Reducing roll while anchored or moored.

[Fletcher500]

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, it’s 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?

 

[Insequent]

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-torque-boat-stabilisers-1820829778223633/?ref=page_internal

 

[rslifkin]

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).

 

[AusCan]

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.

 

[RobertLeatch]

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/

 

[Ralsy]

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?

 

[SeaLion]

These look interesting.

FlopStopper.com

 

[RobertLeatch]

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.

 

[Retriever]

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-design-a-better-flopper-stopper/
https://mvstarr.com/making-a-better-flopper-stopper-one-year-later/

 

[Ralsy]

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-design-a-better-flopper-stopper/
https://mvstarr.com/making-a-better-flopper-stopper-one-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

 

[Simi 60]

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.

 

[ddw36]

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/s3/bilge-keels-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.

 

[Hippocampus]

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?

 

[mvweebles]

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

 

[Hippocampus]

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?

 

[mvweebles]

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.

Peter

 

[mvweebles]

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.

Peter

 

[Fletcher500]

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.

 

[GoneFarrell]

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!)

 

[mvweebles]

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

 

[AusCan]

My full displacement round bilge hull is similar to a Willard 30 and is very rolly at times. If a beam swell is in time with the natural roll of the boat, the roll can get ridiculous either underway or at anchor. Fortunately, any roll minimisation device tends to work best on soft chine FD boat.

I have rolling chocks which help a bit while underway, but do very little when at anchor. The steadying sail stabilizes 90% of the roll while underway, if there is 10-15 knots of wind or more. The magma flopper stopper works well, but I wouldn't count on it holding up long term with heavy use. I'd pay the extra money for something like these.
http://flopstopper.com/FlopStopper/Home.html

 

[Steve91T]

We anchor in protected areas of the ICW. If we are ever rocking at anchor my wife makes a few dark and stormy’s and before long you don’t even notice the rocking. Much cheaper and a hell of a lot more fun than stabilizers!

 

[READY]

Fletcher500: could you expand on your reasons for not running the gyro at anchor. If it is generator noise would it be conceivable to run it off a lithium battery bank? I have been considering a gyro for my NT32 and the ability to run at anchor would be a significant benefit for Catalina trips.

 

[Fletcher500]

Ready, things get twisted around on forums like this, so to put things in context a little background: One of my goals in boating is to be as environmentally friendly as possible. I realize that may sound like an oxymoron coming from a boat owner, but I rarely drive my car, we have solar panels on our house, and we do other things to reduce our our carbon footprint to offset our boat use. I have a single Cummins which I drive at put-put displacement speed and can get 3 to 3.5 Mpg. The Seakeeper is powered by a 9kw Gen, so the water maker, Gyro, and other loads can all be managed with it. It’s an 1800 rpm Gen, so the noise is not bad. I am not shy about running the Gyro. It gets run whenever we leave the dock and was worth every penny for the comfort and safety of having a stabilized vessel while underway. If we are in a very rolly anchor or mooring field, I will run it, but that is rare. With that said, we are spending weeks, not days on moorings and anchored before we stop at a marina for awhile. I don’t want to run the Gen 24/7 for the Gyro because I would use very large amounts of fuel, and I am not going to do it for environmental reasons. You should be able to use an inverter for a smaller Gyro on your Tug, but even with solar panels I still think you are going to be running your Gen a lot to charge your batteries but I may be wrong and you can figure that out with some load calcs. If you are only out for a few days, running the Gen alot is manageable, but a key point I made earlier is we are out here for extended periods of time.

Also, I previously noted the weight of the flop stop was 50 lbs. That was incorrect. It is 22 lbs.

 

[mvweebles]

Fletcher: I don't think you have much of an option except flopper stoppers. I have never tried mine over the gunwale, have always poled-out. I'll be interested in if the results are satisfactory.

As mentioned, I am in the process of having new hardware fabricated for my flopper-stopper poles. If you're interested, would be happy to have a second set built as it would likely save me some money on the package deal (I do not have a quote yet).

I made a few changes to the design I posted a day or so ago. Attached is what I am asking for a quote for. For you (or anyone for that matter), you would have to source the aluminum poles and figure out the rigging. But the hard part - the poles, would be solved.

Peter

 

[Codger2]

Fletcher: I don't think you have much of an option except flopper stoppers. I have never tried mine over the gunwale, have always poled-out. I'll be interested in if the results are satisfactory.

I couldn't agree more! Over the years, since 1995, I've studied the different ways of stabilizing a boat, both underway & at rest. Underway it's hard to beat active stabilizers (Trac) and at rest, some form of a Flopper Stopper. My criteria includes ease of operating, cost and longevity. Yes, gyros work exceedingly well but noise & cost are exceedingly high! Also, "fish" work really well and are, for the most part silent, but can be a giant PITA for quick deployment & storage and don't contribute at all to rolling at anchor.

 

[Fletcher500]

MV, that looks like a nice set up you are building. At this point, I am going to try the midship cleat hang and see how things go.

Codger, agree, active fins are a proven system that work very well. Your comments regarding the Seakeeper Gyro are not accurate. The Gyro is not loud and can be barely heard. Regarding the high cost, wrong again. I have to run the Gen while underway to make water and have plenty of Gen load capability for the Gen to be spinning the Gyro at the same time. The addded fuel cost to spin the Gyro is negligible. It’s ok to have your opinions, but lets work on facts here.

 

[mvweebles]

MV, that looks like a nice set up you are building. At this point, I am going to try the midship cleat hang and see how things go.

Codger, agree, active fins are a proven system that work very well. Your comments regarding the Seakeeper Gyro are not accurate. The Gyro is not loud and can be barely heard. Regarding the high cost, wrong again. I have to run the Gen while underway to make water and have plenty of Gen load capability for the Gen to be spinning the Gyro at the same time. The addded fuel cost to spin the Gyro is negligible. It’s ok to have your opinions, but lets work on facts here.

Fletcher - I assume you had your H43 built and opted for the Seakeepers. A few questions:

1. Would you have spec'd the 9KW generator if you didn't have the Seakeepers, or would you have gone for a 6KW?
2. Given you're in San Diego, do you run your generator for A/C often? I'm in Florida and most motoryacht-style boats run 24/7.
3. Like myself, sounds like you are a firm believer in stabilization. By the time it was all done, would you make the same choice for Seakeepers vs Hydrailic Fins? I'd imagine the Seakeepers would be much better for yaw (fore/aft hobby-horsing) then fins.

My 1970 Willard 36 was originally equipped with Vosper mini-fins, which went out of business 15-years ago. I just had new replacement Wesmar's installed, and while I really like hydraulic fins, in hindsight, I wish I had more closely considered paravanes. The simplicity and lack of equipment in the engine room would be compelling, plus would have the benefit of flopper-stopper rig. I wonder if you have any similar hind-sight insights?

Although I also installed a new 6kw NL generator, I really do not like running the generator more than absolutely necessary, which is A/C only. A Seakeeper is out of the question for me on that basis alone. But they do sound like a nice system.

Thanks in advance -

Peter

 

[Fletcher500]

Peter, please see my comments below.

Fletcher - I assume you had your H43 built and opted for the Seakeepers. A few questions:

1. Would you have spec'd the 9KW generator if you didn't have the Seakeepers, or would you have gone for a 6KW? Fletch: 6KW if no Gyro for sure. Also, my water maker can be fed by either leg 1 or 2 on the Gen in order to balance the load depending on what’s going on.

2. Given you're in San Diego, do you run your generator for A/C often? I'm in Florida and most motoryacht-style boats run 24/7. Fletch: It’s fairly rare to need the AC here, but we do turn them on in the Summer when its hot. I generally wait until the afternoon to charge the battery banks, so the AC can be run at the same time.

3. Like myself, sounds like you are a firm believer in stabilization. By the time it was all done, would you make the same choice for Seakeepers vs Hydrailic Fins? I'd imagine the Seakeepers would be much better for yaw (fore/aft hobby-horsing) then fins. Fletch; Peter, you have extensive time running Nordhavns up and down the coast so I always make sure I read your posts and appreciate the insight you bring to the forum. Yes, I am a 100 percent believer in stabilization. A couple weeks ago we had a very rolly night at anchor. I woke up at around midnight, lost my balance, and slammed my hand on the galley counter directly on top of a glass which shattered. It was dark, and when I turned the light on I expected to see red fluid everywhere, but I got lucky. We all have these stories about being tossed around on boats, so this is nothing new. But as my wife I get older (late 50’s), I find a stable boat is becoming even more important. Regarding the fins vs Gyro - we are only coastal cruisers and never more than about 50NM offshore. Our runs average from 4 to 12 hours so running the Gen For the Gyro and to make water and supply other domestic systems works for us. If we were long range blue water cruisers, the obvious choice is fins off the engine; PTO.

My 1970 Willard 36 was originally equipped with Vosper mini-fins, which went out of business 15-years ago. I just had new replacement Wesmar's installed, and while I really like hydraulic fins, in hindsight, I wish I had more closely considered paravanes. The simplicity and lack of equipment in the engine room would be compelling, plus would have the benefit of flopper-stopper rig. I wonder if you have any similar hind-sight insights? Fletch - I have no experience with paravanes. Interesting story from a long range cruiser I know: He had a killer whale get tangled up in his paravane rig. Apparently the whale was ok and he released quickly.

Although I also installed a new 6kw NL generator, I really do not like running the generator more than absolutely necessary, which is A/C only. A Seakeeper is out of the question for me on that basis alone. But they do sound like a nice system. Fletch - agree, we all have different environments and conditions we are boating in. Lots of good choices out there.

Thanks in advance -

Peter

 

[Codger2]

Codger, Your comments regarding the Seakeeper Gyro are not accurate. The Gyro is not loud and can be barely heard. Regarding the high cost, wrong again. I have to run the Gen while underway to make water and have plenty of Gen load capability for the Gen to be spinning the Gyro at the same time. The addded fuel cost to spin the Gyro is negligible. It’s ok to have your opinions, but lets work on facts here.

Fletcher, you are certainly entitled to your opinion but i have been on a 42' boat, at anchor that had a SeaKeeper Gyro running. The noise from the generator + the Seakeeper was irritating at best & the cost I was referring to was the purchase price and installation of the gyro. No matter how you slice it, it's expensive to buy & install! When "working on facts", let's not leave the most expensive part of a Seakeeper out of the conversation!