Well, after a lot of investigation and thought, I am going to extend the Bennett tabs on my boat. I have an extra set of tabs, and have stripped the powder coating and will give this template to a local fab shop and have them tig some extra length onto them, Add a few strengthening ribs and should be good to go.
I realize that replacing with K planes would be better, but this is too involved and costly now....maybe later if I see that the improvements in length is worth it. Season is getting too short, and I want to see about how this will work. I really want to get rid of the proposing tendency of the 292. It all goes away at 50mph, but I would like to move the proposing threshold(new term?....like it?) lower. Not sure if this will help, but I am willing to try.
As a reference, these will move to 17.75", or an additional 6.25" and are 12" wide and taper to 10" to assure no issue with drive collision. K-planes are 19.25" long and 9" wide at the tip as a reference. That is too long to extend these, as I worry about the Rams and mounting hardware.

More to come.

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I like your thinking. I have done this and discovered in rough water single Rams won't cut it...the tabs hold up and do a great job until you push them as I did...ripped the single ram to shreds. You need to also increase the number of mounting screws to the transom hinge...another failure point.

I'll try to find a damage pic to show you.

Great point, I also have another set of transom plates. Sounds like I should drill more holes in them and add screws. Also, mine has double Rams....maybe that will help keep them together. Pictures would be great. Thanks

I have a pair of Lenco? tabs (no rams) that are close to 280 K plane dimensions. Mounting is a little sturdier than Bennetts . If you can make these work , just pay shipping from Fla. Good Luck,W. 941-681-1870

The double ram has a better chance of survival than the single of course. I had a folded single ram at the "hinge" upper mount in my 242SS. Maybe the double can spread enough load to make it work, good luck.

http://www.bennetttrimtabs.com/wp-co...stallation.pdf

Concerned about the mounting screws, Big #10s. K planes are Lagged or through bolted. There is a reason why. Bennett's are sheet metal screwed into the transom. Much less pull on the small tab........until you extend it.

Trim your drives down a little will likely stop the porpoising at lower speeds.

Are saying it is OK to lag bolt K-Planes on? I had thought they were always thru-bolted.

Some manufactures do lag bolt...They should be through bolted because of the load..

When installing K Planes , always drill pilot holes first . Many times , when you position it where it needs to be , you will have a bolt hole going directly in a stringer. You can lag that hole and thru- bolt the rest , unless you already drilled it 1/2"....