Porpoising C180 - Trim tabs or pump wedge?

[SLOWBRAH]

I've got a 2005 Challenger... LightiningStruck mentioned that 2005 Challengers specifically were are bad about porpoising (Inlet Plate Picture). Why is this, inlet design flaw? After reading all this about porpoising and the cavitation problems I'm having... mine is going up for sale. I can't believe Seadoo would release a product that performs this badly. I can't give my boat 70% throttle out of the hole without bouncing to redline. I am planning to replace the impeller and wear ring as soon as I can find an impeller that will work... hopefully this will fix the cavitation for the next guy.

 

[Aquaman1]

The ride plate is the problem. With the Mercury M2 jet drive on the Sea Doo jet boat by extending the ride plate solved the Porpoising issue for me. Trim tabs work as well but in some applications but the reverse is compromised. Here is my solution.

 

[murray4schnauzers]

I'm wondering if trim tabs are the answer. Does anyone know the best trim tabs out there? My boat a utopia 19.5 foot , bounces all over in even small chops. Murray

 

[Lightningtruck]

My understanding is that the factory trim tabs for the C180 (2005-up) do not affect reverse. This was coming from my engineering buddies inside BRP.

Dr. H, I'm gonna get you the prints and CAD files if you are still interested in doing a small run.

 

[Lightningtruck]

Slowbrah,

Just sent you a PM.

Thanks,
Kevin

 

[ken0276]

You may talk to the prop builder and see if they have some high lift props for your boat,they worked good on all my RC gas powered boats and corrected all the bouncing issues.

 

[Lightningtruck]

I have an update to this.....that does NOT involve trim tabs. I believe there is a low-cost, simple solution to the porpoising problem. I got something in the works and need to snap some pictures, but I'll definitely be on it over the next week. Will post back soon...

 

[Lightningtruck]

It's done, and I got some pictures. Ended up using an adjustable trim nozzle from a GSX with the 155mm pump, then a manually-adjustable strut to position it. Got 10 degrees of nozzle-down adjustment range pretty easily, with plenty more available if I want to grind on it more. Will be testing this weekend and will post results and pics. Hoping this takes care of the porpoise...

If this works, then will look into making it cockpit-adjustable.

 

[Aquaman1]

Let see some pictures.

 

[Lightningtruck]

Let see some pictures.

How did you know this is what I was logging in this evening to do, LOL.

Stand by...

 

[Lightningtruck]

Pics of adjustable trim, via nozzle



On the first and second pictures, you can see the new nozzle, plus the front strut mount I made. Front strut mount was a chunk of 3/4" aluminum bar stock, sandwiched between the reverse bucket mounting bracket and the pump nozzle. I had to cut off 3/4" from the reverse bucket mounting bracket post to fit my mount in there. No pictures of that, unfortunately.

Third picture is the quick-and-dirty adjustable strut. There are RH and LH threads on the heims, of course to make this work.

Fourth picture is a simple aluminum spacer to position and attach the rear of the strut to the nozzle tab.

Fifth picture is all together.

Hope this helps. I can't wait to test it out on Saturday.

 

[Lightningtruck]

More

Couple more of the finished product. Will see how this works on Saturday.

 

[Lightningtruck]

Got out on the river today. At 10-degrees down, this definitely helps. I could never run at full wide open throttle and try to make a top end run before. I can now. There is still a bit of porpoise at full WOT (glassy water condition, and also in slight chop), but it is much much much improved. Where I like to cruise at.....about 6400 to 6800 RPM.....it's really nice now. Is it the end-all solution? Not yet, but it's heading in the right direction.

Going to machine some on the reverse bucket bracket so I can increase the down angle on the nozzle. Will be working on it this week, and hope to test again next Saturday...

 

[Aquaman1]

How is the speed. Did you loose any? What engine do you have in your boat?

 

[Lightningtruck]

How is the speed. Did you loose any? What engine do you have in your boat?

4-TEC, 215hp SCIC powered. Single.

Couldn't tell on speed, as I have never trusted the speedo, and didn't GPS it before the whole ordeal. If it lost any it "feels" like it was minimal. I'm not into full top-end runs, so even if I did lose a couple of mph I'm not going to get bent out of shape. Do a lot of cruising and towing of the kids out back. I think I will see if I can get a good speed reading on it next time, just for fun...

Thanks,
Kevin

 

[Aquaman1]

I have been making these.


It works awesome. I am not sure what type of ride plate you have on your boat, but if you could instal one they fix the porpoising problem.

 

[Lightningtruck]

Nice.

I might be interested in trying that, also. Any chance you have a picture from underneath? Just curious how it's attached to the ride plate. I would assume using the original ride plate fastener locations?

 

[Aquaman1]

I do not have a picture of it underneath. I'm on vacation and won't be home for a few days. But here's a picture of the ride place itself compared to the stock ride plate.

 

[renomaan]

I put a set of adjustable tabs on my 05 Speedster and did full documented writeup on how I did it-search under my username.

Best thing I ever did for the boat!!! They do cause alittle drag when down but the stability from porposing/bouncing is a no brainer!

good thing w tab is if you set them up correctly then they will be above trailing edge when in the up position and its like it was wo them. A perm wedge...well your stuck with whatever effect it has at any speed.

 

[louisb]

[MENTION=69837]louisb[/MENTION]
I have deleted your posts in regards to the tabs. I was kind of leaving it alone to see where it was going to go. But, I see you have mentioned it in other threads as well.

Selling things through the site is an acceptable practice, however, there are policies in place to do so. Please contact the site owner and you two can make arraingments. For example, if this product turns out well, you can sell them through the PWCMUSCLE site. This will allow you to generate sales as well as benefit the site.

Appreciate your understanding with this.

 

[louisb]

I wasn't selling them. That was going to be my cost. The plan was to give away the prints so people could do it on their own.

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[Coastiejoe]

I wasn't selling them. That was going to be my cost. The plan was to give away the prints so people could do it on their own.

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Your initial post(s) were not clear. As we have a member here that does trim tabs, I felt the need to figure out the direction this was headed.

To be clear, myself and others did not feel it was your intention to bypass the system. I am sure there are others that would like the prints once/if you do get them as they are a desired product.

Again, based on how you posted it really wasn't possible for me to have "guessed" what you end intention(s) were.

 

[louisb]

Hey guys,

Not sure how many people are following this thread anymore, but I had the trim tabs made that lightningtruck had in his posts. I am heading out this weekend to test them out. I will let you all know how it goes.

 

[Pirana]

Cool! I just came back from a great lake weekend and it was terrible. Couldn't do over 26mph without breaking backs!

 

[louisb]

Hey guys, I can't even put into words how much better the ride is with these tabs. Was seriously thinking about selling the boat and have completely done a 180. They were worth every penny.


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