Need some trim tab location help

[seabob4]

Tom,
I think this transom is not designed for tabs

Me thinks you're right... :(

[Tabman]

Tom,

I think I have to make a choice between two bad

 

This is the position starting at the chine going down with a proper shim as you recomended
Now I have the actuator all the way to the edge
Was thinking if I make the bottom of the tab not in line withe bottom of the boat
Say make the inboard side of the tab a little higher from the bottom that will turn my actuator more to the outside and give me maybe the possibility to bring the actuator more to the center
So the big question is,is this a good option and if so how much can this be ofset
Or shall I just average my tab between where I can fit it a litle over the chine
I think this transom is not designed for tabs

No matter where you place it will not be ideal.  We do make shorter actuators that will lower the mounting point on the transom, but if you move it outboard you will still run into the issues I mentioned before.

If I had to install those 12 x 12s I would move them outboard and shim as you have done.  That would be the best you could hope for.

Tom
Bennett Marine

[Georgie]

Any reason why the ouboard margin of the tab can't just be trimmed/customized so that the tab margin aligns with the chine?  that way the tab can be mounted to the stock transom without shims. Hydrodynamically it would obviously lose a tiny bit of lift over the traditional install just because of some lost surface area, but that way the tab doesn't result in any unintended drag or tubulence outboard of the chine.   The actuator being on a slight angle wouldn't matter b/c the whole unit is out of the water when at speed, and I'd think you can still find a way to affix the actuator near the center of the tab to balance the load.  To me that would seem like such a simple and minor but effective modification and would give the operator probably 90% of the function of the unmodified standard tab without getting into some really complex geometry and fabrication.

2 cents!

[wingtime]

So what Ryan is saying is taper the outside edge of the tab so it is parallel with the centerline of the boat.  Great idea.  You would just need someone with a brake to bend the outer edge up.

[Georgie]

Precisely.  

[xo4001]

Any reason why the ouboard margin of the tab can't just be trimmed/customized so that the tab margin aligns with the chine?  that way the tab can be mounted to the stock transom without shims. Hydrodynamically it would obviously lose a tiny bit of lift over the traditional install just because of some lost surface area, but that way the tab doesn't result in any unintended drag or tubulence outboard of the chine.   The actuator being on a slight angle wouldn't matter b/c the whole unit is out of the water when at speed, and I'd think you can still find a way to affix the actuator near the center of the tab to balance the load.  To me that would seem like such a simple and minor but effective modification and would give the operator probably 90% of the function of the unmodified standard tab without getting into some really complex geometry and fabrication.

2 cents!

Ryan,
That's a very interesting idea and worth 5 cents  :sunny:
I will make a tab template from a piece of plywood and see if this can work
If this can then it is for me no problem to make adjustments on the metal one
Will post a pictures of progress
Thanks
Martin

[xo4001]

Ok think found the solution
Made smaller tabs and a little longer to compensate for the width
Had also change the angle of the foot to mount on the flat surface
Filled the gap with marine epoxy to dived the force on to the tab and not solely on the screws
Unfortunately no change to get out to try weather is not nice lately
Will let you know how it go

[Georgie]

Martin-your boat is too shiny!  The reflection is screwing up my ability to see exactly what you did!  

[xo4001]

Martin-your boat is too shiny!  The reflection is screwing up my ability to see exactly what you did!  

 
Thanks for the tip Ryan
Without it was probably still struggling how to go about it

[dburr]

Martin fabbing a new tab plate for your application is the way to go, stick to Tabman's area dimensions  and you will be all set.. As mentioned before if you shape the outboard edge to be parrallell to the axis of flow is the way to go.  You can splash the boat so get someone else to run her, and go aft and get a good look at the flow off the stern..  You can take pictures, draw diagrams etc. to get the shape of the water flow around/by the tab.  Then go to the table and draw it up...  If the shape ends up not being straight, that is ok..  Cut the tab to the shape and find a TIG guy to put a good flange on the outboard edge for you to add some strength..

Georgie is correct, that hull is too damn shiny to get a good idea of how the tab set up looks!!  

Any misspellings are do to an invasion of the Captain.. My kid left a bottle behind and it does not get along well with  my Goslings stash so it had to go...