Cav. Plate Material Question?

[sawtooth]

I am going to start making new plates for my boat and was wondering what to use, stainless or aluminum. Any info on pros and cons for both would be a big help, boat is a 21' cruiser. :confused: Thanks
BTW, is longer better ? (I know what your going to say, I ment for the plates) :jawdrop:

[J540]

I am going to start making new plates for my boat and was wondering what to use, stainless or aluminum. Any info on pros and cons for both would be a big help, boat is a 21' cruiser. :confused: Thanks
BTW, is longer better ? (I know what your going to say, I ment for the plates) :jawdrop:
S.S That way you only make them one time they wont where out.
make them 10" 12" longer than the transom. What kind of HP do you have?http://www2.***boat.com/image_center/data/510/1062111-1116_IMG-med.JPG

[sawtooth]

If things go as planed it should be around 800-850 hp. (twin tubro deal).

[J540]

Then go 12" long. thats what mine are in the pic,. 850, what size motor (cu)

[sawtooth]

I was thinking 572ci. will 3/16" thickness work for the plates or is 1/4" better. The ones on the boat right now are 3/16" alum. Thanks for the info.

[Dave Sammons]

These are 1/4" stainless. As far as length, the ones pictured are 10" at the outside edges and 12" at the center. You have to take into consideration the angle of the transom vs the bottom, this one was 97 degrees. You want the plates to be square across the back or it won't look right and the turnbuckle angles will be all be different. Take a look a the "SpectraBrent's boat is coming together" thread for a couple more pictures.
http://www2.***boat.com/image_center/data/520/1517dn1.jpg

[steve d]

These are 1/4" stainless. As far as length, the ones pictured are 10" at the outside edges and 12" at the center. You have to take into consideration the angle of the transom vs the bottom, this one was 97 degrees. You want the plates to be square across the back or it won't look right and the turnbuckle angles will be all be different. Take a look a the "SpectraBrent's boat is coming together" thread for a couple more pictures.
http://www2.***boat.com/image_center/data/520/1517dn1.jpg
What is your plate alloy of choice for cav plates, engine plates, brackets etc.......6061-0,t6,t65..7075-t6.......? Seen and welded alot of cracked pieces, but not sure what the alloy actually was....Thanks--- Steve

[Dave Sammons]

What is your plate alloy of choice for cav plates, engine plates, brackets etc.......6061-0,t6,t65..7075-t6.......? Seen and welded alot of cracked pieces, but not sure what the alloy actually was....Thanks--- Steve
6061-t6 works well for almost every application within an installation. I use the 7075 for washplates. The cracking I've seen has come from a mis-designed part or from using to thin of a material for the application. I'm 3/8ths guy when it comes to motorplates, although alot of guys use 5/16ths, especially in unblown applications. You'll see alot of the circleboats rigged with 5/16ths, just not my choice of a place to cut a little weight and I'll take a little more rigidity as well.

[GofastRacer]

6061-t6 works well for almost every application within an installation. I use the 7075 for washplates. The cracking I've seen has come from a mis-designed part or from using to thin of a material for the application. I'm 3/8ths guy when it comes to motorplates, although alot of guys use 5/16ths, especially in unblown applications. You'll see alot of the circleboats rigged with 5/16ths, just not my choice of a place to cut a little weight and I'll take a little more rigidity as well.
Yep 7075 for the blast plates and 3/8" for motor plates on anything other than a ski boat!..

[steve d]

6061-t6 works well for almost every application within an installation. I use the 7075 for washplates. The cracking I've seen has come from a mis-designed part or from using to thin of a material for the application. I'm 3/8ths guy when it comes to motorplates, although alot of guys use 5/16ths, especially in unblown applications. You'll see alot of the circleboats rigged with 5/16ths, just not my choice of a place to cut a little weight and I'll take a little more rigidity as well.
Thanks Dave......Thanks Art....Your reply is greatly appreciated. I can see where my K has an issue or two-----will have to re-think...Thanks...Steve

[sawtooth]

Hey thanks for the info and the pics guys, if I go with the 1/4" ss like in the pic do I also need to use a hinge on the transom or will they flex enough attached to the bottom of the boat ?

[J540]

For cav, plates use 3/16" thick 316 s.s. 304 can get rust pits in it and its is harder to keep clean in hard water area's like the river/Havasu.
Laser or water cuting is not that much $$. plus they can put all the holes in it for you which is a lot better then drilling them. they can use your old ones for the hole local, or you can make a template with some thin sheet Alum, .020 .035. mock it all up then take it to them so they have a pattern.
Any good polisher shouldn't have any prob, doing them. There is no need to polish the hole plate thats a wast of time and $$$ you have them brush finish the bottom and the top and polish the top part that you see and 1" beyond and the side's. water will have less friction = less drag if you brush finish the bottom of the plate's. not like you are going to see the dif, or gain 10mph but it is the best way to go. smooth /polished surfaces have more drag.
I have a guy here in so-cal S.F valley that can make the plates/laser cut not sheared. Shearing them CAN bend them, some times it does, why skimp do it right. and I know someone that can polish them. If you can give me the size of them i can give you a price on it.
You can use Alum, but why s.s. is far better. then you dont have to make a seperate blast plate then drill more holes then the bottom of your boat looks like swiss cheezzz :( .
OH far as hinge, you only do that if you dont have a recessed area for the plates to locate in.

[schiada96]

6061-T6 $2.75 a lb
302/304 sheet 1.75 a lb
316 sheet 3.16 a lb
321 sheet 3.75 lb
You can get a 4b finish in any stainless sheet.
It is alot easier on the polish guy than the standard 2b.
Full polished sheet can be had but is expensive and
you have to be very careful in the fabrication.

[J540]

:( DAMN, J540 !!! just slam away !!! i was just giving the dude a lil insight on my project i just finished, if you think polishing the top & bottom is a waste, cool, I just wanted them all shiny :p , they look real nice that way, having been a machinst in a prior life, the fabing, drilling and finishing were, we'll say stress release, and I guess ita matter of opion on the 304 / 316 s.s., Schiada has been using 304 forever, my 20 year old plates look pretty shiny, some small pits on the bottom(those were brush finished)but not bad, sorry I ck'd on laser/water and got some step prices per inch ? no biggy, the shop that did the shearing had just put a new set of blades in,nice !! The trick to polishing big s.s. plates is the shop needs to be equipped, that all i was saying, a small machine will mess the finish up, other than that they SHINE !!!!! :p .
Scott.
Iam way sorry i didn't mean it like that. 304 s.s is a lower grade s.s than 316 but 316 is surgical steel it holds up better. I know what you mean on the polishing, it does look cool all polished, but you wont see the bottom or the part under the boat. and the money is better spent on other things, but they will work better if you have them finish sand the bottom. again you mite not notice any thing............TILL you get over a 100 :D The guy that dose my polishing did it on a 2" wide wheel. but he sands them a few different times then hits them on the wheel.
I've sheared Alum, its ok like you said if the guy know's what hes doing and has good Equipment. but if you lay them on a flat table they will be bowed a bit. We use to run a Top Fuel Flat and alk, flat and i've dunn an seen how they use to do the plates. back in the day they use to say do not sheare them cuz they will bow, but for what we do i dont think it will make any dif,.
you are right on with the stress relese, or just to get out of the House so I dont have to here the wife yak yak yak. :D :D
Again Iam sorry about that. OK iam a D*%^ :D
John.

[Schiada76]

Hey 540! Lay off the meds they're making you grumpy. :argue:
Shit when you have a wife that's as hot as yours who cares how much she yaks! :p :D

[J540]

Hey 540! Lay off the meds they're making you grumpy. :argue:
Shit when you have a wife that's as hot as yours who cares how much she yaks! :p :D
Did i tell you my shoulder is F'n kill'n me. Dr. said not to drive the boat........................with that hand :D :D I start Therapy next week can I start it at your river Hs. :D :D

[sawtooth]

:D Having just upgraded my plates on my 21 Schiada to the newer wide plates, i'll give you some info.
The plates were made from 304 S.S. 3/16" Thick, mine were raw cut 18"x36", then final sheared to size, if you laser/water cut its real expensive, then final shaped.Schiada's are bolted to a notched out section under the transom. 1/4" is way to thick and heavy. I believe I paid about $125 for each plate.
The polishing of the plates is where it gets expensive, make sure your polisher can handle s.s. plate that size, I have a MIL Certified polisher in the phx area if you need one, mine are polished top and bottom, around $350 to do a mirror finish.
Hope this helps, scott.
Hey Scott thanks this does help, I am redoing my Schida 21RC (major makeover....outdrive to a v drive). The boat has small fixed plate on it now about 4" past transom so I know about the recess for the plate I was just wondering if the hinge thing was like the new way to go, I have seen a few 210 Hallett's set up like this. I am suposed to have an in with a water jet guy, I will see when I call in the favor. As far as the polishing goes I am planing on going with the brushed look top and bottom....trying to get away from the bling bling look. Would it be cool if I pm'd you in reguards to picking your brain on your set up, if not I would compleatly understand.
Thanks,Chris
Thanks everybody for the help/info. Some of the stuff you read on here would take two lifetimes to learn, it is nice that everybody puts their info out to help others-
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