Best stabilization

[JCM-Houston]

Power trimaran...not the 50 knot mega-yacht kind, but one that comfortably cruises long distances at 10 or more knots. Cross oceans in 1/3 the time. Move away from oncoming bad weather.

I'd give up beamy leather couch/recliner comfort for the speedy constantly stabilized efficiency of a trimaran of about 60' in length. The destination would be my goal, rather than opulence while getting there.

Not what you were asking, but still an option.

Have a look at the new Neel power trimarans in 56 and 70.
https://leen-trimarans.com/

 

[klee wyck]

Keep hearing Trac make the best stabilization and to stay away from Wesmar. Also fins are better than fish as you just push a button with no need to deploy or take them in . Also that gyros are great for coastal but potentially dangerous offshore and magnus effect the reverse as they stick out so far.
Is this all hearsay?
Would like to hear about your experience with your stabilization.

I am late to this party but have been thinking about this thread for awhile.
In addition, since the original post sought comments born of experience, I am not qualified as such since my current boats are stabilized by hull and ballast design criteria but not active or passive appendages. I have no experience.

Nonetheless, a couple of thoughts about the dangers of these appendages under 'ocean' conditions.

I think of active or passive stabilizing devices as serving needs of comfort and not so much safety in adverse sea states. That safety, I think, must be design criteria inherent in the ship itself in terms of scantlings and stability parameters.

If true, then the concern of a fin or a gyro tearing a hole in a hull because of the forces necessary to offset heel, is not well found. The hull itself should already be equipped to handle those forces (assuming proper attachment of the fin or gyro) in terms of scantlings. In addition, a boat with good stability characteristics has the ability to contribute to the righting moment by design as the ship heels in response to the action of the sea such that not all of the righting force is supplied by the fin or gyro.

Now, putting a large fin or a Seakeeper 1200 on a vessel without the scantlings and built in stability characteristics to handle it would likely be a hazard both inshore and offshore.

If you are going to sea, you best be in a sea boat, stabilized or not.

 

[Hippocampus]

KW my thoughts exactly. Few builders make designs aimed at open ocean use. The economic drivers are too strong. Given such a small fraction of the buying public will use a vessel for that service and the additional expense of building to allow that usage it doesn’t make sense to do up the scantlings and design elements required. The few past and active builders that do are able to charge a premium so survive. That expense is much to my detriment.
It’s been a transition to understand that whereas 130 degrees of AVS (angle of vanishing stability) is the bare minimum accepted for blue water sailboats but 90 degrees is considered adequate for power. Similarly down flooding risks are looked at differently. Still I have certain go/no go biases.
Adequate glass and seals to survive boarding seas or knock down. Storm boards a plus. Not keen on any sliding glass. Seems to hard to do correctly as to prevent them from blowing out.
Adequate righting arm and Gz curve.
Ability to slide off a wave face and not be overcome.
Passive position (no power) not at 90 degrees to wave train lowering risk of broaching or provisions to prevent broach and turning turtle.
Although EU and ABYC standards are to the good they apply only at the time the new boat is delivered. The real concern is function and strength after prolonged service. Some years ago when grp was first coming into common use the USN studied service life. That seminal work has been expanded and there’s now sufficient field experience to allow a neophyte like me to have grounded opinions on nature of construction and scantlings. My other concern is ability to repair to original strength and function after mishaps. To this end personally only want to deal with stick built boats.
In the past there was much overlap in both power and sail. Many designs could serve adequately in coastal, near shore and open water. As time has gone by the divide has become much more delineated. Totally agree with your sentiments and opinion.

 

[mvweebles]

Two different topics here. Assuming David Gerr is correct (I certainly assume so), stabilization does not change or alter the ultimate design stability of the vessel. Just makes it more comfortable which certainly has safety benefits as the crew is more alert and rested, but the underlying design attributes regarding ultimate stability are unchanged. I don't fully understand the premise, but given the respected source, I accept it.

 

[sunchaser]

I've seen active stabilizer installations where the in the hull section is in its own water tight enclosure. Worries about a stabilizer breaking off are effectively negated. These installs are on Al power boats and part of the original build process.

As far as under water appendages, sail boats with bolt on keels and twin rudders have indeed suffered some well documented sinkings and roll overs. Over the past few decades there are two MV stabilizer related sinkings I've read about. One in the already mentioned Rideau Canal area and the other in the Caribbean. Both were shallow water muddy groundings with composite hull vessels.

Active stabilizers are pretty much standard on most non planing +45' builds of the past couple of decades with the benefits easy enough to see and feel. Gyros are interestingly becoming common options on the larger +45' outboards.

Passive stabilizers and their well understood benefits gravitated to different types of stabilization during the past few decades. No matter which type of install the advantages and perils of each stabilizing method are well understood.

I remain optimistic that the spool up time for gyro setups will see some innovations. To my mind the PTO requirement for hydraulic stabilizers could easily be utilized by installing a hydraulic powered generator. Thus no need to run the genset nor a large on engine alternator for gyro operation while cruising.

 

[Hippocampus]

T thanks for posting about Astra and Magnus effect rotors. The engineering seems very appealing which is why I brought them up. Particularly like how they rotate so can be enclosed in protection when necessary. This thread has mentioned slow acceptance of gyros but I wonder about the even slower acceptance of Magnus effect rotors. To my uneducated eye it seems a preferable system. Less weight. Provides lift. Suitable for retrofitting. No issues of increasing instability. Less loss of interior space. Gets around the vulnerabilities of fins but still deploys by pushing a button.
Will ask again. Anybody with experience or thoughts about Magnus devices.

 

[IRENE]

Magnus demonstration in this video...

https://youtu.be/ZX5gggHgAB0

 

[twistedtree]

T thanks for posting about Astra and Magnus effect rotors. The engineering seems very appealing which is why I brought them up. Particularly like how they rotate so can be enclosed in protection when necessary. This thread has mentioned slow acceptance of gyros but I wonder about the even slower acceptance of Magnus effect rotors. To my uneducated eye it seems a preferable system. Less weight. Provides lift. Suitable for retrofitting. No issues of increasing instability. Less loss of interior space. Gets around the vulnerabilities of fins but still deploys by pushing a button.
Will ask again. Anybody with experience or thoughts about Magnus devices.

I wonder how much lift you get out of a Magnus rotor vs from a fin of equal protrusion from the hull. The effectiveness of any type of stabilizer comes from the lift it provides. And the down side is the degree to which it protrudes from the hull.

 

[Snapdragon III]

My old boat I am now selling has Paravane stabilizers. They work really well, and under most conditions are not too much hassle to deploy or bring in, although they do require some strength and climbing around on the roof. I would imagine there will be an age where I would not want to do it anymore. The biggest downside that we experienced was a couple of situations were it was extremely rough right outside the marina or inlet you needed to enter, and having to be outside wrestling with them to get them in as the boat went crazy at zero speed. It happened once right outside our home marina with a very strong Westerly coupled with a 2kn ebb tide running against it, creating crazy breaking waves. And another time on the West coast of Vancouver island where we were entering an inlet in rough conditions, and I wasn't comfortable with the depth, and had to bring them in right outside the breakers to either side of the small entrance. Both times if felt very dangerous to be out there in those conditions, and it was no fun for my family inside the boat either. My new boat was originally built with Paravanes, but was changed to Keypower Hydraulic stabilizers by the previous owner. I haven't gotten much time in the boat to test them yet, but the brief trip I took in the boat they seem to work really well, and the delivery crew reported that they worked well from Fiji to Hawaii once they started using the right settings. I called Keypower for some tech support while I was in Hawaii, and had a very favorable experience. I am looking forward to having stabilizers that turn on with the touch of a button. I echo what others in this thread have said, that once you have owned a boat with stabilizers, you will not be interested in going back to a non stabilized boat.

 

[Simi 60]

One I have liked for a while
No stabilisation needed
How much does an 80ft Nordhavn cost again??

https://yachthub.com/list/boats-for-sale/used/power-boats/custom-82-power-catamaran-bonefish/228003

33ft beam will be interesting, but I know people with trimarans that are that and some.
If you actually use the boat, it likely will only be an issue every 2 years when slipping and even then, you could always do a sneaky dry out.

 

[Hippocampus]

Some folks don’t like the motion of a multi in a seaway. Until you’re at ship not boat size they float on the water not in the water. So they have a more sudden motion and more tendency to hobbyhorse. Especially when going to Windward so facing the wave train. They also “burp” especially if the bridge deck isn’t high enough and “stall”. The “stall” is really a sudden deceleration when the hulls and air between them are caught in the same wave.
I have no experience with power multis but have done passage on sail. Found it nice to not be living life on a slant but it doesn’t mean you’ve escaped motion.
USN and NASA have studied motion sickness. Although just about everyone can get seasick there seems to be 3 general groups. Those quite resistant, those sensitive to high frequency motion and those sensitive to low frequency. I have a friend who barfs when taken fishing on a small center console but does just fine on passage. Weird but consistent with current understanding. So before looking to buy a multi spend sometime on one.

 

[FF]

"Some folks don’t like the motion of a multi in a seaway. Until you’re at ship not boat size they float on the water not in the water. So they have a more sudden motion and more tendency to hobbyhorse. Especially when going to Windward so facing the wave train."

This describes the basic motion condition of a catamaran , a trimiran is far more like a monohull, just less tippy.

The amas (the floats on either side) do not carry half the weight of the boat so will push deeper into the water , rather than snap up.

45ft Headly Nichols Voyager built in (then) British Honduras 1966.

Great for Carib sailing but too much surface area for northern winter live aboard.

In the 1960's for sailors, the mantra was Cats for coastal , Tris for trans ocean.

 

[balder8]

My new boat was originally built with Paravanes, but was changed to Keypower Hydraulic stabilizers by the previous owner. I haven't gotten much time in the boat to test them yet, but the brief trip I took in the boat they seem to work really well, and the delivery crew reported that they worked well from Fiji to Hawaii once they started using the right settings. I called Keypower for some tech support while I was in Hawaii, and had a very favorable experience. I am looking forward to having stabilizers that turn on with the touch of a button. I echo what others in this thread have said, that once you have owned a boat with stabilizers, you will not be interested in going back to a non stabilized boat.

I can tell you that far from West Canada, I have had a very friendly and efficient support from Keypower provided by Mr Dean YULE. I bought my trawler as a demoboat, not completely finished but with many systems already installed as hydraulic bow an stern thrusters, get home drive and stabs from Keypower. My english is not 100% perfect and when you are in trouble with a mysterious solenoid, you are not very proud! Mr YULE gave instructions to a very professional dealer in Florida to sell and ship to me in Med ( I was in Balearics) THE mysterious solenoid and sent me all technical infos available to fix it. Of course, I did not change my point of view: have a back up system like paravanes in case of failure. But it is so comfortable and easy to push on the button, immediatly after leaving the marina and read on the display, the corrections done by these powerful stabs!
The key is the maintenance and I need a serious training to understand more and more about hydraulics etc...
Should Mr Trudeau accept soon we travel again in Canada and let me open my house in Quebec ( I am not resident), I will make as well a trip to BC to visit the Keypower factory and learn more from their technicians

 

[Hippocampus]

Have done passage on a Chris White Tri. Admittedly only Newport to Bermuda and racing. But the issues with hobbyhorsing and very sudden motions were present. Still needed lids on the coffee and thought before moving. Respectfully disagree about about tri motion being less than cat from past experiences. Will note several motor tris have proportionally very small amas in comparison to central hull. As stated above have no personal experience with those and motion maybe different. Motion maybe different as these vessels are quite large.
Matter of personal opinion but rather be a on a Outremer, Gunboat Or Catana (cats) on passage than a Neel (tri). However a Rapido 60 (tri) would be my dream boat if I was going back to sail. With advances in naval architecture (super thin hulls, wave piercing bows, no bridge deck forward of the mast, high bridge deck etc.) for open water use are understood so the break isn’t tri or cat. It’s is the boat aimed at the charter market or passagemaking.

 

[Simi 60]

Some folks don’t like the motion of a multi in a seaway. Until you’re at ship not boat size they float on the water not in the water. So they have a more sudden motion and more tendency to hobbyhorse. Especially when going to Windward so facing the wave train. They also “burp” especially if the bridge deck isn’t high enough and “stall”. The “stall” is really a sudden deceleration when the hulls and air between them are caught in the same wave.
I have no experience with power multis but have done passage on sail. Found it nice to not be living life on a slant but it doesn’t mean you’ve escaped motion.
USN and NASA have studied motion sickness. Although just about everyone can get seasick there seems to be 3 general groups. Those quite resistant, those sensitive to high frequency motion and those sensitive to low frequency. I have a friend who barfs when taken fishing on a small center console but does just fine on passage. Weird but consistent with current understanding. So before looking to buy a multi spend sometime on one.

I have.
I have owned 3, built two for ourselves and several for others
Have done over 50,000nm on them both sail and power.
They have a different action for sure but never have we seen it bad enough to loose stuff off of a table.
The hobbyhorsing and burping you mention is more a poor design and overloading issue, too much boat and weight on not enough hull and that I personally have not experienced but have seen.

 

[Hippocampus]

Simi hope you didn’t construe my prior posts as my being down on multis. That’s not the case. One of my dream sail boats is a Rapido 60. Beautiful design and a great seaboat. Only wished to point out there’s good and bad seaboats in that category and some people are sensitive to their motion. Particularly those that attempt to maximize living quarters and load capacity. Although properly executed they make amazingly fast passages Still, it’s always interested me that on the SDR, ARC and other cruising flotillas transit times aren’t that much different than modern monos. It’s not infrequent to throttle back to improve comfort. Have noted this particularly when going to weather.

 

[DDW]

I wonder how much lift you get out of a Magnus rotor vs from a fin of equal protrusion from the hull. The effectiveness of any type of stabilizer comes from the lift it provides. And the down side is the degree to which it protrudes from the hull.

In theory, Magnus rotors operate at many times the lift coefficient of fins, and can therefore have a small fraction of the area with the same lift. That seems to be the case in practice, looking at the photos of real installations. You'd think the L/D of the Magnus would be a disaster, but they are probably comparable: in aircraft studies, about 1/2 at the same aspect ratio, but due to much smaller area the aspect ratio of actual installations is much higher than fins.

I was particularly intrigued by the simple ones mounted on the transom as shown upthread. Looked easily retractable, easily retrofittable, and less vulnerable to damage.

 

[Simi 60]

Simi hope you didn’t construe my prior posts as my being down on multis. That’s not the case.

All good but I am pissed at myself for typing loose instead of lose.
I hate that.

 

[75Driver]

This is a great discussion for newbies although some might be too technical. Most everyone wants real life experiences and whiles there’s plenty of that the other stuff is a tad deep for most. Overall great topic though, thanks for all the input.