Stabilizers: A Must for Passage-Making?

[Mako]

@Marco, passive flume tanks are IMO a great roll reduction technique. I had spoken with Dr Bass previously about designing one. He mentioned that they achieved about 65% reduction in roll and acceleration, with a water load of about 2.5% to 3% of displacement. This was a traditional baffled tank. Phil with Swan Song (who has passed on) had one installed and he was very happy with the results although he never took measurements.

It would be helpful if you posted numbers for degrees of roll and accelerations, with and without your water loaded. Simple apps for your smart phone would work.

BTW, the naval architect of my boat stated that the large rolling chocks they normally install in their fishing boats achieved about 35% reduction. This is a very high effectiveness for passive chocks. Personally though, out at sea, I would want at least 1/2 roll reduction minimum.

 

[Delfin]

Beebee considered some form of stabilizers to be essential for an ocean going vessel, and I certainly agree. Absent sails, a power boat in the open ocean is a real mix master. Can you tolerate it? Sure. Would you want to if there is another option you can afford? I don't think so.

We're on the West Coast of Vancouver Island and have been traveling the same path as a Diesel Duck ("Duckin A", which is a great name) that has passive stabilizers so I've been able to see how they work on that boat since our paths keep crossing. Never seen the poles in, but he lowers the fish when underway or at anchor, just like every other fishing boat up here. He was able to fish with not much roll off Ucluelet, which I thought was a real benefit to that system. Active fins don't work well well at trolling speeds.

We're both underway now in 4 - 6 ft swells off the stern quarter. I have zero roll, and he looks to be moving through about a 10° arc. I'd have either system, but it sure is nice to just hit a button and relax.

 

[Marco Flamingo]

Mako,

I've done some preliminary testing, but not super-scientific. I'm in a marina that gets some occasional wake, making my experiments less accurate. I've rocked the boat and gotten some idea, but when tied to the dock sooner or later the lines snub and affect the results. I would need a giant undisturbed tank for accurate numbers (a money loser for me). Probably why most anti-roll tank research seems to come from grad students using grant money.

Some basic numbers. When rocking the boat to 10 degrees each way (a point at which I find the motion annoying), my boat will continue to rock about 20 complete rolls to the "point of barely detectible" (not very scientific). With the flexible tank it was 5 complete rolls to damp the motion. My side-to-side roll period is 3.4 second (although somewhat variable with degree). To me, that seems fairly snappy, which is why I thought about anti-roll. With the flexible "tank" (actually more like a slug) the roll period was over 3.5 seconds but that tiny difference from the natural roll period seemed to be enough to "choke" the roll. With the tank on the FB, it was very difficult to jump from dock to boat and back again and attain the 10 degree roll that I had used as my base line.

One last thing. I wonder if the simplicity of the passive system is why it is seldom used. Were I operating a business, I'd much rather sell a $35K whizbang gyro system that needs parts and maintenance instead of a $100 bag of water.

Dang, I may have highjacked the thread.

 

[Jmarsh203]

I think stabilizers have most to do with cost and intended use of boat. Having owned both stabilized and non stabilized boats I would not go without as long as I can afford them. Two boats that are equal in all things except one having and one not having stabilizers will generally have a cost difference of between 30-50k. At least with fin or paravanes. Now if you haven’t bought a boat yet and you can afford the extra 30-50k and plan on doing open ocean work or going out on days that are less than perfect than you should just initially invest in a boat that already has them as you will never recover the cost of install. If you plan on never leaving protected waters than they are a waste of money that could be used elsewhere. Stabilized boats tend to hold there value better and do command a premium comparatively. Now if you cannot afford the extra for the stabilized boat then I would say buy a boat without the stabilizers just so you can go boating now. I’d rather be on the water and unstabilized than on land dreaming of being on the water in a stabilized boat.

 

[Fletcher500]

As noted, if extended time is planned cruising, especially in unprotected waters they are worth every penny. If it’s more of a live a board situation and staying in the marina and limited day cruising within a harbor, then I would not worry about your potential boat not having them.

 

[Simi 60]

As noted, if extended time is planned cruising, especially in unprotected waters they are worth every penny. If it’s more of a live a board situation and staying in the marina and limited day cruising within a harbor, then I would not worry about your potential boat not having them.

With reliable weather forecasting, personnel observation and time to wait for a window, 3 to 4 day hops of easy weather are pretty easy to pick at least in our part of the world

That's enough time to run 700nm to next port in another land

In the US, Bahamas and Carribbean is a day @ 7 knots
Cancun is 2 days @7 knots

 

[Hippocampus]

MF sure like to see that article.

From multiple sources I’ve read gyros seem to be more rather than less effective for trawlers in the common range of 40-60’. Issue is fins need movement to be efficient. Faster you go better they work. So for SD and definitely FD hulls you need to increase surface area to gain function. Bigger appendage more drag and energy required. Yes gyros require a lot of energy to spin up but once done that decreases.
So range impact is a more complicated trade off
Worst fish. Take awhile to set up and retrieve. Look at Beebe’s appendix and other sources seems as bad or worse the fins for impact. From what people tell me not used until in deep water given the hassle. Not used in skinny water coastal given the risk. Fish do fly when not rocking but to prevent roll they work by increasing resistance as they rise. Unlike gyros they don’t resist movement at the very start of the movement so even the most effective requires some rolling before a effect is seen. Fins generate lift and generate less resistance than fish. They are a foil and some even cause the waterline to rise when in neutral and at speed.
Fins have come a long way. Now zero fins available so useable at rest. But they still impact range unfavorably. You still have a load either from your hydraulics or electrical if Humprees. You still have appendages so increased drag. Not insignificant.
I own a gyro. Like most people I look at the weather frequently so know well in advance if I need it spinning. Recently spin it up on shore power or before leaving with the genset. Try not to spend anytime in ship channels but know well in advance if that’s in my future. Find the instant on a true non issue in actual use.
Yes I need power. It’s about 1/4-3/4 g/hour additional (no AC or watermaker use) from the real world calculations from days work. However, they are real sloppy calculations as when it gets bumpy the gyro is on so only have one run non gyro and bumpy. My drag is the same as a non stabilized boat scepter for a minimal effect from having a additional thousand pounds on board giving a minimal effect on wetted surface.
For energy and near instant on along with minimal appendage risk would think Magnus leads the pack.

BTW think your cost estimates are way off. Think for a 40’-50’ boat $70-100k give a better ballpark idea of costs for gyro, current tech fins or Magnus as a final installed total cost. Depending upon hull, size and use interceptors may be needed so above reflects that.

Opinions vary but PO is talking about passage making on a existing boat. Then think fins still lead the list for that application. Would definitely hire a NA before putting any moving fluid high up in a boat seeing blue water. Can’t be good for the angle of vanishing stability. The lower down the fluid the less effect it would have so a catch 22 for most stock designs. For coastal, gunk holing and occasional long near shore hops real pleased with the gyro. No impact on top speed when I need it. Amazingly effective (my boat was used for the SeaKeeper promo literature. They claimed 85% reduction and I believe it.) the list issue has been seen (yet). But if I intended to occasionally see force 7 or greater would go with the biggest fins that were reasonable.

 

[Taras]

Once you go "stabilized", you never go back.
I've owned both non stabilized and stabilized boats and it really, really makes a huge difference in the comfort (and safety) of the captain and crew.
You may want to "sea trial" both kinds of boats to really get the picture. If you're in love with the DeFever (which is a great boat, I had a 51' which was stabilized), then my suggestion is to add Paravane Stabilizers due to the much reduced cost AND the ability to deploy them "at anchor" which will dramatically improved your comfort while you are just sitting at anchor. Rolling back and forth while trying to sleep is also no fun......

 

[mvweebles]

Flopper stoppers (at-anchor outriggers) do not need to be nearly as robust as paravanes for underway use. My original set of flopper stopper outriggers were rigged to my mast. I removed the mast to make room for a hard top and lower bridge clearance for ICW use. I had the poles and mechanism remade with very nice stainless knuckles and 10-foot aluminum poles. Cost was under $2k, installed, plus I need to do the rigging.

I should have more closely considered paravanes when I needed to replace my old 1970-era hydraulic stabilizers. I probably could have them built and installed for around $10k-$12k and I like them for multi-day runs. But I have to say, there's a lot to be said in favor of fins. They are instant-on/off, so much so that if I see a boat wake coming, I'll throw them on for a few minutes.

Several Willard 40s have had roll chocks installed and report satisfactory results, but mostly they seem to attenuate the roll frequency and prevent oscillation momentum from developing. Install is modest - in the $7k range plus haul.

In the end, people who have had stabilized boats generally wouldn't own another without stabilization. What kind of stabilization is best? Varies - there are benefits and shortcomings with each. Depends on your tastes, budget, and how you use the boat .

That said, not sure i buy into the stabilzer tank theory. 20+ years ago a Roughwater 58 with a stabilizer tank was making the rounds in the trawler press. Never caught on. I guess putting 500 gals of water on a flybridge has its demerits (not sure the volume, but you get the idea)

Peter

 

[DegoRed]

Put me in the must have category, I would not buy a boat without them, and from my own shopping, nothing concrete, you pay about half price for them on an existing boat vs adding them later.

 

[slowgoesit]

Passive stabilizers are for very few and are practical in only open ocean cruising.

By passive stabilizers, if you are speaking about paravanes, I have to ask the question:

Have you ever even RUN a boat with paravanes?!? Because we've used them to great benefit on the inland passage to Alaska, as well as in Puget Sound, neither of which even remotely qualify as "open ocean cruising". 10 minutes total to deploy or recover. Made the difference between an arduous, unpleasant trip and a very pleasant and comfortable trip on many occasions. . . . I wouldn't own another large boat with out stabilizers. We use our paravanes as flopper stoppers at anchor as well. . . .

 

[Mac2]

By passive stabilizers, if you are speaking about paravanes, I have to ask the question:

Have you ever even RUN a boat with paravanes?!? Because we've used them to great benefit on the inland passage to Alaska, as well as in Puget Sound, neither of which even remotely qualify as "open ocean cruising". 10 minutes total to deploy or recover. Made the difference between an arduous, unpleasant trip and a very pleasant and comfortable trip on many occasions. . . . I wouldn't own another large boat with out stabilizers. We use our paravanes as flopper stoppers at anchor as well. . . .

Totally agree. It would be worth it for the flopper stoppers alone. I put the single magma arm flopper stopper on my last boat. I cursed myself for not putting it on 10 years earlier! What a difference at anchor. Can't imagine two. Do you find people giving you more room in an anchorage with them out? Another benefit perhaps....?

 

[hollywood8118]

By passive stabilizers, if you are speaking about paravanes, I have to ask the question:

Have you ever even RUN a boat with paravanes?!? Because we've used them to great benefit on the inland passage to Alaska, as well as in Puget Sound, neither of which even remotely qualify as "open ocean cruising". 10 minutes total to deploy or recover. Made the difference between an arduous, unpleasant trip and a very pleasant and comfortable trip on many occasions. . . . I wouldn't own another large boat with out stabilizers. We use our paravanes as flopper stoppers at anchor as well. . . .

We had pretty much the same experience on our boat with paravanes. About 5 min to launch, 8/10 to bring in and lift. Ran a N46 up the coast of California with electric winches to retrieve, took 5 min max. The place they stow the fish was a P.I.T.A. but the system worked well. It lost .5kt at the same rpm cruising vs. running clean. If I was setting up a new offshore boat I most likely would do paravanes as they are slightly more complicated that an anvil if set up right. It is for simplicity only I would go that way. On a coastal boat I would do active fins. Gyros seem cool but they freak me out a bit.
As we look for the next boat some system is a must if I want the Admiral to be at all happy.
Hollywood

 

[Mac2]

We had pretty much the same experience on our boat with paravanes. About 5 min to launch, 8/10 to bring in and lift. Ran a N46 up the coast of California with electric winches to retrieve, took 5 min max. The place they stow the fish was a P.I.T.A. but the system worked well. It lost .5kt at the same rpm cruising vs. running clean. If I was setting up a new offshore boat I most likely would do paravanes as they are slightly more complicated that an anvil if set up right. It is for simplicity only I would go that way. On a coastal boat I would do active fins. Gyros seem cool but they freak me out a bit.
As we look for the next boat some system is a must if I want the Admiral to be at all happy.
Hollywood

Something to consider: At 90 tons I don't need stabilizers of any kind for coastal cruising. I have active stabilizers and thought they were broken the first year I owned my boat. I wonder at what point (weight) Paravanes stop working? I imagine the fish would have to get bigger and at some point, impractical.

 

[lkevinadkins]

This was great real-world information, thanks to everyone for sharing on this wonderful forum, it was very helpful to us. Thanks! --Kevin&Kellie

 

[ksanders]

Here is my take on stabilizers as someone who actively cruises unprotected waters in an un stabilized boat.

The days I choose to travel are days with a predicted wind of no more than 15 knots. Most days are wonderful. Some days though the swell is just perfect to be very uncomfortable. On those days I vary my course to allow a less rolly ride or I add throttle to push the aft down and stabilize the ride.

I also keep my boat heavy, with the fuel and water tanks as full as possible.

I have thought about stabilizers but just cannot stomache the 50-70,000 to add them to my boat. I chose to retire at 60 to go cruising, and that means that I need to be careful with my money.

If I had an unlimited supply of money of course I would have stabilizers, but I would also have a different boat, etc... Perhasps I could have spent an extra 5 years at my desk at work dreaming of cruising while I paid for the optimum boat with stabilizers.

So...

My advice is to buy stabilizers if they will not affect your departure date from work to actually leave the harbor and go cruising.

But... remember that you can always work longer to buy a bigger, or better, or more capable boat, but you cannot get that time back and your life clock is ticking.

 

[Simi 60]

^^^^^^^^^

It's like you're in my head

 

[Mako]

That said, not sure i buy into the stabilzer tank theory. 20+ years ago a Roughwater 58 with a stabilizer tank was making the rounds in the trawler press. Never caught on. I guess putting 500 gals of water on a flybridge has its demerits (not sure the volume, but you get the idea)

Peter, that Roughwater is Swan Song which I referred to earlier. Flume tanks work well if they can be accommodated, but they are certainly not mainstream. BTW, I was negotiating a contract for SS, and I think we were off by about one dollar, but the son decided to keep the family boat for himself.

 

[Simi 60]

Peter, that Roughwater is Swan Song which I referred to earlier. Flume tanks work well if they can be accommodated, but they are certainly not mainstream. BTW, I was negotiating a contract for SS, and I think we were off by about one dollar, but the son decided to keep the family boat for himself.

More here


https://www.trawlerforum.com/forums/s3/anti-rolling-tanks-11208.html

Full search for "Dr Bass Anti Roll Tanks"

https://www.google.com/search?q=dr+...GYAQCgAQHIAQjAAQE&sclient=mobile-gws-wiz-serp

I have some homework to do.

Be warned, it's a rabbit hole you may not want to jump down

 

[Marco Flamingo]

Thanks for the link. I've been down that rabbit hole a ways. Seems one can always go deeper.

As with all "best equipment" evaluations, it is highly dependent on the boat and boater. If a 6 knot boat (like mine), the effect of paravanes may not help much. If travelling at 2 knots and trolling (like mine), the last thing I want is stuff hanging in the water or protruding from my hull. That's what the big salmon is going to wrap the line around. If you have owned or worked on boats that require "one hand for you, one hand for the boat" (like me), the motion is expected and routine. If the crew suffers motion sickness in the car ride to the marina (like my brother), stabilizers may be beneficial or even required. My wife has only thrown up on board once and that was long ago. Now growing seas only prompts her stow-the-gear mode. Problem solved (for me). Still, if I intended to spend days and weeks in +5 foot seas, I'd probably spend as much as necessary to stabilize my little boat as much as possible. But for my intended se and cruising area it seems like most systems are overkill.

 

[Mako]

A few years ago when I was still in the Middle East I started designing a flume tank for my panga, which I ran out in the Persian Gulf. I had been using a local steel shop to fabricate my dive ladders, handrails, etc. (all out of carbon steel actually). Was about to pay them to start cutting sheet metal but then I had to sell the boat and leave the country. Definitely would like to experiment more.

Honestly I would trend towards fixed boxes, not the flexible bladder like @Marco is using, but I can see the advantage of simplicity by going that route for smaller vessels. The key is just to get the water to roll 180° out of sync with your boat. Likely by minimizing the amount of air in your bladder you can achieve that.

Still hoping you can take some measurements with/without and report back.

BTW, the bulk of Dr Bass' clients were heavy fishing boats.

 

[Simi 60]

Interesting video

 

[Simi 60]

.

Honestly I would trend towards fixed boxes, not the flexible bladder like @Marco is using, but I can see the advantage of simplicity by going that route for smaller vessels. The key is just to get the water to roll 180° out of sync with your boat. Likely by minimizing the amount of air in your bladder you can achieve that.

Still hoping you can take some measurements with/without and report back.
.

I have a 200 litre bladder in the tender that, now that we have a water maker have not used.
If I remember I'll put it In front of the wheelhouse on the Portugese bridge next time we do an outside run and 3/4 fill it and see if it does anything at all.
It's only 2m wide so I doubt it'll do much but even if it knocks the edge off of the roll it'll be something for nothing.

 

[DDW]

At $30,000 plus, no
Plus continual drag - extra fuel burn even when not needed.

I had rolling chocks installed, carefully measuring before and after cruise speeds and consumption vs. rpm. There was no measurable difference at any rpm.. They will not do the same job as active stabilization but do make a difference. They cost me $4K to have installed. The only downside I've discovered after 3 years is they are exposed to the sun more than any other part of the bottom, and grow weed at a quicker rate.

I also had Magnus rotors quoted for the boat from two different vendors. My boat is really too small for the systems they have, the quotes were in the $50 - 60K range.

 

[Martin J]

If your serious about ocean and rough water, you need stabilizers probably installed. My last 3 boats had them and I would never go back. There are many boats of the size you are looking at that have them. Although I'd probably got to 50ft if your use is going to be extensive and long passages. To have a competent company service the stabilzers on a older boat is not overly expensive compared to fitting new. You are also looking at older boats 84's which are older simpler models 250/251/252 etc. I would not fit a new system in a older boat , but find a boat that has them and requires overhauling. In closing I'm not interested in ocean passages without them.

 

[Mako]

@Simi that would be a great experiment. The weight is just two adult males, and it’s more effective the further away from center of gravity. If you can tie it down to the top of your bridge deck house, say middle of vessel over a bulkhead, that would be best.

Put your water in and squeeze out all the air, then add small amounts of air until it times correctly. A proper flume tank for your boat would contain about 1.5 tons of water instead of the 1/5th ton in your bladder, but you might measure a small difference.

 

[Steve1.0]

Anyone have pics of a rolling chock system? I've never seen one.

 

[Portage_Bay]

Anyone have pics of a rolling chock system? I've never seen one.

Rolling chocks on fiberglass hulls. Steel and Aluminum are welded on.

 

[Muirgen Afloat]

We are returning from our first long trip to Glacier Bay from Washington state. We have stabilizers on the boat that we used a few times. While it's not impossible to go places without them, they sure make things a lot more comfortable if you have them. So I think it's a question of comfort.



What are you comfortable with? When we are out on rough water or lumpy water as the fishermen in Alaska call it watching the other boats get tossed around or tipped side to side, I'm very grateful to have them.



So what's you're comfort level? Only you can answer that.

 

[socalrider]

We are returning from our first long trip to Glacier Bay from Washington state. We have stabilizers on the boat that we used a few times. While it's not impossible to go places without them, they sure make things a lot more comfortable if you have them. .

The passive stabilization systems (paravane, rolling chocks, Flume tank) are very appealing in that they can function at anchor as well. Here in SoCal the anchorages are extremely rolly. We have a flop stopper off each midship cleat which helps a lot but it'd be great to pole them out.

Muirgen, do you use the same fish on your paravanes at anchor, or do you hook a separate device (i.e. flop stopper) for use at anchor?

Flume Tank people: Could you possibly utilize existing tankage for this? We have port and starboard diesel and water tanks (400 gallons total of each, so ~6,000lb max on a 30,000lb vessel). I'm not quite clear on how the tank is "tuned" to be out of phase with boat motion, but it seems plumbing a larger transfer tube between saddle tanks could do it, possibly with some sort of a large gate valve to tune the frequency? Would it change as the tank levels go down?