Pat McPherson

+2 on checking the bottom to see if there is a hook or rocker. +2 on check drive center and straightness. I think it was also suggested to check the slop in the steering system...

My boat will porpoise at low speeds but can correct with trimming down. I don't need tabs. I only use tabs to correct an unbalanced load or to keep the bow down in rough water.

Other props to try - my boat came with a Mirage non-plus and she handles OK. I like the Mirage non-plus better than the newer Mirage plus; I think the difference is in the cupping. I tested the Turbo 1 and Turbo Vector and both worked OK; not all that different than the Mirage and Mirage plus, I liked the Turbo 1 best of the 3 blade props I tried.

The best prop I've tried is the Merc Revolution 4; this is what I run...

snave8

I'm going to try some different props before I go any further. I talked to Bret at BBlades, he suggested the Merc Rev 4, so I'm going to try that in a 23P under their test program. I have little if any confidence that any prop is going to cure the awful handling of this boat. I hope I'm wrong.
I get what to look for on the bottom, but what exactly should I measure on the drive? Just make sure it's centered? Is there a reference point to measure from?

Mark

joefitness123

I run a 14.25 diameter 3 blade 23 rapture and it handles great at all speeds.. I have an 87 22 classic Limited with a 454/330HP Alpha. It is a stock boat. The X on this model is raised a bit more than in the other models..Haven't had an issue with proposing or chine..

Pat McPherson

I'm going out on a limb and betting the Rev 4 is going to help you a lot. I'd test the boat with on you, the driver, and maybe one passenger. Don't touch the tabs, leave them up and just use drive trim.

Use a long level or straight edge to check the bottom at each strake and at the chine.
To check center, I'd just measure from each side at the chine to the drive transom assembly.

snave8

I certainly hope you are right. I have a 6' level to check the bottom with.
As far as not using the tabs, I'll give it a try with the new prop but so far, it's been impossible to not use them. Just to be clear, this is not the type of porpoise you see where the boat is happily lopping down the lake with a steady bow up, bow down rythem. The porpoise I'm experiencing is impossible to "drive through". It's sharp, rapidly developing cycles, where the bow takes an increasingly lower and lower attitude when it contacts the water with each cycle. If I were to let it go, the bow would eventually stuff, even in calm water. It's downright scary and dangerous.
I've seen video of a classic running in the low 80's while porpoising, but it's a steady and even (for lack of a better term) porpoise. Nothing like I'm experiencing. With the previous Bravo One prop it wasn't anywhere near as bad as with the Turbo One....As long as I had over half a tank of gas. Below half the boat handled progressively worse as the fuel level went down. With 5 gallons in the tank, I couldn't go (safely) past 58 Mph or so.

Mark

Pat McPherson

You should be able to run at any speed with tabs full up in calm water or in small chop. Tabs should only be needed to correct an unbalanced load or slight lean from prop / engine torque. There may be a speed range you can't adjust trim to smooth the ride but I've only experienced that at lower speeds, like 30ish... If you can't drive 60+ without tabs with a Rev 4 then there is definitely something wrong with the hull or drive setup... The boat really shouldn't be that hard to drive... My wife drove ours last weekend at 60+ with very little instruction for adjustments...

snave8

In my original post I mentioned that I can run up to 63 mph with the tabs down, with not much trouble. The problem occurs when I raise the tabs to obtain top speed. The boat immediately starts to porpoise.....Although not always....The severity seems to be related to how much weight I have (fuel and passengers) in the boat.
Here's my original post:

I recently purchased 22 Classic Anniversary Edition with a 496 Mag/Bravo One.
Compared to where I started out, I'm much more comfortable with the boat now. I switched the Bravo One prop that came with the boat for a Turbo One 25P.
The boat seems too handle better overall and I picked up a couple more MPH with the new prop but.........Here's the problem: I'm getting an extreme intermittent porpoise that starts at 63MPH.
I'll take the boat out with 4 adults in light chop and she'll do 67mph the whole length of the lake. I'll take the same people out the next day in the same conditions, and can't get over 63 before the boat starts to develop a severe porpoise.
I know this is a drivers boat, and believe me...I'm drivin it. I'm a commercial seaplane pilot, so I'm used to operating complex machinery, that requires constant control inputs on the water.
Here's what I'm doing, and what happens:
I typically run the boat with an eighth up trim and tabs halfway down for normal cruising (25-40 mph). Any less tab than that and the boat porpoises. When I want to go wide open, I open the throttle, raise the tabs all the way up, then trim to max speed. This configuration puts the bow WAAAAY up in the air, leaving just a few inches of the transom in the water. Some days everything goes well (although it's a scary ride when I encounter boat wakes) and some times at 63 MPH the boat develops a NASTY violent porpoise, with each cycle getting progressively worse, with the bow going increasingly lower, to the point where I'm sure, if let go, it would stuff. The only way to stop it is reduce power and aggressively down tab.
The only way I can go anywhere near top speed consistently, is to leave the tabs down slightly, but this knocks 3-4 mph off my top speed, and even then, I have to drive with my hand on the trim tab control, so I can immediately drop the tabs at the first sign of porpoising
Fuel level effects this also. with full fuel, the porpoise is less likely to develop, and when it does is less severe.
When I first got the boat, I ran it out of gas (When the gauge reads 1/4, there's about 1 gallon left in the tank). In any case, I put 5 gallons in it to get me home. I figured I'd see what she'd do with just me and 5 gallons aboard. Couldn't even go 60 before it would porpoise uncontrollably.
I've owned high performance boats all my life and have NEVER experienced anything like this. Obviously they're not all like this, so I'm wondering.......Do I have a bad hull possibly? could the drive height be wrong when it was installed. Should I try a different prop? The bravo one caused the boat to chine walk and porpoise some, but nothing like it's doing now,.........Help!!
Mark

Pat McPherson

I read your post Mark. Your boat should not be that sensitive to weight and should not need tabs to run without bouncing all over. Check the bottom for straightness both sides at chine and both sets of strakes. Try the Rev 4 prop. One other item to check is the spacer in the drive were the bolt connects the trim Pistons; it should be to the transom side so the drive trims deaper...

class6

Do you have indicators on the tabs. Have you ever run the boat wher you feel comfortable and don't move the tabs. Take it out of the water and see where they really are compared to level. Maybe your just running too much tab keeping the bow down and lifting the rear up out of the water. I would start a run. Tabs up all the way keep the drive trim in and trim up to level only. Do it very little at a time and give the boat time to react and settle at each stap of the button. Check and mark that adjustment also. So you really know where level is. Last thing. Bravo drive. If it's a newer model with ecentric adjustment at rear ram connection. Make sure it's at the most rear setting. This often gets moved when taking the drive off. Let us know how it goes.

class6

Or bolt some lead way up front.