Design idea. 2 degree pump wedge (downward)

[dan144k]

Idea?
I am looking for someone who can help locate an existing product or make a pump wedge to go downward for 155mm inpeller jet boat. 2 degree, 4 degree, I don't know exactly.

I want a pair to angle down, this will reduce the spray on tubers, push the nose down when waves are choppy (smother ride), and help with the wake surfing wave.

I have already done this to some extent in my jet boat (2010 AR240) by welding and filling in (payed someone) the top and bottom factory turning nozzle holes and then redrilling the new holes to angle the exit nozzles downward some. I lost about 5mph in top speed but it improved my hook up, reduced cavitation, and improved the ride quality in my mind. (Light boat nose use to bounce off waves, rather than push through them)

They make they these for waverunners but always angle up to improve top speed.

 

[dan144k]

I looked into this (down wedge idea) a little more on my and I do not think the upward wedge can simply be installed upside down. bolt holes will not line up.

I still have one of my downward nozzles (the other one the bottom screw fell out and then snapped the top house off, my mistake was either too loose or forgot lock tight) Well I installed it last night on the port side, We usually surf that side and it should help, but I have the later thruster and had to do some trimming with grinder on the lateral thruster and on the nozzle, turns freely and will work well.
Gonna test this weekend

 

[Beachbummer]

cable control pivot? There are some wave runners that had an electrical actuated trim-like nozzle adjustment, but electrical/near water always fail, so they did not stay in fashion for a long time.

Something like this:

Seadoo XP SPX HX 720 Jet Pump Steering Nozzle With VTS Adjustable Trim 96-99 | eBay

Seadoo 720 XP SPX Jet Pump Steering Nozzle With Adjustable VTS Trim. Ready To Be Put Into Service.

www.ebay.com

 

[AZMark]

Idea?
I am looking for someone who can help locate an existing product or make a pump wedge to go downward for 155mm inpeller jet boat. 2 degree, 4 degree, I don't know exactly.

I want a pair to angle down, this will reduce the spray on tubers, push the nose down when waves are choppy (smother ride), and help with the wake surfing wave.

I have already done this to some extent in my jet boat (2010 AR240) by welding and filling in (payed someone) the top and bottom factory turning nozzle holes and then redrilling the new holes to angle the exit nozzles downward some. I lost about 5mph in top speed but it improved my hook up, reduced cavitation, and improved the ride quality in my mind. (Light boat nose use to bounce off waves, rather than push through them)

They make they these for waverunners but always angle up to improve top speed.

5mph is a big drop. Not such a big deal if you don't need to go 50, but that probably has a pretty big impact on cruising fuel consumption too. It would be great if you could turn it on and off like trim, but I don't think many would want their boat permanently set up like that.

 

[BigAbe75]

Lucky 13 cones come with additional pump spacer wedges, don’t they? I wonder if you could contact them about just getting spacers?

 

[dan144k]

@BigAbe75
I have the Lucky 13 cones, I did not know Lucky 13 made a wedge, I will look into it. The Lucky 13 really have did helped a lot with cavitation. It completely resolved it for me for a while.

I just pulled my impellers and replaced them with some spare like new stock ones I had in my spare parts pile. I am pretty sure I resolved my cavitation again, just need to test it out this weekend. Left modified nozzle and fresh impellers will be a huge difference. The impellers that came out did not look bad at all, I was surprised how not damaged they were.

I was glad the impellers came apart well, the never seize on the impeller threads made a huge difference.
Dont listen to the yamaha manual, Always use Never Seize when changing impellers (my opinion)

 

[BigAbe75]

@BigAbe75
I have the Lucky 13 cones, I did not know Lucky 13 made a wedge, I will look into it. The Lucky 13 really have did helped a lot with cavitation. It completely resolved it for me for a while.

I just pulled my impellers and replaced them with some spare like new stock ones I had in my spare parts pile. I am pretty sure I resolved my cavitation again, just need to test it out this weekend. Left modified nozzle and fresh impellers will be a huge difference. The impellers that came out did not look bad at all, I was surprised how not damaged they were.

I was glad the impellers came apart well, the never seize on the impeller threads made a huge difference.
Dont listen to the yamaha manual, Always use Never Seize when changing impellers (my opinion)

I’m probably not using the right terminology. This quick video mentions the spacers a bit.

 

[AZMark]

@BigAbe75
I have the Lucky 13 cones, I did not know Lucky 13 made a wedge, I will look into it. The Lucky 13 really have did helped a lot with cavitation. It completely resolved it for me for a while.

I just pulled my impellers and replaced them with some spare like new stock ones I had in my spare parts pile. I am pretty sure I resolved my cavitation again, just need to test it out this weekend. Left modified nozzle and fresh impellers will be a huge difference. The impellers that came out did not look bad at all, I was surprised how not damaged they were.

I was glad the impellers came apart well, the never seize on the impeller threads made a huge difference.
Dont listen to the yamaha manual, Always use Never Seize when changing impellers (my opinion)

What does cavitation feel like on these? Like a slipping clutch on a car or bike?

 

[dan144k]

@BigAbe75
yeah I did testing with the cone spacers several years ago. One gold spacer gave me the best no cavitation results.

@AZMark
When the boat is full of 2000lbs for surfing and can't get to 10mph, rpms are very high, and the jets are throwing white foamy water full of air from cavitation. It usually gets past it and operates normal, but it makes surfing more difficult. The jets don't form a wave, it is just very frothy behind the boat.

We have actually (at times) had to have 2 guys in the front of the boat to get started without cavitation, then once we get to 10mph, and the rpms settle, then they move to the back of the boat. Sounds crazy but it works shifting 500lbs of weight. Start ballast and then surf wave ballast.

Another example of cavitation is when someone forgets to put the clean out plugs in. The engines Rev, the boat moves, barely, you know pretty quick something is not correct.

EDIT. Also to note on the port side I have a replaceable wear ring insert, it was grooved up some and not smooth any more. That may have been my cavitation problem.
And also on the starboard side, when I pulled the shaft it had some ski rope wrapped around the frontward part of the shaft, maybe 2" long and 3/4" height.
These 2 conditions may have been causing my cavitation. And I just went overboard replacing the undamaged impellers, but that OK was only a few hours of work.

 

[2kwik4u]

@dan144k What about something like this.

https://jetboaters.net/threads/adjustable-trim-and-directional-reverse-bucket-install.17569/