Paravanes

About two months ago I started manufacturing the Paravans with the corresponding equipment.
I have found a lot of information here on the forum, so I want to share my progress with you.
Because the mast should be easy to go down through the many bridges, I did not want booms next to the mast, so the booms are horizontal.
The existing boom, which is attached to the mast, is replaced, at least that is the intention, for two booms that are extendable.
Here a few pictures, as first making the pulleys, six pieces.













Pascal.

Wow, you are a craftsman. I wish I would be able to do this. When I see this craftsmanship I understand why you built your boat all by yourself............you can do it better than most yards.

If you have some spare time................I do have some things on my wish list for my boat.

Mambo42 said:

Wow, you are a craftsman. I wish I would be able to do this. When I see this craftsmanship I understand why you built your boat all by yourself............you can do it better than most yards.

If you have some spare time................I do have some things on my wish list for my boat.

Click to expand...

Thanks for the compliment, time, time is my biggest enemy but sometimes I make parts for other people. :lol:

first, I make one boom, if it is mounted then we will test. When the test is good, we continue and 'I make the second boom.
The intention is to operate the paravanes electrically.
the two electric winches are also purchased after the test.
one part of the boom is made of plywood.
In the wooden boom comes a stainless steel tube that can extend.
The stainless steel tube locks automatically when the tube is extended.
Here are a few pictures of how to make the boom.





















Pascal.

do you have a sketch showing what the entire rig will look like?
Hollywood

hollywood8118 said:

do you have a sketch showing what the entire rig will look like?
Hollywood

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Hello, I have edited a photo on which you get an impression of how the booms are placed.
The booms can be turned outwards, then the paravanes can go down



Pascal.

When you swing the booms out do you have a fore guy to the end of the boom to take the paravane load as well a a cable to the top of the mast. The loads can be fairly large and all of the component need to take up the load as the boat roll and pitches.

In your sketch there would be a thrust load on the boom end on top of the house. Is it properly supported, Do you have a sketch of the deployed paravane with all of the lines? It would help.

DennisB1 said:

When you swing the booms out do you have a fore guy to the end of the boom to take the paravane load as well a a cable to the top of the mast. The loads can be fairly large and all of the component need to take up the load as the boat roll and pitches.

In your sketch there would be a thrust load on the boom end on top of the house. Is it properly supported, Do you have a sketch of the deployed paravane with all of the lines? It would help.

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First of all, great Dennis that you think along, that is also the reason that I started the toppic here.
For me this is an unknown road as well as for 99% of the Dutch people.
I will make a few sketches of the rigging.

Thank you!

Greet,

Pascal.

Again a few steps from making the boom with the corresponding stainless steel parts.
A lot of work goes into polishing the stainless steel parts.
The boom is provided with 9 layers of epoy / paint, no maintenance in the coming years.



















Pascal

Elegant for sure. I’ll assume that with so much forethought, the vessel will be equally enforced to spread the considerable loads. Very interesting design.

How heavy are the booms? Commercial fishermen make the booms and mast from aluminum because it's lighter. Weight up high causes more rolling and less stability. Stabilizers need strong rigging and solid attachment points.
A doubt your cabin top is strong enough. In mild weather, maybe.
The booms should align with the mast and except for small boats the booms are mounted on the sides. When deployed, the booms are about 45°. Too close to the water's surface and they my be torn off when the pole end dips into the water.
The booms are self supporting via the mast. And you need lines running to the bow and stern from the boom end to keep the boom in position. And another line usually attached to the hull below the boom mounting to keep the boom from jumping as the boat rolls.
You do nice work.

Enclosed is a diagram for a commercial boat of 43'.
It's from https://www.kolstrand.com a major supplier of commercial gear.
There is more info there.

Lepke said:

How heavy are the booms? Commercial fishermen make the booms and mast from aluminum because it's lighter. Weight up high causes more rolling and less stability. Stabilizers need strong rigging and solid attachment points.
A doubt your cabin top is strong enough. In mild weather, maybe.
The booms should align with the mast and except for small boats the booms are mounted on the sides. When deployed, the booms are about 45°. Too close to the water's surface and they my be torn off when the pole end dips into the water.
The booms are self supporting via the mast. And you need lines running to the bow and stern from the boom end to keep the boom in position. And another line usually attached to the hull below the boom mounting to keep the boom from jumping as the boat rolls.
You do nice work.

Enclosed is a diagram for a commercial boat of 43'.
It's from https://www.kolstrand.com a major supplier of commercial gear.
There is more info there.

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Thanks for the support Lebke and the information.
The boom weighs 21 kilos (46 ib) times two, which is quite heavy.
Compared to the boat I think it is not too bad, boat is 36.74 feet long and 12.46 feet wide and weighs 14 tons (30864,716 ib )
The fixing points of the booms come on a stainless steel plate that is fixed on the deck, on this plate the two winches are also mounted on.
The stainless steel plate is fixed on the mast base and that is a strong point.
The mast base rests on the wheelhouse roof and also runs through the wheelhouse by means of a very heavy stainless steel tube.
This tube goes through the wheelhouse floor and eventually rests on the diesel tank, the tank is also very heavy built, I see no problem in that.
I understand the forces that come on the rigging, I will make a drawing how I think I will perform the rigging.
Sorry for my flawed writing style, I use a translator.

Pascal

So far the last pictures so far I have come with the manufacture of the boom.
I hope to mount the boom at the location of the existing boom in the coming days.
Then the testing can start, if the test is successful then I can start with the final actions, placing the boom on the wheelhouse roof
















Pascal

Pascall said:

The mast base rests on the wheelhouse roof and also runs through the wheelhouse by means of a very heavy stainless steel tube.
This tube goes through the wheelhouse floor and eventually rests on the diesel tank, the tank is also very heavy built, I see no problem in that.

Pascal

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Hi Pascal. Be very, very aware that the compression load on your mast base will be several times that of any other load on your system. Geometry is not your friend! Construct an accurate rigid body diagram of your paravane system. Make sure you have the dimensions accurate. Then solve for the various forces in each part of your paravane system. I expect you will be very surprised by the compression load in your mast.

You state this load will be landed on the diesel tank. That's a poor design choice. The mast compression should follow through to the keelson of the boat, NOT on the tank. I simply can't imagine a sound mechanical design of such a system ultimately resolving it's loads via a diesel tank. Ever been aboard a sailboat where the mast base lands on a tank? No, they land directly on the keelson. Even deck-stepped masts land directly on a bulkhead, which ultimately transfers this load to the keelson.

Regards,

Pete

jungpeter said:

Hi Pascal. Be very, very aware that the compression load on your mast base will be several times that of any other load on your system. Geometry is not your friend! Construct an accurate rigid body diagram of your paravane system. Make sure you have the dimensions accurate. Then solve for the various forces in each part of your paravane system. I expect you will be very surprised by the compression load in your mast.

You state this load will be landed on the diesel tank. That's a poor design choice. The mast compression should follow through to the keelson of the boat, NOT on the tank. I simply can't imagine a sound mechanical design of such a system ultimately resolving it's loads via a diesel tank. Ever been aboard a sailboat where the mast base lands on a tank? No, they land directly on the keelson. Even deck-stepped masts land directly on a bulkhead, which ultimately transfers this load to the keelson.

Regards,

Pete

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I understand your reasoning, but if you saw the construction of the tank you would look at it differently.
The tank is made of a waterproof bulkhead.
In the tank there are various pendulum bulkheads plus the tank is part of the engine foundation.
The steel varies in thickness from 5 to 10mm is stronger than the hull.

But great that you think along!

I'm going to buy a digital force meter, then I can measure how much force is ultimately applied to the different components.

Pascal

paravanes

I do not think that a paravane system necessarily leads to large downward forces on the mast. On my Willard 40 (~18tones) I have used paravanes in very rough conditions extensively for 15 years. The line supporting the pole ends goes HORIZONTALLY to the mast head. Loads are transferred from one pole to the other but there is minimal compression on the mast. I have never understood why most boats have the pole-supporting lines making an upward angle to the mast head.

Also, there is no need for an aft guy on the pole end. The aft drag of the vane is plenty to keep the pole from moving forward.

I agree that the mast should not be supported by a tank top. On my Willard the mast thrust goes down to a heavy horizontal beam in the engine room. that beam is supported by vertical members at the ends that go down to the engine beds which are part of the hull..

rpackard said:

I do not think that a paravane system necessarily leads to large downward forces on the mast. On my Willard 40 (~18tones) I have used paravanes in very rough conditions extensively for 15 years. The line supporting the pole ends goes HORIZONTALLY to the mast head. Loads are transferred from one pole to the other but there is minimal compression on the mast. I have never understood why most boats have the pole-supporting lines making an upward angle to the mast head.



Also, there is no need for an aft guy on the pole end. The aft drag of the vane is plenty to keep the pole from moving forward.



I agree that the mast should not be supported by a tank top. On my Willard the mast thrust goes down to a heavy horizontal beam in the engine room. that beam is supported by vertical members at the ends that go down to the engine beds which are part of the hull..

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A worthy post and opinion - as I recall, in addition to years of sail and trawler cruising, you are a retired Professor of Physics from UC Berkeley.....

Peter

I would suggest that you hire an engineer/naval architect to take a careful look at what you have built and the structural load paths thru your boat. Also look at the shift in cg with the equipment you are adding and stability of the boat. In my opinion you need an engineered solution which is not possible with just A number of suggestions from this forum. Goal is a safe design that accomplishes your requirements.

DennisB1 said:

I would suggest that you hire an engineer/naval architect to take a careful look at what you have built and the structural load paths thru your boat. Also look at the shift in cg with the equipment you are adding and stability of the boat. In my opinion you need an engineered solution which is not possible with just A number of suggestions from this forum. Goal is a safe design that accomplishes your requirements.

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Hi DennisB1.

Yes, right on. Attempting this sort of work, while relying on anecdotal information from this forum is not a good idea. The forces exerted on a vessel in a seaway are little understood by the laymen. And how those forces are resolved into the structure of the vessel, in a configuration including paravanes, are neither intuitive nor trivial. These forces can, and do, cause damage to a poorly designed vessel, and can lead to unsafe conditions at sea.

Regards,

Pete

Ya know....everytime subject of paravanes comes up, there are a handful of posts admonishing the OP to get a naval architect, about how the forces are extreme, how he will sink in a storm, blah-blah-blah.

Y'all realize this guy built this boat 25+ years ago, has sailed it in the north Atlantic? I mean even a brief glance at the pictures in this thread show some topnotch talent, a well-equipped shop, and some serious knowledge.

Pascal (OP): Thanks for sharing - looks great. I can't quite figure out how your booms will swing out without the standing rigging interfering, but I have no doubt you've already figured that out.

Peter

We’ve considered fabricating paravanes many times, even engaging an NA (who proposed bildge keels instead bc that’s what he preferred).

I would get pretty worked up about this project after reading posts here and there. Yes there are forces involved, yes you need to plan and do it right but when I walk the commercial docks in Seattle or Bellingham or in BC I see many many aluminum, steel and even wooden boats with paravanes that look like were were fabricated by the crew over a weekend with a stick welder and a case of beer (sometimes two cases).

For now, we opted to use our sails for steadying. Not as effective as fish and certainly not useful in some sea states but they work essentially by applying a horizontal load to the mast which is taken up by the rigging and chainplates. Paravanes work very much the same way.

Love following your project. Great ideas and craftsmanship.

mvweebles said:

Ya know....everytime subject of paravanes comes up, there are a handful of posts admonishing the OP to get a naval architect, about how the forces are extreme, how he will sink in a storm, blah-blah-blah.

Y'all realize this guy built this boat 25+ years ago, has sailed it in the north Atlantic? I mean even a brief glance at the pictures in this thread show some topnotch talent, a well-equipped shop, and some serious knowledge.

Pascal (OP): Thanks for sharing - looks great. I can't quite figure out how your booms will swing out without the standing rigging interfering, but I have no doubt you've already figured that out.

Peter

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Hi Peter,

And y'all realize that for every successfully paravane project like this, there are many, many unsuccessful projects that are NOT reported back to the WWW? And no, the Original Poster has NOT provided anything other than pretty pictures that indicate he has some fabrication knowledge and fabrication talent. Not design talent, however, which is a totally different bucket of worms. Your statement of knowledge of his 25+ years of operation on the North Sea is fine and dandy, but has little relevance to the topic at hand. And to date, I don't believe anyone has suggested to Pascal (the OP) that he will "...sink in a storm". Kinda overly dramatic, in my opinion.

I'm also in agreement that there are paravane projects completed by amateurs over a weekend after consuming a couple of cases of beers. Are these successful and safe? Time and circumstances will tell. Each to his own. In this case, it's the OP's (Pascal's) choice on how he goes forward. My professional experience, educational background, and decades of life at sea make me a little more circumspect given the unknowns and the potential high loads and risks involved.

Regards,

Pete

On topics like this, my sense is there are a lot of people who wring their hands and deflect. Fair enough - they lack practical experience, knowledge, or are not comfortable jumping in and figuring it out. And they need someone else to figure it our for them. Nothing wrong with that.

To listen to the naysayers, the world's fishing fleets should never leave port unless signed off by some schmoe with a Naval Architect moniker. There are a lot of engineers who's degree is in practical experience. I just don't see paravanes as an especially complex construction problem. It's the type of thing that for people who have built a bunch of stuff, is pretty straightforward, at least on a fairly small boat.

I know of two paravane setups that were professionally designed. They still needed considerable tweaking once installed, including some refabrication and redesign. I consider that normal, and I'm sure Pascal will undergo the same.

It's one thing to ask questions such as "have you considered how the added weight might change the boat handling?" Or "how are you transferring loads?" But to speak of doom and gloom and negativity is annoying. It's not helpful. Neither is the chest-thumping on decades of experience. Show me you're experience, don't tell me about it. The OP has definitely coughed up some creds (assuming he isn't BS'ing about building the boat in the picture).

A few posts up, Rpackard - a professor emeritus in physics, a lifelong boater, and a longtime cruiser of a paravane equipped Willard 40, essentially said that the forces aren't all that. And yet there is always a chorus about "oh, the forces....you must have a Naval architect!!!" Never - as in never - do any of these apocalyptic naysayers offer any intelligent insight as to what these forces might be, just some regurgitated sky-is-falling gobbly-gook.

I'm sorry, but given the choice of a Naval architect and a drafting board and a knowledgeable operator with solid fabrication and construction skills who can see how to make attachments to carry loads, I'll take the latter. Almost invariably they end up over compensating and over-engineering and over-constructing the result. Of course, using both a NA and a good builder is great - I can guarantee you that a good designer relies on the builder to correct deficiencies. It's why as-built drawings are always developed for complex projects.

I'll stand down.

Peter

There are very few naval architects that have any experience designing paravane stabilizers. Jeff. Leishman designs them for the Nordhavns but he is the only NA I recall with experience. It would be prohibitively expensive to have a NA start from scratch and analyze all the forces. You would be basically lying for them to learn.

The paravane stabilizers used on almost every commercial fishing boat in Alaska (gill netters excepted) are made by the owners themselves or some local welders who have seat-of-the-pants experience with the construction. The word "design" would hardly be what they would call their work. And these fishermen, who are at sea 24-7, have met worse conditions than most of us, without any rig failures.

Dear people,

I take every argument that is posted here seriously and take out those things that I think, I can do something with that.
I understand that there are doubts about the design, and that is mutual for me.
That is why I find the discussions here very enriching and I hope that it results in a positive result.
I understand that doubts have arisen because the mast rests on the diesel tank.
But that's because people don't know how it's constructed.
I can assure you, that diesel tank will never fail!
This is not a standard ship, it is built to the standards of commercial shipping.
Meanwhile, the boat has sailed more than 12,000 hours and is still brand new.
Anyway, so far thank you everyone for the suport because everyone does it with good intentions.

Pascal.

The word, hand made has been mentioned here several times, now I want to share these pictures with you as a joke.
From jam jar to anchor light.



Pascal

Hello

Yesterday the boom mounted and with the necessary rigging.
Then we started testing.
It is amazing how much resistance the paravane generates.
Adjusting the line on the paravane also makes a huge difference.
At the end of the day, we can say that the system is in balance.
By setting the lines too correctly, the boom does not bend.
The boom can be placed horiznally or at 45 degrees depending on the conditions.
Putting the system into use is very easy, extending, pulling the paravane against the boom, booming out, and lowering the paravane.
The chance that the paravane will hit the boat is therefore very small.
Now that this test has been passed, the next step is to mount the boom on the wheelhouse roof.
And of course, the following step is testing is worse conditions, but the first impression is good.

Question, I have read that there are people who use a paravane in mild conditions and two in bad conditions, does anyone here on the forum have experience with that?










Pascal.

Nice work Pascall!

Where did you get the paravanes? I haven’t seen them in Europe.

Xlantic said:

Nice work Pascall!

Where did you get the paravanes? I haven’t seen them in Europe.

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I have not seen them in Europe either, they are self-made.
Greet

Pascal.

Of course! Having seen your work I suspected as much.

Could you tell us more about them? Your own design? Materials? dimensions?