N46 without Stabilizers

I'm a new member and had a question for those who may have had some experience with the Nordhavn 46. I'm interested to get some viewpoints on how the boat handles without stabilization (either the paravanes or fins). I have been told (as we look at these boats) that they can be uncomfortable due to the shape of the hull which is more like a large sailboat. I'm thinking about using the boat for conditions like the ICW, but will also be doing some offshore to the Caribbean/Newfoundland. Any observations would be appreciated.

In our ICW experience (Atlantic side of FL from Titusville to Miami), rarely would you want stabilizers. (The only time I've ever wondered about having ours on was when we got waked by a big sportfisher, but I don't think even stabilizers would have helped in that situation.)

Going to the Bahamas or elsewhere offshore, you'll want to pick your days, I'm guessing. If you've got much of a beam sea, you're going to roll, but it may not be uncomfortable if it's only 1-2 feet, or a little bigger with a nice long period. But 2-3 feet and a period less than 6 seconds, from either side, and I'm guessing you're going to be wishing for stabilizers.

We have a 52' trawler with stabilizers, and have gone to the Bahamas in it once so far. We used the stabilizers some of the time, not all of the time - but we had decent weather, too.

Hope that's somewhat helpful.

Greetings,
Welcome aboard. As Mr. BS noted, pick your days. Both the Gulf of St. Lawrence and the Gulf Stream can get downright snotty.

We have a N40 with active stabilizers. We don't use the stabilizers on the ICW. We leave them in the "centered" position. No problem. Did they build a N46 that doesn't have stabilizers?

Some of the N46 have paravanes and some have the fins, a few even have both! I'm looking at some boats with just the paravanes and since it would not make sense to deploy these unless heading off shore for a longer passage, I'm wondering if the boat would be uncomfortable for normal coastal cruising? I do however like the idea that the paravane set up allows for flopper stoppers at anchor. I would hate to buy a boat that was uncomfortable 80% of the time but good for the 20% when I take those longer trips. That said, I want to be be able to tackle those areas where stabilization would be necessary.

The only time I've ever wondered about having ours on was when we got waked by a big sportfisher, but I don't think even stabilizers would have helped in that situation.)

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Actually, they do. At least if they are Naiads, they should be on all the time.

+1 on Cal's comment. We activate ours 95% of the time we are underway. And they are very effective dealing with large wakes.

I would not recommend a boat used for extensive cruising that does not have them. Even coastal cruising can present many rough water conditions. Examples: Coastal Maine, Coastal New Jersey, Albemarle Sound, Chesapeake Bay to name a few open water passages typically transited by loopers and coastal cruisers.

Sure, many, many enjoy cruising without them. Not right or wrong, but stabilization sure is nice when needed. Like air conditioning....

Greetings,
The ONLY gripe I have about our Naiads is I forget to center them when maneuvering. Wander all OVER the place particularly if there is any current involved. I need a BIG sign!

W30 Without stabilizers

Works just fine 99+ percent of the time.

Stabilizers make a hell of a difference especially with other boats wakes. we use our active fins all the time , and being an older model we have the same issue about not centering them before we commence manouvering.........they should have a warning light when you go into neutral ???


if you can buy a vessel with them, then that to me is the answer!!!


cheers Chris D Liberty Australia

The newer Naiad's automatically centre when below 4kn or if in reverse. Sounds like it is a desirable feature! Like some others, I turn them on straight after starting the engines, and turn them off after I stop the engines. They are always on underway. Sure, in calm conditions they stay centred. That's fine. If there are unexpected wakes they deal with it.

I doubt that I would buy a vessel without them. And if I did, they would be added ASAP. Are they necessary. Nope. Do the crew and guests enjoy boating a lot more because they are there and working? Absolutely!

A Nordhavn 46 without stabilzers.... It makes no sense.
If you stay in calm water, why buy a Nordhavn? If you use it in rough water, why would you not get stabilizers?

Getting back to the OP, a good read on the subject (and many others) is the Nordhavn sponsored and Lieshman edited version of Beebe's "Voyaging Under Power".

AusCan said:

A Nordhavn 46 without stabilzers.... It makes no sense.
If you stay in calm water, why buy a Nordhavn? If you use it in rough water, why would you not get stabilizers?

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Logical thinking.

We have just paravanes and haven’t felt the need to add active stabilizers. In the ICW they aren’t needed. It takes less than 5 minutes to deploy them and all we need is 20’ of water and they are great at anchor. In 10 plus years and over 12000 miles with the paravanes deployed, our total maintance costs are probably less than $750.

Getting back to the OP's question, Looks like Larry M had a good response that paravanes can be perfectly fine. Also the OP asked about hull shape: agreed stabs seem to be more useful on full displacement hull shapes like NH. We have none on our AT 435, nor do i want or need them since our hull is semi-displacement and flattens out towards the stern so it doesn't "wallow" as much as a NH.
As for Paravanes vs stabs; seems like there would be less maintenance with paravanes, plus less hardware sticking out from the hull to catch on things when cruising the often shallow ICW... just some thoughts...

We have a N46 with active stabilization (Naiad's). Generally we run with them on but in calm conditions I will often just run with them centered or de-tuned. I will turn them on if I see a wake coming or other conditions that warrant it. They make a huge difference for wakes. In moderate to rough sea conditions the boat rolls a lot due to hull design.

I would not buy a N46 without stabilization. However, as was pointed out, paravanes work great so no worries for a boat duly equipped.

goboatnow said:

We have a N46 with active stabilization (Naiad's). Generally we run with them on but in calm conditions I will often just run with them centered or de-tuned. I will turn them on if I see a wake coming or other conditions that warrant it. They make a huge difference for wakes. In moderate to rough sea conditions the boat rolls a lot due to hull design.

I would not buy a N46 without stabilization. However, as was pointed out, paravanes work great so no worries for a boat duly equipped.

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GOBOATNOW speaks of true experience, the N46 has to have some form of stabilization to go offshore.. that efficient hull comes at the cost of rolling in a beam sea.. I have spent a lot of miles off the California and Mexican coasts on N46's and they do roll.. Don't be afraid of a paravane equipped boat, they work great and would be my choice over active stabilizers for the reliability and multiple uses.
Good luck on the hunt for a boat
HOLLYWOOD

RT Firefly said:

Greetings,
The ONLY gripe I have about our Naiads is I forget to center them when maneuvering. Wander all OVER the place particularly if there is any current involved. I need a BIG sign!

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I have KeyPower active fin stabilization from Vancouver Canada. They were recently acquired by Kobelt Manufacturing. My control unit has an input that will center the stabilizer (put them in PARK position) immediatly after the transmission shift lever is placed in neutral. that kind of prevents you from forgetting them on and going in reverse with the fins trying to correct! Ouch, not a good thing if you get some wave rolling you even a little...
maybe the NAIADs have such feature/input too?

For whatever reason, Nordhavns seem to be very rolly boats, at least judging from how much more they rock around in a slip than nearby boats do. I hvae been told that Norhavn explains this by saying that they have designed the boats to have a "resonant frequency" that exposes the boats to excessive rolling in calm conditions, while correspondingly diminishing the rolling in heavier seas. I am not sure that is even possible, but if true, it may be that use even in the ICW would benefit from stabilizers.

MYTraveler said:

For whatever reason, Nordhavns seem to be very rolly boats, at least judging from how much more they rock around in a slip than nearby boats do. I hvae been told that Norhavn explains this by saying that they have designed the boats to have a "resonant frequency" that exposes the boats to excessive rolling in calm conditions, while correspondingly diminishing the rolling in heavier seas. I am not sure that is even possible, but if true, it may be that use even in the ICW would benefit from stabilizers.

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OK! here goes my controversial posting that might shock some:


Simple hydrodynamics lesson: to be stable, floating object waterline need to stay parallel to the water.
With other words - rolly boat is trying to stay parallel to the water when even slightest wave passes underneath the boat. The rolly boat has more dynamic stability than the boat that do not roll. Described above is only one of the many factors that influences boat stability, so please let's not argue about it. Some might not agree, but this is the principle and if you don't believe me, please read your physics textbooks from high-school or many books by nautical engineers on boat stability.
While having rolly and snappy boat helps stability, it does not help the human comfort. The opposite, one feels quite bad being thrown around an quick rolling snappy boat.

The active fin stabilization systems usually use predictive algorithms to try to prevent the boat from starting to roll. Once the boat is rolling there is very little they can do for stopping the momentum. the best effect will be just slowing down the roll period to acceptable (for the humans on the boat) level.

Any respectable Active fin manufacturer will NOT claim that their system improves boat stability.... because it does NOT. It helps "poor" people inside feel better - and this is the real benefit from having active fin stabilization system.

And remember, almost any boat will be able to handle much more than it's occupants.

In conclusion: the easier the boat rolls the easier will be for stabilizer fins to return the boat in the desired horizontal position but not parallel to the water underneath.
cheers!

AusCan said:

....If you stay in calm water, why buy a Nordhavn?....

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Because they are really really cool!!

SeaMaster101 said:

In conclusion: the easier the boat rolls the easier will be for stabilizer fins to return the boat in the desired horizontal position but not parallel to the water underneath.
cheers!

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So, rolly boats roll more in relatively calm conditions (like ICW) and would therefore benefit more from stabilization in those conditions but the stabilizers wouldn't have to work too hard?

MYTraveler said:

So, rolly boats roll more in relatively calm conditions (like ICW) and would therefore benefit more from stabilization in those conditions but the stabilizers wouldn't have to work too hard?

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Not really! That's the beauty of the of the active fin systems. They work only when they have to. If it takes very little to roll the boat, it takes very little to prevent the roll. Usually the response of an active system is controlled by GAIN setting and the respond will be proportional to the trigger. All Stabilization systems that I know of have something called proportional–integral–derivative controller PID. More info here: https://en.wikipedia.org/wiki/PID_controller. The autopilots employ the same principal.

So the short answer is No, the stabilization does not work any harder as as I mentioned before. It tries to predict the roll and stop it before it occurs. The deflection of the fins will be dependent on few internal sensors and the settings of the parameters for the PID control

SeaMaster101 said:

Not really! That's the beauty of the of the active fin systems. They work only when they have to. If it takes very little to roll the boat, it takes very little to prevent the roll. Usually the response of an active system is controlled by GAIN setting and the respond will be proportional to the trigger. All Stabilization systems that I know of have something called proportional–integral–derivative controller PID. More info here: https://en.wikipedia.org/wiki/PID_controller. The autopilots employ the same principal.

So the short answer is No, the stabilization does not work any harder as as I mentioned before. It tries to predict the roll and stop it before it occurs. The deflection of the fins will be dependent on few internal sensors and the settings of the parameters for the PID control

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I think you misread my question. I suspected that the stabilizer would NOT have to work as hard on a rolly boat (which you are now confirming), and I asked whether a rolly boat would not be more in need of stabilization in light condtions such as ICW, which based on your prior comments it seems it would.

I also have a rolly, round bilge hull that has great stability but in certain conditions gets really rocking and rolling. Messy inland waves aren’t a problem as they usually do not have a regular frequency.

The rolling is at its worst when there is a steady swell with a frequency that matches the boat’s natural roll frequency.
It’s a bit like pushing someone one a swing. If you push at random intervals you won’t gain a lot of momentum. If your pushing is in time with the swings frequency, a lot of movement is generated.