[PCP]

……
Paulo, are you still working on the answer to the static curve question? (chuckle)

Oh Paulo , how are you doing with the curves ??
I have a few more names by the way :…….
Now jeff, don't get in a puff, Paulo and you are all big guys now.

Paulo ,
It has now become apparent to me that you do not know how to interpret the static curves, I am concluding you have it totally backwards.
re: post #28, to allow me to understand your thinking , could you evaluate the differences between the Hanse 430 and the 36 foot Bavaria? just those two. OK?
kev

Not only are you not technical and obviously can't properly interpret a static curve, you attempt to school me and quite frankly
you sound like you have not gotten beyond a sales brochure.

Well, I would not have the trouble to analyze a stability curve for you (after all I am still waiting for the Ericsson 46 stability curve that you have said you were going to post, three weeks ago), but since I have done that already more than two years ago, and it can be interesting information to the forum, I will post it.

Of course, you have to remember that I am polite and I was on that forum (their forum) looking for information about the Hanse 430. The last thing I wanted was to be rude, or to say bad things about their boats, so I was "gentle" in a way I addressed the Hanse 430 stability. I have to say that I have also some doubts about that stability curve, but that is another story.

"I am not saying that the boat has not a good potential for speed (much more than the Oceanis) I was saying only that the Hanse 430 has an unusually big inverted stability and I am not saying that based on almost meaningless data but on the stability curves provided by the manufacturers, the ones that are used for certifying the boat.

Those curves are pretty close to reality and if there is some difference is for worse, because they don't take into account the weight of the furling sails and radar.

The ones I am posting are RM curves (moments), they are in T/m and all boats are in maximum charge condition, except the Bavaria 36 that is on minimum sailing charge condition.

I have made this graphic for making a personal evaluation of the Hanse 430 stability compared with some of the boats I am considering. I didn't consider the Oceanis 43 because I prefer the other two and because it would give me more work, but the Oceanis 43 stability curve is not very different than the one from the Jeanneau 42.

I have considered the RM 1200, the Jeanneau 42 and the Hanse 430. The Bavaria 36 serves as a measure in what regards inverted stability.

The overall best curve is the one from RM 1200. It is only a 40ft and the lighter of the three boats (7,8T against the Hanse's 10,4T) but it manages to have only less 4% of the Hanse's positive stability and 93% less negative stability. The negative stability of the Jeanneau is similar to the RM's.

The Jeanneau and the RM have not a particularly good inverted stability (they are too stable for my taste), I would say they are slightly below average, they cannot compare with the inverted stability of a Malo 43, a Finngulf 41 , a Wauquiez 45 or a J 133. Comparing with the data I have seen about the issue, I would say that while the last ones would right themselves up (giving a sea condition capable of rolling them) in about 30 s the Jeanneau and RM would need an average time between 1 and three minutes.

For the Hanse 430…the energy needed to overcome that huge inverted stability is bigger than the one needed to invert the Bavaria 36 (1,2 X). The Bavaria 36 is a class A boat and that means that it can stand 7m waves. There are several that circumnavigated and several that have been caught in storms without being rolled.

Of course, for inverting the Hanse 430 (from a 0º heel position) you need two times more energy than the one needed to roll the Bavaria 36, but that is not true if the boat suffers a broach and comes to 90º of heel.

If both boats are at 90º of heel you need more energy to invert the Bavaria, comparing with the one needed to invert the Hanse. That's why I was saying that you should take a lot of care if you decide to carry a lot of sail in bad weather (racing).

I could have said nothing. I have already taken away my doubts but I believe that sailors should know how their boats behave even on those situations that almost never happen. If you know your boat you know how to act, even in extreme conditions…and after all the Hanse 430 has also a big positive stability…just keep it upright if there are waves."

myHanse - Hanse Yachts Owners Forum: Polar diagram for 430 ?

Regards

Paulo

 

[PCP]

Paulo,....

You are constantly confused because you don't read thoroughly.
I left a trap and you failed. I said 2/10 of 8 kts was 2 ..... And it is not
It is 1.6 kts and that passed right over your head.

Sometimes you are confusing, but this time you were clear. You were saying that at 17º degrees of heel your boat would do 7.8K and with more sail, heeled at 30º you would do 8k. A difference of 0.2k for 13º of heel.

..at 15 to 17 degrees heel too. I can do it with whatever sail I choose to keep the boat at that heel. I get within 2/10 of my target speeds.

When I say I come "within" 2/10 that means if my target says I should be
making 8 knots with 16 kts true wind at 50 degrees, getting "within" 2/10
means I will be making 7.8kts

I have said:

But what you have said and are still saying doesn't make sense.

In a boat like yours, that has a soft stability curve, the difference between 20º of heel and 30/35º roughly corresponds to 1/3 of the righting moment that is used for sailing. That is, about 1/3 of the boat "sailing power".

Pretending that 1/3 of the power will only bring the boat from 7.8 to 8.0k is absurd. You know, I sail, members of this forum are sailors, we have boats and we know that on most boats (boats designed to offer the best performance at 30º of heel) a difference of 10º of heel (and the sail power needed to accomplish that) will translate in much more than 0.2k, as you say.

In my old boat, that would be translated in about 1.5K. Of course, we are talking about sailing upwind.

Paulo

So, no you are saying that I am right, that the difference in speed between 17º of heel and 30º (upwind) is 1.6k (I was saying 1.5K while you were saying 0.2K) and the way you say it is : "I left a trap and you failed"

You are an interesting guy .

Regards

Paulo

 

[kevlarpirate]

Again you persist with numbers with no backing in addition to your assumptions.

my polar diagrams or any for that matter are NOT repeat NOT based on any
set heel angle. Again you don't study these things.

My highest heel for any one target is 28deg and that is the 20kt curve and the BAW is somewhere around 120 deg if I remember right .
The earlier target speed 8 kt at 50 deg in 16kts. (UPWIND) and that heel is around 24 or so .. You are TOTALLY WRONG about the 1.6 kt
when I say 2/10 I have data to back it

Please quit with the assumptions, Another one you made is the energy to invert back to upright , Where on God's earth do you find these numbers?
you mention 1,2 X Look more closely at the curve , You are way off!

then you mention a factor of 2 ??? where did that come from????

integrating under the curve I see a factor of between 3 and 4

 

[kevlarpirate]

you may also be informed I have 12 headsails to choose from on my 41
and i have 6 on my E-46...so I generate a lot of data over the years.


I have probably used up another 12 over the years.

 

[tdw]

The acerbic nature of this thread is becoming quite tedious.

Keep it civil.

Threads can quite easily disappear you know....and you wouldn't want to have that on your conscience now, would you ?

 

[kevlarpirate]

If Paulo loves this boat so much , then why doesn't he own one
or any other which meets his needs. Then he can tell us about it instead of dreaming how the boat will behave.

I listen to people who take data and can talk technical
this conversation is vacuous. Time to end here

 

[Iveywing]

Hi,

I am making a short list of blue water boats (for a potential purchase and sabbatical) by looking at their ratios, and one of the criteria my girlfriend and I are trying to understand is the comfort ratio.

While I understand how it is calculated, and what is the overall meaning, I have no clue (due to being an inexperienced sailor, still taking sailing classes) what 5 to 10 points difference really make once blue water sailing.

Case in point (from online database):

• Tayana 37 - CR: 43.8 -> Reference point (RP)
• Pacific Seacraft 37 - CR: 38.0 -> -5.8 of RP
• Cabo Rico 36 - CR: 35.6 -> -8.2 of RP
• Shannon 37 - CR:33.5 -> -10.3 of RP

My question isn't which boat is better, I am not there yet. What I'd like to understand is whether the differences between these boats, in term of motion comfort, can truly be perceived at sea? Is a Shannon 37 really less comfortable than a Tayana 37? Tayana 37 vs. PS 37? PS 37 vs. CR 36? etc... or am I paying too close attention to what is just a number?

None of the boats I am considering seems to be apart of more than 10-12 points on the comfort ratio. Should I be happy their comfort are in the 30-40 range and move on to care about other numbers / other issues?

Thank you for your help,

Cheers
Philippe

FYI. Your delta between the Pacific Seacraft and the RP Tayana is actually -6.8 vs. -5.8. Moving on, there is more than just the CR to consider because it's also a question of how and where the weight is distributed to avoid hobby horsing. For example the 2018 Boreal 47 centralized it's fluid tanks over the keel area and the two water tanks either side of the keel stepped mast without restricted access to keel bolts, etc.. The windless was positioned aft of the bow and just ahead of the mast so that the chain can be stowed above the keel travelling down adjacent to the mast column without being seen in the cabin and keeping the weight of the chain out of forward chain locker. As such, all of the weight is low and centralized and makes for a very comfortable sea going vessel. This is much more important to consider than a +/- 5 or 10 point delta above or below a reference vessel, respecting your market is used vessels.

 

[Jeff_H]

As I posted back in 2010 when this tread was active, the Capsize Screen Formula contains none of the main factors which controls the likelihood of a capsize, and the Motion Comfort Ratio provides none of the critical factors which control motion comfort.
The current science suggests that the primary factors are static and heeled weight and buoyancy distribution, waterline length, waterline length relative to length on deck, damping, and waterline beam (rather than beam on deck).

These formulas are so grossly inaccurate, as to be dangerously misleading. One example of why this is true is that these formulas have the impact of beam backwards. The current understanding is that beamier boats are less likely to capsize while the capsize screen sees beam as a negative.

Jeff

 

[Iveywing]

Thank you Jeff. Agreed and why I am still searching for the perfect beamy compromise. Regards, Jon

 

[MoonBeamEstate]

When someone is searching for the "perfect" solution I always think about this General Patton quote. Not much in our world it perfect. I sail an imperfect boat. I wonder if the OP from 10 years ago ever found his perfect boat. LOL
"A good plan violently executed now is better than a perfect plan executed at some indefinite time in the future."