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Old 09-05-2020, 05:00 PM   #1
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Reducing roll while anchored or moored.

We have a Gyro that is on whenever we are running the boat. I only run it while stationary if conditions are very bad for environmental reasons.

I have been thinking of a flopper stopper for a few years now and watching the guy next to me the past week rolling a heck of a lot less than we are, itís time to do it.

I know extending it away from the boat horizontally like sailboats do with their boom is best to get a larger Moment arm to resist the boat rolling. But my plan is to just hang one on a midship cleat, possibly both sides.

The folding plates shown below appear to be the most popular, but I have seen people use the stacked ones as well.

Thoughts as to the best solution, or other products out there I may be missing?
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Old 09-05-2020, 05:30 PM   #2
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These are the ones I will likely install, providing I can make contact and the price is OK. They do not appear to have a webpage anymore so I am unsure of their status.

https://www.facebook.com/Ocean-torqu...=page_internal
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Old 09-05-2020, 05:55 PM   #3
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The stacked cones with weight at the bottom aren't a magic bullet, but even hung from the spring cleats, they help significantly.

I'm probably going to drill a few big holes in mine and add rubber flappers to reduce resistance to going down. Even with about 15 lbs of with for 4 cones, they don't always reset fast enough on a significant roll due to my boat having a very short roll period (about 3 seconds).
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Old 09-05-2020, 06:11 PM   #4
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I have the Magma flopper stopper and find it works fairly well. It gets deployed whoever we anchor unless is perfectly calm. I use their 8 foot telescopic outrigger to extend the reach rather than mounting it off my sail boom.

I measured my roll motion with and without the flopper stopper while at anchor. I found it reduced roll from an average of 18 degrees to 4 degrees. Mounting it directly onto the midship cleat, the effect is noticeably less, perhaps 18 degrees to 10 or 12 degrees (although I didn't measure it.

There is considerable stress on the rigging, so ensure whatever you use is heavy duty. I beefed up the Magma flopper stopper by thru-bolting the hinges as they were just spot welded in place.
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Old 09-05-2020, 06:52 PM   #5
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Haven't personally tried it but using a Seabrake as an ad hoc flopper stopper was recommended to me. Lighter and easier to store than the typical options but I was always a bit sceptical about how fast it would sink on the down cycle.

https://boatcrewgear.com/burke-seabrake-drogue/
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Old 09-05-2020, 07:49 PM   #6
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Haven't personally tried it but using a Seabrake as an ad hoc flopper stopper was recommended to me. Lighter and easier to store than the typical options but I was always a bit sceptical about how fast it would sink on the down cycle.

https://boatcrewgear.com/burke-seabrake-drogue/
Do you think you'd have to attach some weight on the end of the drogue?
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Old 09-05-2020, 08:06 PM   #7
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These look interesting.

FlopStopper.com
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Old 09-05-2020, 08:10 PM   #8
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That was suggested and would seem to be an easy fix. Not sure I get the physics of it (is the turbulence induced drag really that effective?) but a number of sailors I've spoken to routinely hang one of these from their boom and swear by it. It may be that its real benefit is that if you have one on board anyway then why not get a second use case from it.
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Old 09-05-2020, 09:02 PM   #9
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A previous owner of my boat had Outbound Yacht Services in Dana Point add a flopper stopper setup, a ~10 foot pole with a Magma plate and associated rigging. It took a few tries to get used to launch/retrieval, and a few rolly anchorages to convince me (and particularly my better half) that it really worked. Now, unless it's totally calm, I deploy it. It takes about 5 minutes to deploy if everything is stowed; less if it was used at the previous anchorage. Retrieval is similarly quick, although takes a bit more grunt. I'm 30 and reasonably fit, which I'm sure helps!

A friend who has much more experience with offshore cruising and flopper stoppers wrote this up, and I'll probably swap the Magma for something else before we leave the PNW:

https://mvstarr.com/how-can-we-desig...opper-stopper/
https://mvstarr.com/making-a-better-...ne-year-later/
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Old 09-06-2020, 12:46 AM   #10
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A previous owner of my boat had Outbound Yacht Services in Dana Point add a flopper stopper setup, a ~10 foot pole with a Magma plate and associated rigging. It took a few tries to get used to launch/retrieval, and a few rolly anchorages to convince me (and particularly my better half) that it really worked. Now, unless it's totally calm, I deploy it. It takes about 5 minutes to deploy if everything is stowed; less if it was used at the previous anchorage. Retrieval is similarly quick, although takes a bit more grunt. I'm 30 and reasonably fit, which I'm sure helps!

A friend who has much more experience with offshore cruising and flopper stoppers wrote this up, and I'll probably swap the Magma for something else before we leave the PNW:

https://mvstarr.com/how-can-we-desig...opper-stopper/
https://mvstarr.com/making-a-better-...ne-year-later/
Website Disabled is definitely interesting. Only apparent downfall I can see is retrieval. If you watch the video he says to pull them up slowly, but if the floopers are activating due to a rolly anchorage it may be quite difficult to retrieve. A light line attached to one side would help lift it up vertically suspended and facilitate an easier retrieval, imo
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Old 09-06-2020, 01:24 AM   #11
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I was quite surprised at the difference an extra 3 tonne of diesel made.
The lighter we get the more she rolls.

3 tonne of lead when we get back might be on the cards - probably easier to get organised than flopper stopper arms which I've been trying to get on and off for 4 years.

As a working trawler there would have been several tonne of ice and prawns in the cold room
Now there's just several boxes of wine, inverter/charger and some oil and filters.
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Old 09-06-2020, 05:35 AM   #12
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Over a year ago, there was considerable discussion about using "rolling chocks," which are basically longitudinal "fins" on a hull. A good discussion here, esp. the link to an article: https://www.trawlerforum.com/forums/...els-43050.html


Despite the generally favorable comments regarding them, I'm at a loss why most later discussions about boat stabilization don't include them. It seems people prefer much more expensive and/or troublesome products to use. I've been reading a lot about power boating. Flopper-stoppers seem a big hassle to deploy and retrieve in some videos I've seen, that is if you're using them underway, and I don't understand using them solely at anchor.


Powered stabilizers and gyros are far too expensive and troublesome imo. Why not install or spec out rolling chocks for your boat, whether an addition or in a build? Seems to me the cheapest, best, and most effective way to stabilize your boat, either at anchor, or underway.
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Old 09-06-2020, 06:01 AM   #13
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I’m a newbie to power. I’m currently actively looking to buy a liveaboard trawler. On commercial fishing craft around here commonly see strakes welded outside the vessel running nearly its length. Do they prevent roll at anchor and underway? To what degree?
I’ve also been looking at vessels that drag fish. Do fish do anything at anchor? Or do they only have a significant effect if underway? How much hassle are fish? Been told in a serious seaway they should be taken in as to not damage the boat. Counterintuitive, one would that’s when they would be most needed. What’s the usual limitation? Force 5? Force 8? See current fins stated to prevent roll at anchor. Do prior generations of fins do anything when turned off at anchor?
Do immersed hard chines decrease roll? On sailboats bulbed fin keels May roll more as a harmonic can occur. Does the same occur on power boats? Do displacement boats roll more than semi displacement?
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Old 09-06-2020, 06:27 AM   #14
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Several Willard owners have installed roll chocks and generally report perceptible roll reduction underway. The reports are difficult to qualify because the lag between install and use - not like flipping a switch. But the owners I've talked to are experienced owners with significant time aboard their vessel and an obvious commitment to long term ownership, so I do not question the benefit of roll chocks underway. I know of one Willard 40 owner with paravanes who recently installed roll chocks, though has not fully sea-trialed. I am not aware of any benefit at anchor. My sense is roll chocks are worth the time/money to install, but do not expect the same roll control that either hydraulic or paravane stabilizers provide.

Flopper stoppers. First, some nomenclature. I consider flopper stoppers to be used exclusibely at-anchor. If the system is beefy enough and used whilst underway, it is a "Paravane" system. The paravane "Fish" are much smaller than at-anchor flopper stopper plates, and because the fish trail behind the vessel, the tethers are much longer than flopper stoppers. Net result is that a paravane setup would have different flopper-stopper gear for at-anchor use. My Willard 36 has hydraulic stabilizers for underway and a flopper stopper system for at-anchor stabilization (see my avatar pic).

Under-sized paravane systems may launch the fish in rough seas which is obviously very dangerous. When a Willard 30 went from Chesapeake Bay to Bermuda, it had paravanes. Steve D'Antonio (then yard manager for Zimmerman Marine, dealer for Willard at the time) and Bill Parlatore (PMM Editor) were aboard and reported a tendency to launch fish. They believed the fish were too small. So there is no sea-state where they should be retrieved - it's a design issue. That said, the movie "Perfect Storm" shows a fish crashing into the PH windows.

As far as the need for stabilization, it's a personal decision. Many cruisers remain in protected waters and can be very selective about open water (ICW with jaunt to Bahamas for example). For me, even moderate ventures into open waters and areas of rolly roadstead anchorages mean stabilization is a requirement, not an optional comfort item. But it does add considerably to the cost of a powerboat.

Peter
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Old 09-06-2020, 06:36 AM   #15
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Thank you for the links to other threads. Very helpful. But questions remain. Seems rolling chokes have minimal effect (15-20%) compared to fins or fish. About the same as a riding sail which would also help with hunting at at anchor. Note that when a north swell is seen down in Windwards the cats snap roll a bit, the monos roll more but slowly the trawlers are highly variable. What hull shapes roll less? Or is this observation a reflection of who has Seakeepers?
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Old 09-06-2020, 06:58 AM   #16
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Do immersed hard chines decrease roll? On sailboats bulbed fin keels May roll more as a harmonic can occur. Does the same occur on power boats? Do displacement boats roll more than semi displacement?
I wouldn't say the displacement boat rolls more or less, but they do roll differently. FD hulls are quick to roll the first 5-degrees or so until whatever ballast is present offsets. A SD hull has form-stability that resists the first 5-degrees, but does not have the added leverage. SD hulls are often characterized as having a 'snappy' roll.

My Willard 36 (39-hulls built between 1961 and 1970) came off Wm Garden's drafting board in the 1950's with very slack bilges - Willard's Naval Architect Rod Swift filled-out the bilges for the 1974 introduction of the Willard 40. The deckhouse on the W40 is also higher to gain more accommodation so the A/B ratio is higher, similar to a KK42 or N40. My guess is the Willard 36 may be the roundest-bottom production trawler out there. However, Garden designed-in a full keel, and she carries 6000-lbs of her 25,000-lb displacement as ballast - almost 25% (for comparison, KK 42 and N40 are under 10%). As expected, my W36 is tender to 5-degrees or so, then gets pretty dang stable.

I can tell you from many miles of running with long swells in the Pacific, it's a nice ride to swing 10-15 degrees on a heavy-ballast FD hull. A friend calls it akin to an old Buick Roadmaster going down a country road.

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Old 09-06-2020, 07:09 AM   #17
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Seems rolling chokes have minimal effect (15-20%) compared to fins or fish. About the same as a riding sail which would also help with hunting at at anchor. Note that when a north swell is seen down in Windwards the cats snap roll a bit, the monos roll more but slowly the trawlers are highly variable. What hull shapes roll less?
Some will disagree, but in my opinion, 99% of the installed steadying sails are worthless. The 1% exception are the Diesel Duck layouts that have full sail plans. Even then, you'd need a mainsail that was cut flat to use. So I give steadying sails a 5% grade (and that's generous in my book). The 20%-25% for roll chocks 'feels' about right from reports I've seen.

As my previous post describes, SD hulls will resist initial roll, just as a catamaran will (even more so). A friend's 52-foot Power Cat is really nice at-anchor, though it is definitely snappy. Any mono-hull is at risk of developing a significant harmonic pendulum swing in the right swell/chop and it can get pretty severe. Flopper-stoppers are a must in my book, especially if you like your wine out of Riedel stemware.

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Old 09-06-2020, 10:31 AM   #18
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Insequent - That product looks interesting and I would think the spring would be helpful in both dampening roll, and reducing the load on the cleat where its hung. Looks like the product is only available in Aus.

AusCan - Good feedback regarding the roll reduction for a midship cleat, vs. telescoping it out. At this point I dont want to start adding hardware in order to telescope it. Also, some of the mooring fields I visit in the Summer can get tight, so having it deployed closer to the boat is better in my case.

SeaLion - The Flopper Stoppper product looks very solid and durable. My concern is the weight. At 50 lb’s, taking it in and out the Laz would not make my lower back happy, which has seen better days.

Ralsy - agree, I noticed most people have a line tied to the side of it for easier retrieval. I swam over to a boat yesterday with one deployed and it was interesting to see it in action, under the water. He has a Defever 49 with a telescoping pole set up on each side. A very cool boat overall.

I will probably go with the Magma product noted in my first post. At 17 lbs, it will be much easier to stow and retrieve out of the Laz. Physics would tell me the 50 Lb FS product (which I believe has a larger surface area) would work better, but I will give the Magma product a go on one side, and then possibly a second one for both sides.
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Old 09-06-2020, 10:36 AM   #19
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mvw, does your single-sided setup reduce or dampen swinging at anchor? My boat has a lot of windage and can tramp pretty good in a stiff breeze. I use a single-line snubber over the bow to help keep the anchor in the mud.

I'm thinking to try the door-style with some sort of boom a few feet outboard, then up to my mast, which is aft of midships (just another "boat buck" project!)
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Old 09-06-2020, 11:20 AM   #20
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mvw, does your single-sided setup reduce or dampen swinging at anchor? My boat has a lot of windage and can tramp pretty good in a stiff breeze. I use a single-line snubber over the bow to help keep the anchor in the mud.

I'm thinking to try the door-style with some sort of boom a few feet outboard, then up to my mast, which is aft of midships (just another "boat buck" project!)
I have them on both sides. I believe they were from original owner circa 1970 as he used to head down Baja from Newport Beach to go fishing. I'm sure he encountered many rolly anchorages.

The current rig is 4-inch diameter x 14-food long spinnaker poles. They are heave and awkward, and frankly, too long. Essentially gives over 36 feet width tip to tip which is unnecessary. I thought about storing them upright with a rigid/hinged arm as a support, but decided I preferred them stowed in a more inconspicuous manner. I'm getting a quote to fabricate the end pieces using a stainless steel U-joint from McMaster Carr and 1-1/2" aluminum tubes as supports. Attached is my rough sketch. I can rig two "tipping lifts" to each pole and one down haul.

EDIT: Also attached a rough sketch of my flopper stopper plate. I lost one at Cojo Anchorage about 15-years ago. I was lucky to find they were still made by a guy in San Diego. I can no longer find them. It's a good, simple design that would be easy to replicate. I am not close to the boat so can only guess, but suppose they are about 20"x30" in size, probably 20-lbs each. I've never needed an extra weight, but could be that my poles are so long that it doesn't take much to steady the boat. To my eyes, much better than the Magna design. Not as good as the shutter-design on the FlopStopper design though.

Peter

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