Stabilizers: A Must for Passage-Making?

[long-cours.62]

One of the Dutch companies selling the Magnus rotors also sells a wing like you are talking about, mounted on or near the transom and horizontal. It is electrically controlled however.

Yes, I think I posted here a photo of boat fitted with that type of equipment...somewhere on this site but don't remember where ...

 

[Sweetypie]

It's amazing that so much effort and attention is placed on stabilization, while ignoring what almost every commercial fishing boat uses, which are called "rolling chocks" or bilge keels"

These simple, zero maintenance, relatively inexpensive, popular devices are for the most part ignored by the recreational boating community.

for $20,000 I changed my Bayliner from a rolly polly boat, into a stable boat in a beam sea.
I do not need to deploy anything.
I do not need to maintain anything.
They work equally well at anchor or underway.

The amplitude of my rolling is dramatically decreased.
The roll period is the same.
That results in much lower roll velocity, and much lower roll acceleration and deceleration, which is what people feel when a boat rolls.

Why do recreational boaters ignore this proven, popular, roll reduction technique?
Do we somehow need to make things difficult or complex for our minds to be satisfied?
Or is this just the result of our online, information available world, where we need to overanalyze things to the N th degree?

I can not answer for others, but for myself it's more about the creativity.
If my sole goal was to have a stable boat I would install a Gyro or buy a Multihull.

Rolling chocks absolutely would work to some degree, I am thinking more along the lines of creating a system that is simple, requires no electronics and can be lifted out of the water just like a wind vane (Self steering system used on blue water Yachts) this system is simple and requires no power to operate.

All concepts and ideas start with thinking outside the box a little and most of all not following the trends of normal.

I believe having stabilisers that act to counter the forces or a vessel rolling rather than just dampening the forces will have more of an effect.

I have only seen rolling chocks on 2 vessels here in Western Australia.

 

[Pascall]

Dutch ships are almost always equipped with bilge keels.
I think it's because Dutch ships are usually built of steel and it's very easy and cheap to install bilge keels.
Often the bilge keels are also used for cooling the engine and as a support to let the boat fall dry.

Greeting,

Pascal.

 

[long-cours.62]

https://no.yachtworld.com/yacht/1995-pieter-beeldsnijder-60-explorer-yacht-4187678/

 

[Hippocampus]

Read NASA and USN papers on motion sickness. There are people more sensitive to fast frequency motion and others slow. Some are intolerant of ships but not boats. Some are tolerant of ships and full displacement hulls but not multi hulls or planing boats. Tolerance varies but with the right stimulus anyone can get sick. I’m fortunate and resistant but did get sick when upside down fixing a stay from ama to ala while cold and overtired.
For moving around both speed, rhythm and amplitude of the motion are important for ability to function.
Most people are fairly resistant to motion in one axis. That rarely occurs on a small boat. You nearly always have some pitch, heave and roll. Most stabilizing techniques address only one parameter. In order to have decent impact that technique should ideally decrease that motion by 70% or better. In moderate conditions fins, fish and Magnus does exceed that value. Rolling chocks don’t. Definitely help but not as well as other measures. In a commercial application where cost is a major driving factor they make sense. There is no need to go recreational boating in any form. As percentage of total cost making the jump to more expensive techniques is more appealing.

 

[Mako]

Thanks for throwing some actual numbers down @Hippocampus.

From my research I’ve learned that the “average” rolling chock is rather worthless at less than 10% effectiveness.

The better designed, larger ones, like what KSanders has, are pushing about 35% reduction. That’s the maximum my naval architect claimed could be achieved. For our design he indicated a width of about 12-14 inches.

When I spoke with Dr Bass he stated the max reduction of a well-tuned flume tank is about 65%. My feeling is that a flume, coupled with a heavy chined hull, would be sufficient, especially because they work at anchor.

If one wants to achieve greater effectiveness then only active stabs of some type are required.

Now that my search has shifted heavily towards used vessels, I actually find that those with traditional hydraulic fins are a mixed blessing. That’s because they don’t work at anchor, which is an important use-case for my wife.