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Old 04-13-2012, 11:27 PM   #21
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Why not just get a catamaran and be done with it? But then, that wouldn't be a trawler, would it? ... I'll stick with sails and avoid the inherent difficulties of gyroscopes, protuberances, and "wild" paravanes.
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Old 04-14-2012, 07:29 AM   #22
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"Why not just get a catamaran and be done with it? "

CATS CAPSIZE

And give a hideous ride in a beam sea.

Like being in a box barge , the cat takes up the wave shape even quicker as they are usually light.

"After the early 2000s, few if any Nordhavn 50s, 52s, 55s, 57s, 60s or 62s had them installed. They were quite common on the early 62s but with better active stabilizer designs and increasing reliability, paravanes went kaput."

Perhaps the new trawler folks had no concept on their use?
And no use for offshore stability , just a boat that looks "offshore"?

For a lumpy ICW or short coastal cruise the hyd setup is perhaps better as it is simply switched ON , not deployed.
And a MR Fix It is only a phone call at the next marina

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Old 04-16-2012, 05:30 PM   #23
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Does anyone have an opinion if this would be practical or cost effective?

Big question is weather you can get to the area the fins are installed , and can easily beef up the hull in the local area.

FF
I have calculated where the fins/actuators need to be mounted and fortunately it's just forward of the fuel tanks - in a relatively clear area. The solid glass hull, with frames and stringers, at close centres will be easily reinforced at this location.This is work I am confident to do myself after I get someone to determine the layup required. I will do more investigation re cost of parts - it may be gross overcapitalization!

I too have thought about catamarans but they make me sick (literally).
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Old 04-16-2012, 05:53 PM   #24
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After the early 2000s, few if any Nordhavn 50s, 52s, 55s, 57s, 60s or 62s had them installed. They were quite common on the early 62s but with better active stabilizer designs and increasing reliability, paravanes went kaput.
Seems it all depends on how much money you have.

Cheep and low tec.

High tec and expensive.

SD
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Old 04-16-2012, 10:25 PM   #25
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I have calculated where the fins/actuators need to be mounted and fortunately it's just forward of the fuel tanks - in a relatively clear area. The solid glass hull, with frames and stringers, at close centres will be easily reinforced at this location.This is work I am confident to do myself after I get someone to determine the layup required. I will do more investigation re cost of parts - it may be gross overcapitalization!

I too have thought about catamarans but they make me sick (literally).
My parts from Niad 11 years ago 6' blades and 9' machinery came to over $35k and the last I heard was it was over $40k. the Installation is involved as there is a lot more than just a pump and reservoir
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Old 04-16-2012, 10:35 PM   #26
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If they were to be located in a close to "vertical position", they will actually alo work as rudders and can therefore influence the steering system. They should be installed as close to horizontal to avoid this.
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Old 04-16-2012, 11:34 PM   #27
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paravane

Can you be specific about where you can purchase these paravanes?
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Old 04-17-2012, 12:16 AM   #28
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FF

Call Jim Leishman at Nordhavn and inform him his boat purchasers (the biggest group of MV world travelers by brand yet) have no concept of paravane operation and you have just the way to instruct them. I can't see the paravanes in your boat picture, Where do you have them attached?
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Old 04-17-2012, 03:50 PM   #29
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Sunchaser,


i have not posted any pictures of my paravane system

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Old 04-18-2012, 12:37 AM   #30
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Active fin angle

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If they were to be located in a close to "vertical position", they will actually alo work as rudders and can therefore influence the steering system. They should be installed as close to horizontal to avoid this.
My Niad active fins are on about a 60deg angle from horizontal so thirty deg from vertical. One of the reasons for this is so the vanes don't protrude beyond the gunnels. The vanes are set with a lot of tow in, close to 10deg by estimate, maybe more. The fins are located at about the center of effort or turning point of the boat. Not at either end so there is little rudder effect. They are self centering and have to lock in center position when backing down. They do effect steering but maybe not in the way you would expect at first thought. Many round bilge boat lean out under hard turns, the opposite of banking like a planing hull. So do Cats for that matter. The stabilizer vanes stop the heeling and keep the boat near perfectly vertical. When running in large following seas that tend to broach many boats as the stern is lifted and the bow starts down the wave face. When the boat starts to turn and broach the fins correct the heel and direct the boat in a straight line. Hands off no steering needed. My boat tracks like it's on rails in following seas regardless of whether the wave are quartering or directly astern. I can literally set my auto pilot on a course heading and the boat will track straight and true with almost no cross track error. If you can afford them and have room they make an incredible difference on a round bilge boat. I'm not as certain that will work as dramatically on a semi-planing hull form because of the extra primary stability of a hard chin / rounded chine boat.
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Old 04-19-2012, 11:51 PM   #31
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Scary, thank you for the great article! That link was chalked full of great information.
the author seems pretty positive about "passive fins". this looks like a valid option.
My question is "why is it you don't ever see these on any boats?"
Thanks all for the comments.

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Old 04-20-2012, 08:02 AM   #32
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Seeing the "Perfect Storm" kinda put me off them...
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Old 04-20-2012, 10:55 AM   #33
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ParaVane are ok in my book

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Seeing the "Perfect Storm" kinda put me off them...
just remember... anything you see in a movie is never embellished!!

I had the good fortune to deal with para vanes for nine years... with the exception of the down cables picking up stuff every now and then they worked remarkably well.. in the open ocean set and forget was the norm. The worst thing that ever happened was snagging a log in the Strait of Georgia in less than ideal conditions.. I noticed the boat was applying a lot of port rudder to maintain course then noticed the stbd. vane was trailing much further aft causing loads of drag to stbd. It took about a hour to get the waterlogged log up out of the water and to use a hatchet to cut the log free of the cable. I think chain down lines would of solved this and a slight harmonic sound caused by the s.s. cable slicing through the water, Nordhavn paravane rigs use chain and I can see why.
We did have a set of flopper stoppers that could be rigged at anchor to reduce swell roll... but they never really were worth the hassle of rigging at anchor. My kids did really like to use the rig poles to hang a rope swing for use at anchor too.
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Old 04-20-2012, 11:13 AM   #34
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I love my Paravane Stabilizers.
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Old 04-20-2012, 11:46 AM   #35
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I wonder why more manufacturers' do not build their hulls with bilge keels. They are basically free stabilizers. There is a coefficient equation, with the waterplane entered into it, that tells you the size of bilge keel that can be added to a hull for maximum stability as it is related to drag. Most bilge keels on full displacement hulls are about 50-75% of the total hull length and greatly reduce roll and add to tracking. Just a thought.
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Old 04-20-2012, 12:26 PM   #36
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Can you be specific about where you can purchase these paravanes?

Kolstrand Marine Supply, Seattle. 206-784-2500

If you email me yur email address I will email you information that I have.

Plan on adding bilge keels before Fish Stabilizers. The keels are to reduce the roll but also help to keep the Eagle up right when grounded and/or on the hard/grid.
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Old 04-20-2012, 01:09 PM   #37
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Good Question

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Scary, thank you for the great article! That link was chalked full of great information.
the author seems pretty positive about "passive fins". this looks like a valid option.
My question is "why is it you don't ever see these on any boats?"
Thanks all for the comments.

Taras
It seems to me this would be a fairly simple addition to many boats. I suspect that appearance when not in use may have something to do with it. This an Australian study and I have to say from experience that Australians have approached boating in innovative ways. they were among the first to really champion high speed catamarans and have always thought out of the box when it comes to small sailboats. I think there is a lot of things we do out of tradition without really thinking things out. If those passive fins are as effective as their study implies they would be a very cost effective way of controling roll. We certainly have the ability to build foil shaped centerboards that same technology could be used to built passive foils for fins. I lose 1/2 knot and fuel economy running my active fins, if these work close to as well and cost a fraction of the active stabilizers why not give them a try. From my experience sailing small boats with centerboards, this system should have seemed obvious. It also fits in well with those of us that are minimalist and want to keep it simple.
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Old 04-20-2012, 01:25 PM   #38
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Quote:
Originally Posted by Taras View Post
Scary, thank you for the great article! That link was chalked full of great information.
the author seems pretty positive about "passive fins". this looks like a valid option.
My question is "why is it you don't ever see these on any boats?"
Thanks all for the comments.

Taras



Because fish stabilizers are UGLY and require activation/deployment/retrieval. Fish stabilizers are active not passive by definition. You do see them on commercial and trawler type looking boat like the Eagle. I mean the Eagle is ugly already so a little more ugly will not hurt.
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Old 04-20-2012, 03:11 PM   #39
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Quote:
Because fish stabilizers are UGLY and require activation/deployment/retrieval. Fish stabilizers are active not passive by definition. You do see them on commercial and trawler type looking boat like the Eagle. I mean the Eagle is ugly already so a little more ugly will not hurt.
I won't call pavanes ugly. They're just an other piece of boat hardware. We keep the rigging up to date so it looks good IMHO. I get more questions about what they are. Most cruisers don't realize that we run with them under way. They think there just flopper stoppers. If I've had a few beers I just tell people they're "sissy bars".

I won't call paravanes active but passive. Ours require no activation other than me putting them in the water.

Don't let Eagle here you call her ugly. She could get even with you when you least expect it.
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Old 04-20-2012, 04:14 PM   #40
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Passive Fins are fixed to the hull and except when up.

Take the time to read the article on Stabilizers I posted earlier. It's an Australian research article on fishing stabilizers. These are located like active fines but fixed. Like having apposed centerboards on a sailboat.
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