Rocker Stoppers(?)

STeveZ · Post by **STeveZ** » Dec 4th, '06, 08:02

I'm sure most here are familiar with the B28's unfortunate propensity to roll when not under power. Has anyone tried out Rocker Stoppers? I hate to fork out 60 or 80 bucks for them, plus storage space, without some assurance that they work.

Carl · Post by **Carl** » Dec 4th, '06, 14:45

I haven't tried but can vouch for a sea-anchor tossed off the bow or stern. On a breezy day it makes a difference.

If off the bow ya just gotta remember it's out there before yo go to move.

In Memory of Vicroy · Post by **In Memory of Vicroy** » Dec 4th, '06, 16:22

A lot of the big shrimp boats around here use similar (but a lot larger) devices off their trawl outriggers. Obviously the farther outboard they are the better they work.

UV

Preston Burrows · Post by **Preston Burrows** » Dec 4th, '06, 18:37

Steve:

I use a 24" diameter sea anchor to point up...............once you can keep away from being beam to the waves the rocking is usually gentler,more like a B31.........the sea anchor folds/stores easily.....you do have the drunk rails still?

STeveZ · Post by **STeveZ** » Dec 4th, '06, 20:27

"you do have the drunk rails still?"

I do, though I've been tempted to remove them to open up the cockpit. The problem is worst when we anchor and chum on a busy weekend. Even though we may be seated three or four across the stern every boat wake sends us sliding back and forth across the cockpit. And queasiness is liable to follow for some.

Preston, your suggestion sounds like a good one for drift fishing.

Bruce · Post by **Bruce** » Dec 4th, '06, 20:38

UV's right, the further out the better and the further down the better.

The deeper they go, the heavier the column of water they have to resist.

I've heard that in real sloppy seas, the rapid motion does not give the cones enough time to settle to work properly and they end up working half ass.

Make your own out of 5 gal buckets.
Take 3 buckets, you can always add more.

Drill a 3/8 hole in the center bottom of all three.
Run a 3/8 line thru the hole on the buckets and leave a loop to attach a 10lb weight under the last bucket.

Every 4 or 5 feet knot above and below the hole in the bucket bottom and then around the handles.

Becareful to not hang the weight on the handle. The handle is only to keep the buckets upright.

Leave your self enough line to experiment with depth.

ScottD · Post by **ScottD** » Dec 5th, '06, 18:00

All right Bruce, your one of the smartest guys on the board, and I'm sure I'll regret this, but I'm going to have to disagree with ya on this one. First, I think the flopper stoppers work against the resistance thru water, not the weight of the water column, unless you lifting them out of the water. Second, a bucket will have about the same resistance going up or down hanging from the sides so will not be very effective. Granted, the rope will be taught on the rise and slack on the fall (slower down) which will work to some extent. I believe flopper stoppers have little water resistance on the fall, and high restance on the rise, as long as the surface is not broken, depth shouldn't matter. Like I said, I'm sure I'll regret this, but at least I think I'm right.

Scott

ed c. · Post by **ed c.** » Dec 5th, '06, 18:39

I have a bunch of traffic cones in the garage, they would probably work.

neil · Post by **neil** » Dec 5th, '06, 19:05

i agree with scott regards neil

Bruce · Post by **Bruce** » Dec 5th, '06, 19:56

Scott,
Your 100% correct if the floppers have some sort of flap check like the old par pumps. They will work much better than the buckets.

Having never seen the floppers I don't know how they are made only that two people in the past have tried them and both said the results were not what they expected and seemed to get worse the rougher the seas got.

Both individuals were fairly bright boaters and I assumed they were deployed correctly.
One tried the bucket theory I passed on and reported it worked to some extent and worked better the deeper they were lowered.

I figured it was the resistance of the column of water they were trying to move.

Buckets are certainly not a replacement for a well designed and deployed anti roll system.

In Memory of Vicroy · Post by **In Memory of Vicroy** » Dec 5th, '06, 21:03

Hmmmm.......deeper means more weight on the flopper, so harder to pull up. I'm no engineer, wanted to be one, but the math kicked my butt in the early 60's so I opted for law school where reason is thrown to the winds.

I remember a college physics class where the prof was explaining that a huge bridge pier exerts as much force down as it holds up.

Let's imagine a 50 foot diameter disc suspended below the boat, say one on each side, with a rope thru the middle of each disc attached to the outriggers on each side. I challenge any of you engineers to explain to me why one of the discs that is suspended deeper will not exert more drag on the rope than one near the surface, even if the shallow one never breaks water. Sure, the friction in the water is most of it, but as Bruce says, the water column is heavier on the deeper one.

Eagerly awaiting an answer......

UV

scot · Post by **scot** » Dec 5th, '06, 21:48

Gismo's of this nature work based on diameter, or resistance. Not the weight of the water. Water column is measured in PSI, not linear weight as relates to gravity. Every 33 ft the PSI doubles. Atmospheric pressure is 14.7 PSI, at 33 ft the pressure is 14.7 PSI, 66 ft= 29.4 PSI and so on. That's why 33 ft is commonly refered to as (1) atmosphere. This works out to roughly .5 PSI per ft. i.e. 200 ft of water has a pressure of approximatley 100 PSI.

With that noted, the "weight" or force pressing on the bottom IS based on depth.

The reason they do not relate to depth is that the water is pushed out of the way to the sides as the disc rises. If the disc were sealed in a pipe like a piston the column weight of the water WOULD apply.

I believe this applies assuming the depth of both is deep enough for the surface not to be capable of relieving the movement of the water. Say all disc being deeper than 10ft or so. If one disc is 2 ft deep and the other is 50ft deep there would be a difference because the surface can relieve some of the reaction of the shallower disc.

So your all correct, but for the wrong reason. Deeper works better.

My .02 cents
Scot

scot · Post by **scot** » Dec 5th, '06, 21:56

One more concept; The PSI exerted on the disc is the same on both sides, top and bottom...so top and bottom cancel each other out. Neutral PSI as relates to rising or falling.

In Memory of Vicroy · Post by **In Memory of Vicroy** » Dec 5th, '06, 22:13

So why not put the disc in a long PVC pipe so you get the advantage of the added water column?

UV, the never satisfied......

scot · Post by **scot** » Dec 5th, '06, 22:16

Anchor the pipe to the bottom, put an o-ring on the disc and you've got something. Make sure the top of the pipe extends past the surface. I think you should patent it.

In Memory of Vicroy · Post by **In Memory of Vicroy** » Dec 5th, '06, 23:13

No, ya'll still dodging the issue of water weighs more than air. If the disc is inside a PVC pipe, won't the deeper the disc is make it harder to move?

I may be dumb, but after hauling the Bride's pot plants in before the freeze last nite, I can tell you water weighs more than air. My back tells me that too.......

UV

Harry Babb · Post by **Harry Babb** » Dec 6th, '06, 08:39

Scot,
I have to differ with you slightly on the pressure debate. Every 33 feet the pressure is increased by one atmosphere. On the surface we are experiencing 14.7 PSI which is one atmosphere. At 33 feet the pressure is 29.4 (which is doubled) but... at 66 feet the pressure is 44.1 (increased by only 1 more atmosphere) and at 99 feet the pressure is 58.8 etc.

Its my opinion that these "Rocker Stoppers" work based on resistance only and that weight and pressure do not even enter into the equation.

I think that this is one of those conversations thats only solveable with a bottle of Crown and a Patio Fire on a cool brisk evening.

Harry Babb

ScottD · Post by **ScottD** » Dec 6th, '06, 08:42

Think about this, if water depth increased lifting resistance, your anchor would be almost impossible to pull up in deep water, and would get eaiser as it came up, and ya know that ain't so.

ScottD

scot · Post by **scot** » Dec 6th, '06, 08:51

You are correct. My brides pots that are full of water weight more than the ones full of air also.

We got-ta-get the pipe out of the discussion...it appears to be confussing the hydraulic logic.

The krux of it is that the weight of the water is also appling itself (in PSI)to the bottom of the disc as well...it's an even pressure, therefore it cancels out additional downward force on the disc.

Density of the water, not weight makes them work. Getting them deep removes two elements; surface reaction and wave action. Got-a get'um down past the waves.

You must be a lawyer, I can't put up much of a defense agin mamma's flower pots. LOL

Now, putting them farther from the boat on out riggers makes perfect sense. That creates leverage and the stabilizing force of the disc is multipled at the boat.

Try to hold one of mamma's full flower pots with your arms fully extended.

scot · Post by **scot** » Dec 6th, '06, 09:10

Harry,

At 33 ft water weights 14.7 PSIG, or "Pounds Square Inch Gauge" thats because ALL the instruments that we use are calibrated to remove the 14.7 atmosphereic pressure and read "0" at the surface. You are talking about PSIA, I was speaking of PSIG.

All of your statements are true, I'll take Jim Beam please....but I'm running on memory and didn't bother to break out the calculator, or clarify correctly.

Scot

Chiles · Post by **Chiles** » Dec 6th, '06, 10:34

OK, now time for the Virgina boy to add his .02 cents.

I believe it is all drag. The design of the device appears to allow for less drag on fall, and more drag on being pulled.

Think about it this way, when you have a streatch 30 on your trolling rig, does it pull harder when it is at depth then it does when it is only 5 feet from the surface? It may slightly because of the drag of the line thru the water, but I don't think the depth itself causes it increase drag.

Planes fly high because the air is less dense, and less dense means less drag and they can fly faster. Water does not change in density and has the same density at the surface as it does at 200 feet. Water can exert pressure, but can not be compressed (unless it is heated to steam, but that is another conversation).

Therefore it is the opinion of this slightly educated red neck that only the drag created by the top of the design of the device that makes for the friction needed to slow the roll of the boat. I also concur that the bucket would work similarly, and maybe not need to be the full 5 gallon, but somewhat less.

Let the criticism begin.

Chiles

Chiles · Post by **Chiles** » Dec 6th, '06, 10:36

On more thing...

Gentleman Jack please.

scot · Post by **scot** » Dec 6th, '06, 11:08

In Memory of Vicroy · Post by **In Memory of Vicroy** » Dec 6th, '06, 12:27

So whatever happened to inertia????? Objects at rest tend to stay at rest, objects in motion tend to stay in motion????? Energy must be applied to change either, so where does the energy come from to move the disc?????

UV, Esq.

randall · Post by **randall** » Dec 6th, '06, 13:41

UV....well i often explain to people that the water isnt the wave....the wave...a huge and powerful band of energy moving through the ocean (originally wind energy....and before that solar energy)..makes the water do that......same concept.........i think.....btw...after i left you folks at dinner i walked the wrong way cause i was blabing with caren on the cell phone.....i surely would have missed my bus but i realized my mistake in front of a taxi depot............................luck counts......was great to see you

Chiles · Post by **Chiles** » Dec 6th, '06, 13:42

Well, How about this?
The oncoming wave exerts a force on the side of the boat which causes the boat to move. If the boat were tied too tightly to a dock, the lines would be forced to obsorb that energy and transfer it to the pilings.

The rocker stoppers are deployed and energy is transferred from the boat, thru the line to the stoppers which in turn use their coefficient of drag to transfer that energy to the water. The more surface area of the device, the more drag can be transferred. The further the divice is away from the boat, the more fulcrum effect would be exerted.

I've given some further thought to the depth question. Assuming the water less turbulent at depth, the drag would be greatest when the water is still. At or near the surface, wave action will make the water turbulent and reduce the drag that is exerted on the device. Therefore, I would believe that more depth would preferred.

Chiles
(Not enough to do at work today)

capy · Post by **capy** » Dec 6th, '06, 13:42

Haven't been around for a while but I got to add the following

Rockers stoppers work on the principle of drag thru the water, no question on that.

The longer the moment arm, the better they will work cause roll is a torque applied about the boats center of gravity, and the T= (Force) X (Length of the moment arm from the center of gravity)

So for a given torque ....... F=T/Moment arm

Since the torque is constant, varying the moment arm or force can counteract the torque and keep it from causing roll.

Longer moment arm equals smaller force to counteract the Torque.

By extending the depth, you are essentially increasing the moment arm.

My 2 cents.

TailhookTom · Post by **TailhookTom** » Dec 6th, '06, 13:46

Don't forget to have your cutting torch on board so when those birds start swinging through the air, you can climb the outriggers and cut the chains free while pitching about in 30 foot seas.

Okay, so that was The Perfect Storm -- I guess you could get away with a fillet knife!

TailhookTom -- now I know why they say I am Physically challenged

scot · Post by **scot** » Dec 6th, '06, 14:15

The moment arm is horizon, the distance the disc is from the boat. The vertical element (depth) is constant as relates to the moment arm. Depth does not alter the moment arm.

Between mamma's flower pots, inerta, wave energy and pipes my head hurts, you guy's can finish this one. LOL

Scot

Hal · Post by **Hal** » Dec 6th, '06, 15:11

I don't know if those little orange cone things will work or not, but I had the same problem with that roly-poly tossyourassouttathetower 28 footer Xanadu. Instead of tossing the cash out for the rocker stoppers, I figured an even better way.

Check out the avatar for a sure fire way to end the hyena from rocking and leave momma's plants on the porch.

randall · Post by **randall** » Dec 6th, '06, 16:17

tom....that was a fun movie......really liked the computer animation of huge waves BUT....if you was an experienced sword boat cap't and were about to run the storm of a life time.....wouldn't you harden the windows and pull in the birds before it got snotty?

TailhookTom · Post by **TailhookTom** » Dec 6th, '06, 16:39

Randall: One would certainly think so -- especially considering most of those boats are backyard engineered one offs. Something comes to mind -- batten down the hatches!

Hey, on a completely different issue, did anyone see the report of a 77" Bluefin tuna taken in Bogue Sound in only 3' of water on a spinning rod. My understanding is that the fish was put into a 15 Carolina Skiff and was greeted at the dock by various government officials who wanted to see the tuna permit. The operator showed his permit, which was actually for his 25 Parker -- at seeing the frown on the Confiscators faces, he supposedly said, "I thought it was a yellowfin, not a bluefin!" Sorry Charlie! Reminds me of a couple of years ago with the fiasco up here where surfcasters were catching School Bluefins right off the beach on Block Island -- can't land them, cause you can't get a land permit!

Anyhow, I digressed, something about 3 hours of sleep the past 2 nights and numerous pots of coffee.

Tom

Harry Babb · Post by **Harry Babb** » Dec 6th, '06, 19:28

Okay guys.........I am at the bottom of that bottle of Crown.......Have we made a decision yet???? The original question is is it worth the 80 bucks???

My decision is NO......spend the 80 bucks on enough gasoline to get your ass out of that sloppy crap........go home and change the oil or something...

Its been fun

I enjoyed this post and the following threads

Harry Babb

Tony Meola · Post by **Tony Meola** » Dec 6th, '06, 22:31

Ok after reading all the theory's I have a question. I understand drag is drag and water weight is water weight. But if we lowered a rocker stopper down 5 feet and used a scale to somehow measure the pull at that depth, then tried it at 30 feet, it would stand to reason the scale should show two differant pulling weights due to:
a) the differance in the drag of the water, or
b) the weight of the water, or
c) the pressure of the water, or
d) the denisty of the water.

and of course one of you is going to say all of the above.

What am I missing here? Tony Meola

In Memory of Vicroy · Post by **In Memory of Vicroy** » Dec 6th, '06, 22:41

You forgot the added weight of the longer rope.

Very little gets past this crowd......

UV

STraenkle · Post by **STraenkle** » Dec 7th, '06, 07:53

OK I will finally pipe in on this one being a lowly Aerospace Engineer. To cover Tonyâ€™s question, the pull would be identical, except due to the difference in the weight of the rope like UV pointed out, however since some line floatsâ€¦ it would be less.

Water is essentially incompressible and the density is the same if you discount the salinity difference, which at these surface depths is identical. A gallon of water weights the same at 50 feet as it does at 5 feet.

Drag = Â½ * (Coefficient of Drag) * (Density) *(Velocity)^2 * (Surface Area)

Thatâ€™s it. The coefficient of Drag for what ever will not change, the surface area did not change, assume the velocity is the same, and the density is the same. The amount of pressure does not matter, because water is incompressible.

Do you really think it is harder for a fish to swim at 50 feet than near the surface? Does the hydraulic hose get heavier on the high pressure side when you turn the wheel?

Scott

Eddy G · Post by **Eddy G** » Dec 7th, '06, 08:44

Rocker Stoppers have been on the market for years, so they must do something. I say buy a half dozen of them from Worst Marine, string them up and try them. If they don't work well enough, return them after Christmas as an unwanted gift. (Staying away from the science and going straight to the R & D) I did see a variation of these things somewhere that was two aluminum plates with a hinge between them. It collapsed on the down stroke to be streamlined and opened up to a wide vee on the up stroke. A small weight was used to collapse and pull it down. It would seem they would store away easier. If you try the Rocker Stoppers, let us know if they work. I anchor out a lot and the roll is a pain.
Eddy G.

thuddddddd · Post by **thuddddddd** » Dec 7th, '06, 08:53

OK I stayed out as long as I could......... There is a reason everyone calls them RLDT's, if you didn't want a roller, should have bought a Tubbbbbb
Can't fix a enginering flaw

scot · Post by **scot** » Dec 7th, '06, 09:06

That took you a long time Timmy, I was waiting for the "Rolling" coments from the first post.

Rawleigh · Post by **Rawleigh** » Dec 7th, '06, 09:54

Timmy is trying to be good since it is right before Christmas!!!

Brewster Minton · Post by **Brewster Minton** » Dec 7th, '06, 10:09

I knew he would say something. I was worried he was sick or his computer died.

Bruce · Post by **Bruce** » Dec 7th, '06, 14:32

Scott,
Being the engineer.....

We know a fish, like a sub is built streamlined. Going horizontal thru the water makes no difference at depth unless your at the surface as a sub goes faster submerged.

But the stoppers are not going horizontal or streamlined.
They are designed with a surface area to catch the water and slow or prevent the boat from rocking by the resistance of moving the water that is above them out of the way.

While some of that water will move to the sides, some wants to come vertical or lift up depending on the vertical speed of an object.

Tie a rope in the center of a 4x4 sheet of ply and submerge 10' then pull straight up, some water will move off to the sides, how much will depend on speed, the rest will resemble a dome on the surface right before the ply comes out of the water.

Now take into consideration the weight of the rope for deeper depths, would it not require more force to verticaly raise that ply the lower you go because of the water above it and having to move it out of the way?

Or does that water weight only come into play at the surface?

thuddddddd · Post by **thuddddddd** » Dec 7th, '06, 16:40

Scott, don't know about a aerospace enginer(or how to spell it) but I agree with you about being lowly.

The rest of you , wern't you proud I was able to make 2 pages??
Santa better be real nice to me, maybe one of those cool mid atlantic shirts, or the oak bluffs one, (running out of UVI bilge rags) maybe even one of the Mt gay rum ones, nah I like those.

In Memory of Vicroy · Post by **In Memory of Vicroy** » Dec 7th, '06, 17:18

Bruce, I agree with you 100%. All this engineering b.s. these pretty boys are spouting don't account for the fact that a heavy thing is harder to lift than a lighter gizmo.

Case closed.

UV, Esq.

Harry Babb · Post by **Harry Babb** » Dec 7th, '06, 17:29

Glad to see this problem analyzed and solved

Now its time for the "Crown Royal"

Harry Babb

Bruce · Post by **Bruce** » Dec 7th, '06, 17:47

Timmy,
How bout this t shirt. We'll all chip in and get it for you since you've been so kind.

neil · Post by **neil** » Dec 7th, '06, 17:47

timmyyyyyyyyy we are glad you liked the shirts neil

In Memory of Vicroy · Post by **In Memory of Vicroy** » Dec 7th, '06, 19:52

Let's say I put a one ton (2,000 lbs for you engineeringly challenged, like Timmy) weight on one side of the boat off a rope, and a two pound weight on the other side. Both suspended the same distance below the surface on identical ropes. Both have the same vertical cross section, imagine a sash weight a foot long, the onther a few hundred feet long, but the same cross section, the heavy one just a verrrry long sash wieght.

Which one gonna put the most resistance to rocking the boat?

Huh???? C'on you engineers, come out of your techno holes and give an honest answer. This is important......

UV, Esq.

randall · Post by **randall** » Dec 7th, '06, 21:34

neither...the two ton side will pull the scupper under and the boat will sink............

Terry Frank · Post by **Terry Frank** » Dec 7th, '06, 21:41

And who REALLY cares. If it's that rough I'm not fooling around with that crap. I've got better things to do. Maybe hanging out with Timmy on the Tubb . Too old to be surviving something that's supposed to be fun.

Terry

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