Can anyone explain

[Mr Cassandra]

Can anyone explain , that when we were holed up in Naxos Marina in a bit of a blow . The boat next to us was a Najad42 .next to that was a Ben 45.1First.My boat is Sun Magic 44. Regatta. Every time a ferry came into port the boat would roll about .Mine the mast would about 1 1/2 mts each side of vertical. about the same with the Ben First. However the Najad rolled about 2 1/2 mts it was very noticible .all owners had a chat about it. I and the Ben 45 have a deep fin keel 2.5mts the owner of the Najad said his was 1.8 but longish! Anyway when we decided to leave both I and the Ben owner thoght it OK the Najad said he would leave it a little longer until the sea calmed down.Now from all the post that ive read most people think that the Najad the better sea kindly boat .But if it tosed about like this in a marina what the hell is it like in a big sea? Is it really the better boat or something that we belive ,but not true ?I am not talking about standard of finish . Cheers bob t

Bob T

 

[AndrewB]

Beam and stability.

Think of the difference between a plank weighted with lead along one edge, floating other edge up, and an unweighted plank floating on its flat side. The first will wobble with each ripple, but however hard it is pushed, it always bobs back. The flat plank is quite stable at first, but a big enough wave will eventually flip it right over.

That is the nature of the difference. Your yacht has 'form stability', i.e. it is beamy. That means it is quite stable to minor displacement, as there is plenty of volume in the sides of the yacht to push it back upright in moderate winds and flat water.

The down side is that Beneteaus and Jeanneaus are far less stable in bad conditions and open seas. The Najad relies instead on its heavy displacement and keel for stability. It may heel sooner, but after a certain point it will 'harden up' and be very resistant to further heeling, even as the wind strengthens. It will be able to make steady progress to windward more easily as the sea gets up. Moreover your yacht will capsize more easily in extreme conditions, and be more resistant to coming back upright.

There has been an excellent series on stability in recent issues of YM.

 

[Mr Cassandra]

Re: Beam and stability.

Thank s not quite the answer I wanted to hear though.If what you say is true , and I have no reason to dought you .As i know from experiance that my boat is still very stable in f8/f9 quite a regular occurance in Aegean.The word extream must be something worst than that.So . Turning the answer on its head ,what you are saying is ,is that Najadis are less sea kindly and stable, in wind that most people would expect to caught out in .So that for 99.9% of the time Bav ben and Jen are the better boats
For now I will rest my case.Cheers bob t

Bob T

 

[30boat]

Re: Beam and stability.

I don't think you got it quite right.Form stability will stop you from heeling when the heeling force is applied to the boat through the mast and rigging ,the resistance being proportional to the beam.However when it is a wave that is pushing the boat out of the vertical then it actually makes it worse because the beam acts as an arm resulting in a lot of leverage.Slimmer hulls are less prone to rolling due to wave action .The answer to your question must lie somewhere else.

 

[jimi]

Re: Beam and stability.

Without wishing to be too simplistic, is not stability only really relevant in breaking seas. So that it almost becomes irrelevant in the Med or even in the northern hemisphere unless one is caught in shoal water or in an exceptional weather system?
I of course am talking of boats with 120+ stability curves.

Jim

 

[Mr Cassandra]

If you could all give steve101 a bit of space .any chance of some answers here please . cheers bob t

Bob T

 

[kingfisher]

Resonance

Each boat has a diffirent wobble frequency. If that happens to coincide with the wave frequence, the boat will start to resonate with it.

So in an anchorage it could be that one boat is in synch with the waves and wallows more than the others.

Group of people on the pontoon: skipper is the one with the toolbox.
http://sirocco31.tripod.com

 

[kingfisher]

Resonance

Each boat has a different wobble frequency. If that happens to coincide with the wave frequence, the boat will start to resonate with it.

So in an anchorage it could be that one boat is in synch with the waves and wallows more than the others.

Group of people on the pontoon: skipper is the one with the toolbox.
http://sirocco31.tripod.com

 

[Skyva_2]

Could we have a little more information - were you moored alongside in a marina, moored to a buoy or at anchor? Were other boats alongside you or what?

I've rolled like crazy in an anchorage because of reflection of waves off the shore reinforcing the roll. Other boats not far away were OK.

Keith

 

[Twister_Ken]

Not beam, but waterline beam

It's not the overall beam that would count in damping out a static roll, but the waterline beam. I'd hazard a guess and say that the HR is much narrower at water level. This would allow her to roll more before dipping more turn of bilge into the water to counteract the roll. This hardly matters when sailing as there is some heel to increase waterline beam, but at rest it might be the reason.

Another factor might be distribution of ballast in the vertical plane. Ballast low down creates a greater pendulum effect which both magnifies the roll and keeps it going longer. Of course a low c of g is a positive benefit in the ultimate roll situation - a potential capsize.

One more thought - weight of the rig, especially high up weight like radar, radar reflectors, cutter rig, in mast furling, etc. Weight in the rig is like 'upsidedown ballast' and will also promote a roll and help keep it going.

 

[Mr Cassandra]

Hi we were moored stern to the pontoon all with anchor out . I was on the outside the Najad by my starboard side and the Ben next to the najad starboard side . Both I and the Ben owner were worried that the way the Najad was rolling ,that the rigging would clash together.as we were unable to move apart .My thinking is if it rolls about in these conditions, is it such a good boat for a avarage sea state? The owner of the Najad could see the same problem as us ,and to be honest was a little pissed off with it . It allright saying great boat for extream conditions but for the rest of the time Imho not very good cheers bob t

Bob T

 

[Skyva_2]

Should have realised you were stern to, normal in the Med!

The only thing I can add is that 'extreme' in my opinion refers more to wave action not wind strength, in which case Andrew Bs post is still relevant. If you are all reefed properly in a F8, heeling might well be the same.

Sea kindly also refers to ability to ride waves without slamming or pitching, and the narrower hull boats with long keels certainly have more ability to do this than beamier hulls, as they go through the waves rather than over them. But their form stability is initially less so heel more in a gust.

When moored other factors may take over, but what you saw is not what would be expected.

Keith

 

[ean_p]

mmmmm looks like your looking to boost your confidence factor in your boat here Bob........when you know the truth already......

 

[Mr Cassandra]

Sorry but I think that remark offside .I have sailed various types of yacht over the years . What I saw suprised me ,the owner of the Ben, and was a total supprise to the Najad owner And this was not on one occasion only ,if you have been to Naxos The ferries come in and out every 15 min we were there two days I and the Ben owner left , when the it was blowing 25- 30 kts to go to IOS the very experianced German left it for another 24hrs then meet up with us there .
I from these obsevations now dought that the Najad is a better boat for liveaboard use other than the quality of finish and also dought that this is worth the extra£100000 to own one. I think of emperors clothes .
With regardes confidence in ones boat I paid £100000 for theyacht 10 years ago she was £120000 new in all the years that we have owned her not once have I felt affraid that she could not cope with the conditions thrown at her .And I would not let I or my family sail in her if I though different.I have enough money to buy what I want and until I can find better she is what i want.The Aegean is not the Solant,You can have no wind for hours then 40kts for an hour, or a week ,then flat calm again .and in this enviroment she is one of the best.If you have used this forum you will know Billskip he has a Gibsea 126 ketch . When he has traveled with me he remarks how much better the Magic is over other boats he hase owned ,and he has sailed 50yrs
Cheers bob t

Bob T

 

[ean_p]

thats what I said Bob...your obviously very confident in the abilities of your boat already......don't think I.ve ever sailed in the Solent Bob so wouldn't really know what its conditions are......most of my sailing is in the North Sea.....and a rather pleasent place it tends to be....