Transom angle on a 1995 Classic Blackhawk 22

[blackhawk]

Does anyone know what the transom angle on a 1995 Classic Blackhawk 22 is? I THINK they have the same transom as a standard 22 but I could be wrong. Mine is locked up in storage so I can't get to it to measure it.

Thanks

[GEOO]

I think it's 12 degree's. My 18 is 12-12.5.

Thinking of Rocker Plates??? wink

[Murphy]

Can't say if the Blackhawk and my 86 Classic 22 are the same mold, but the transom angle is a complex, compound curve. The angle changes constantly from side to side and from top to bottom. So there is not absolute answer to this question. Depending on where you measure you'll be at somewhere between 8-12 degrees.

The way I found mine was to mark the water line with waterproof tape. Water is true level. From this line, you can calculate the transom angle of the boat at rest in the water. I needed this angle to know what angle my swim platform brackets should be so the platform would appear level when the boat is at rest. The answer in that case was 10 degrees based on where the brackets got mounted. Otherwise, the question is "what is the transom angle in relationship to what other fixed point on the boat?" Depending on what that is, jack the boat until the set point is level on either a vertical or horizontal axis and measure at the transom at the exact spot you want to know about. A level and angle finder (hardware store) will work. Good Luck.

Murph

[blackhawk]

By looking at the transom I can tell there are some curves to it. I am looking for the transom angle where the K-planes/trim tabs are mounted.

[blackhawk]

Geoo. I am "thinking" about it! wink

[Jamesbon]

Best thing to do IMO, get a .99 cent plastic protractor and a couple paint mixing sticks. Hold the sticks vertically and horizontally against the desired location, lock 'em in place, then set on top of your protractor...

Hope this helps.

[blackhawk]

Murphy and Jamesbon,

Th eproblem is my boat is in storage and I can't get to it. :(

I was hoping that someone on the board would know.

Thanks

[Murphy]

At the point where K-Planes mount the transom is pretty flat. I'd say you have a 10 degree angle at that point.

Murph

[Woodsy]

You DO NOT want to put the Arneson Rocker Plates on your hull. You already have too much rocker built in to the hull already. All these will do is cost you lots of $$$ for no gain. They are designed for boats that are running surface drives or extremely high X-dim's with no rocker on the bottom of the hull. Surface drives by thier nature do not generate any signifigant amount of bow lift. With extremely high X-dimensions, trimming the outdrive gives you very little gain. They create rocker, thus causing the nose of the boat to rise. If anything, a Factory BlackHawk boat has no need of that. They would help out GEOO & Waleye because thier boats have no rocker, and the surface drive generates very little bow lift. They would also work in my application as well. But a factory rocker hull? No way! You would be better off spending your $$ on an extension box.

Woodsy Von BlackHawk :D :D

[CDMA]

Woodsy,

Keep in mind a rocker plate can just as easily be used to create hook and reduce the hoping tendency of a rocker hull.

Chris

[blackhawk]

Woodsy,

Have you ever seen the rocker plates? They are not designed to just add rocker to a hull. They are also designed to ADD HOOK. I am looking into them to add hook, not rocker, to my hull when needed.

[Woodsy]

I understand that they may create an artificial "hook". I say artificial, because for there to be a proper hook you need a concave surface. The Arneson Rocker Plates do not create a true concave or "hook" surface. The difference between the Arnesons & the K-Planes is the however, I stand by my statement. In essense your existing K-Planes do the same thing. The difference is the mounting location... the K-Planes mount about 1/2" off of your running surface, the Arneson's mount flush to your running surface. When in the down position, the only difference between the two is the pivot point. They essentially do the same thing... Its when the Arneson is in the up position that it works really well... Then they create rocker...

Woodsy :D :D

[CDMA]

Woodsy,

The rocker plates DO create a concave surface. They overextend past straight creating the "bent" shape.

Chris

[Woodsy]

Chris..

I didn't say that they did not create hook.. they do... read the post... the hook that is created by the Arneson Rocker Plates is the SAME as the hook created by the K-Planes... the difference is in the height of the pivot point... flush with running surface (Arneson), vs 1/2" above running surface (K-Plane)..

They will do nothing for that hull to justify thier cost... especially when he already has K-Planes...

Woodsy :D

[GEOO]

Rocker Plates are an extention of the hull. The 1/2" plate is bent with the trim ram to form a concave or convex, airfoil type of shape. This will create transom lift or suck the transom down thus creating more bow lift.

The faster you go the more transom lift you'll have from the props. At some point the Black Hawk Hull may need more bow lift too.

[blackhawk]

Woodsy,

Remember, the rocker plates are a "running surface" and the K-planes are not. As far as it being artificial hook, that is simply not true.

Since the plates are a running surface they are basically an extension of your hull. So, when I have the plates in hook position, they are convex and do create a "true hook" surface. With K-planes you are simply "dragging" the planes to lower the bow and stabalize the boat.

With the plates you have a hook in your hull that brings your bow down and stabalizes the boat. A K-plane cannot create hook, all they can do is "drag" to stabalize the boat. They are not even close to the same thing.

Again, one is a running surface and one is a dragging surface. :)

[Woodsy]

I don't think I am explaining myself all that well..

If you look at the pix of the Rockers at the Arneson Website, ( www.arneson-industries.com (http://www.arneson-industries.com) )they show the Rockers in the neutral position (parallel to the running surface of the boat). The plate is in a fixed location where it meets the hull. In other words, there is no "defined" pivot point on the actual plate itself. The plate is designed to flex. If you put the Rockers in the up position, the hydraulic cylinder pulls on the lever, that causes the plate to flex and move upward until it gets to the stop plate. This creates the rocker. The water flows along this surface at speed, and because of the surface tension of the water, it creates a suction that causes the bow to rise. (Simple terms). This is what the plates were designed for. In the down or hook position, the opposite occurs. The hydraulic cylinders pushes on the lever, causing the plate to flex downward. It may (I would have to see it) cause the plate to form a slightly concave shape. This would be the hook that you are seeking.

However, in order to form that convex shape, the TRAILING EDGE of the plate gets below the actual running surface of your boat, (it has to, otherwise you would have no neutral position (flat plate parallel to the running surface), Judging by the pix it has to. As soon as that TRAILING EDGE gets below the actual running surface of your boat, the Rocker Plates are essentially acting like the K-Planes you have now. They act like a lever, transmitting the force of the water against the plate to your transom, bringing your bow down. The Hook that you are hoping for is more than negated by the pressure of the water. Essentially, regardless of shape (flat or concave) if the TRAILING EDGE of the Rocker Plates is below the actual running surface of the boat, they are acting like any other trim tab. If they are in a concave shape AND the trailing edge is below the running surface, then they are inducing serious drag.

For another debate... hook is drag... so although you can debate the pro's & con's of the K-Planes, inducing hook artificially (with the Rocker Plates) or built in from the factory, hook = drag. Lowering the nose of your boat, also causes drag due to increased wet surface area.

Without posting drawings to the web, this is the best I can do to explain it. I stand by my original statement, that these are no better than your existing K-Planes when it comes to keeping your bow down or increasing/maintaining control of your boat at speed. If you didn't hav an extreme amount of rocker already built into the hull, the rocker aspect would be beneficial. As for creating hook, I disagree.. totally useless.

Woodsy :D

[blackhawk]

Woodsy, I see what you are saying. The rocker plate must induce drag to create the hook because the trailing edge is lower than the boat. But it's still not an apples to apples comparison.

There will be some drag when in the hook position just like there is some drag when the hook is built right into the hull. But, K-planes are designed to "drag" in order to bring the bow down. Rocker plates are designed to manipulate how the water travels across the surface. Yes, there will be some drag created but it will be much less than a K-plane produces to get the same result. So I agree with your statment, they both create drag. However, to get the same result(handlling at speed) the drag created by the K-planes will be much greater. More drag = less speed. Does that make sense?

[Woodsy]

BlackHawk...

Give me a call & I will explain it to you... It's alot easier than typing... 978-502-5465 You need to think levers & forces...

But to answer your latest post, in a nutshell, NO. As soon as the trailing edge is lower than the running surface of the boat, it will create drag. In all actuality, because the K-Plane is Not flush to the transom, it could (in theory) generate less drag. The drag is a transfer of energy at a given angle from the Plates (K-Planes or Rocker) to your transom. The transom acts like a lever, the force applied to your transom causes the bow on your boat to rise or lower depending on the position of the plate. The drag caused by the rocker plates is twofold. One, in the lower or "hook" position, the trailing edge is lower than the running surface of the boat, at this point it is NO DIFFERENT than a run of the mill trim tab. It transfers the energy of the water to your transom, which acts like a lever and forces the bow down. (I know repeating myself) Two, because the rocker plate is mounted flush to your running surface, the surface tension of the water following the surface of the plate will create even more drag. most of the plate will be creating drag as soon as the Trailing Edge is lower than the running surface. With your existing 280's, Because they are mounted off of the running surface, (in theory) the work is being done by the Trailing Edge only. Most of the plate is not in the water.

What you need to do is address WHY the boat handles poorly... That is because you have too much rocker on the bottom of the hull. Short of removing the rocker (I would not do that) what would work? I stand by my original statement, that the hook created by the Arneson Rocker Plates in this application is negligible at best. I wonder about the effectiveness on a straight hull (hook position, not rocker position, we know that works) never mind a hull that has alot of rocker already built in. Its a really expensive goodie, I think they run new for about $3500 or so, that really will not work for you.

The fix I would pursue is getting the props off the back of the boat and into cleaner water. Spend the $$ on an Imco Extension Box instead of the Rocker Plates. The boat will handle ALOT better, it will "think" its larger than it is. The advantage of getting the props off of the back of the boat are numerous, they run in cleaner water, the stern lift created by the drive will be able to overcome the rocker in the hull to minimize porpoising... I could go on. I think you can score a neutral extension box setup for about $2K or so new. If I remember right, you already have external steering, so all you will have to do there is get your rams shortened or lengthened to fit the IMCO...


Woodsy :D :D

<small>[ March 05, 2003, 05:42 PM: Message edited by: Woodsy ]</small>

[BigGrizzly]

In this discussion you are all correct but Geoo explained it short and to the point The Black hawh has too much rocker for the blackhawk drive. the drive is lifting the stern and dropping the hull right on the apex pf the rocker which then id causing the porpoise. which is why if its smoothe with the tabs up you get a great speed and lift than one change oe a ripple and it does the 1-2-3 bounce trick. When you put the tabs down you force the rocker in the water end ofr problem. I would like to see a Black hawk with a bravo and a Imco lower on it. This could be a fun ride. I too don't think rocker plates are your answer. It would be easier to put the sweet 16 hook-wedg on the top step.

[blackhawk]

Woodsy,

After seeing you recommend an extension box I have have come to the conclusion that you and I just have two totally different lines of thought! :)

I think we are both right in theory, but theory does not always work in the real world. I totally see what you are saying, but I still disagree. wink

Rocker plates manipulate the water flow. I think this is where we disagree. This manipulation RAISES OR LOWERS YOUR STERN. That is how the rocker plates work - manipulation of the water flow. Of course there will be some drag in the hook position. But, it is the MANIPULATION OF THE WATTER FLOW that changes the whole ride attitude of the boat, not just "dragging" the bow down.

Enough theory, real world talk! wink

My boat handles awesome when the waves have good rythem to them. My goal with the rocker plates is to improve the handling of the boat in "sloppy water". I boat on busy inland lakes and the combo of normal waves with boat wakes and sea walls makes 2 foot chop coming in every direction. In these conditions I am forced to drag the tabs enough bring the bow down and stabalize the boat. How much speed do I lose? TOO MUCH! My friend has a Four Winns U-19 which has a very prominent hook in the hull. In flat water or small chop with rythem he runs 65 mph on GPS. Guess how fast he runs in that "sloppy water"? That's right, 65mph all day long. That boat can handle anything you throw at it! It is so stuck to the water it's hard to believe it can even go that fast!

My ultimate goal? Simple, to have the best of both worlds. To get back the speed I lost with the 280's and run 78 mph again in "perfect conditions AND to run 70+ mph in the slop. I believe that the plates will do that by changing the attitude of my boat when needed. I hope I am right. Because if you're right they will be for sale on this board! wink

Okay, I'm tired of typing(and thinking!) now. I'll leave with a link that I thought was interesting. The rocker plates were developed using the Bernoulli Principle. Check it out:

http://www.sciencejoywagon.com/physicszone/lesson/02forces/bernoull/wings.htm

[blackhawk]

BigGriz,

If I keep my boat long enough AND ever have anough money I would love to throw a whipple on it and strap on a Bravo XR with an IMCO shorty. Ahhhh, the sleepless nights laying there and dreaming! :)

[blackhawk]

Now let's talk about why an extension box WILL NOT work on a blackhawk.

Ahhhh, I'm too tired! wink