Desirable and Undesirable Characteristics of Offshore Yachts

[estarzinger]

Then they were wrong.

Hove to is a very specific thing, not an opinion.

Even among American usage, that is a SUPER narrow definition -  how a sloop rig will often do it but for instance is not how ketches commonly heave-to.  

And you may (or may not) realize that the Brits do in fact define some terms differently than American English and neither is 'wrong' per say.

I would think a more 'complete and correct' definition would be something like 'balancing the sails, and rudder in the combination which most stably and completely stops (or nearly stops) the boat's forward motion with its bow pointed up into the waves at roughly the angle used in close reaching'

 

[Elegua]

The full keel aficionados boast about how they can hold a course like on rails. I call that "doesn't turn well." The displacement aficionados boast about calm motion in rough seas. I call that "not moving." They wax romantically about restful tradewind cruising. I say "boredom."

Put down the beer El Borracho. No one is saying we all have to sail Westsail 32s. 

Cripes. This place is getting like Cruisers Forum. 

 

[Zonker]

Generally speaking, designers are a lot more clever than rule-writers.

There are more of them. 100's of designers will find the loopholes that <10 rule-writers came up with.

Hove to is a very specific thing, not an opinion.

Our 40' cat would heave to quite well. It did have a tendency to rocket forward until you got it balanced.

It would also lie ahull quite happily in moderate seas like a big raft. Useful for when we broke a spin halyard and shrimped the whole sail. 

Did you like it? Hate it?

Read it a LONG time ago. It is dated in many ways about what a desirable offshore boat is. I'd be super happy in a Pogo and not so pleased in a Bermuda 40. The motion of the Pogo upwind wouldn't be as nice, but I'd get to my destination much faster if it was off the wind or a reaching course.

Jud - read Steve Dashew's books that are now generously free. I think the weather books is very valuable, especially for those in the mid latitudes.

https://setsail.com/free-books/

 

[fufkin]

Your mistake is in failing to distinguish between two types of beamy boat:

1. a beamy IOR boat which carried some of its ballast in the ceiling, and the rest high up in the keel
   
2. a modern beamy boat, which carries its ballast in a deep bulb
   

That gives the modern boat a higher AVS than the IOR boat.

 And your mistake is not inputing hull shape as one of the key variables in determining AVS, in addition to ballast, displacement and CE, which is why it probably wouldn't be tough to locate various IOR hulls with similar AVS numbers to a POGO. I am happy to be proven wrong for the benefit of the discussion.

The old school from 'Desirable Characteristics...' pushed for 130 degrees as an offshore standard, I think some shorter POGOs, or one of them not sure which is 124 degrees but I can't find to many numbers(maybe ShaggyBaxter can chime in...Oh wait he just showed up as I write this!!). These measurements are not necessarily rock solid when you account for sails on/off or carrying loads. Still, its not as if every single IOR boat was languishing at 115 degrees or something. 

Maybe have a look at the AVS curve of a catamaran. I won't be the guy to start the bar fight as to what the ultimate right AVS number is for an 'offshore safe boat', but will question the inverted stability stats of IMOCA/POGO type hulls, even with canting keels to aid with their righting moment.

Here is a good short article with special mention to the AVS/LPS of 'modern flat racers'.

https://www.oceannavigator.com/assessing-stablity/

And here is a mention of other stability variables that often escaped measurement.

https://cdn.ussailing.org/wp-content/uploads/2018/01/Stability-and-Hydrostatics-Datasheet-Explanation.pdf

...and here is another good article, also mentioning hull shape, free board, and loading as variables on LPS. It makes good mention of the notion that a lighter boat's LPS will be more adversely affected by loading from initial light ship than an initially heavier boat. It also mentions that lately topical IOR dinosaur, the Swan 44, with a very healthy LPS rating of 135.

https://www.practical-sailor.com/safety-seamanship/in-search-of-stability

 

[accnick]

Your mistake is in failing to distinguish between two types of beamy boat:

1. a beamy IOR boat which carried some of its ballast in the ceiling, and the rest high up in the keel
   
2. a modern beamy boat, which carries its ballast in a deep bulb
   

That gives the modern boat a higher AVS than the IOR boat.

I'm not sure anyone is or should be using the typical  flat-out IOR race boat as an example of anything good when it comes to sailing qualities or seaworthy designs.

 

[TwoLegged]

 And your mistake is not inputing hull shape as one of the key variables in determining AVS, in addition to ballast, displacement and CE, which is why it

If I had made such an omission, then you would have a good point.  But I wasn't writing a treatise on stability; I was simply critiquing your conflation of wide boats without considering that one had its ballast in the ceiling and the other has its ballast in deep bulb.

 

[estarzinger]

AVS . . . . the French centerboard boats used commonly in the south always interested me. They (mostly) have low AVS, but in return they will not trip on their keels nor pivot on and round up in big waves, and they tend to be extremely stable running off especially when a rear dagger is added.  We knew several that spend years down in the southern ocean with quite good 'storm success'.  It just demonstrates how complicated and multi-dimensional the storm safety issue is. OFC they are not (common) among any racing fleet so would not be taken into consideration in racing oriented literature.

 

[fufkin]

If I had made such an omission, then you would have a good point.  But I wasn't writing a treatise on stability; I was simply critiquing your conflation of wide boats without considering that one had its ballast in the ceiling and the other has its ballast in deep bulb.

Like I said, maybe keep ballast out of it to avoid mistaking my explanation for your imagined conflation and have a look at the stability curve of a catamaran. Bye for now.

 

[TwoLegged]

Like I said, maybe keep ballast out of it to avoid mistaking my explanation for your imagined conflation and have a look at the stability curve of a catamaran

Keep ballast out of a discussion of stability?  If that makes you happy.

 

[fufkin]

Keep ballast out of a discussion of stability?  If that makes you happy.

You seem to have difficulty in isolating hull shape as a key variable, so as a learning exercise only.

 

[Zonker]

Things that matter in terms of self righting:

- VCG
- beam (skinny is better)
- rig weight, especially the weight of furled sails aloft
- COACHROOF BUOYANCY

Things that matter less:
- freeboard unless really extreme one way or another
- IOR induced hull distortions such as bustles, pinched ends
- fluids in tanks, unless the tanks are really wide

The way various ratings rules have ignored the coachroof buoyancy is silly. If the coachroof is not damaged, it contributes significantly to self-righting. If damaged, and the hull is full of water, you are probably not going to self right.

Big curvy shapes like IMOCA 60 coachroofs are required to meet the rule AVS. A Pogo 12.5 has a small enough coachroof that it doesn't matter too much.

Here's a POGO 12.5 stability curve. The lower curve is with the keel up. The Positive Area under the curve with keel down is much more than the negative area. It's actually quite impressive and better than I would have expected. The deep keel is probably the main reason.

 

[TwoLegged]

You seem to have difficulty in isolating hull shape as a key variable, so as a learning exercise only.

I have no such difficulty, and am unsure why you are so keen to project one onto me.

Have a lovely weekend.

 

[fufkin]

Your mistake is in failing to distinguish between two types of beamy boat:

1. a beamy IOR boat which carried some of its ballast in the ceiling, and the rest high up in the keel
   
2. a modern beamy boat, which carries its ballast in a deep bulb
   

That gives the modern boat a higher AVS than the IOR boat.

2 beamy boats and one carries its ballast way deeper. Got that part.

Yet strangely you'll not have a problem finding IOR boats with an AVS close to a POGO/IMOCA, or better in some cases.(Though as Zonker mentions, 124 isn't bad)

Regarding my keen habit of projecting and conflating, I don't see any mention of or acknowledgement of hull shape or any other factors in AVS in either your comments or responses, just this vague statement and doubling down about two beamy boats with different draft and ballast placement, so what am I supposed to do...infer that you've said things that you didn't say? I can only go by what you say, not by what you don't.

Again, hull shape matters, especially with stability when inverted. (catamaran)

Depth of ballast/VCG sure matters as well, but as part of a whole package. If you start to narrow the hull, a shallower draft can score a much higher AVS than the big beamy racer with 15 foot draft.

 

[TwoLegged]

Regarding my keen habit of projecting and conflating, I don't see any mention of or acknowledgement of hull shape or any other factors in AVS in either your comments or responses, just this vague statement and doubling down about two beamy boats with different draft and ballast placement, so what am I supposed to do...infer that you've said things that you didn't say? I can only go by what you say, not by what you don't.

Fufkin, you are persisting in making a mountain out of nothing.  You mentioned two eras of beamy hulls, and simply I noted that your comparison omitted a huge difference in approaches to ballast between the two eras.  That's all.

You have now made about 27,000 followup posts trying to pick a fight about that, including this latest one where you denounce me for not having mentioned every other factor involved in stability.   I have no idea what on earth you are trying to demonstrate by all this, but it's bizarre to watch.

 

[fufkin]

If I had made such an omission, then you would have a good point.  But I wasn't writing a treatise on stability; I was simply critiquing your conflation of wide boats without considering that one had its ballast in the ceiling and the other has its ballast in deep bulb.

As and afterthought, a whole lot of that book was about vanishing stability for IOR boats, if I'm phrasing that correctly. Its interesting that today's pancake pizza wedges seem to be a little bit of a throwback in that regard. 

You do realize that your critique is about comments I made in the context of a book you haven't read, or no? Any comparison of an IOR boats ballast or draft with a 'modern' deep drafted flat racer is yours, not mine, so I'm not sure how conflation comes into it. You were the one who mentioned two eras with beamy hulls, not me. I said todays racers were a throwback in a certain context, which I guess was misunderstood.

My afterthought comparison was regarding AVS, and how both IOR boats and todays style of racer probably have similar AVS numbers in comparison to more conservative designs. That's it. This is not picking a fight, it is fighting for clarification in the midst of obfuscation. Big difference.

You have a nice weekend as well.

 

[MikeJohns]

Suitability of any boat comes down to its operational requirements.

A boat is a vehicle and it's chosen for it's characteristics like any other vehicle.   Where, when, how far, how many and what stores.

Generally, offshore boats should be seakindly and habitable.  No violent motions,  comfortable, as in low Motion sickness index (MSI). Forgiving of inexpert operation. Have a good steering response, have good shelter above deck and an offshore interior, with good sea berths.

Capable well manned hard crews can make a very un-seakindly boat seaworthy in heavy weather.  But the same craft may eventually incapacitate a short handed crew.

MSI limits can be next to impossible to achieve in some combinations of sea state and heading without a resonabale displacement to waterplane area.

Beamy light displacement Wedge type hulls are best as limited coastal cruisers.  The Pogo 12.5 is typical of this.

 

[TwoLegged]

Any comparison of an IOR boats ballast or draft with a 'modern' deep drafted flat racer is yours, not mine, so I'm not sure how conflation comes into it.

No so, Fufkin.  Here's the quote where you suggested a comparison between the two types:

As and afterthought, a whole lot of that book was about vanishing stability for IOR boats, if I'm phrasing that correctly. Its interesting that today's pancake pizza wedges seem to be a little bit of a throwback in that regard. 

And here's my reply which pointed out that ballast placement is a key distinction:

I think that you are mistaken there, @fufkin.  The problem in 1979 was that the IOR penalised stability, so boats were built with as little of it as possible.

Now, for the love of god, please stop this bizarre exercise.

 

[fufkin]

No so, Fufkin.  Here's the quote where you suggested a comparison between the two types:

And here's my reply which pointed out that ballast placement is a key distinction:

Now, for the love of god, please stop this bizarre exercise.

Throwback. That's the word I used...as long as this is a game of mincing them. I never compared types. Honest. 

I said that in a certain context(intended as AVS)that  today's racers were a throwback to IOR and you added the rest. I initially never mentioned ballast, draft or beam.

I'm willing to drop it if you are. This is tiresome for you, me and everyone in the discussion.

Let's move on. 

Everyone have a good one, and TL, that means you too. 

 

[TwoLegged]

So "B is a throwback to A" is not in any way a comparison between A and B.

No at all.

 

[Elegua]

This has turned into Desirable and Undesirable Characteristics of Offshore Posters.