2100 Cajun porpoising

[bsimon1975]

Just bought a 94 Cajun 2100 with a 94 Johnson 150 Ocean Runner....Ive read that porpoising is a problem with these boats that cant be corrected. Here are the Specs.... 14-1/4 X 25 3blade Stainless Prop. Prop to pad is around 5-1/2 inches below. My problem come when i'm looking for that sweet spot in my steering. The boat jumps out on plane and will run out to about 39 GPS at about WOT...Tack only shows about 4500, not sure if it's correct had to tap on it a few times to get that..I have no problem with the speed i just cant get it to effectively trim out to break loose the steering...I have a feeling it might just be the steering Cables because its a little tight to turn out of the water...Feel free to chime in with any feed back....Thanks for the input if any!

 

[Texasmark]

Re: 2100 Cajun porpoising

You running a double cable steering or single? If double expect more resistance.

If in doubt otherwise, disconnect the steering cable(s) from the engine and move both the wheel and the engine. What do they feel like? Is it the engine or the cable(s)?

There is usually a grease zerk at the pivot on the engine and you might be able to get some lube in the cables, at least on the ends. A '94 may need some new cables. Morse-Teleflex are a great company and have great customer service. I replaced mine a couple of years ago and bought their "No Feedback" rack and pinion. Really like it as it does a good job for me of isolating the engine torque from the wheel which is what you are fighting per your comments.

Do you have a trim tab on the rear of the AV plate on the engine? If so have you tried to adjust it, turning it in the direction your boat wants to move when you release the wheel.

Trim has an impact on the sweet spot (you already know that) and if you are going to tweak the trim tab you have to tweak it for best performance where you run the most.

On porpoising, it's a matter of prop thrust angle vs speed. The more you trim out the faster you have to be going to prevent porpoising. But you probably already know that. Just leave the engine trimmed out and reduce the throttle a thousand rpms.....got your answer right there. Either tuck it in till it stops or speed back up.

Mark

 

[steelespike]

Re: 2100 Cajun porpoising

Using a 1.85 gear ratio your slip at 39 mph is about 32%.Seems really high to me.
Do you know your rpm range?

 

[bsimon1975]

Re: 2100 Cajun porpoising

Thanks for the input guys....Going to try and clean the cables and tube as suggested as well as trying a 14.5x21 pitch with a new rpm guage...

 

[jestor68]

Re: 2100 Cajun porpoising

Here are the Specs... Prop to pad is around 5-1/2 inches below.

Most riggers will tell you to start at 3.5 inches below the pad and adjust from there.

 

[bsimon1975]

Re: 2100 Cajun porpoising

Cleaned cables....Cleaned steering tubes....motor moves nice with the steering disconnected....helm moves nice when disconnected still a touch stiff though...tight as heck when all buttoned up....talked with some guys over at coastal propeller and they just propped out pretty much the same boat with a laser 2 14.5x19... let me take one home to try over the weekend.....regardless of the outcome I believe I will get the steering changed pretty quick.....train in the forecast tomorrow...worked three weeks straight and wouldn't ya know it will rain.....

 

[chriscraft254]

Re: 2100 Cajun porpoising

Might look into some trim tabs as well.

 

[dan02gt]

Re: 2100 Cajun porpoising

+1 on the Trim Tabs. You couldn't pry Bennetts out of my cold dead hands. Best thing ever for my porpoise happy Stingray.

The 19P Laser II will be better than your current prop that is way to much pitch for your motor.

If you like the Laser consider the Tempest it has great lift and is built for bigger, heavier boats than the Laser.

 

[bsimon1975]

Re: 2100 Cajun porpoising

Okay my rpm gauge needs to be replaced...the 19 pitch laser 2 had a ton of lift on the bow took a longer to bring down the nose but maybe I was trimming down to low...steering will need to be replaced asap along with a new rpm gauge and trim gauge since it is wired for one but not on the dash..I have one pro left to try..a stock Johnson 14.25x19...after that who knows...guys thanks for all the input and general support...

 

[Texasmark]

Re: 2100 Cajun porpoising

Sounds like the port holes in your Laser II were too large...needed smaller plugs. Get them from Mercury and try different sizes till you get what works best for you. Change all 3 simultaneously to the same size to prevent vibrations. What were your rpms in the hole shot? Trimming all the way in is one way to drop the bow faster not keep it up as you said, but holes too large will dilute your thrust and cause the problem you mentioned. Don't give up on the Laser till you diddle the holes. It is one super fine prop.

Mark

 

[bsimon1975]

Re: 2100 Cajun porpoising

Okay stock omc 14.25x19 prop and a little adjustment on the trim tab under the cavitation plate and we are 100% better than last weekend.....shot out of the water with very little bow rise...planed out still pulling a touch to the right but not fighting the wheel like I was last week. 3/4 tank of fuel me and my boy clocked 45 on gps before it started porpoising....now time to start the restore.....I got the bug!

 

[V153]

Re: 2100 Cajun porpoising

What were your RPMs?

 

[bsimon1975]

Re: 2100 Cajun porpoising

What were your RPMs?

Still not sure rpm gauge will not register above 5000....be picking up a new one this week....