Scarab Porpoising Problem

[Speed_Freak_039A]

Has anyone looked into this yet?

 

[Luc Lafreniere]

I just came across this thread. I also have a 165 (no tower) and mine also does this at certain times. I also correct it by adjusting speed or simply turning. I've noticed it more when we have more or heavier people in the boat. Not so much when it's just my wife and I and 2 year old daughter. I'd be curious if there are any conclusions... My next plan was to simply shift gear around the boat from stern to bow area to see what happens. But it's not a huge issue in my case.

 

[Cobra Jet Steering LLC]

Without reading all this thread so forgive me if someone already mentioned this, but the jet ski nozzles are interchangeable with your nozzles and they have a reversible nylon bushing that can be set to angle the nozzle up or down quite easily , I would look to see if you have that type nozzle the bottom bolt hole for the nozzle is oval shaped and you can rotate the nylon bushing to change the nozzle angle thus trimming the boat up or down.

 

[Luc Lafreniere]

Interesting... thanks. I'll have a closer look next time I have the boat out of the water.

 

[Cobra Jet Steering LLC]

A bit of a crappy picture off the internet but you can see the oval bolt hole and the insert can be reversed, as it is set in the picture since it is the bottom bolt you would raise the nose if the bushing were reversed it would lower the nose.

 

[Luc Lafreniere]

So I finally got around to trying this. Sadly, although that bushing does indeed exist, it pushes my nozzle UP, not down. Therefore, it actually would make the porpoising problem worse in my case. Essentially, it's already pointing as far down as it goes with stock equipment.

After now using it for about 70 hours, I have a pretty good feel for it. It seems to porpoise when the boat is full of gas and I have adults sitting in the main three seats. My wife likes to sometimes lie down on the bench seat, when she does, it reduces the porpoising. If the gas is down below a half tank, the porpoising seems to go away entirely. So I'm going to look into adding some weight at the front. I already have an anchor, but I may see what else I can do. It's not a huge issue, but definitely annoying.

 

[Beachbummer]

Trim tabs are awesome and not terribly expensive. That is the permanent fix to what you are experiencing. If this issue is bothering you, you will not regret buying the trim tabs.

 

[Cobra Jet Steering LLC]

If the nozzle bushing was already set to point the nozzle down then yes reversing it will not help I do believe that you can add a pump wedge to angle the back of the nozzle down to address this issue.

they go between the pump and forcing cone that your nozzle mounts to and they angle the nozzle down for around 100 dollars this picture is the opposite as it is narrower at the top however I believe there are some that are available to drop the back so it would be worth looking into.

 

[Luc Lafreniere]

Thanks to both of you. Yeah, both are appealing solutions but both require a reasonable amount of work/holes to be drilled (for tabs), bucket adjustment, etc. I'll try the weight first and see how it behaves. I'll go from there.

But thank you for your input guys.

 

[2kwik4u]

Trim tabs are awesome and not terribly expensive. That is the permanent fix to what you are experiencing. If this issue is bothering you, you will not regret buying the trim tabs.

I concur.

I ran Nauticus tabs on my Rinker. With the outdrive trimmed anywhere above about 1/2 it would porpoise badly. Took having 8 adults to keep it from porpoising any more. Once I put the tabs on it the ride was significantly improved, and I picked up about 1-2mph as I could keep the trim high and the ride would remain stable. It seriosuly felt like it jumped out of the water as well. Even with the little 3.0L Mercruiser motor it would easily run 42mph, and plane as fast as my AR190 does now. They were easy to install and worked as advertised.

They will destroy your wake for wakeboarding though. I put the "trolling brackets" on mine, but used them "upside down" so that I could retract the tabs when wakeboarding. Here's a picture of the setup I had.