porpoising real bad need help
 

hi i have a 96 talari 209 this is the second season i have owned the boat
it had a hydrofoil on it when i purchased it ran fine last season with foil
foil got broken towards the end of last season now when i'm cruising at 3000 rpm and 30 mph
with trim adjusted it starts porpoising bad if i trim all the way down is stops but when i start going back up it starts again should i get a new foil or is there another way to fix this i have read where so members believe that foils are the worst

Re: porpoising real bad need help
 

Smart tabs will fix that for you.

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Re: porpoising real bad need help
 

Agree, but even with the Smart Tabs it may porpoise if you trim up enough and encounter the right choppiness. You can probably adjust the tabs stiffer to stop it but then you will loose top end speed. You will just have to play with them to strike the balance you prefer but it is nice they are easily adjusted.

Adding a foil to the lower unit is putting the wrong correction in the wrong place IMO and won't provide some of the other benefits you get from the tabs.

Re: porpoising real bad need help
 

For the cheaper option you can buy a new hydrofoil. It may have warped while sitting over the winter without you noticing. The more expensive way is installing trim tabs.

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Re: porpoising real bad need help
 

Personally, I think the hydrofoil can cause issues over time. You are essentially extending the anti cavitation plate and incurring additional stress on the plate and trim rams. Over time this can cause failures. The Hydrofoil will exaggerate the affect of trimming the outdrive but at what expense?
To truly address the problem the hull needs to be stabilized when on plane. That's where the Smart Tabs come in. They will allow quicker planing and a more stable ride and limit the porpoising to some extent. With that said by trimming the outdrive too far you can still cause porpoising which I think means the hull is losing plane surface which causes the bouncing.
By the way the SmartTabs can be had for $100 to $130 so I don't think they're that much more expensive than a nice Hydrofoil. Just my $.02

Re: porpoising real bad need help
 

thanks for the responses i was figuring that smart tabs was going to be the best route i was just hoping that there was something that i didnt think of that didnt require putting holes in the boat

Re: porpoising real bad need help
 

Yeah, I was there as well last year as well. Measure 3 times before and after dry fit [emoji15]. 3M 5200 fast cure made sure I did not have any issues. Best value $ I have spent on the boat.

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Re: porpoising real bad need help
 

Anyone who sticks a hydrofoil on their outdrive needs to be shot and pissed on, and not necessarily in that order.

USE SMART TABS.

Re: porpoising real bad need help
 

Wow!

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Re: porpoising real bad need help
 

Had the same problem on my 94' Talari. Spoke to a buddy at the marina and asked if he had any ideas. First thing he asked after I described the problem is if I had a hydrofoil. His response was to take it off and enjoy my weekend lol. Removed it and I was good to go. He said his marina won't even install them anymore due to too many people having them put on and coming back a day later VERY upset. If it's not something you really need, be done with the thing and enjoy.

Brasky

Re: porpoising real bad need help
 

I bought my boat used with one installed. Should I remove it? Why do people install them?

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Re: porpoising real bad need help
 

I"m not sure it warrants the punishment that mikeyt suggests but many of us feel these hydrofoils don't provide the value the manufacturers claim. I'm not a Fluids Engineer so take my opinion with a grain of salt. My experience is most people install a hydrofoil to get better performance from their boat. If you think about how the hydrofoil works it doesn't make sense that it would improve performance. Quite the opposite, the hydrofoil exaggerates the effect of trimming the motor. If the motor is trimmed all the way down the hydrofoil increases the pressure on the bow of the boat and vice versa in the trim up position.
The problem is that while the hydrofoil provides increased lift on the bow as the motor is trimmed up, it has the inverse effect on the stern and pushes the stern down as it grabs water. The nose up position is what causes the porpoising. Trim tabs on the other hand provide lift on the stern of the boat and allow the motor to more naturally effect the attitude of the hull which allows for better handling and performance. Most boats are stern heavy and are designed to run on the back 1/3rd of the hull at speed. The challenge is we don't pull skiers or do most of our boating at full speed. Trim tabs allow the hull to ride in a similar attitude at slower speeds. They also help with getting on plane quicker due to the increased lift on the stern.
The other concern I have about hydrofoils is the increased pressure it applies to the anti-cavitation plate and the trim rams. This can cause issues over time.

Re: porpoising real bad need help
 

I know some guys who are genius with the tools to look at fluid mechanics. I actually spoke with one of them about this sort of thing a couple years ago when i got mine and he would agree.

In fact he would probably say if you fix the hull you don't need much on the outdrive but a propeller. A dynamic hull would be more effective than a dynamic drive, more like an inboard.

I'm surprised Mariah didn't put something like the smart tabs on the hull from the factory with them offering so much improvement for a low cost.

Re: porpoising real bad need help
 

Tell me how you really feel about whale tails, Mikey.....


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Re: porpoising real bad need help
 

I have a 94 Shabah Z206 that had the same problem. I went with the less expensive "plastic" smart tabs (vs steel) and they helped a ton. I'd recommend them as the others have. Good luck.

Re: porpoising real bad need help
 

I like the term composite better than "plastic". Plastic sounds kinda cheap:)

Re: porpoising real bad need help
 

Keep in mind that there is more adjustment capability on the SS tabs rather then the composite ones. Also, they stick out less but are wider.

Re: porpoising real bad need help
 

May be fixing to piss y'all off but my personal opinion is;
Trim tabs are solely for leveling boats due to either, lopsided loading or, steep deadrise hulls, inherently unstable. The absolute best situation for "the perfect plane" is, as little contact with the water as possible. Sticking trim tabs in the water flow is added drag. Remember, the ONLY purpose of the outdrives "trim" is to get as much boat (front) out of the water. And you want as much boat (drag) out of the water to make a more efficient plane.
Every boat I've ever owned, albeit they were all big bass boats, used trim up till either cavitation, prop out of water OR till you started porpoising.
You have to first understand why porpoising happens. When you trim up too much, the engine has enough power to lift the bow up but doesn't have the power to keep the bow up at that position. As the bow falls, the too high trim setting is now exaggerated and the motor snaps the bow up even higher. There is no problem here.
There are really only two ways to PROPERLY fix this.
Either, put a higher horsepower engine that can support the higher trim OR, quite simply, trim it down just enough to stop the galloping. What I'm saying is; if it's galloping, it's the boat and motors way saying "Too much". Ease off the trim just a little at a time till you find that split second between "too much" and "what the engine and hull can SUSTAIN."
There is no recommended trim height. The trim gauge is not meant to show you where your trim should be. Trim is set by the feel of the seat of your britches, by the sound of the engine (you can hear when your prop is biting and when it's just making bubbles) and by your speed.
Driving the nose back down with trim tabs, at the expense of mph, is counter productive because what they are doing is REVERSING the effect out the motor being too high, from the first place.
Try this game. Trim down, note your speed at exactly 3000 rpm. GPS is the best for this. Now, keeping the rpm at 3000, start bringing the nose up in short lifts. Watch your speed go up and notivce you'll have to ease off the throttle after every trim up. Keep lifting it in short burst till it starts galloping. What you'll find is your fastest speed was well before porpoising started. If you add trim tabs and use them for , untrimming of the engine(???), you WILL LOSE SPEED AND HULL EFFICIENCY.
Flame away boys!! I can take it.

Re: porpoising real bad need help
 

The tabs on my boat were added solely for minimizing the idle speed steering wander. The tabs eliminated that and I am happy because that was a real deal breaker for me. I lost no top speed, 55 mph before and 55 mph after. I do have them set to the lowest angle available.

Re: porpoising real bad need help
 

Same here GaryDoug. I have the port side all the way up and the starboard down just enough to level it. I've monkeyed with them to see if I could get any more top end but the more I lowered, the more top end I lost.

Re: porpoising real bad need help
 

"Level it" ?? Why? You may want to read this topic in another boating forum. You may have the same symptom if there is no explanation for the imbalance.
http://www.thehulltruth.com/boating-...l#post10546710

I should mention again, that I have the stainless versions and those have more adjustment capability (if you fix the design issues;-).

Re: porpoising real bad need help
 

Sorry dude, I've not made my point clear. What I was talking about, unstable, is only while underway. When I do get underway, I ask all my passengers to please stay in their seat ! The constant trim tab adjustments drive me crazy cause, I guess I'm Marine OCD. I want my boat perfectly level, side to side, while on plane ! (MOCD)
BTW, my boat sits level while at rest.
The best scenario I can come up with, to better explain what I'm TRYING to say about using trim tabs to the job of the engine trim.......
Let's pretend you're cruising along and you run the port trim down to level the boat. You accidently run it down too far and now it's listing to starboard. Instead of raising the port tab, you run the starboard tab down to over come your too deep port setting. BUT, you run the starboard tab down too far and now you're listing BACK to port. SO, you run the port down even more.......You get point, right? The fix would have been to lift the port tab a little, in the first place.
SO, your boat is porpoising and porpoising is from TOO MUCH UP TRIM. Lower your trim enough to stop the gallop.

There's several times I look back at something that I opined on and wish I'd kept my opinioned mouth shut. This is one of those times !!
Good day boys !:D