Smart Tabs Question

Ok I read about 5 or 6 threads on this subject but none of it really answered my question. maybe even made me have more..

I just did the install on a 17.5 foot 73 arrowglass viper tri hull 165 hp I/O omc stringer.

I am pretty sure I have them installed pretty well. although I was a little curious as to how to align them with the tri-hull part of the transom.
it's not flat, it curves.. so I split the difference. I am centered on the arc, flush with the center of the arc and about an inch up on the outer part of the arc. I think I am good to go there.

Here's my real questions, How Do I set my trim? I have selectrim, and just installed the motor (have not used it yet) I had been trimmed with the front of the motor all the way up.. mostly because the bow came up pretty hard on acceleration. once I got on plane it seemed to level out ok... but hit some wake etc and the front end still came up more than I would like. also when towing a tube with the kids on it.. I lost a LOT of speed and the motor tended to run warm like it was working to hard (never got over 210 but thats too hot for my liking.. especially since it runs about 160 -180 when NOT towing. oh and yes it's got a new impeller)

Do I set the trim center and start from there? or leave it closer to the top where I was running before I got the motor?

How do I know if I need to adjust what hole I am in? their website and instructions are a little vague.. what do I look for? and how do I know if it is trim or mart tabs that need adjusting?

I can't wait to get her out on the water and see how it handles...

Hope there is enough info there to get me pointed in the right direction... I can post pics if it will help.

Thanks

Re: Smart Tabs Question

I would set the trim as high (front mounts low) as you can get away with. You're going to have to test it . . .

Re: Smart Tabs Question

I suggest you send an email to the manufacturer, Nauticus, and ask for their advice. The customer service team there is VERY responsive; you'll probably have an answer within 12 hours.

Re: Smart Tabs Question

Thanks guys I was just hoping for some pointers. I guess I'll find out.

Re: Smart Tabs Question

Hey man, your motor should be all the way down why getting on a plane. The best trust and best bang for the work of the motor is at a 90 degree angle to the hull. With the smart tabs installed, you should have to do very little trimming if any with the motor when they are dialed in right.

I would try the center position first. If the bow stays down nicely while getting on plane it is probably ok in that position. But each time you go out for the next few times,change the position and see what you think works best. Remember though, the motor should be all the way down for best thrust at idel to planing speed. Once on a plane you can adjust your trim to gain a little speed. To much trim and you will porpouse, but you should be able to tell when it is to much trim. You will love these trim tabs, they helped improve my boats performance in alot of catagories. good luck and enjoy.

metalwizard said:

Ok I read about 5 or 6 threads on this subject but none of it really answered my question. maybe even made me have more..

I just did the install on a 17.5 foot 73 arrowglass viper tri hull 165 hp I/O omc stringer.

I am pretty sure I have them installed pretty well. although I was a little curious as to how to align them with the tri-hull part of the transom.
it's not flat, it curves.. so I split the difference. I am centered on the arc, flush with the center of the arc and about an inch up on the outer part of the arc. I think I am good to go there.

Here's my real questions, How Do I set my trim? I have selectrim, and just installed the motor (have not used it yet) I had been trimmed with the front of the motor all the way up.. mostly because the bow came up pretty hard on acceleration. once I got on plane it seemed to level out ok... but hit some wake etc and the front end still came up more than I would like. also when towing a tube with the kids on it.. I lost a LOT of speed and the motor tended to run warm like it was working to hard (never got over 210 but thats too hot for my liking.. especially since it runs about 160 -180 when NOT towing. oh and yes it's got a new impeller)

Do I set the trim center and start from there? or leave it closer to the top where I was running before I got the motor?

How do I know if I need to adjust what hole I am in? their website and instructions are a little vague.. what do I look for? and how do I know if it is trim or mart tabs that need adjusting?

I can't wait to get her out on the water and see how it handles...

Hope there is enough info there to get me pointed in the right direction... I can post pics if it will help.

Thanks

Click to expand...

Re: Smart Tabs Question

ChrisCraft, thank you that is the kind of input I was hoping for.

My Trim motor got delayed by the hurricane... so I may not have it for the weekend. Right now it is trimmed all the way up... going to get the Makita out and trim it down at least half way maybe more.. (yeah I made a little thingy to run the trim with my Makita until I get the right motor. I can't adjust it while its running but I can when I am stopped and engine off..

Redneck engineering at its finest LOL

I REALLLLY can't wait to get her on the water with these Tabs on her...

Re: Smart Tabs Question

My advice was based on thinking you had fixed trim. Sorry for the confusion. I couldn't remember if selectrim was their fixed trim name or not.

Once you are at speed the tabs should be pretty much out of the way. They do always exert some pressure down, but at the same time you want to be able to get the bow out of the water. While Chris' comments about 90 degrees seem logically true, the fact is that positive trim (up or out) gets the bow up and out of the water, which is faster and more efficient at planing speeds. 90 degrees is actually not optimum for speed. You need to consider efficiency and speed as kind of the same thing. While in a car that may seem counter-intuitive, if the throttle setting is the same and trim gets you more speed, in effect it is more efficient. Actually faster for the same amount of fuel (throttle setting). This is not a scientifically perfect example, but for simplicity you should consider it as true.

Sooooo, what I will say, at higher speeds, you should at least try for the highest trim settings possible without porpoising. If you are not porpoising, and you can't trim all of the way out or up (OMC selectrim front motor mounts down) then I would try for a lower pressure setting on the tabs. What you want is help at low speeds, but as little as possible pressure at higher speeds so you can trim the bow up and out.

And to head off any possible confusion, those of you that do not understand Stringer trim systems need to know that trim and tilt are absolutely different and separate systems. There is no "trim" setting that is too high for the u-joints, because there are none . . .

Re: Smart Tabs Question

If you trim too high your thrust gets wasted.
Water being denser that air is better to push against.
90 degrees is in fact closer to optimum than one would think, it really depends on hull design.
People far to into trying to over trim which can very easily cause an unsafe situation and is less efficient.
It's a balance you need to learn on your boat, non are the same.

Example: Mercury decided to do all their outboard testing on Velocity's after noting that they ride bow down at top speed. Once they get up on their pad they run level. Some even had hook built into the hull to keep the bow down. Hydrostream did the same with windsheilds.

Trying to shove the boat upward past a point wastes power. For one your losing thrust, two your spend it on moving up not forward, and third your making the front of your boat a bigger wall that your pushing through the air.

Play with it! It's the only way you'll find out.

Re: Smart Tabs Question

I don't know your specific model tri-hull, but most that I do remember from that time frame, were very stabil boats, fast planning, but hull pounded in chop, and turns were more wider than a v, and kind of slid like a flat bottom boat. But maybe yours has more characteristics of a v bottom. If you need more bow lift, that is only going to come from your trim adjustment or choosing the right prop. Smart tabs help with reducing bow rise on planing, and high speed porposing. Smart tabs are great, and I love the changes they did to my boats, but having a "cloudy" vision of how they can help a tri-hull.

Re: Smart Tabs Question

Hey man, we are basically saying the same thing. Don't know if you have experience with the Nauticus smart tabs or not,but when they are set in the right position, they will keep your bow down while getting on a plane. Once you reach a certain speed/pressure under the tabs, the tabs relax through a bypass valve. The tabs will still have pressure that will constantly adjust, but with less drag. Keeping your motor/prop at 90 degrees to the boat transom is most definately the most effecient use of the motor. I get what your thinking that by trimming the motor while on plane you will gain speed, but the fact is, though your gaining speed and getting more speed, you may not be getting better fuel economy. Why, because your motor is caused to work harder while not in the most optimal thrust position. If your motor is working harder, it will be burning more fuel and putting more stress on the motor..

Though, I do trim my motor after on a plane sometimes, the trim tabs I installed have made it so I really never have to use the motor trim. The other areas these smart tabs have helped is I can make hard turns at any speed and get no cavitation. While trolling or cruising the boat doesn't wonder any more at all because the tabs constantly adjust keeping the boat going straight. I gained 4mph on the top end/wot. My bow stays down atleast 50 percent lower than it use to without the tabs. And I can plane off in half the rpm/speed and time it use to take to get my beast out of the water.

The reason I mentioned all these things, is this equals fuel efficiency, when you have to pull only half the rpms to get on a plane and your bow is on a more level plane while getting on a plane, it keeps that prop/motor at a more efficient angle at all times in reference to the water.

If you guys want to see some very good and edjucating information on prop thrust and effeciency, check out this link!!! I promise it is very good info. http://www.nauticusinc.com/pdf/nauticus_smart_tabs_tech_info.pdf

QC said:

My advice was based on thinking you had fixed trim. Sorry for the confusion. I couldn't remember if selectrim was their fixed trim name or not.

Once you are at speed the tabs should be pretty much out of the way. They do always exert some pressure down, but at the same time you want to be able to get the bow out of the water. While Chris' comments about 90 degrees seem logically true, the fact is that positive trim (up or out) gets the bow up and out of the water, which is faster and more efficient at planing speeds. 90 degrees is actually not optimum for speed. You need to consider efficiency and speed as kind of the same thing. While in a car that may seem counter-intuitive, if the throttle setting is the same and trim gets you more speed, in effect it is more efficient. Actually faster for the same amount of fuel (throttle setting). This is not a scientifically perfect example, but for simplicity you should consider it as true.

Sooooo, what I will say, at higher speeds, you should at least try for the highest trim settings possible without porpoising. If you are not porpoising, and you can't trim all of the way out or up (OMC selectrim front motor mounts down) then I would try for a lower pressure setting on the tabs. What you want is help at low speeds, but as little as possible pressure at higher speeds so you can trim the bow up and out.

And to head off any possible confusion, those of you that do not understand Stringer trim systems need to know that trim and tilt are absolutely different and separate systems. There is no "trim" setting that is too high for the u-joints, because there are none . . .

Click to expand...

Re: Smart Tabs Question

Agree with all of these posts. It's just important to note that if higher trim increases speed it doesn't matter if it's pushing on water or air or sideways, it's more efficient. The proof is in the results, not whether it is a hull with a hook, or rocker, or porpoising or a flatbottom, or with or without tabs. If more trim gets more speed, it's mobetta . . . This also does not take into account safety, or ride, or anythign else but trim position vs. speed/efficiency. And consequently SmartTabs should be adjusted to allow as much positive trim as possible as long as other conditions, or desired results, are also acceptable.

Re: Smart Tabs Question

Agree. Mobetta.

Re: Smart Tabs Question

I have had same/similiar results on my v boats. Just not sure how much applies to a tri-hull, or was your installation on one?

Re: Smart Tabs Question

Mobetta! that's sweet

Re: Smart Tabs Question

Your wrong. Speed and effeciency have nothing to do with each other. Your boat should be put in the best angle of entry at all speeds, thats what trim tabs are for. The more level the boat is, the better it is going to perform and more efficeint it will be in all speeds. Doesn't make much sense just to be efficient at one speed does it? You may like more speed but it has nothing to do with effeciency. Your other statement is not true either, It does matter what the hull design is, the wind, at what angle your entry is, weight distribution, bottom paint, drag from debri stuck to the bottom and other things like how fast the boat is put into high rpms..All these thing effect the performance in relation to efficiency.

A boat is on an axis all the time, the most effecient way running is with the boat on top of the water for less drag and perpindicular with the water. If your bow is raised up to far by way of prop angle, it is inefficient. If it is trimed to far down, or tucked in past 90 degrees it is inefficient also because you will be burying the bow to far .

If trim tabs keep the boat on a more even level axis, the efficiency is much better than trimming the motor.

The boat will be more efficient at all speeds with trim tabs. Doesn't make alot of sense to say the boat is more efficient on a plane with the motor trimmed if it took twice the amount of time for the boat to get on a plane to begin with. Your efficiency comes from the boat being on the best axis through all speeds including while your getting on a plane. When you trim your motor off a 90 degree angle to the boat, you lose thrust, that is fact!

Now, if you don't have trim tabs, chances are your boat is riding wrong to begin with, or atleast in a less efficient manner. Bow up, stern buried is not an efficient way to get on a plane. You want the tabs to bring the stern up and push the bow down so it is running on a more level surface all the time. If you try and accomplish this by trimming the motor, you loose efficiency.

I'm not going to knock other brands of trim tabs here, but this is exactly what the nauticus trim tabs are for. With regular trim tab, it is up to the operator to adjust the tabs to get performance. The Nauticus tabs are self adjusting, based on the weight of your boat. These tabs keep your boat in the most efficient position at all times. While on plane there is no drag because of the relief valving. But you still have enough pressure so the tabs react eimmediately to the changing water conditions.

It is impossible for a human to adjust regular tabs quick enough to be efficient all the time. On a very fast boat, regular tabs can actually be dangerous, to much tab or not enough tab can put you in a bad position. Thats why these smart tabs are great for smaller more adgile boats.

By the way, I am not affiliated with Nauticus, I just have seen such a great performance change since installing them, that I will always recommend them and comment when there discussed.

I will say this, regular tabs have there place.

Basically, the only way speed relates to efficiency is to get more speed at lower rpms.

QC said:

Agree with all of these posts. It's just important to note that if higher trim increases speed it doesn't matter if it's pushing on water or air or sideways, it's more efficient. The proof is in the results, not whether it is a hull with a hook, or rocker, or porpoising or a flatbottom, or with or without tabs. If more trim gets more speed, it's mobetta . . . This also does not take into account safety, or ride, or anythign else but trim position vs. speed/efficiency. And consequently SmartTabs should be adjusted to allow as much positive trim as possible as long as other conditions, or desired results, are also acceptable.

Click to expand...

Re: Smart Tabs Question

At any given throttle position, the trim position that equates to the highest speed will be the most efficient.

I am not any hydrodynamics expert, but with my v hull and smart tabs, the 90 degree position is not the most efficient for any speeds over 30mph. The more hull out of the water means less drag, which means more efficency. You don't loose thrust past the 90 degree point until you do loose speed.

Re: Smart Tabs Question

I have used and installed SmartTabs, Lencos, Bennett's and K-plane knockoffs. I am totally in favor of helm adjustable tabs for me. I am not the only one who operates boats though

Anddddd . . . as John S has stated, if trim changes (bow up or down) result in more speed for the same throttle position then she is more efficient than the previous setting. Period. This one really cannot be debated.

Re: Smart Tabs Question

This can be debated! You are correct in saying that if you change the trim and increase speed it is more efficient (IF) the increase in speed is acheived without increasing rpms! Throttle position doesn't mean anything if the rpms change. The motor is then working harder to acheive the extra speed and is not the most efficient. You may gain speed, but not efficientcy! Next time you out, check it out for yourself, watch your rpm gauge!

QC said:

I have used and installed SmartTabs, Lencos, Bennett's and K-plane knockoffs. I am totally in favor of helm adjustable tabs for me. I am not the only one who operates boats though

Anddddd . . . as John S has stated, if trim changes (bow up or down) result in more speed for the same throttle position then she is more efficient than the previous setting. Period. This one really cannot be debated.

Click to expand...

Re: Smart Tabs Question

Sounds like you may not have the right actuators or have them adjusted properly. I agree that the more hull out of the water means less drag, If your not making the motor work harder with higher rpms to acheive this then it would be more efficient. You can gain speed by tilting the motor, everyone knows this, but it is acheived by sacrificing proper thrust, which in turn lessens the effeciatcy. Its just like changing a prop to get out of the hole better. You may get out of the hole better but you are loosing top end speed. Simply put, efficiency is directly related to the rpms it takes to acheive a certain speed. When the rpms increase at any given speed, the motor is working harder, thus not efficient. Tilting your motor will increase the rpms because it is working harder to acheive the thrust to go that speed.

Re: Smart Tabs Question

You guys really do need to check out this link! Pictures speak a thousand words and I have typed atleast that many:facepalm:
http://www.nauticusinc.com/pdf/nauticus_smart_tabs_tech_info.pdf
Anyone have a fuel flow meter on there boat?