Stepped Hull Trim Tabs

[rtgogo]

OK guys...I've gotten a few days of seat time in and need advice. She's my very first boat, a 2000 22zx stepped hull with a 454 MAG EFI and Teleflex hydraulic steering unit. Saturday was pretty windy with a decent chop so i started playin with the trim tabs. I was glad to see they actually worked and enjoyed gettin a little more control over the balance of the boat...hit the wrong one a time or two, but didn't take long to get the hang of it..sorta...Then i remembered all those nightmare stories I was tormented by regarding stepped hull spin outs.

That Said...I need pointers on what to use these things for and what never to do. (High speed...low speed..straight shots, big turns...)

My main concern is makin sure i stay in a safe range while my five year old is screamin "go faster daddy"...

Please give me some insight so i can stay safe and have fun!

btw...I really appreciate all of your advice in my voyage. I found the right boat!

[BlownCrewCab]

If your using them to coutner effect a bad weight set up (Like a Fat friend sitting in the passanger seat) then you don't want to be going fast and juming wakes.

When going fast and jumping wakes both tabs should have the same input (both in the same position) but depending on what type of tabs you have, some should be UP when jumping, The bennets don't like hard landings when they are down, K planes don't usually care, though I have seen broken ones.

I don't think the tabs have much to do with a spinout on a step bottom, that usually accurs when the keel in front of the step has a good bite and the keel behind the step looses it's bite, It doesn't have to happen, slow down enough to make the turn you want. the stepped hull was built for speed going straight, not turning, just keep that in mind and you'll be fine.

[BlownCrewCab]

Also I feel if your boat goes over 60mph, trim tab indicators are a must. so you know exactly where they are. theres some made for every kind of tab...

[VetteLT193]

You can run tabs all you want as long as you are running straight.

In turns, the rule is tabs up drives out.

If you turn drives in / tabs down the nose wants to dive in too much which can cause a spin-out... during a spin the bottom can bite with the water causing a sudden braking force on the lowest part of the hull... the top naturally wants to roll from momentum so the boat flips.

Stepped hulls are more likely to have a problem because they already run loose so they are more likely to slide.

By putting the drives out and tabs up, the bottom stays firmly connected to the water which stops the slide in the first place.

[Tom A.]

Follow the above three rules and you can't go wrong. I also found on my 29' Kryptonite (27' running surface) that in a rough head on sea that I got my best ride by running the tabs neutral or just a tick down and the drives trimmed normal. This kept the boat level and better planted, reducing bow slap and letting the v do its job of slicing. I found by going slower, I was going overall faster.

[rtgogo]

Thanks for the advice...,makes sense, except i need clarification on the terminology "Drives in / out". I get the up and down on the tabs, but think I may be runnin the outdrive inproperly. I have basically left the tabs up and the outdrive trimmed "down" all the way. This past weekend was my first experience with the tabs and trimming the outdrive up a quarter or so to keep the boat from walkin on water at high speeds. Think I was hitting high 60's, but didn't have GPS and speedo just bounces all over the place so i don't pay it much attention. Please help me with the "in/out", i realize this is a stupid question, but i bought a Donzi for my first boat and just wanna know the right way to drive it.

That said, I hear ya on the indicators and picked up on one of the comments about the indicators being specifc to the tabs. I have Bennett tabs and wondering if I need to go with their inidicators or will Livorsi work? I want to mount them in the spare dash panel and Livorsi is the only one's I found that have a horizontal slimline mount. Are there any others universal ones i should research? Should i go with the Bennett indicators?

I really appreciate the advice! Sorry for my ignorance... ......Thanks!

[BlownCrewCab]

Stainless Marine makes good ones, with the no slack cable they are the ones I would use. they have a horizontal display also. You could even get the heads up display if you really wanted to be cool. The no slack cable lets you see exactly the movement of the tabs or drive.

[rtgogo]

I noticed the Bennett indicators are electric...Are the mechanical better?

[The Hedgehog]

I noticed the Bennett indicators are electric...Are the mechanical better?

The mechanical are more accurate and have more precise increments. The same story with drive indicators.

[Tom A.]

With the drive down (side profile of boat the drive is at a 90 degree angle to the hull) it will keep the bow down and you will be pushing through the water. This is what you want at idle and to get on to plane. The faster you go, the more you can and should trim the drive out (tilting slightly up from the 90 degree angle creating a more than 90 angle from a side profile). At each speed you will find a sweet spot of trim. The best way to do this is to take the boat out on a calm day, and start at a slower cruising speed (say 40mph). Slowly trim the drive out in increments. You should feel the boat pick up speed slightly and it will feel looser in the water. This is good. When you trim it too far it will feel real loose and and start over-reving for that speed and actually slow down. Do this through out all the different speeds to find the sweet spots. The amount of trim will typically coincide with the speed. i.e.- the faster you go the more trim.
One note, the rougher the conditions the less trim you will want to use to keep the boat planted, however it will usually have at least some trim.
Hope that helps.

[BigGrizzly]

Considering your talking about a 22ZX, The ball game changes! If you have not driven a 22ZX (no offense intended ) then your opinion is just hear say!!! That hull is different then any other stepped or normal V that I have driven. I have had lots of seat time in that boat over 60MPH as well as many other boats. It is a bread unto itself!! Tads are only good in idle to planing and should not be used except for ballast reasons then at a minim. The hook and the horror stories were when pushed to the limit and a non thinking driver! Donzi stopped putting tabs on that boat for a reason! Now if somebody doesn't jump in, but only if you have driven a 22ZX with a big block. Such as Baby Donzi or L'ill Grizz, both thoes have had lots of seat time and have pushed their boats to the limit!

[VetteLT193]

Considering your talking about a 22ZX, The ball game changes! If you have not driven a 22ZX (no offense intended ) then your opinion is just hear say!!! That hull is different then any other stepped or normal V that I have driven. I have had lots of seat time in that boat over 60MPH as well as many other boats. It is a bread unto itself!! Tads are only good in idle to planing and should not be used except for ballast reasons then at a minim. The hook and the horror stories were when pushed to the limit and a non thinking driver! Donzi stopped putting tabs on that boat for a reason! Now if somebody doesn't jump in, but only if you have driven a 22ZX with a big block. Such as Baby Donzi or L'ill Grizz, both thoes have had lots of seat time and have pushed their boats to the limit!

I'm in the hear say category, I've never driven a 22ZX... listen to Griz!

And: drives in = down. drives out = up

[Boiler56]

I have lots of seat time in my 22Zx, that is not stepped. I never use the tabs except getting on plane. I have found that you can manage just about all your trim needs at various speeds and conditions just using the drive.

[Uncle Fester]

I got lots of seat time in my 22ZX (big block). I've done the spin out at 60 (not fun).

I usually start with my tabs all the way up and the drive all the way down (unless I got a load and then I will tab all the way down to get on plane). Once I get on plane I run about 3500 RPM and start to bring my drive up. Just before the rooster breaks the water seems to be the sweet spot (watching GPS speedo). If I do break the water with my rooster I start dropping MPH so I look over my shoulder and get the rooster to just surface. Once I get the drive set, I hit the throttle. When I get up to about 60 the boat wants to porpoise. I then tap the tabs down for about one second on the switches evenly. Usually about 3 taps on the switch takes away the popoising (no tab indicators). Sitting on the trailer I've timed the length of travel (about 7 seconds from full up to full down). I leave the tabs alone from there for the rest of the day for the most part. Sometimes I'll pull them all the way up if I'm turning real tight but try to avoid turning tight and definitely not over 3200 RPM (I can still remember the spinout like it was yesterday)

[The Hedgehog]

I have driven the 22ZX step. I am in the "Listen to Griz" category on that one. It is a great hull but don't do too much bow down and turn.

I have owned a 27ZX non-step and now have a 26ZX step. Steps and non-steps have different rules. So do Pad V-'s and step Pad-V's. I have heard that a Velocity pad-v likes bow down in heavier water.

My 27ZX non-step was a superbly handling boat. It was pretty hard to screw up turns with tabs and trim. Don't wig out about the step but do exercise caution.

[rtgogo]

I'm learnin how to drive my boat and I'm nowhere near the water...thanks guys!....I wanna learn how to drive the boat and have some fun before i start wrenchin it for every horse. Please correct me if I'm wrong, but sounds like I should only be using the trim tabs to correct some tilt in the boat when i have a heavy side or throw them down temporarily to plane up at slow speeds...right?

To be on the safe side i might just leave them up for now and play with the outdrive trim to see what difference it makes. I really didn't plan on pushin the buttons till later in my first season except for the strong winds and big chop was pushin her to one side last weekend and I figured i had a good test environment. Will the outdrive trim make a big difference in the ride at 60+? I've left in all the way "in" most days, but sounds like that needs to be my first lesson instead of the messin with the tabs?

I really appreciate all your advice. Helps me understand what i have and how to respect it.

Thanks...keep it cumin, would love to learn more before i hit the wakes again this weekend!

[srlbrodkin]

I to have a 22zx stepped hull 7.4mpi procharger. Allot of good advice has been posted. I would add the conditions will play big role in tab input crosswind chop etc. I'm in Hawaii and a nice dayl is probably 2-3' chop on top of large swells makes florida water on a rough day look calm. Don't be afraid of the boat just use caution. A turn at 60 mph in any boat commands respect and caution. The drive angle will change speed and bow rise considerably. Bow down in rough water drive in. I would not recommend high speed turns with a 5 year old on board at any drive tab angle.
I also have a 7 year old. I have seen broken ribs in other boats v bottom from high speed turns with adults and experienced drivers. Bad hop or catch a wave.

Bruce

[rtgogo]

I took her out again this weekend. Water wasn't as choppy and wind was not as bad as last time, so instead of playin with the tabs i learned more about the outdrive trim...wow..had no idea it would make such a difference in ride...defintely got a lot looser with the drive out and felt like a rock skippin over the water instead of plowing thru it. One question... since i'm still nervous about the hull and turns and safety of my cargo.....I slow down for turns to say mid to high 40's and have the tabs up. Just wondering the safest position for the outdrive to make sure the boat is planted in the water? Felt like tabs up, drive in sits the a$$ in the water... but again...my first boat, so please tell me if i got it wrong.....I'm learnin....THANKS!

btw...sales guy at the dock approached me to say how much he loved the look of the boat....didn't say anything about those Sea Ray's he wuz pushin....:wink:

[The Hedgehog]

I took her out again this weekend. Water wasn't as choppy and wind was not as bad as last time, so instead of playin with the tabs i learned more about the outdrive trim...wow..had no idea it would make such a difference in ride...defintely got a lot looser with the drive out and felt like a rock skippin over the water instead of plowing thru it. One question... since i'm still nervous about the hull and turns and safety of my cargo.....I slow down for turns to say mid to high 40's and have the tabs up. Just wondering the safest position for the outdrive to make sure the boat is planted in the water? Felt like tabs up, drive in sits the a$$ in the water... but again...my first boat, so please tell me if i got it wrong.....I'm learnin....THANKS!

btw...sales guy at the dock approached me to say how much he loved the look of the boat....didn't say anything about those Sea Ray's he wuz pushin....:wink:

Your boat is much cooler than the Sea G....well I won't continue what my wife calls them.

Like Griz said, use the tabs for leveling for now. Do NOT trim it bow down and hit a hard turn. Keep it trimmed moderately. Maybe Lil Griz or someone can tell you exactly how much.

Do a key word search on the site. I know that Brian Tuvell, Frank Civatano or someone like that has initiated a spin out on purpose to see how it works.

[mjw930]

Your boat is much cooler than the Sea G....well I won't continue what my wife calls them.

Like Griz said, use the tabs for leveling for now. Do NOT trim it bow down and hit a hard turn. Keep it trimmed moderately. Maybe Lil Griz or someone can tell you exactly how much.

Do a key word search on the site. I know that Brian Tuvell, Frank Civatano or someone like that has initiated a spin out on purpose to see how it works.

I agree with HH 100%, DO NOT trim down for high speed turns. Ventilated bottom boats had less rear bite than a traditional hull and if you let the bow grab you can easily hook the boat since the front will have significantly more bite than the rear.

Ventilated hulls slip more in turns that traditional hulls but you want to make sure you keep the inside part of the hull in the water. Most of the spinouts are caused by hooking bows or hitting off camber waves that let air under the inside hull. That causes the inside to lift and the boat to roll over to the outside causing a weight shift and the spinout.

I think anything under 40 mph wouldn't be considered a high speed and all these "horror stories" are more for the 50+ turns that you see in racing or other competition.

If you are a snow skier think of the difference between carving a turn (traditional bottom) with long downhill skis vs sliding with shorter skis (ventilated hull)

[rtgogo]

OK..thanks for the advice...now please help me understand. sorry for my ignorance...think i get it as far as the tabs go. I keep them up unless I'm idling at a slow pace..say 30mph and wanna drop the bow OR I need a little help balancing the boat when I don't have a rider or one has joined that hasn't missed any meals...right?

Now for the outdrive trim...I noticed the boat felt much looser when i trimmed it out...the ride was a lot smoother than what I've had up to this point by keeping the drive in. figure that must be from pullin the bow up outa the water where i had it buried the whole time I was runnin with the drive all the way in. SO my false sense of security to trim in when makin turns was actually more dangerous...right?...fellin kinda stupid right now...I really appreciate all the insight and boating lessons...friends don't have fast boats and don't understand why i keep askin about things that don't impact the ride of their water taxi's....

think I'm gettin it.....

thanks!

[ltl_mac2000]

I have a '99 22ZX with a 502MAG, stepped hull, and have a decent amount of seat time too. I agree that it is important to keep the drive trimmed up, especially when making turns so the bow of the boat is always elevated. 1/4 to 1/3 up tends to be sweet spot for me depending on speed. I have used GPS to find best speed/feel combinations.

Although it seems contradictory to some of these posts, I tend to use the trim tabs a lot when running through the ocean on choppy days. I certainly am careful about turning, but keeping that bow down and tabs in the water can give a 22' the feel of a longer boat in the chop. You actually are using the V of the bow to cut through the water rather than keeping the a~~ of the boat from hopping across the water. Certainly only my opinion, but since I can't afford to buy a 26', I have spent a decent amount of time trying to get a smoother ride in this boat.

I am curious to see if some of you will say to just trim the drive down instead. I have tried that too, and seem to get better RPMs/speed with drive up and tabs down. I feel like the tabs offer more stability and actually work to put more surface length on the water.

[The Hedgehog]

I have a '99 22ZX with a 502MAG, stepped hull, and have a decent amount of seat time too. I agree that it is important to keep the drive trimmed up, especially when making turns so the bow of the boat is always elevated. 1/4 to 1/3 up tends to be sweet spot for me depending on speed. I have used GPS to find best speed/feel combinations.
Although it seems contradictory to some of these posts, I tend to use the trim tabs a lot when running through the ocean on choppy days. I certainly am careful about turning, but keeping that bow down and tabs in the water can give a 22' the feel of a longer boat in the chop. You actually are using the V of the bow to cut through the water rather than keeping the a~~ of the boat from hopping across the water. Certainly only my opinion, but since I can't afford to buy a 26', I have spent a decent amount of time trying to get a smoother ride in this boat.
I am curious to see if some of you will say to just trim the drive down instead. I have tried that too, and seem to get better RPMs/speed with drive up and tabs down. I feel like the tabs offer more stability and actually work to put more surface length on the water.

What kind of speed are you getting out of that 502 mag / 22ZX combo. It should run pretty good.

[ltl_mac2000]

What kind of speed are you getting out of that 502 mag / 22ZX combo. It should run pretty good.

My top speed on the GPS is 73 MPH. Got that once, by myself, perfect wind and chop. I can get a consistent 69. I am actually a little disappointed right now, because I am only getting about 5800 RPM after a new motor last season. I added Stainless Marine Headers and Risers too. I used to get about 6200 RPM but didn't have GPS so I am not sure about speed. Don't get me wrong, 70 MPH on water is awesome but still wonder if something is a little off.

Anyone feel free to comment if they have any suggestions or comments about RPM loss.

[mjw930]

I have a '99 22ZX with a 502MAG, stepped hull, and have a decent amount of seat time too. I agree that it is important to keep the drive trimmed up, especially when making turns so the bow of the boat is always elevated. 1/4 to 1/3 up tends to be sweet spot for me depending on speed. I have used GPS to find best speed/feel combinations.

Although it seems contradictory to some of these posts, I tend to use the trim tabs a lot when running through the ocean on choppy days. I certainly am careful about turning, but keeping that bow down and tabs in the water can give a 22' the feel of a longer boat in the chop. You actually are using the V of the bow to cut through the water rather than keeping the a~~ of the boat from hopping across the water. Certainly only my opinion, but since I can't afford to buy a 26', I have spent a decent amount of time trying to get a smoother ride in this boat.

I am curious to see if some of you will say to just trim the drive down instead. I have tried that too, and seem to get better RPMs/speed with drive up and tabs down. I feel like the tabs offer more stability and actually work to put more surface length on the water.

The discussion / argument regarding tabs vs. outdrive for rough water trim depends a lot on how big the water is and how fast you are going.

If the water is big enough and you are going fast enough to get airborne (and I mean completely unweight the boat) then there are 2 reasons to use the drive instead of the tabs for attitude.

1. Unless you have K-Planes (and I've seen enough of them break too) you run the risk of snapping the plate or pulling it out of the hull. Bennett's are not intended to carry the entire weight of the boat in the vertical axis and that's exactly what happens when you re-enter the water.

2. Using the drive trim allows you to power into the wave and force the boat to maintain it's forward or horizontal trajectory. If you have the drive trimmed up and are powering into the wave you will add a vertical component to your boat's direction and that will cause the bow to fly up if you hit a wave wrong or apply power at the wrong time. If you are not powering into the waves and just trying to maintain a constant speed then it's not as much of an issue but you are still putting two forces against each other, the bow rise caused by the trimmed out drive and the stern rise caused by the trim tabs.

Here's an exercise you can try that's reasonably safe and will give you a feel for how to handle rough water. Assume you are running at a moderate cruising speed, say 40 mph. When you are crossing over the wake of another boat (doesn't matter if you are overtaking or passing) turn the bow into the wave to get perpendicular and as you feel the boat start to rise into the wave give the throttle a bump. You'll feel the boat maintain more of a horizontal motion than you are used to, the bow won't rise as much and your re-entry will be smoother. You can play around with this until you get a feel for just how much power to apply. Don't mash the throttle down because you could lose control if you time it wrong.

And as with everything else, there's no substitute for seat time.

[mjw930]

My top speed on the GPS is 73 MPH. Got that once, by myself, perfect wind and chop. I can get a consistent 69. I am actually a little disappointed right now, because I am only getting about 5800 RPM after a new motor last season. I added Stainless Marine Headers and Risers too. I used to get about 6200 RPM but didn't have GPS so I am not sure about speed. Don't get me wrong, 70 MPH on water is awesome but still wonder if something is a little off.

Anyone feel free to comment if they have any suggestions or comments about RPM loss.

Same prop?

[mjw930]

Now for the outdrive trim...I noticed the boat felt much looser when i trimmed it out...the ride was a lot smoother than what I've had up to this point by keeping the drive in.

Loose = Fast. Comfort = Seat Time.

As with everything else you are safer doing this in moderation. Don't do anything that makes you uncomfortable but probe the limits because you'll never stop learning about boat handling. Once you get comfortable at one speed then bump it up a notch. I as taught to run fast by some pretty experienced guys (Steve Stepp, Steve Kildahl, Pepper Ernest, and others with the Velocity team) and they moved me up in 10 mph increments. I was originally intimidated with the 65 mph boat when I first bought it but after a season we did the motor and was well into the high 70's. After another season there we did some motor, drive, bottom and prop tweaks and had her running on the low 80's. Had I tried to run low 80's the first year I had the boat I probably wouldn't be here to type about it. When it was all said and done I was able to feel perfectly comfortable making 90 degree turns at 80 MPH with the boat aired out :D It's not point and shoot at those speeds, your hands are always moving but you drive more by what you feel the boat doing under your feet / ass than you do looking over the bow. Hence the term "Seat Time".

[The Hedgehog]

My top speed on the GPS is 73 MPH. Got that once, by myself, perfect wind and chop. I can get a consistent 69. I am actually a little disappointed right now, because I am only getting about 5800 RPM after a new motor last season. I added Stainless Marine Headers and Risers too. I used to get about 6200 RPM but didn't have GPS so I am not sure about speed. Don't get me wrong, 70 MPH on water is awesome but still wonder if something is a little off.
Anyone feel free to comment if they have any suggestions or comments about RPM loss.

Are you sure that it is not 5,200 and 4,800?

[ltl_mac2000]

The discussion / argument regarding tabs vs. outdrive for rough water trim depends a lot on how big the water is and how fast you are going.

If the water is big enough and you are going fast enough to get airborne (and I mean completely unweight the boat) then there are 2 reasons to use the drive instead of the tabs for attitude.

1. Unless you have K-Planes (and I've seen enough of them break too) you run the risk of snapping the plate or pulling it out of the hull. Bennett's are not intended to carry the entire weight of the boat in the vertical axis and that's exactly what happens when you re-enter the water.

2. Using the drive trim allows you to power into the wave and force the boat to maintain it's forward or horizontal trajectory. If you have the drive trimmed up and are powering into the wave you will add a vertical component to your boat's direction and that will cause the bow to fly up if you hit a wave wrong or apply power at the wrong time. If you are not powering into the waves and just trying to maintain a constant speed then it's not as much of an issue but you are still putting two forces against each other, the bow rise caused by the trimmed out drive and the stern rise caused by the trim tabs.

Here's an exercise you can try that's reasonably safe and will give you a feel for how to handle rough water. Assume you are running at a moderate cruising speed, say 40 mph. When you are crossing over the wake of another boat (doesn't matter if you are overtaking or passing) turn the bow into the wave to get perpendicular and as you feel the boat start to rise into the wave give the throttle a bump. You'll feel the boat maintain more of a horizontal motion than you are used to, the bow won't rise as much and your re-entry will be smoother. You can play around with this until you get a feel for just how much power to apply. Don't mash the throttle down because you could lose control if you time it wrong.

And as with everything else, there's no substitute for seat time.

Yes...I should have stated that this is when I am in "relax" mode with some people on the boat and don't feel like working the throttle. Although airborne is a lot more fun, its equally as much work!! I run the Bennett's and I have seen them broken out of hulls too. So if I am out of the water...they are all the way up.


Same prop?

Yes, same prop. I actually was anticipating having to re-prop in order to not hit rev limiter.

[ltl_mac2000]

Are you sure that it is not 5,200 and 4,800?

My bad...yes..4800 and 5200. It's been a long winter....lots of Crown Royal and late nights. Can't wait to get the cover off and back out on the water!! Thanks for the correction Hedgehog.

[mjw930]

My bad...yes..4800 and 5200. It's been a long winter....lots of Crown Royal and late nights. Can't wait to get the cover off and back out on the water!! Thanks for the correction Hedgehog.

What else changed between the 2 tests?
What motor did you have before the repower?
What prop are you running?
Did you replace gauges?

[ltl_mac2000]

What else changed between the 2 tests?
What motor did you have before the repower?
What prop are you running?
Did you replace gauges?

Same size motor. I replaced the block, pistons and the valves. I am not a mechanic, but I would assume a new CAM is included in block replacement. Also, changed from stock headers and risers to Stainless Marine Headers and Risers. Expected to gain 200 - 300 RPM from that alone.

Pretty sure I run a Bravo 26P. (Boat has been in storage all winter and I can't find my notes).

Didn't replace any gauges.

[The Hedgehog]

I unless something is amiss, you should pick up 100-200 rpm for the exhaust alone.

[ltl_mac2000]

Yes I that is what I thought. I have two conclusions; 1) my tachometer is not accurate 2) potential CAM ratio is different from previous motor.

I feel like my speed is about right, so I am not going to spend a lot of time chasing it. But it would be nice to know if there is something wrong.

Thanks for all of your questions/comments.

Danny

[mjw930]

Not really rocket science, if you didn't change the gauges or prop the only way it's turning less RPM's is because it's making less power.