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21RC Cav plates length

Groper

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I have an older 85'RC and the plates appear to be 3-4"s shorter than the 2000RC I had a few years ago but I never measured them.

I plan on removing the Cav plate hardware to polish and I might as well replace the plates with some a little bit longer.

What is the plate length from the transom on the newer 21's ?

Thanks
 

X Hoser

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I believe I went to 14" on mine but not 100% sure. If you extend the plates you will need to extend the pillow blocks also to keep the geometry correct.
 

BamBam

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It's kind of a snowball. There are several different items to consider. When the plates were lengthened on the newer boats several things changed. The location of the cav. rod on the transom (height), the design of the transom blocks, the length of the arms on the cav. rod and the length of the plates. As stated above the transom blocks were built to set the rod further off the transom. If you bolt the new blocks in the old location you will compound your geometry problem because they will actually lower the cav. rod. The rod was raised so the push on the plates is down not out. The arms are lengthened because the plates are longer and need the throw in the arm to get the plates to move the same amount. I'm sure you can get it to work, but it's not necessarily a simple change to the length of plate...
 

Groper

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Here are two photo's one is the new 21RC and you can see where the Rods are in about 3" from the edge of the plate.
The old set-up has the Rod's right at the edge of the plates, these plates are 11" in the center and 9-1/2" at the edge of the transom. My plan was to extend the new plates just 2" from 11" to 13" center and from 9-1/2" to 11-1/2" at the edge and by mounting everything in the same place without changing any geometry.

Or I could start all over and rebuild the whole system but then Im at the mercy of a shop getting everything completed before boating season. 🙄
 

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jmeads

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I have an older 85'RC and the plates appear to be 3-4"s shorter than the 2000RC I had a few years ago but I never measured them.

I plan on removing the Cav plate hardware to polish and I might as well replace the plates with some a little bit longer.

What is the plate length from the transom on the newer 21's ?

Thanks
Longer is better. I went from 14 to 18 on my Schiada It made a big difference. (Just my 2 cents)
 

Groper

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Longer is better. I went from 14 to 18 on my Schiada It made a big difference. (Just my 2 cents)
Is that the overall length or from the transom to the edge of the plates ?
 

BamBam

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Your red boat actually had some special fitting to get all of the rods at the same angle. Typically the plate pads are all the same distance from the back edge of the plates. You could get away with lengthening the plates a little and leaving everything else as is. With the inner plate pad not at the edge of the plate you do risk that portion flexing as there is a tremendous amount of force on that part of the plate. Notice how on your red boat the center plate pad was at the back edge.
 

lenmann

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As an additional data point, my RC will have 1/4" stainless plates, 18 1/2" from the transom at the keel and 17" from the transom at the chine. The plate pads will be tapered/angled like your red boat so when viewed from the side the turn buckles all line up.
 

Groper

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As an additional data point, my RC will have 1/4" stainless plates, 18 1/2" from the transom at the keel and 17" from the transom at the chine. The plate pads will be tapered/angled like your red boat so when viewed from the side the turn buckles all line up.
I asked Lee about Stainless plates and he mentioned that it takes a ton of force to move the stainless.
Have you cycled your 1/4" plates yet ?

And who made your new Cav setup ? or let me guess you fabbed those up too lol

The older boats rods are all at different angle's and the newer boat are all at about the same angle.




20201206_111756.jpg





512.jpeg
 
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lenmann

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I asked Lee about Stainless plates and he mentioned that it takes a ton of force to move the stainless.
Have you cycled your 1/4" plates yet ?

And who made your new Cav setup ? or let me guess you fabbed those up too lol

The older boats rods are all at different angle's and the newer boat are all at about the same angle.




View attachment 949264




View attachment 949261
I will be fabricating the plates in the next couple of months and will be using a linear actuator with a max of 800 lbs of force to move them. No way a pedal would work with plates that thick, unless you had some pretty serious leg strength. Me not so much, so I will have the actuator buttons integrated into the steering wheel instead of a cav plate pedal and lock-out lever.
 
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