNED!

Your post should be deleted! You should be banned!

Putting aside the fact that it is a piece of crap, have you tried to check the balance?

Could you explain the reason or motive behind your comment for better understanding?

Your post is totally irrelevant and added nothing to the topic.

You posted anonymously, which is something we don't like. If you're going to say something have the strength and conviction to put your name to it.

Crude, but effective comes to mind.

The area shown is not in the water flow path. So cavitation is not a problem because of the blocks welded to the cavity. Can't say much for the workmanship, but...........

Cavitation is caused by too much suction for the conditions. This may be caused by numerous issues.

Crude balancing is NOT the issue. Imbalance will manifest itself by vibration, not cavitation.

Need more details. Why do you think cavitation is the problem?

If the impeller blades are not uniform, the amount of water being moved will not be balanced...possibly causing cavitation on a blade that is not shaped similar....This might not be noticeable at low speed, but may indeed be a problem at high speed....the number of balancing weights show there was a very difficult problem, much more than just a little more weight on one side....

Hi you are correct, I am in dispute with a company (Castoldi) that claim the water jet they sold me is constructed to the highest standard, I have had vibration cavitation issues from new,they blame the hull design etc for the problems. Until I removed the impellers (two units) and discovered the balancing job, blades all different profile and thickness among other issues. They still insist all with in acceptable tolerances, I do not believe this and looking for other opinions. I have a series of photos and video of the impeller in a lathe if you wish to see and comment further.

thanks

Looks like a Butcher job (pun intended).

There certainly is better ways doing it. Looks like whoever did it was lucky to get it to a point where it was balanced.

Welding layers come to mind without the metal knobs. Or if you want to use defined block weights gluing them in place might be an option.
Finding out why it was imbalanced would prove interesting.

Last thing said, if it is balanced now and working you might want to leave it so!

I have assumed that cavitation is the issue.

It usually is with jet drives.

Excuse me if poor workmanship is you issue. If so, that's a piece of crap.

If the boat is at speed, the impeller blade out of shape may be pushing more water than the others , or less than the others, this would cause suction in the under performing channel adjacent to the over performing channel...possibly leading to cavitation...

If you say so, I've never owned a jet boat. I'm a prop snob.

This type of thing never seen before. Better to get it renewed.