Nordig Tug 37 stability

Do you think in some known Nordig tugs 37/39 GZ-curves and others stability the facts about this boat.

I would like to know how much is too much for this type of boat?

I have found it to be very sea keaping rough weather, but it would be nice to know how much it takes.

Boat is CE-certifications B Which means max 18 bofor wind and The average value of waves 4 meters(13feet) bigest wave can be 8 meters(26 feet)

Here's a little info about the process for getting the CE rating: http://www.glantoa.net/nordic_tugs_stability.pdf

Perhaps the factory can supply more complete information? Have you contacted them?

Two things:

One, go to Nordic Tug directly for the stability data you are requesting. Remembering of course that bad weather avoidance is a good idea.

Second, that heavy dinghy does not help stability. At least park the outboard lower in the vessel.

Retriever said:

Here's a little info about the process for getting the CE rating: http://www.glantoa.net/nordic_tugs_stability.pdf

Perhaps the factory can supply more complete information? Have you contacted them?

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Be aware that no one checks this stuff, the manufacturer does self certification.
After about 4000 surveys and 300 deliveries of powerboats I lean towards the skeptical side regarding advertising bluster and builder spec's.

sunchaser said:

Two things:

One, go to Nordic Tug directly for the stability data you are requesting. Remembering of course that bad weather avoidance is a good idea.

Second, that heavy dinghy does not help stability. At least park the outboard lower in the vessel.

Click to expand...

Maybe .... sometimes weight added high will slow the roll but this is something to be discussed with an NA.

The Nordic Tug 37 will have positive stability up to at least 55-60 degrees heel. That has proven more than adequate for almost all normal pleasure use. Something has to go very wrong (interior flooding or bar crossing for instance) to get this type of boat upside down.

Part of the reason for the Cat B rating rather than Cat A is downflooding angle. The bottom edge of the back door and engine room vents in the topsides are the culprits. Move those engine room vents up and increase doorsill height, and you could come closer to getting an Cat A (Open Ocean) rating. There are other factors, wind heeling and angle of ultimate righting arm are big ones that require precise data which I don't have.

Thanks for all the replies, the link stabilty was interesting, but a little circular text. I contact the manufacturer if you would give the exact facts, I have other matters to them.


Good attention was Themes Changes the owner of the boat, such as a dinky on the roof. I understand the change in the stability of this effect, but its effect may decrease if there is an original Stability information.


Of course this is only theoretical knowledge in terms of stability and the best thing to do to be away from the sea, when there is bad weather. The wave height is not the only factor, the waveform period and direction and also represent a lot. Here, in the Baltic Sea wave is almost always quite sharp and the wave period in relation to the height of a short, in addition to the wave direction is often.


I think these ship stabili information would be available to everyone all of the boats when we're buying a new boat. They could really compare boats and forget about the beautiful pitches and image manipulation features of the vessel at sea.


If something of interest, or is not familiar with the ship stabili things, in this simplified case. link pages, please. Thanks s/y Troldand
From Scandinavian Waters to the Med - Stability

I guess buoyancy might be a little compromised due to the large amount of fresh water influence in the Baltic. Less of an issue in small boats I imagine. Surely not enough to worry about.

What's going on here?

You're right, the density of water affected by the heat and salinity. At the Baltic Sea salinity varies slightly see the picture and is actually much less salt than the ocean. ships swam deeper here if upouma is constant.

What is it you'd do with that information once the builder supplied it? It would be a standard boat or specific one, checked sometime or never actually checked and wouldn't tell you about another specific boat. It might be useful if you had the same data for many boats and could compare, but there are so many other factors. For instance one boat could take a very linear curve to instability and another might just reach a point it goes from fine to over without any graduation. How much fuel and water, even which tanks. How much loose cargo, including people. Then more likely to lead to disaster is the structure including windows, the likelihood of taking water on. Stability at what speed, what size and type waves. Every boat has many factors related to it's stability. Ultimately you hope to never find out the limit. Probably a more important question is what are the maximum conditions you'd feel comfortable boating in with one and the maximum that you would feel safe in.

Just curious as to how you would think you could use the information.

CE-sertification it is a strict law in Europe and the manufacturer is responsible for ensuring legally.


I therefore trust that the ship will take forse 8 waves of on average 13 feet up to 26 feet, all full tanks, max 10 people on board and baggage 1360kg.


subsequently moving the start of the stability over such accessories course change but can be calculated mathematically how, for example at the height affects the weight, for example, GZ curve.


The CE mark boat rules are quite simple and always the same, it was a boat or a sailboat or hinged for another vessel, the comparison is easy to rough level. CE A, B, C or D immediately tells us something vessel where it can move and what kind of weather. If the interest and the link to the CE mark, the boats and what they contain.


http://www.google.fi/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwiU3KSnlOfQAhUEWywKHbRlC_gQFggXMAA&url=http%3A%2F%2Fwww.europarl.europa.eu%2FRegData%2Fetudes%2Fnote%2Fjoin%2F2012%2F475122%2FIPOL-IMCO_NT(2012)475122_EN.pdf&usg=AFQjCNHFJgoN4A-8aXt5kKCuwjqgSpUixQ&bvm=bv.141320020,d.bGg

Having worked in and around EU laws and regs, it would appear they have not yet figured out how to legislate common sense.

Quite simply, your NT 37 is a coastal cruiser. Do not take it out in big waves and strong winds. Especially 8 meter seas and 50 knots!

78puget-trawler said:

I guess buoyancy might be a little compromised due to the large amount of fresh water influence in the Baltic. Less of an issue in small boats I imagine. Surely not enough to worry about.

Click to expand...

Plimsomin sign on the side of the ship, mark well the importance of salinity and temperatures buoyancy.

https://en.wikipedia.org/wiki/Waterline

sunchaser said:

Having worked in and around EU laws and regs, it would appear they have not yet figured out how to legislate common sense.

Quite simply, your NT 37 is a coastal cruiser. Do not take it out in big waves and strong winds. Especially 8 meter seas and 50 knots!

Click to expand...

Then I really hope to be somewhere else, as the saying mass at sea, whether the CE mark its Place.

sunchaser said:

Having worked in and around EU laws and regs, it would appear they have not yet figured out how to legislate common sense.

Quite simply, your NT 37 is a coastal cruiser. Do not take it out in big waves and strong winds. Especially 8 meter seas and 50 knots!

Click to expand...

These are the same standards that permit brass seacocks/throughulls with mis-matched threads and side loading propane lockers (without overboard drains) that open over non-ignition protected engine room hatches.

boatpoker said:

These are the same standards that permit brass seacocks/throughulls with mis-matched threads and side loading propane lockers (without overboard drains) that open over non-ignition protected engine room hatches.

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Whot is this boat model and what ages, CE-certified Venessa gas cabinet was not aired? below what you need to be!

5.5 Gas supply equipment

Gas systems for domestic use shall be of the vapor-withdrawal type and shall be designed and installed in such a way as to avoid leaks and the risk of explosion and be capable of being tested for leaks. Materials and equipment must be suitable for the specific gas used and designed to withstand the marine environment, the stresses and exposures.

Each unit is equipped with a working flame failure device on all burners. In each gas device must have separate gas distribution system, and each unit is equipped with a separate closing device. Adequate ventilation must be ensured for leaks and products of combustion.

All craft with a permanently installed gas system shall be fitted with an enclosure to contain all gas cylinders. Enclosure shall be separated from the living quarters, so that there is only access to the outside, and that it is ventilated to the outside so that any escaping gas drains overboard. Any permanent gas system shall be tested after installation.

Interesting that the max load converts to only about 3,000 lbs. I dont think it hard to add that much weight in cruising gear and supplies.

North Baltic sea said:

CE-sertification it is a strict law in Europe and the manufacturer is responsible for ensuring legally.


I therefore trust that the ship will take forse 8 waves of on average 13 feet up to 26 feet, all full tanks, max 10 people on board and baggage 1360kg.


subsequently moving the start of the stability over such accessories course change but can be calculated mathematically how, for example at the height affects the weight, for example, GZ curve.


The CE mark boat rules are quite simple and always the same, it was a boat or a sailboat or hinged for another vessel, the comparison is easy to rough level. CE A, B, C or D immediately tells us something vessel where it can move and what kind of weather. If the interest and the link to the CE mark, the boats and what they contain.

Click to expand...

You're using and abusing the entire concept of CE as if it's some guarantee of safety in those conditions. It isn't and the safety in the conditions you describe is very dependent on the captain and crew and on the maintenance of the boat.

To me, CE B is a coastal cruiser. Now that is plain and simple in my mind. Will the boat perhaps survive conditions up to 40 knot winds and 13' seas? Yes, but that is worse case and that is thinking of heading out in 20 knot winds and 4 foot seas and things turn ugly on the way, you fight for your life against the seas, you survive, the boat holds up with only a few thousand dollars damage, your guests never get on a boat again after the experience.

I think of CE A as a minimum standard for ocean crossing and cruising. That's not saying under ideal conditions I wouldn't take a CE B boat to the Bahamas or even to the Caribbean, but it would have to be ideal conditions. The things Tad pointed out are minor but could also sink you.

The terminology used for the CE's says a lot. CE B is offshore. That is outside runs and short crossings. CE A is Ocean, longer runs and crossings. CE C is Inshore.

CE B fits the intended use of the Nordic Tug in question well. It's not designed or intended as an ocean passagemaker.

I still am missing your entire point. What is it you're trying to know or prove or find out? Or what are you trying to convince yourself of?

first of all I apologize for the bad language skills and potential misunderstanding.


here is one example of where you can take advantage of the Stability facts. Thanks to a friend of the forum "retriever" by sending the link. Knowledge is unfortunately NT32, the severity of the leak angle of the ship is fully loaded with 40 ° and 45 ° less heavily laden. I have always been equipped with all the boats, the tilt angle indicator, due to previous history of sailing. The angle information can take advantage of changing course if the ship begins to tilt in the waves close up critical angles °. Often, how the ship will not tilt angles critical views even close, but sometimes it is possible. I also have life jackets, I have not ever had to them, if you understand, yet they are reserved for all passengers


http://www.glantoa.net/nordic_tugs_stability.pdf
The results were better than we expected. The boats were indeed well designed. We were nervous that we would have to modify or move scuppers, drains, air intakes or any number of things. The only thing we were required to do was to increase the height of the engine air intake “snorkel” or baffle that extends upward to prevent sea water from entering through the opening. We had to increase its height by ¾” and angle it inboard ¾” (see photos above). The reason for this was the down-flooding point was just barely too low when the boat is heeled over at the maximum calculated angle. That angle is slightly different on each boat but the 32, for example, has a critical down-flooding point of 45.5 degrees when light and 40 degrees when loaded. Aside from passing category “B” and


it would have been good if you had looked at my mail with a link to an earlier regarding CE, as you understand, we think that for the most part as well.


I dot go never Ocean, The Baltic Sea is just "offshore" term, at worst, CE. The largest wave has been average of 8.2 meters of 27 feet and a single wave of 14 meters 46.6 feet. Most waves are 3-6 feet and fortunately the archipelago only 0-4 feet.


the diagram you can see B / A category boat to the minimum angle which it must withstand capsize. This tells me roughly, that the boat will take more than I or the minimum 95 °


I do not see that such factual information is at least no disadvantage?

North Baltic sea said:

I do not see that such factual information is at least no disadvantage?

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Perhaps not, but I still don't grasp what you would use more precise information for. Are you intending to go take a boat to it's very limits? Might even be a disadvantage if one made an assumption based on stability tests at the time of build and then were loaded much differently.

You know that an A likely can handle more than a B and would be more comfortable in rough seas. We have a classed boat with all the stability testing and charts, so we know it's built to a certain standard, but beyond that we don't use the exact information. We don't tilt to the maximum it will handle just because we can. We aim for the least we can achieve.

We're not going to try to cross an ocean in a CE-B but never seen one with the range anyway, and the boat likely would be able to take far more than the crew could. The weakest points in ocean travel of pleasure boats are not the stability. It's a lot of other construction factors that could doom one first. Windows, engine room vents, hull fittings, shafts, propulsion, fuel.

Back to your Nordic Tug. It has many areas problems would surface before stability would be an issue. You say you found it to be very good in rough weather. How rough? I would not consider it a boat for rough seas. It's CE category doesn't indicate it is. Now, is it fine for what it's owners will put it in? Yes. 6-8', even 10' it can handle fine but it would be miserable and I don't know anyone who would take it into 10' wind waves intentionally. It's a great boat. It's not a passage maker or ocean crossing boat. Tad pointed out the issues that would surface long before stability.

Very few ocean tragedies or sinkings have anything to do with stability. El Faro didn't go down because of instability. It went down because of lack of propulsion and taking on water. Now, Baden had a stability problem, but it never made it off the ramp.

You don't want to find out the stability limits of a Nordic Tug. Fact is, you won't ever find that out, because some other serious issue would surface before stability would. Stability and seaworthiness are not synonymous. It's just one factor.

Now the only available stability numbers would be from the factory. But they would only be accurate for the tested boat or designed boat under those conditions, not necessarily for your boat or any other actually on the water.

http://www.dma.dk/Policy/EUStrategy... Fishermen's Occupational Health Services.pdf

https://www.shipownersclub.com/media/web-stability-booklet.pdf

https://www.uscg.mil/hq/cgcvc/cvc3/references/Stability_Reference_Guide.pdf

http://www.rina.org.uk/hres/1996-3 Herd RJ - Simplified Stability Data.pdf

Here is a bit of light reading to get you started on the subject. The last link is a 50 page simplified version for smaller boats from RINA

A stability book can be created for your specific vessel by any competent naval architect. Search the subject on this forum and look specifically for any posts by a member named Tad Roberts. He has posted some extremely well written easy to follow posts that can get the very basic information to calculate the entry level info most recreational boaters may desire.

Here are a couple tidbits emailed to me....

A USCG publication....


NAVIGATION AND VESSEL INSPECTION CIRCULAR NO. 4-82

A lack of knowledge of stability problems and damage control procedures may be another
cause. Capsizings had the highest fatality rate of all accident categories, 45% of the
capsizings resulted in a death. A better understanding of vessel stability might have
prevented some of the accidents, especially if the vessel capsized because of improper
loading or topside icing.

Stability is a moving target...no pun intended...but ultimately the skipper has to decide how to alter the stability BEFORE the concept is really needed. Or decide not to enter conditions that may exist that would exceed the vessels abilities including but not limited to stability.


The Australian Naval Architect From the Division President

Editorial

In this issue I want to talk about recreational craft safety. A survey conducted for the National Marine Safety Committee (NMSC) a couple of years ago showed that roughly 90% of recreational-craft users wanted recreational craft built to some kind of standard. Roughly the same percentage also thought that they were in fact built to some kind of standard. This is interesting, particularly as there is no obligation on
the builders of recreational craft to meet any kind of standard. AS1799, Small Pleasure Boats Code, provides a standard for the design and construction of recreational craft up to 15 metres in length but it is not mandatory and it appears that any compliance with the Code in many cases is accidental rather than intentional. In my view, this is an unsatisfactory state of affairs. Commercial craft must meet strictly defined requirements
for their design and construction, particularly in the areas of stability, subdivision, damaged stability and hull construction. Similar-sized pleasure craft on the other hand are not obliged to meet any specific design requirements. This implies that the lives of recreational craft users and passengers are worth less than those of commercial craft passengers and crew. The ultimate demonstration of the inadequacies of the present state of affairs must surely be the case quoted to me of a builder who is marketing effectively the same vessel as both a commercial and recreational vessel. The major difference between the two is that the commercial craft is fitted with ballast while the recreational craft is not!

I won't even begin to touch on the losses of merchant ships due to stability problems. The Koreans have a great deal of recent experience with one of these "very few" events that took the lives of hundreds of people Sewol, Namyoung,Seahoe ... the list of stability related sinkings and deaths is nearly unbelievable. I disgusts me that someone like B would post such garbage to the people who need valid information most..

BandB said:

Perhaps not, but I still don't grasp what you would use more precise information for. Are you intending to go take a boat to it's very limits? Might even be a disadvantage if one made an assumption based on stability tests at the time of build and then were loaded much differently.

You know that an A likely can handle more than a B and would be more comfortable in rough seas. We have a classed boat with all the stability testing and charts, so we know it's built to a certain standard, but beyond that we don't use the exact information. We don't tilt to the maximum it will handle just because we can. We aim for the least we can achieve.

We're not going to try to cross an ocean in a CE-B but never seen one with the range anyway, and the boat likely would be able to take far more than the crew could. The weakest points in ocean travel of pleasure boats are not the stability. It's a lot of other construction factors that could doom one first. Windows, engine room vents, hull fittings, shafts, propulsion, fuel.

Back to your Nordic Tug. It has many areas problems would surface before stability would be an issue. You say you found it to be very good in rough weather. How rough? I would not consider it a boat for rough seas. It's CE category doesn't indicate it is. Now, is it fine for what it's owners will put it in? Yes. 6-8', even 10' it can handle fine but it would be miserable and I don't know anyone who would take it into 10' wind waves intentionally. It's a great boat. It's not a passage maker or ocean crossing boat. Tad pointed out the issues that would surface long before stability.

Very few ocean tragedies or sinkings have anything to do with stability. El Faro didn't go down because of instability. It went down because of lack of propulsion and taking on water. Now, Baden had a stability problem, but it never made it off the ramp.

You don't want to find out the stability limits of a Nordic Tug. Fact is, you won't ever find that out, because some other serious issue would surface before stability would. Stability and seaworthiness are not synonymous. It's just one factor.

Now the only available stability numbers would be from the factory. But they would only be accurate for the tested boat or designed boat under those conditions, not necessarily for your boat or any other actually on the water.

Click to expand...

I ask you to take a look at this link point with 4 pieces of the same weight and length of various shapes can be found in boat hulls A, B, C, D. below GZ-curves for these boats. Explore the behavior of various boats Curves, for me, this explains the behavior of the ship's lateral swell all how the vessel would behave and what they can expect before it's too late liiana, to sink or fall over.


Understanding monohull sailboat stability curves | M.B. Marsh Marine Design



an example of how quickly and unexpectedly severity will be lost

CPseudonym said:

http://www.dma.dk/Policy/EUStrategy... Fishermen's Occupational Health Services.pdf

https://www.shipownersclub.com/media/web-stability-booklet.pdf

https://www.uscg.mil/hq/cgcvc/cvc3/references/Stability_Reference_Guide.pdf

http://www.rina.org.uk/hres/1996-3 Herd RJ - Simplified Stability Data.pdf

Here is a bit of light reading to get you started on the subject. The last link is a 50 page simplified version for smaller boats from RINA

A stability book can be created for your specific vessel by any competent naval architect. Search the subject on this forum and look specifically for any posts by a member named Tad Roberts. He has posted some extremely well written easy to follow posts that can get the very basic information to calculate the entry level info most recreational boaters may desire.

Click to expand...

Thank you or answers and links, A lot of lessons to be learned from each!

You appear to know boats well, and do surveys but I am confused by this statement. I have 0 training in naval architecture, but I would think any extra weight added to an upper area of a boat like a dinghy and outboard will change the boats meta center, and have an adverse affect.

boatpoker said:

Maybe .... sometimes weight added high will slow the roll but this is something to be discussed with an NA.

Click to expand...

Fletcher500 said:

You appear to know boats well, and do surveys but I am confused by this statement. I have 0 training in naval architecture, but I would think any extra weight added to an upper area of a boat like a dinghy and outboard will change the boats meta center, and have an adverse affect.

Click to expand...

He said that weight up high will slow the roll. The slower roll may impact comfort in a positive way at the cost of a reduction in the angle of no return where a boat rolls over.
A great example of this is a sailboat. When a sailboat looses a rig (say in a storm?) people who are aboard speak of the awful motion that results. The weight of the rig up high slows the rocking/rolling motion way down.
Am I making this any clearer?
I tried...
Bruce

An over ballasted boat may roll so quickly from port to starboard and back again that it can throw crew around inside the vessel (i've been on such a boat). Weight added high can slow that roll period but like everything else it's a compromise .... to get something, you give something. You may gain some initial stability but give up some ultimate stability.
It's not something I would suggest without an NA involved.

BB

F500 raises the meta center question -- no pun intended.

Don't you think the possible initial stability benefits of added weight up top to a furled and ballasted sail boat is a bit different than an NT? CPs nice attachments in Post 22 discusses the weight placement advisements of the Danish authorities and USCG for MVs. Of note are details for stability and dynamometer tests. Interesting stuff.

But, since the NT is a wonderful coastal cruiser, the dinghy up top with a big outboard should hardly be an issue for the prudent fair weather skipper. Having sailed out of Helsinki and heard from the skipper about putting weight from up top lower into the cabin to lower the CG during a big blow, those waters can turn very unfriendly to coastal cruisers.

I haven't read every word here but an interesting comparison could be made ....

The AT and NT are very similar both being "tugs" but they differ greatly in their proportions. The length to beam ratios would suggest that the AT has considerably more stability .. at least from looking at them. I haven't looked at the numbers. It would be interesting to know if how they look is not how they are. Most everybody that looks at the NT or the AT brobably does a lot of comparing the two. Has anyone compared the stability numbers of thesen boats and ... how do they compare?