Hull Shapes and Behaviour in Heavy Seas

[B23iL23]

Let's not use the 79 Fasnet as a guide. Those were IOR (yuch) designs and very weak rudders by todays standards. Also the IOR rule meant very tender boats with narrow sterns which is not a good combination.

Originally Posted by NevisDog

Briefly:
(1) Vessel safety depends on structural strength, as mentioned above. Try not to confuse these two issues.
(2) It's not what I think - it's the findings of the report into the '79 disaster - folks lost their lives due to the then-current trend towards excessively wide, excessively-shallow, tender hulls that were/are, beyond any question, seriously at risk of knockdown in storm waves, due to their hull shape.

[boatman61]

Seeing as it was me who brought up rudder out of water let me say this.. it was not survival conditions as I'd not have been sailing but hunkered down.. in fact it was more like f7.
The boat was a Bene 321 on a solo transat and I was running down wind with 50% genoa no main.
As a big wave came up it started to break as it passed under lifting the stern.. rudder in broken water then exposed and the boat pivoted as the wave peak centered the boat.
Got no bones in this and could not give a $hit what youall love in particular.. I will sail any and everyting, multi chine, round, V, flat whatever.
So call me what you want.. Liar, a$$hole, crap sailor, but I just say what can and did happen..
Normal squabling may now resume.

[Don C L]

Originally Posted by boatman61

Normal squabling may now resume.

yeah don't bother our squabbling, will ya!

[boatman61]

Aye, Aye Cap'n..

[NevisDog]

Thanks Dale, Paul for pushing the other side of the argument - I'm kinda hoping for some consensus that might help the OP, so it's no good saying 'it all depends on which modern design', and 'nothing nowadays looks like an IOR anyway so don't worry' - we need to outline what to look for and what to avoid, surely? Why else pose the question?

So, let's find some common ground for the OP that may benefit him; here are some suggestions:

1. Structural strength is a given, important in heavy seas and in groundings - agreed.
2. IOR designs of 1970s era were crap, too beamy, too shallow underbody, inadequate stability, too stable inverted.
3. Modern, wide transom, twin rudder, downwind racing sled designs are somehow different to those crappy IOR designs - I dunno how they might be different but folks here claim they are and they have vast experience; maybe one of them will explain how they are different.
4. Not all designs are created equal but it's complicated; look to John Kretschmer for some fair, reasonably unbiased guidance on which modern and which traditional hull designs to choose from when deciding on a suitable hull shape for heavy seas.
5. If it doesn't meet Cat A stability as an absolute, total, basic, no exceptions, minimum - don't walk away, run!

Those with wide experience, feel free to delete/modify/change each point as necessary.

[Westsail-32]

Originally Posted by daletournier

Pat has not been attacked. His strong biases and generalisations have been called out. You have a guy called Jim here that has 250k nm under his belt that has sailed the same waters Pat claims are regularly unsuitable for anything but his style boat, this is obviously not true as Jim has sailed those waters on fin keelers as just one eg.

He says that only a full keeler will survive a heavy grounding, yet I give you a real world recent case of a fin keeler bashing on a reef for five days and surviving intact, another eg of Pats bias dismissed.

As for comfort at sea there are other mistruths here, some need to have things black and white and that just isn't how it is, so many variables. The full keel boat I had which was a similar length as Pats was by far the most uncomfortable downwind boat I'd ever had, rolled like a pig!

I'm not the most experienced here BUT I'm definitely more experienced than many and aren't getting my opinions from numbers and books. As someone that has a reasonably modern hull design with a big bum and a pointy nose and has sailed it across an ocean, beaten into heavy weather, run downwind in a strong gale under bare polls I'm here to say that Nevisdogs view of modern hull designs being incredibly uncomfortable is INCORRECT.

The problem with Pats writing is he presents the Newbie with a bias view as ifs its 100% fact, and in doing so is painting a poor picture of modern designed boats, propelling myths through bias that suit "HIS" view of the world.

Also most will never ever see waves an sea state so steep that the rudder is coming out of the water other than crossing bars etc, which I've done many times and crossing in such conditions is bad seamanship.

Regarding southern ocean going sleds, the young lady in GGR wasn't on an ocean going sled she was on an old full keeler yet she end to end pitch poled in the southern ocean. As pointed out in another post, the Winston Churchill was a big heavy displacement yacht that sunk in the 98 Sydney to hobart, not just fin keelers, just a couple of examples where Pats theory falls down. I know a RYA instructor that was in that sydney to hobart (he's done many) and asked him what they could have done differently, he said "not gone" he laughed at the suggestion made by some that heavy cruising boats would of faired better. He's sailed many boats.

My point is so many variables come into play in heavy weather, just making statements like "full keelers are better" when things get tough is ignoring all those variables....... it dosent work like that.

Tolerance people, tolerance.



I've been following this forum for quite a while and this is my first post.


CptPat was asked a direct question by the original poster in post number 252. He did his best, in an honest effort to answer that question, and then took the extraordinary step of including a disclaimer to fend off more attacks.


He was called "thick headed" etc. in this thread, among other insults, had his writing misquoted and misrepresented to fit a distorted image, and faced truculent demands for specificity when specific descriptions are impossible. And had experience used not as a source of wisdom but instead as a "mine's bigger than yours'" weapon. These uncivilized people have used every dirty rhetorical trick to attack this poster. He was even criticized for saying fin and full keeled boats behave differently in heavy seas. Really??? They are the same??? Seriously??? CptPat isn't the first person to believe the trend for greater speed can result in reduced stability and safety.


I'm dismayed at how the fangs came out and went for this poster's throat. And then by the audacity of accusing him of being non-civil. The pot is definitely calling the kettle black. These types of partisan attacks belong with childish politicians in Washington - not among civilized adults. I have no desire to jump into this maelstrom to post anything. I'd rather jump into a wood chipper.


I'll just go back to reading here. This is my first and last post.

[Don C L]

Originally Posted by Westsail-32

Tolerance people, tolerance.



I've been following this forum for quite a while and this is my first post.


CptPat was asked a direct question by the original poster in post number 252. He did his best, in an honest effort to answer that question, and then took the extraordinary step of including a disclaimer to fend off more attacks.


He was called "thick headed" etc. in this thread, among other insults, had his writing misquoted and misrepresented to fit a distorted image, and faced truculent demands for specificity when specific descriptions are impossible. And had experience used not as a source of wisdom but instead as a "mine's bigger than yours'" weapon. These uncivilized people have used every dirty rhetorical trick to attack this poster. He was even criticized for saying fin and full keeled boats behave differently in heavy seas. Really??? They are the same??? Seriously??? CptPat isn't the first person to believe the trend for greater speed can result in reduced stability and safety.


I'm dismayed at how the fangs came out and went for this poster's throat. And then by the audacity of accusing him of being non-civil. The pot is definitely calling the kettle black. These types of partisan attacks belong with childish politicians in Washington - not among civilized adults. I have no desire to jump into this maelstrom to post anything. I'd rather jump into a wood chipper.


I'll just go back to reading here. This is my first and last post.

Well, hope it won't be your last! A few intelligent, well-reasoned, responses help calm the waters sometimes... so we can get back to fighting!
But seriously, welcome aboard Westsail!

[B23iL23]

Ok I'll take a stab at this one.


The current trend in boat design is wide/flat sterns. What this does is make the boat more stable, especially off the wind and faster. You also get fuller bows which reduce pitching upwind - remember the old IOR designs were very narrow up forward, max beam just aft the mast and then getting narrow again at the stern. All gone with the new designs.


You also get (these days) twin rudders which reduce cavitation and increase safety by having a second blade. An additional benefit is the increased volume which is great for cruising gear storage.



Very good paper here from Yachting world http://www.humphreysdesign.com/wp-content/uploads/2013/06/Modern-cruiser.pdf



on the current trend in designs. His photos and comments are a little extreme in terms of the designs he shows (more racing than the current breed of cruiser designs).

Originally Posted by NevisDog

..
3. Modern, wide transom, twin rudder, downwind racing sled designs are somehow different to those crappy IOR designs - I dunno how they might be different but folks here claim they are and they have vast experience; maybe one of them will explain how they are different.
...

[B23iL23]

Well said. Hope it's not your last post!

Originally Posted by Westsail-32

Tolerance people, tolerance.



I've been following this forum for quite a while and this is my first post.


CptPat was asked a direct question by the original poster in post number 252. He did his best, in an honest effort to answer that question, and then took the extraordinary step of including a disclaimer to fend off more attacks.


He was called "thick headed" etc. in this thread, among other insults, had his writing misquoted and misrepresented to fit a distorted image, and faced truculent demands for specificity when specific descriptions are impossible. And had experience used not as a source of wisdom but instead as a "mine's bigger than yours'" weapon. These uncivilized people have used every dirty rhetorical trick to attack this poster. He was even criticized for saying fin and full keeled boats behave differently in heavy seas. Really??? They are the same??? Seriously??? CptPat isn't the first person to believe the trend for greater speed can result in reduced stability and safety.


I'm dismayed at how the fangs came out and went for this poster's throat. And then by the audacity of accusing him of being non-civil. The pot is definitely calling the kettle black. These types of partisan attacks belong with childish politicians in Washington - not among civilized adults. I have no desire to jump into this maelstrom to post anything. I'd rather jump into a wood chipper.


I'll just go back to reading here. This is my first and last post.

[Don C L]

OK never sailed one. Like to though! But the added yaw stability with twin rudders definitely appeals to me.

[NevisDog]

Originally Posted by daletournier

...As for comfort at sea there are other mistruths here, some need to have things black and white and that just isn't how it is, so many variables. The full keel boat I had which was a similar length as Pats was by far the most uncomfortable downwind boat I'd ever had, rolled like a pig!

I just wanted to expand on this one point. Rolling heavily going downwind is an indicator of good high-angle stability. Modern downwind sleds are made more comfortable downwind, at least initially, due to wide beam, flat sections, and having variable water ballast, so can reduce the pendulum effect of that lump of lead low down. This comes at the cost of ultimate stability, hence those photos we've seen of those sleds being equally stable in an inverted state. So the cost of that improved downwind comfort is reduced safety in big seas - a trade-off that's acceptable in large raceboats (at least until the high-power AP spits the dummy).

[Don C L]

I confess, my ol' CCA boat rolls, DDW, like a... isn't there something more elegant than a pig? If I can broad reach with gybes, I'll turn to that, and that is very pleasant to my sensibilties... otherwise I just keep thinking how much I like her other attributes... while I am rolling like a graceful...

[B23iL23]

Understood and you are probably referring to some of the more extreme racing/single handed downhill sleds that we've all seen photos off happily bobbing inverted.

I sincerely doubt any of the current crop of cruising boats would stay inverted especially as none (many) use water ballast - almost all have to rely on the lump of lead hanging off the bottom.

Originally Posted by NevisDog

I just wanted to expand on this one point. Rolling heavily going downwind is an indicator of good high-angle stability. Modern downwind sleds are made more comfortable downwind, at least initially, due to wide beam, flat sections, and having variable water ballast, so can reduce the pendulum effect of that lump of lead low down. This comes at the cost of ultimate stability, hence those photos we've seen of those sleds being equally stable in an inverted state. So the cost of that improved downwind comfort is reduced safety in big seas - a trade-off that's acceptable in large raceboats (at least until the high-power AP spits the dummy).

[NevisDog]

Originally Posted by B23iL23

...I sincerely doubt any of the current crop of cruising boats would stay inverted ...

Look again at the GZ curve published for the HR 57 cruiser then tell me it won't stay inverted. Size alone will (hopefully) keep that thing outa trouble, not its stability curve. Other similar designs were mentioned; maybe worth checking those out too if you think them good in heavy seas.

[MartinR]

We have to be careful comparing modern wide stern cruising boats with racing sleds, even if they superficially look alike. Many of the cruising yachts, for example Janneau, HR, the new Amel, have a fairly conventional underbody, not flat, flaring above the waterline to the wide deck. These sterns are not made for planing, so there is little speed advantage here. The stern is there to provide ample external space for socialising, not for racing performance.

Not my cup of tea, but nothing that should affect seaworthiness much. My experience with these modern boats is that they tend to move more quickly and jerky than narrower designs. My personal preference is for narrower boats.