Paravane

[dwhatty]

Tidahapah wrote:

Claude,
I have PM'd you re info from Monk and Ocean Haven yachts.
Attached is a couple of photos of static roll stabilisers.
Also a couple of boatrs with paravane arms, I'll also track down some with fold away arms as used on prawn trawlers here in Aus.
Benn

Can you explain how this one is deployed? Interesting looking gizmo.

 

[Singleprop]

http://www.boatexec.com/Photo%20Gallery.htm

http://boatexec.com/Paravanes.htm

http://boatexec.com/flopper_stoppers.htm***
**

these links hves some good pictures and*there is also a good written description of how the system is installed.

-- Edited by Singleprop on Friday 18th of March 2011 09:20:01 PM

 

[FF]

At a wind speed of 17K , a square foot of sail (or anything else) produces one pound of force .

The F-S are far more powerful to create a righting moment unless its blowing like crazy!!!

No wind and old rollers will pay for the FS the first time.

I was contemplating a new build , but the economy sucks so its on hold.

MY stabilizing concept was a wide centerboard trunk , (6 or more inches), with a foil shaped board that could pivot on its fat middle about 25% from the leading edge.

A simple air ram would induce the angle of attack that would create the righting force , just as stabilizers do.

Of course mine would be zero drag when not in use , and would simply push up like every CB on ground contact.

Ripping off or knocking a hole in the boat would no longer be the choice.

Cheap to build and operate , but the interior might be compromised by the center board trunk requirement.

 

[Tidahapah]

David,
That foto is of the flap type suspended from the arm or arms.
There is a center piece that has a spring and a weight to keep it all in the water and absorb some of the shock load.
It just acts as a sort of flap valve creating a resistance on the up side and allowing the water to flow when falling.
That unit is fitted on a 50' Nordie next door to me.
Benn

 

[Moonstruck]

Tidahapah wrote:

David,
That foto is of the flap type suspended from the arm or arms.
There is a center piece that has a spring and a weight to keep it all in the water and absorb some of the shock load.
It just acts as a sort of flap valve creating a resistance on the up side and allowing the water to flow when falling.
That unit is fitted on a 50' Nordie next door to me.
Benn

Benn, I may have missed something here.* Will this system work at anchor and underway?* Depending on the diameter it seems it would produce allot of drag.

 

[Tidahapah]

Strictly an at anchor roll modifier.
Benn

 

[LadyMJ]

We had paravanes on our 43' Defever that had winches for lowering the outreaching "booms". They were heavy, took time to operate, difficult to retrieve, BUT Worth every bit of the trouble!!! We took the boat over 15,000nm, and even though we are fair weather boaters, we got caught several times in what we considered "rough seas"! The paravanes made the voyage "bearable", although when it really gets rough, the fraction of roll that is not removed can be endured! The biggest mistake is going out in the open and NOT putting the fish in the water! The rough water seems to "sneak up on you"! This, we never seemed to learn! The "fish", reduced our average cruising speed about 1 knot, well worth the improved cruising characteristics! Some boats have the fish also, deployed on winches, which would be a great feature! We seldom had fish come out of the water, and then it was only straight up a foot, or two. We did not feel there was a danger from "flying fish", on our boat! The paravanes definitely do continue to perform even at anchor, particularly in some of the Pacific coast "rolly anchorages, from the Panama Canal northbound. An important feature when you're trying to play "Mexican Train" dominoes! We have not owned a boat with Naids, or a steadying sail, but would certainly not criticize either, and would welcome them as an improvement, I'm sure! You'll appreciate any improvement, after many hours in a long passage, in heavy seas! Dick & Mary Jo

 

[FF]

A quick look in Beede's book and he had both steading sails and FS.

To him there is no choice the FS work , the saILS WERE A WASTE OF TIME AND EFFORT.

28% from the stern is the preferred location for their swim.