Smart Tabs vs. Whale Tail- My Experience

[JoLin]

I used Smart Tabs several years ago, on a 21' Pro-line I owned. I liked them. Right now I have a 16' Sylvan aluminum Fish 'n Ski. I took out the rear fishing platform and fitted a bench seat in its place, so the boat is tail heavy with 3 people seated across the back. The boat came with a whale tail when I bought it and I used it for a season. It worked but it took awhile to plane out, and I was never comfortable with the boat's handling at 25+ mph. It felt kinda 'twitchy' at speed.

I bought a pair of the composite Smart Tabs (blems) that iboats was selling for $100. a few months ago, and mounted them up before the boat went in the water. They worked great with 2 people aboard (seated forward) but I've been waiting for a 'stress test'. Day before yesterday I had a full load of 5 adult passengers and 3/4 tank of fuel. Night and day difference. The boat jumped right on plane and felt rock steady at speed. My buddy, who had been aboard the last time I ran the whale tail with that many passengers, just looked at me and said 'wow'.

My .02

 

[ondarvr]

Again, a "whale tail" or whatever you want to call it, being used for the wrong purpose without trying to dial it for the desired results. I'm not saying a fin would have solved this issue like tabs will, tabs are designed for that purpose and do it very well. Fins don't go about doing it in the same way and need other adjustments to be made for best results, which may not be as good for this as tabs. This is like saying a hammer is better for driving nails and pounding on things than a Crescent wrench. Just because people frequently pound on things with a Crescent wrench doesn't mean that's what it's designed to do. A fin is actually designed to do something very different, better planing can be a side affect of that.

 

[burtonrider11]

Thanks for posting JoLin! I just bought the $99 blemished tabs from Iboats and plan to install them this weekend. I may need a drink before drilling holes in my hull though lol. I'll try to take pictures so I can share with folks on here who may be interested. Unfortunately, I am a good 2 months away from putting her back on the water as it's still February in Michigan

I am curious about the depth of the mounting holes. Did you drill all the way thru your hull or did you pre-set a depth on the drill so as not to go thru. I think I want to not go thru if I can help it. I am imagining that the transom should be much deeper than the depth of the screws...Thanks.

 

[JoLin]

Burton, on a boat with a thick transom, I do set a depth and simply mark the bit to the length of the screw using a piece of tape. It isn't a real big deal if you go through, as you're going to seal the screw hole with 4200 or 5200 or something similar.

 

[JoLin]

Ondarvr, forgive my ignorance, but... what adjustments do you make to a fin? Mine was just bolted to the anti-cav plate. Not arguing with you, but if the fin isn't designed to help plane and stabilize the boat, what is it designed to do?

 

[ondarvr]

To get the best results you need to raise the motor to find the best performance.

A fin is nothing more than an oversized AV plate, the AV (anti ventilation) plate's purpose is stop the prop from pulling air from the surface during hard acceleration. Enlarging the AV plate allows the motor to be mounted higher and not ventilate, this can result in several improvements in performance. When the lower unit is higher it has less leverage on the hull, possibly resulting in less bow rise and faster planing. With less of it in the water it will reduce the drag, which may result in a higher top speed and better Mileage. At no time is the fin supposed to drag in the water at speed, it should be out of the water, being in the water can result in all sorts odd behavior.

Most boaters just bolt a fin in place and head to the water, they may be satisfied with one aspect of the change, but having it drag in the water typically results many negatives. The boat owner then reports that they are evil and have no right to exist. Tabs and foils are just tools that are designed to do very different things, some of the possible benefits overlap though, so people try to use them in the same way. The marketing people are just interested in selling them, so will claim all sorts of things, but never tell you how to achieve them.

All of the the benefits are just possibilities, not guaranteed, so it won't help every boat, tabs typically have no downsides and are the correct tool for what 99% of boat owners want to achieve.

 

[burtonrider11]

Burton, on a boat with a thick transom, I do set a depth and simply mark the bit to the length of the screw using a piece of tape. It isn't a real big deal if you go through, as you're going to seal the screw hole with 4200 or 5200 or something similar.

Gotcha, that was pretty much my plan, I'll mark it, dab some 4200 in there and bolt it in there. I can't wait to see what the tabs do...our boat has the typical wander in no wake zones and despite having plenty of power, does not like to plane out real well, I am excited to see how much better the boat performs after these are on. Hurry up Spring!

 

[shrew]

The only problem I have with these devices is they are providing 'lift' on the outboard/outdrive. I have always questioned whether they were designed for these types of forces at their attachment point. The drive was not really designed to provide lift to the hull. Tabs will essentially extend the running surface of the hull and affect the hulls running attitude without applying force the running gear. I'm not refuting that it works, just concerned about HOW they work.

Just my .02

 

[ondarvr]

When used correctly they don't apply much pressure on anything, when used incorrectly they can. Since people use the motor to set trim, and in some applications the trim angles can be extreme, I don't see the correct use of a foil creating much of an issue.

The forces on the lower unit and the entire motor are rather high in normal use, it's not like they are just sitting there doing nothing, so for the most part they are designed for it.

 

[bruceb58]

On a previous boat that I owned, it came with a Doelfin installed by the previous owner. After having the stern almost dangerously washout in turns I took it off and never looked back. Taking it off also increased my top speed too.



The following is from a Mercury website on the use of fins:

Can I use aftermarket “fins” to help my boat get on plane faster?

Using a product often referred to as a stabilizer fin is a modification of the gearcase that may change the manner in which the boat operates on the water. With the unit trimmed fully down (in or under), a reduction of the time necessary to get a boat on plane may result. However, some V-bottom boats using a stabilizer fin may exhibit a tendency to roll over far to one side as soon as planning occurs. The direction and degree of the roll will be dictated by prop rotation, weight distribution, and degree of trim under. The boat roll can cause passengers to be ejected. Trimming up or out can reduce or eliminate the roll. Because it is not possible to know how a given boat will respond to the use of such a product without thorough testing, Mercury does not recommend such products be used or not used. Also, use of these products may cause or contribute to the failure of the anti-ventilation plate on the gearcase. Failures caused, or contributed to, by modification are not covered by the limited warranty.

 

[ondarvr]

Again, these are warnings about misuse of the product, so few people understand them that I'm begining to think that it's just easier to along with "they are evil and shouldn't be allowed to exist" mind set.

There was no mention by you that any adjusting or testing had been done, or even to the type of boat it was, so there no way to even discuss the issues you experienced.

I get tired of repeating this. There is no guaranty that a fin will help, it is only a possibility that when used correctly there could be improvements. There are so many different hull designs, outboards, ways the owners wants to use the boat, etc, that there is no way to say one would help or not before testing. And this only applies to outboards, you can't do the correct setup with an I/O, so results tend to poorer.

 

[bruceb58]

I get tired of repeating this

I have a solution for you!

 

[ondarvr]

The exhausting part is that people don't seem to be able to grasp the idea of how a fin works, or what it can and can't do, and there seems to be no understanding of the fact that tabs and fins are two totally separate tools designed for different purposes.

 

[thumpar]

The fins can and have caused cav plates to break off. The drive is not meant for the purpose the fins do. If the were so great the manufacturers would design them in to there engine/drives.

 

[ondarvr]

If the were so great the manufacturers would design them in to there engine/drives.

Virtually every outboard made come with one, it called an anti ventilation plate, a fin is just a larger version, and is designed to do the exact same thing.

 

[thumpar]

Virtually every outboard made come with one, it called an anti ventilation plate, a fin is just a larger version, and is designed to do the exact same thing.

It is an not a fin though. That is just a plate to prevent cavitation. When you put fins on the side you are putting stress on it that the manufacturer didn't design for. If they wanted fins and they worked they would come stock with them.

 

[ondarvr]

The shape of most fins are a sales and marketing aide, not a design requirement, the foil shape is about worthless, the other shapes and little wigs fall into the same category. For the most part a flat plate of alumnum would be a better shape.

 

[ondarvr]

It is an not a fin though. That is just a plate to prevent cavitation. When you put fins on the side you are putting stress on it that the manufacturer didn't design for. If they wanted fins and they worked they would come stock with them.

It is an anti ventilation plate, it has nothing to do with cavitation, cavitation is vary different animal and unrelated. A plate over the prop does nothing to cause or prevent cavititaion, it prevents ventilation. The terms are frequently confused and used incorrectly.

 

[thumpar]

It is an anti ventilation plate, it has nothing to do with cavitation, cavitation is vary different animal and unrelated. A plate over the prop does nothing to cause or prevent cavititaion, it prevents ventilation. The terms are frequently confused and used incorrectly.

The terms don't change the argument about not using them.

 

[ondarvr]

The terms don't change the argument about not using them.

You seem to not understand what they do, how they work, or how it can help, how can you form an opinion from that standpoint.

I keep telling people, I don't think they're a miracle product, they're just a tool that when used correctly may help.