280S Kplane Length

[RickSE]

Does anyone know how long 280S K-Planes are? How much longer are they then the 150S planes.

[gcarter]

I always thought the numbers were the length in milimeters......
If they are, they're 11", and 5", but then, that seems short doesn't it?????:confused:

[RickSE]

Yes a little short George. My 150's, at least I think they're 150's, are 11" long. The tab ends almost right at the cylinder pivot.

[mrfixxall]

my 280's measure from th hing pin to the end of the tap 19'' long..

[CHACHI]

Length is everything. :wink:

Ken

[gcarter]

Doesn't it seem reasonable to think they'd come up w/a numbering system that would indicate length w/o some arcane scheme that no one seems to have the key to???????:nilly::bonk:

[RickSE]

Thanks guys. I'm thinking about switching my 150 plates for 280's. I know some of the Blackhawk guys have done this with good success.

Fixx,

Do you have your 280's on a 22C? If so do you like them?

[mrfixxall]

Thanks guys. I'm thinking about switching my 150 plates for 280's. I know some of the Blackhawk guys have done this with good success.

Fixx,

Do you have your 280's on a 22C? If so do you like them?


no! on a x 18:kingme:












just kidding,,their on a bigger boat 33 formula..


Try lengthening your first with 1/4'' aluminum plate to see if your going to like the longer tabs first..

[yeller]

Switching shouldn't be too expensive. I've seen 280 plates on OSO for $200.

Do it......and test it this year. I need the results. I'd rather you spend your money than have to spend my own :biggrin.:

[RickSE]

Switching shouldn't be too expensive. I've seen 280 plates on OSO for $200.
Do it......and test it this year. I need the results. I'd rather you spend your money than have to spend my own :biggrin.:

Yes, I found some newer take-offs for $200 so it seems to make sense to try. Yeller, since you're doing all the drive testing I think I'll do the tab testing. :wink: I figure, longer tabs, a shortie drive and a blower and I'll be set; but then again I gotta get my boat to stop cracking first. :bonk:

[yeller]

I've been thinking as big as 380's might be what I need. My only concern about going to tabs that big would be "tripping" the boat. If I come out of the water nose high and the tabs hit before the drive, I could "trip" the boat and end up stuffing the bow. Probably not a lot of fun. (understatement) :nilly:

[yeller]

A blower on your engine would be killer. I wouldn't have a hope in catching you. You'll definitely want to beef up the hull/stringers.

[RickSE]

I've been thinking as big as 380's might be what I need. My only concern about going to tabs that big would be "tripping" the boat. If I come out of the water nose high and the tabs hit before the drive, I could "trip" the boat and end up stuffing the bow. Probably not a lot of fun. (understatement) :nilly:

Aren't most of the updated 20-Cig guys running big tabs?

[The Hedgehog]

Doesn't it seem reasonable to think they'd come up w/a numbering system that would indicate length w/o some arcane scheme that no one seems to have the key to???????:nilly::bonk:

Bugs the heck out of me too George.

And what is the length of a 380?

The whole 80 thing:nilly:

[yeller]

And what is the length of a 380?I think they are in the range of 22~24".

I've strongly been considering these:
http://www.eddiemarine.com/store/cart.php?m=product_detail&p=12441&c=37
I've seen them elsewhere for $1600.

[yeller]

I've also been thinking about mounting them in a horizontal position as opposed to parallel with the hull bottom.

I know Fogducker swears by this mounting as it worked great on his boat. Any other opinions? It's not like I can easily relocated them for testing, so I'd like to get it right the first time.


Sorry for tagging onto your thread Rick, but I didn't think you would mind because it's all related. I'll start a new one no problem if you want to keep them separate.

[RickSE]

No biggie Yeller, keep it going.

I'd think the horizontal mounting would work great for the primary purpose of the tabs, bow control in rough water. In horizontal mounting the forces & moments created by the tabs would tend to stay in a single plane, parallel to the surface of the water and function better for its intended use, rocking or pivoting the bow down. Parallel mounting would tend to create two surface planes off camber from the surface of the water and create additional drag as the outward forces and moments only cancel each other out and don't necessarily aid in bow attitude.

[yeller]

I understand what you're saying Rick, just not sure how the tabs would create additional drag if they are off camber to the water. Wouldn't being parallel to the water (when running) cause more drag? I'm just thinking about the first moment(s) the tab hits the water. Less tab initially touches the water when it is off camber.

BTW: based on your answers, your interpretation of my parallel/horizontal mounting is reversed. To clarify; when I say parallel to the hull bottom, I am talking about how the traditional mounting is; such as how yours are mounted (or parallel to the water when the boat is on plane). Horizontal refers to the tabs being mounted parallel to the water when the boat is at rest.

A lot of offshore race boats use (what I call) horizontal mounting. What is their reasoning?

[Sweet Cheekz]

A lot of offshore race boats use (what I call) horizontal mounting. What is their reasoning?

I think the thought is with a longer tab the water is pretty flat that far back from the transom and that makes a horizontal tab setting more effective because the tab does not have just a corner in the water requiring more tab to make the needed adjustment. Least thats what I heard and I will tell you my boat explodes when I bring up the tabs

The cig guys are running mostly 380 s

Parnell

[RickSE]

I understand what you're saying Rick, just not sure how the tabs would create additional drag if they are off camber to the water...

I'd equate it to the differences between a plain flat-bottom hull and a V-bottom hull. The V-bottom hull, which equates to traditional "parallel" tab mounting, pushes water in 2-dimensions, down and out to the side due to the V. The flat-bottom hull, "horizontal" tab mounting, pushed water in only one direction, down. In an essence the outward push forces on the V-bottom hull contribute to drag since they oppose each other.

Isn't a flat-bottom or pad boat always faster then a V-bottom boat? Why? Drag of the V.

The moment or torque created by the horizontal mounted tabs essentially pivots the boat about the axis of the tab hinge which would be parallel to the overall body of water surface or horizon and common for both tabs.

With the traditional parallel mounting method the hinges do not have a common axis and pivot the hull independently per side. Since these two axis are not parallel to the horizon there is a fraction of both pivot torques that cancel out but also work against each other creating drag.

So I guess I'd go for the horizontal mounting but like Sweet Cheekz says you may need long tabs for horizontal mounting.

[yeller]

I think the thought is with a longer tab the water is pretty flat that far back from the transom and that makes a horizontal tab setting more effective because the tab does not have just a corner in the water requiring more tab to make the needed adjustment. Least thats what I heard and I will tell you my boat explodes when I bring up the tabs
The cig guys are running mostly 380 s
ParnellThanks for the response Parnell. You're going to make me hang off the back of the boat at 40mph + to see how flat the water is two feet out from the boat. I'd think it would take 4~5 feet before it would flatten out. Am I way off base??

Do you know why the Cig guys run the big tabs? Is the main reason to control chine walk or porpoising? How do they usually mount theirs?


Thanks Rick. That makes more sense to me.

[yeller]

With the traditional parallel mounting method the hinges do not have a common axis and pivot the hull independently per side. Since these two axis are not parallel to the horizon there is a fraction of both pivot torques that cancel out but also work against each other creating drag. I'm 99% sure I understand what you are saying, but just want to clarify. Basically you are saying that a traditionally mounted tab (like ours) creates two forces because it is at an angle to the horizon. The 2 forces being outward and downward. The outward forces oppose each other and create additional drag. A horizontally mounted tab creates only a downward force and therefore should have less drag.


I realize that's a pretty simplistic explanation.

[Sweet Cheekz]

[quote=yeller;581429]Thanks for the response Parnell. You're going to make me hang off the back of the boat at 40mph + to see how flat the water is two feet out from the boat. I'd think it would take 4~5 feet before it would flatten out. Am I way off base??

Do you know why the Cig guys run the big tabs? Is the main reason to control chine walk or porpoising? How do they usually mount theirs?

quote]

I had a freind put a camera back there pointing down and we got some nice pics. I am not sure but since the boats are not real heavy and the faster you go the higher the boat is sitting in the water I think it flattens out faster than you might think.
The cig guys said it lengthens the boat a couple feet when they are really hauling the mail. So far I notice the same thing

Parnell

[yeller]

[quote=yeller;581429]...Do you know why the Cig guys run the big tabs? Is the main reason to control chine walk or porpoising? How do they usually mount theirs?Parnell, have you talked to the cig guys enough to be able to answer any of the above questions?

Right now, I'm not overly concerned with the high speed handling. High speed handling might be more of a concern if I pull the Blackhawk and go with a shorty. Won't know until I try it. For now I'm looking at bigger tabs to control the porpoising and can use all the info I can get.


Rick, what's your reason for the bigger tabs? High speed control or porpoising?

[RickSE]

...Rick, what's your reason for the bigger tabs? High speed control or porpoising?

Both but I don't know that I really need them since I'm pretty happy with my 150's. I guess I just want to see if the longer tab will allow me to run the port tab a little higher and drag less through the water. The price is fair enough that it seems to make sense to try them.

Yeller, I think you'll be happy with any tab that's hydraulic and gives you accutare indicator capability.

[yeller]

I guess I just want to see if the longer tab will allow me to run the port tab a little higher and drag less through the water.
That's the exact reason I'm thinking bigger is better. Right now I have to drag way too much tab.

Not trying to spend your money, but I'd think you would be able to resell the 280s if you don't like them.

[Sweet Cheekz]

[quote=Sweet Cheekz;581454]Parnell, have you talked to the cig guys enough to be able to answer any of the above questions?

porpoising?

I have and they like how it makes the boat longer especially with the bh. I don't think the 20 cigs porpoise as much as the donzi's do. i cant remember if they mounted them horizontal or on an angle Look thru the lake cumberland pics and see if there are any on the trailer
Also there is a guy named rick on the board here that has one of the fastest cigs and he is on here now and then He would be the man to ask.

280's are the easiest to sell as everyone likes those. Mine are the 380's but they mount to the same transom bracket as the 280's
One thing I noyiced is that at high speeds trimmed out a touch of tab keeps the bow from skying on those pesky boat wakes Nice feeling I will say.

Parnell

[bertsboat]

Long ago i had a 20' open action with a 350 hp v-8 johnson. I had k planes on it and everybody would ask why. Well the reason is to keep the bow down, not slow me down. Those short cheap planes do nothing but slow you down. Sure, the boat will stop the porpose action but you will lose 10 miles at the same time.
The longer tabs dont slow you down, they just do what they are suppost to do. Try dipping a paddle tip in the water at 40 mph, all it will do is slow you down. If you look at all those stainless tabs they are bent from the force of the water. They are too short.
I would use as big of a plane that will not look stupid and that you can afford. You will be happy you did. Thats why i put k planes on the 14 baby donzi.
Just my take.

[RickSE]

So I got my 280 tab plates the other day only to discover that Merc. apparently changed the mounting method for the plates at some point. I'll try to get a picture later but in a nut shell,

My 150's mounted to the backing plate and cylinder with essentially no bushings, 1/2" shafts directly in the aluminum, accept for a rubber sleeve in the end of the cylinder rod mount.

The new 208's mount with 5/8" shafts and according to the exploded views online, they use a different, narrower, cylinder mount and several bushings at the cylinder mount.

It looks like I can make it work but I'll have to modify my cylinder rod ends and make some sleeve bushings for the shafts or buy new cylinders @ $375 ea. At this point I'm not sure I want to modify my existing cylinders. :frown:

[Greg Guimond]

I was going to put a set on Surface Tension, but now I am backing away.

[RickSE]

Yep, Here it is.

K Plane Design Change (http://www.marinepartsman.com/Mercury-Marine-service-bulletins/Race-Sterndrives/2004/EN_05.PDF)

Old Style Mount (http://mercuryperformance.com/845739a10-cylinder-assyhyd-trim-p-16427.html)

I guess I could look for some old style 280 plates.