Learned something new about trim tabs...

[Dave R]

I learned a new new technique for smoothing the ride on rough water last year and have been experimenting with it this year with excellent results. Until recently, I only used my trim tabs to reduce my time to plane, lower my planing speed, and level the boat, which they excel at. I also discovered that that do a phenomenal job of smoothing out the ride at speed.

In the past when I was approaching an oncoming wake that was big enough to cause discomfort, I'd throttle back, ride over the wake at 10-15 MPH below my cruising speed, then throttle up to get back to my cruising speed. It was effective but wasted fuel. Now I just leave the throttle alone and put both tabs way down before I hit the wake. This lifts the stern and forces the bow down rather hard which makes it slice through the wake smoothly rather than ride over it. I only lose 2-3 MPH when the tabs are down, but the ride is remarkably smooth.

If it's choppy, I just leave them down and have found that I can often make the ride even smoother by throttling up, which seems counter-intuitive, but really works. My fuel consumption in MPG is substantially lower at 35 MPH than it is at 20 MPH, so not only do I make better time and enjoy a smoother ride, I save money too.

If you have trim tabs, try this technique out. If you have a planing-hull boat, but don't have trim tabs, put them on or near the top of your wish list if you plan to spend any time on Winnipesaukee. They are worth every cent

[rick35]

I put Smart Tabs on my 18 foot boat that I trailer for just that reason. A light boat will go up and over waves but with the tabs the boat will cut through a lot of them. They're relatively inexpensive and are easy to install with no lines or controls. And they are adjustable and come in different pressure sizes depending on the size of the boat. They work for me.

[jeffk]

In a similar vein, the trim tabs can also be used to reduce or eliminate porpoising. When the wave spacing and current running characteristics of the boat cause the bow to bounce up and down continually, using the trim tabs to force down the bow can be very effective. As noted, there is more drag from the tabs and probably pushing through the waves makes the engine work harder but I just push the RPMs up to compensate and enjoy the smoother ride. Yes, you will burn more gas. C'est la vie.

However, just thinking this through further, when the pounding caused by porpoising would cause me to drop speed to just about planning (18 MPH), it's fuel inefficient. Using the tabs allows me to get closer to the "sweet spot" of fuel efficiency around 25 - 35 MPH as the boat lifts further out of the water. The fuel cost of using the tabs may not be all that much?

[Broken Glass]

I learned a new new technique for smoothing the ride on rough water last year and have been experimenting with it this year with excellent results. Until recently, I only used my trim tabs to reduce my time to plane, lower my planing speed, and level the boat, which they excel at. I also discovered that that do a phenomenal job of smoothing out the ride at speed.

In the past when I was approaching an oncoming wake that was big enough to cause discomfort, I'd throttle back, ride over the wake at 10-15 MPH below my cruising speed, then throttle up to get back to my cruising speed. It was effective but wasted fuel. Now I just leave the throttle alone and put both tabs way down before I hit the wake. This lifts the stern and forces the bow down rather hard which makes it slice through the wake smoothly rather than ride over it. I only lose 2-3 MPH when the tabs are down, but the ride is remarkably smooth.

If it's choppy, I just leave them down and have found that I can often make the ride even smoother by throttling up, which seems counter-intuitive, but really works. My fuel consumption in MPG is substantially lower at 35 MPH than it is at 20 MPH, so not only do I make better time and enjoy a smoother ride, I save money too.

If you have trim tabs, try this technique out. If you have a planing-hull boat, but don't have trim tabs, put them on near or at the top of your wish list if you plan to spend any time on Winnipesaukee. They are worth every cent

When I am approaching a large wake, or if I am riding across and into a chop, I trim the boat OUT of level, and position the bottom of the boat so that it takes the wake or chop evenly across the shape of the bottom of the boat. ("present your bottom") This procedure prevents the hard contact with just one side of your boat bottom which is essentially slamming the flat side of your hull against the rough water. After crossing the wake, or changing the course direction, the out of trim attitude is no longer needed and I return the boat to a level running attitude.
I also installed auto trim tab controls. This makes returning to a level efficient running attitude as simple as pushing a button!

[persistence]

Just be careful not to bow steer. If in a following sea and the tabs are set with bow down to far, the bow can bury into the back of the next wave and 'steer'. You can lose control that way. It can get scary fast.:)

[Dave R]

However, just thinking this through further, when the pounding caused by porpoising would cause me to drop speed to just about planning (18 MPH), it's fuel inefficient. Using the tabs allows me to get closer to the "sweet spot" of fuel efficiency around 25 - 35 MPH as the boat lifts further out of the water. The fuel cost of using the tabs may not be all that much?

I installed a gauge in my boat the measures speed and fuel flow and compares them to display near real-time MPG to two decimal places and it updates once per second. Running with the tabs down at a full plane is substantially more efficient than running at barely planing speed (regardless of tab position). I lose about 10% economy when I run the tabs down at speed. I lose at least 30% when I am barely on plane.

[Dave R]

Just be careful not to bow steer. If in a following sea and the tabs are set with bow down to far, the bow can bury into the back of the next wave and 'steer'. You can lose control that way. It can get scary fast.:)

The ride is typically smooth enough in following seas that I don't need to bother with tabs and if it's bad enough for bow steer to be an issue, I'm usually going slow enough to surf. Also, my hull has laminar flow disruptors that seem to do a great job of preventing bow steer. They make a really cool noise when they are working too... You can see them in this picture of a boat that's like mine:http://www.boatingabc.com/photos/data/500/medium/regal_side1.jpeg

[radiocontester]

Tha is for the tip Dave! I will give that a shot the next time I'm on the lake. I have a 28' cruiser and have only used the tabs to get on plane quicker with a heavier load as well as level it out on plane if uneven weight distribution. In all other circumstances I leave them up. I look forward to trying them out the way you describe.


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[VitaBene]

I added tabs to my boat this off-season mainly to level (24 degree hull really exacerbates weight distribution issues), but I am really looking forward to this benefit as well.

[Descant]

In a similar vein, the trim tabs can also be used to reduce or eliminate porpoising. When the wave spacing and current running characteristics of the boat cause the bow to bounce up and down continually, using the trim tabs to force down the bow can be very effective. As noted, there is more drag from the tabs and probably pushing through the waves makes the engine work harder but I just push the RPMs up to compensate and enjoy the smoother ride.
In my experience, porpoising is often caused by improper outboard/outdrive setting i.e. the drive is too far out from vertical. You may be able to stop spanking by bringing the engine in a little, then you can use the trim tabs for all the other things described in this thread.

[jeffk]

In my experience, porpoising is often caused by improper outboard/outdrive setting i.e. the drive is too far out from vertical. You may be able to stop spanking by bringing the engine in a little, then you can use the trim tabs for all the other things described in this thread.

I might agree except that I can be traveling along for quite a while without a problem, i.e. the engine trim is fine, and then, without a change of speed, the porpoising starts. You can correct by changing the engine trim or you can use the trim tabs. Either one can force the bow down, which is the effect you want.

[jeffk]

I installed a gauge in my boat the measures speed and fuel flow and compares them to display near real-time MPG to two decimal places and it updates once per second. Running with the tabs down at a full plane is substantially more efficient than running at barely planing speed (regardless of tab position). I lose about 10% economy when I run the tabs down at speed. I lose at least 30% when I am barely on plane.

Really neat. I was envisioning that someone could monitor this to find out but not without installing special equipment. :D Nice to know.

[Woody38]

The only boat I had with tabs was the 37 foot Egg Harbor and they worked wonders. On my boats without tabs when crossing a wake I would come along parallel to the wake then steer into and over while steering the opposite direction when on top of the wake. Like a lazy S curve. Seemed to work fine for me.

I am a retired workaholic and continuing aquaholic.

[Dave R]

Tha is for the tip Dave! I will give that a shot the next time I'm on the lake. I have a 28' cruiser and have only used the tabs to get on plane quicker with a heavier load as well as level it out on plane if uneven weight distribution. In all other circumstances I leave them up. I look forward to trying them out the way you describe.


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Please report back, I'm eager to hear about your results.

[MeredithMan]

I found it to be extremely annoying and had the marina disconnect it. I like to set the tabs and forget about them...not have to continually re-set them every time you start the engine. A real pain when tubing/skiing or other water sports from the back of the boat when you are starting and stopping the engine every few minutes to allow people to get in and out of the water.

[Dave R]

I found it to be extremely annoying and had the marina disconnect it. I like to set the tabs and forget about them...not have to continually re-set them every time you start the engine. A real pain when tubing/skiing or other water sports from the back of the boat when you are starting and stopping the engine every few minutes to allow people to get in and out of the water.


I'd like to have two push buttons, one that puts them all the way down with a quick push and another that retracts them all the way up with another push. I should build a circuit for that... Right now, I have to hold two toogle switches up for 12 seconds to put them down, and hold the same two toggle switches down for 12 seconds to retract them.

[jeffk]

I'd like to have two push buttons, one that puts them all the way down with a quick push and another that retracts them all the way up with another push. I should build a circuit for that... Right now, I have to hold two toogle switches up for 12 seconds to put them down, and hold the same two toggle switches down for 12 seconds to retract them.

I would also like a memory feature that puts the tabs into the "usual" position for operation. The "usual" is just my wife and I in the boat, one on each side. If the load or conditions are different, I can make small changes from there.

[Broken Glass]

Last year I installed a new control on my trim tabs that does just that. The way that it works is like this. You set you boat up for the desired cruise speed and attitude desired. Hold in two buttons until you get a steady light. Now whenever you set your throttle to that desired cruise speed, just hit the power button and the auto feature does the rest. .IF two people got up and moved to one side of the boat, the auto tabs would keep the boat level. It is a pretty cool feature and not very expensive to install.
https://www.westmarine.com/buy/bennett-marine--ac3000-auto-trim-tab-control--8618662?cm_mmc=PS-_-Google-_-GSC%2520-%2520Product%2520Type-_-8618662&product_id=8618662&adpos=1o4&creative=108421551724&device=c&matchtype=&network=g&gclid=COn7kM_8i9QCFYaPswod7_kA0w

[bobkatfly]

So I don't have tabs on my boat but after reading all this I'm feeling really incomplete. Can any of you make a recommendation on brand, electric vs hydraulic, etc. I'm running a 21 ft Regal LSR bowrider with Merc 4.3/Alpha one. Maybe should have started new thread? Oh well, I'm pleading junior member.
Bob F.

[Rich]

I'd like to have two push buttons, one that puts them all the way down with a quick push and another that retracts them all the way up with another push. I should build a circuit for that... Right now, I have to hold two toogle switches up for 12 seconds to put them down, and hold the same two toggle switches down for 12 seconds to retract them.

Bennett has an auto trim pro that seems to have these features, plus two preset settings, and more. It's only money, right?

[Dave R]

So I don't have tabs on my boat but after reading all this I'm feeling really incomplete. Can any of you make a recommendation on brand, electric vs hydraulic, etc. I'm running a 21 ft Regal LSR bowrider with Merc 4.3/Alpha one. Maybe should have started new thread? Oh well, I'm pleading junior member.
Bob F.

My Bennetts are 17 years old and still working perfectly. When I had a 1998 Regal 2100 LSR, I was planning to install Bennett M120s on it, but I bought a different boat before made the upgrade. I think they would be a great choice for you. Lenco tabs are also popular and have a good reputation. Smart tabs may have the desired effect for much less money, but are not adjustable on the fly.

Your boat has the same David Livingston hull design as mine and I am very confident it will respond astoundingly well to the technique I started this thread with. If you can get that extremely fine-entry bow down so that it pierces the waves, the boat should ride much much more smoothly.

[Dave R]

Bennett has an auto trim pro that seems to have these features, plus two preset settings, and more. It's only money, right?

That's a sweet piece of kit, but 400 bucks, yowza....

[BroadHopper]

I could write a book on these. As well as single vs dual drives.

Trims adjust the 'attitude' of boats. I think of engine trim to adjust porpoising and bow steer. Engine trim also adjust for the bow rise when accelerating. Once I get to a cruising speed, I adjust the engine trim to level the boat to an optimum comfort level base on speed and condition of the chop.

Trim tabs are used to adjust for the port/starboard attitude of the boat. If the boat is lower on the port side than increase the port tab. Bennett trim tabs are wire so that when you lower the port button it does the opposite, it lowers the port trim and rise the starboard. And vice versa. Increasing both tab buttons lowers the trim.

As in Dave reply above, you can use the trim tabs to adjust the attitude of the boat when approaching a rough wake. depending on the type of hull, increasing the trim tab buttons can make the boat 'plow' the wake. Deep vees prefer to slice the wake under the driver like a knife.

I can go on and on, but that can be discuss over a beer at the NAZ. Anyway I think you get the drift.

[bobkatfly]

Great info everyone. I'm gonna do it. Now decision time.

1) Self leveling or controlled. I like pushing buttons and tweaking things but there's a considerable cost difference. Anyone had remorse after installing self leveling?
2) Bunch of choices from Bennett. Tab sizes, tab shape, standard trim, sport trim. Some, like the Bolt series, require the controls to be purchased separately. Dave, what drove your decision for the M120? I'd rather a complete kit.
3) Convincing wife that it's a good idea. Maybe this has to be #1.

[Dave R]

Dave, what drove your decision for the M120? I'd rather a complete kit.


I just used the Bennett size guidelines. The 120s are recommended for 19 to 23 foot boats.

See: https://bennetttrimtabs.com/tab-sizing-guidelines/