Flopper stopper

[bobs]

I was thinking of making my own flopper stopper , been reading/hearing good reviews on the rock 'n roll (magma) and have a few questions about the size of the wings.
Magma "Rock 'n Roll"™ Boat Stabilizer / The Mad Dogs, Exploring to Inspire...™

Apparantly each wing is about 27cm high , but would there be a technical or efficiency-wise obstruction/counterargument of making the wings bigger ?
Meaning , bigger is better , but I'm not quite sure if that's the case in this case.
I was just thinking that bigger flaps would need more distance (rise) to unfold , and thus reduce the dampening effect.
So the main question is , are the ratio's of the rock 'n roll sizes scientifically determined and therefor crucial , or is it a compromise between the use of material (read the price of it) - in this case stainless steel - and still have a sufficient dampening ?

If the last were to be true than there should not be an objection to enlarge the flaps ,...or do I miss something here ?

Thanks
Beste regards

[bobs]

No one ??
Looks like the rock 'n roll system isn't popular or well known.

Regards

[Kokanee]

I've seen other brands advertise multiple sizes depending on the size of your boat. I would think the only negative of large would be cost and storage space.

But no - I did some googling and accord to this person...
Flopper Stoppers
He says they can work too well, and place too much shock on the rigging.

It might take a bit of trial & error to get them just right.

[Paul L]

Except on rounded bottom trawler type boats, I see very few people actually using flopper-stoppers -- even in the open rolly anchorages of Mexico's Pacific coast. Within reason, bigger is probably better. More important is probably how far you mount them off the rail. If you have a paravane then they should be easy to mount. A spinnaker pole works on a sailboat, but does tend to be a bit of a pain to setup.

[JPA Cate]

bobs,

Jim built a roll dampener like that, out of aluminum, rather than ss, and we used it a few times. The main problem we had with it was chafe on the sheet that went through the spinnaker pole end. It is so long ago, that I don't remember if we tried adding a snatch block to the fitting for the downhaul, but found the whole contraption rather a nuisance to use.

Since that time, we have seen the roll dampeners that look like a series of pie plates used. Also new one guy who partially filled his dinghy, and suspended it via the spinnaker pole route, and that seemed to work.

IMO, it is your body feeling secure that allows you to sleep in rolly anchorages, so using a cozy sea berth and lots of pillows works for me [Jim is less bothered by motion than me], and is much less trouble to rig. We just kept experimenting till we found what works for us.

Ann


Ann

[Jim Cate]

Originally Posted by Ann T. Cate

bobs,

Jim built a roll dampener like that, out of aluminum, rather than ss, and we used it a few times. The main problem we had with it was chafe on the sheet that went through the spinnaker pole end. It is so long ago, that I don't remember if we tried adding a snatch block to the fitting for the downhaul, but found the whole contraption rather a nuisance to use.

Since that time, we have seen the roll dampeners that look like a series of pie plates used. Also new one guy who partially filled his dinghy, and suspended it via the spinnaker pole route, and that seemed to work.

IMO, it is your body feeling secure that allows you to sleep in rolly anchorages, so using a cozy sea berth and lots of pillows works for me [Jim is less bothered by motion than me], and is much less trouble to rig. We just kept experimenting till we found what works for us.

Ann


Ann

Jim chiming in here!

The one I built twenty years ago looked almost exactly like this store bought one, but bent up out of 3 mm Aluminium, and with a plastic piano hinge along the full length of the blades. The size was scientifically determined by the size of the scrap aluminium sheet that I found at the scrap yard.

We suspended it from the spinny pole, wung out at 90 degrees to the boat and stabilized with fore and after guys. We did use a snatch block at the end for the suspending rope but it still managed to chafe a lot. It did a very good job of roll dampening, but we didn't use it much. First, it was as Ann said, a PITA to rig/unrig, and second, it was quite noisy in action. The oscillating loading on the pole found every little bit of slack in the system, and it would bang about unmercifully all night, rather counteracting the calming effect of the roll dampening!

It went with Insatiable-one when we sold her, and I haven't bothered to make a new one for this boat.

Ji,

[bobs]

Oh thanks alot guys , and also the lady of course , your remarks do help .
Now please , don't get me wrong here , I'm not advertising , being a mod on that board I mean , but maybe you could also have a look here :
flopper stopper | Jeanneau Owners Network Forum
Not sure where that topic will lead us , but maybe like on this terrific board some postings could be very useful or/and contributing.
I'm just trying to get as much info as possible , since I will be welding the hinges on this week . And after that has been done , reconfiguring the concept (adjust the size) will not be that obvious anymore.
Think before you act ,.....right .

Regards

[rcmpegasus]

I have a similar flopper stopper, rectangular frame with louvers that open and close. I suspend from a spinnaker pole and a snatch block. It works very well and I use it a lot when anchored in any area with some roll. It makes it much more comfortable onboard cutting out a lot of the sharp accelerations in roll. I have a second one that I use off the mizzen boom, only had to do that once, it really damped out the roll. I like the units, they take a bit of effort to rig, maybe 10 minutes, but really work well.


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[bobs]

Originally Posted by rcmpegasus

I have a similar flopper stopper, rectangular frame with louvers that open and close. I suspend from a spinnaker pole and a snatch block. It works very well and I use it a lot when anchored in any area with some roll. It makes it much more comfortable onboard cutting out a lot of the sharp accelerations in roll. I have a second one that I use off the mizzen boom, only had to do that once, it really damped out the roll. I like the units, they take a bit of effort to rig, maybe 10 minutes, but really work well.


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Hi Bob , thanks for sharing you insights .
I'm absolutely convinced this system works great , it has to be ,but I've read somewhere the flaps make a irritating noise when they close ?
Could you confirm or is there some sort of dampening too ?

Regards

[Dennis.G]

We have the Magma Rock n Roll unit, and it works well. Do not expect it to completely eliminate roll, but only dampen it. In a rolling anchorage it can keep you from going insane. You do need to experiment and find just the right way to rig it so as to minimize chafe and noise. No noise from the flopper unit itself, but can have spinnaker pole fittings etc. clanking on each roll of the boat. If rigged right you can prevent the noise and also minimize any chafe.

We do not use all the time, and it is a hassle to rig, but worth it on the occasions it is needed. It is our friend.

[bajatrawler]

Bobs,
We have been using the Magma system on our trawler for some years in the Sea of Cortez. It works well after I made some modifications.
I lengthened the original 8' poles to 12' and this made a significant difference. The 6061 aluminum poles slide inside each other for retrieving / storage.

Also, I replaced the original nylon end pieces on the poles. As the flopper down line rubbed through these end pieces during rolling of the boat, it would squeak and drove the Admiral crazy. This action also wore a groove in the nylon, down to the pole; not good. I fabricated new end pieces from aluminum and no more squeak.

I changed the fore and aft guys on the poles to braided cable with snaps on the ends to make hook up easy. When underway, we just lift the poles, remove the floppers using snap shackles on their lines, and secure the poles vertically.

Using these "roll dampeners" on our shallow draft, semi-displacement hull trawler has been well worth the cost, and made uncomfortable nights at anchor much less of a problem.

[CaptTom]

Originally Posted by bajatrawler

I lengthened the original 8' poles to 12' and this made a significant difference....

Using these "roll dampeners" on our shallow draft, semi-displacement hull trawler has been well worth the cost, and made uncomfortable nights at anchor much less of a problem.

It's interesting that you had to get them that far away from the hull to work. I also have a shoal draft semi-displacement hull with soft chines that rolls quite a bit.

I don't really have room for outriggers, either on the boat or in the budget. I wonder if anyone has tried the round "rocker stoppers" that just hang over the side?

[wsmurdoch]

An older thread.

http://www.cruisersforum.com/forums/...rs-117639.html

[bobs]

Originally Posted by bajatrawler

Bobs,
We have been using the Magma system on our trawler for some years in the Sea of Cortez. It works well after I made some modifications.
I lengthened the original 8' poles to 12' and this made a significant difference. The 6061 aluminum poles slide inside each other for retrieving / storage.

Also, I replaced the original nylon end pieces on the poles. As the flopper down line rubbed through these end pieces during rolling of the boat, it would squeak and drove the Admiral crazy. This action also wore a groove in the nylon, down to the pole; not good. I fabricated new end pieces from aluminum and no more squeak.

I changed the fore and aft guys on the poles to braided cable with snaps on the ends to make hook up easy. When underway, we just lift the poles, remove the floppers using snap shackles on their lines, and secure the poles vertically.

Using these "roll dampeners" on our shallow draft, semi-displacement hull trawler has been well worth the cost, and made uncomfortable nights at anchor much less of a problem. Attachment 93719

Oh boy bajatrawler , that really make sence , getting them further out gives you more leverage. I'm sure there's a mathematical formula somewhere to calculate howmuch you gain each foot the stopper is further from the boat.
But then again , the more the pole sticks out , the more a warning light (led blinker) at the end of the pole imposses itself no ?
Other yachts getting in the bay or anchorage during the night you see.
I can imagine getting those poles out and in position is quite a mission.
As a sailing yacht we can use the boom , limited in lenght of course.

I was also thinking of using D-shackles as a fix on the welded lifting eyes on the wings to reduce/eliminate wear , but I'm a bit concerned about the clicking/rattling noise they could make. Unfortunately they will also disturb a complete folding up . Compromises ....right.
No ropes but thin s/s cable or chain to the central connection to prevent chafing , and no doubt a halyard block at the end of the boom .

I have been using a cone-shape drag anchor up to now , that is close to being a nightmare to get it out again. Not just that , this shape causes friction on the way down resulting in a loss of dampening when the roll-motion reverses.
I'm looking forward to the use of my new stopper and will most likely post some pics on one of the boards.

Thanks for the valuable responses sofar.
Regards

[rcmpegasus]

I have had no issues with noise from the flaps. Never heard a thing even in big rollers, the flaps are underwater so they flap back pretty softly. I use a good block on the end of the pole, so never had a issue with chafe. My pole is 21 ft do it does stick out a bit which has been a minor issue in mooring fields at Catalina a couple times, as some of the moorings are close together.


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