Trim tab extension

[BigRS]

Currently my 2010 2520xl has the 12x12 trim tabs in a pocket under the stern. I guess my question is. I am thinking of extending the current tabs instead of removing and replacing. My thoughts are to widen the tabs by 4" on each side and extend the tabs by 6". It won't just be a 20" by 6" plate I was going to make it 20" wide by 10" square then cut 12" out of the center deep enough to allow 4" of the new plate to extend along the edges of the existing tab for more welding strength. Anyway, was wondering if anyone has tried this and how it might have worked. Can't see at least not trying it before deciding to remove existing then filling pocket buying new and reinstall. If it works it would be a quick and easy fix. Basic tabs have 144 sq inches. After make over they should have around 270 to 275 sq inches. Any thoughts?

 

[DaleH]

I like the idea and would be trying it if it were mine. Just remember, that if ANYTHING - go wider before going deeper. Width not depth gives best performance. That said, you may have to go deeper to affix the new extension to the old, but wider is better,
- wider is better,
- .... wider is better,

 

[BigRS]

Thanks dale good idea. It was getting long so I failed to mention that I was going to add some 3/4 flat plate stood on edge on top of the tabs and weld them in place for added strength also. Would you try wider then 4" on each side? Maybe 5 or 6 ?

 

[DaleH]

Angle plate (for stiffeners) would work too. Without seeing measurements, it's tough to comment, but I would try to go wider, maybe even an upside-down 'V' or 'T' tail, where the rearward projections were WIDE off to each side, but behind the old 12" wide tab .... there was only enough depth to attach the new width. Capice?

 

[warthog5]

http://www.classicmako.com/forum/topic. ... ichpage=37

Scroll down to see how to fix one right.

Fill the hull in and start fresh with the right size tab.

 

[BigRS]

Thanks warthog, I don't think that guy had any other option but to do that, his tab and actuator were both under the boat pretty far. On the parker there is a lot more tab exposed out the back of the boat. Not saying my idea is going to work, but before I invest all that time and money I am going to give it an old fashioned good try. Lol. I will prob go over to the boat today I will take pics of how the tabs look now and I will make some marks on it then remove it and bring it to the shop. Going to weld it all up reinstall then take more pics. Really hoping it works, I really can't see why it wouldn't .

 

[TWOBOATER]

Kudos for your ambition but I would think you'll run into trouble with the hinges on the existing and added section of tab. they need to be in exact allignment to work properly. How can you accomplish that if the existing tab is recessed into the bottom? You can't leave them unattached.

 

[Ludicrous40]

Not trying to highjack the post, but I'm in the same situation with my 2003 2520XL. It has the tabs that are recessed into the hull, but I believe they are 12x14 on my year. I really want to go as wide as possible (probably 24"), as I've read nearly every "tab" post on this site, and finally have a good understanding of the fact that my drag to lift ratio sucks. Has anyone posted pictures on filling in the void in the hull? I would imagine that the area would need to be roughed up so that the fiberglass has something to bond to, but I'm also wondering about incorporating anchor points for the fiberglass to leach into. Thoughts or suggestions appreciated.

Also curious if the guys with really wide tabs have thru-hull transducers or transom mounts? If I went to 24" it looks like (without measuring) it would be right up to my tranducer.

 

[BigRS]

Here is what I have to work with, I think it's plenty to do what I need to do. I will keep everyone posted as to how it works or fails. Lol

 

[warthog5]

If you install "Spill Plates" on the edges of the tabs ....The tabs will act like larger tabs. What this does is hold the water on the plate better.

The M120 Bennets are a example of this.


They actually call tis a "bat Wing" design, but look at the edges of the plate.

This can be accomplished by adding a piece of 90deg metal on each side.

 

[BigRS]

I noticed the existing tabs have rolled down sides and I had planned on trying to incorporate that into the extension. Thanks for that bit of info.

 

[warthog5]

If I was doing it..... I'd trim that rolled angle off the tab in the saw......Then I would add angle...Placing the angle on the top surface of the tab as apposed to fastening to the bottom surface. The vertical height of the 90 would be aprox 1in.

 

[BigRS]

Finally getting started on the tabs, here is where it is so far.

 

[Ludicrous40]

Just thinking out loud……..What will be the effect of the water being able to travel over the top of the new "wings". Typically the trim tab has it's width completely fastened to the boat such that the water only travels underneath, but with the wings being deployed down, some of the water coming off the bottom of the hull will be able to travel over the top…..will this create more drag???

 

[BigRS]

It's funny you ask that question, I have been thinking that same thing. I should be ready to splash sometime next week so I will give you an update then.

 

[BigRS]

I hit send before finished, my thoughts about that situation is this. When you put those wings on your lower unit the water flows over and under those also yet you still get the lift. Was hoping that the same principle applies here also.