Desirable and Undesirable Characteristics of Offshore Yachts

[Bryanjb]

So sorry to hear Ish. Good that you were near by and able to spend time with them.  I miss my folks every day.

 

[MikeJohns]

The problem is, everyone's experience is limited. Nearly all recreational sailors have sailed particular kinds of boats in particular kinds of weather and had particular kinds of successes and failures with it. The sea in a storm is quite chaotic, and yacht design practice is nearly as chaotic. The sort of repeatable, carefully controlled multivariate experiment that advances knowledge quickly cannot and will not be done, except around the edges (like the tank rollover tests at Southhampton). You would need to drop 10 carefully varied designs in into the middle of a storm with measured and characterized waves and instrument the result, then do that 10 times in 10 different weather conditions. 

Because of this, all the knowledge is anecdotal, with all the unreliability that implies. With boat design changing more rapidly than in the past, the problem gets worse as the anecdotes from 1962 and now even 2002 are dated. 

I tried to do a simple thing, measure the roll excursions on my powerboat. It proved impossible to do: ............

But the predicition of boat motion given say a typical JONSWAP wave spectra along with heading and  speed is quite a refined prediction now. It's a standard exercise for any vessel.

I replied earlier to Zonker; what would a Pogo's RAO would look like in a moderately rough confused sea with little wind ? That's data that's easy enough to generate.

The worst motion for mal de mer is vertical acceleration. I've said before, a challenge to any light cruising boat fan is to sail to windward in a seaway, a trade wind seaway would be good. Then record the vertical acceleration. I've done this an several boats to validate RAO data. I now use a Samsung Android phone and the free physics toolbox app. All the sensors you need for heave, roll, pitch and yaw are in the phone  You can record the data to a CSV.

Anecdotes are not a lot of use, people pick them to promote their choice.  Jimmy Cornell noted  with his cruising surveys amongst Pacific cruisers that people in one sort of boat would rate it as perfect, he'd often meet them a year or two later in a completely different boat that they would also rate as perfect. 

 

[TwoLegged]

It also ensured rich guys building new boats every year or two.

It also started the careers of numberless designers to feed that demand.

It was a true golden age of sailboat racing. IOR boats were much better performing than their predecessors. The fact that boats are better now is hardly relevant, it's just normal progress.

The path of progress doesn't have to go through weird deformations and multiple forms of unseaworthiness; that was an avoidable flaw of a misconceived rule.  A rule  which didn't deform and distort would still have had new boats appearing, tho possibly not as rapidly

 

[Ishmael]

So sorry to hear Ish. Good that you were near by and able to spend time with them.  I miss my folks every day.

Thanks, guys. Sorry, I mangled my language. We are here supporting my aged aunt. We weren't physically there with him, but my wife has been facetiming him at the nursing home while the plague has shut it down. Nobody in the family could see him at all for most of a year, so she was really the only one in contact except for phone calls. She would take him for walks through our garden and house, it gave him a semblance of normality.

 

[Steam Flyer]

Thanks, guys. Sorry, I mangled my language. We are here supporting my aged aunt. We weren't physically there with him, but my wife has been facetiming him at the nursing home while the plague has shut it down. Nobody in the family could see him at all for most of a year, so she was really the only one in contact except for phone calls. She would take him for walks through our garden and house, it gave him a semblance of normality.

Sincere condolences. Sounds like you all did a good job with what was possible, to keep spirits up and to feel close.

It's a good thing to live so that you ahve no regerets

FB- Doug

 

[DDW]

But the predicition of boat motion given say a typical JONSWAP wave spectra along with heading and  speed is quite a refined prediction now. It's a standard exercise for any vessel.

I replied earlier to Zonker; what would a Pogo's RAO would look like in a moderately rough confused sea with little wind ? That's data that's easy enough to generate.

The worst motion for mal de mer is vertical acceleration. I've said before, a challenge to any light cruising boat fan is to sail to windward in a seaway, a trade wind seaway would be good. Then record the vertical acceleration. I've done this an several boats to validate RAO data. I now use a Samsung Android phone and the free physics toolbox app. All the sensors you need for heave, roll, pitch and yaw are in the phone  You can record the data to a CSV.

The problem with that is that the sea state is never a perfect JONSWAP spectra, and can be much more confused than that. While you can record motion on your cell phone, you have but one instance, in one particular seaway. Like taking a pass over the bottom with a depth sounder results in one line of data. Massive data collection would color the picture more, perhaps much more. Predictions aren't everything, if I understand it that is why the JONSWAP fudge factors exist: to make theory agree with measured data. 

 

[Plumbean]

[snip]

Yep, (LWL is a better predictor of "actual" size) and it's also a good predictor of capsize. Lots of the Global Race with very "seaworthy" old school type keels, narrow beams 32-36' capsized. Bigger 45' Beneteau's probably would not have.

The size of a breaking wave required to capsize a typical sailboat is = beam of the vessel. That's the breaking part of the wave, not the total wave height. So if you have  a 10' beam, a 25' wave with the top 10' breaking is enough to flip you if it catches you beam on.

[snip]

This was, to me, one of the interesting results that came out of the Golden Globe Race.  Several cases where it seems as though these well-regarded "seaworthy" but heavy, full-keeled boats tripped over their own keels in a big, following sea.  They couldn't go fast enough to slow down the relative speed of the waves, but they weren't towing a drogue either, so they started surfing until they wiped out.  Would have been interesting if they had some similar era fin keels out there.

 

[Plumbean]

Thanks, guys. Sorry, I mangled my language. We are here supporting my aged aunt. We weren't physically there with him, but my wife has been facetiming him at the nursing home while the plague has shut it down. Nobody in the family could see him at all for most of a year, so she was really the only one in contact except for phone calls. She would take him for walks through our garden and house, it gave him a semblance of normality.

Condolences Ish.  It's been a tough year for issues like that.  My Dad is 91 and had a stroke a few months into Covid.  I'm finally going to be able to travel to see him for the first time in a year and half, in about 2 weeks from now.  He taught me how to sail and I was the only one of his 4 kids to catch the bug, so we did a lot together over the years, including cruising from the Chesapeake to Nova Scotia, with an epic, double-handed passage from Lake Bras D'Or to Nantucket in October one year.  He tried to give me the family boat when he couldn't handle it anymore, and I felt terrible in turning it down.  It was just way too much boat for me at that time (a Cheoy Lee Offshore 41 with a rotten deck).  I bought my boat only 2 years later and he never expressed anything but happiness for me.  His last real cruise was when he spent 4 days helping me deliver it from MA to NY.  

 

[Zonker]

I replied earlier to Zonker; what would a Pogo's RAO would look like in a moderately rough confused sea with little wind ? That's data that's easy enough to generate.

Lumpy? I have no idea - I leave the RAO to the hydrodynamicists in the company. We seldom do any motion prediction for the smaller workboats we design. We did one for the Canadian Navy's new 24m tugs. 

Sea State 6 on the beam? "Avoid. ~50% MSI" 

 

[Zonker]

but heavy, full-keeled boats tripped over their own keels in a big, following sea.  They couldn't go fast enough to slow down the relative speed of the waves, but they weren't towing a drogue either, so they started surfing until they wiped out.

I suspect the mechanism is  like "get picked up by a big breaking crest, broach and then capsize". Just watch videos of sailboats in breaking surf that capsize.  If they can keep perpendicular to the wave, they usually stay upright.

The beauty of the Jordan series drogue is that SOME part of the drogue is in the wave, and it keeps the stern straight

 

[MikeJohns]

The problem with that is that the sea state is never a perfect JONSWAP spectra, and can be much more confused than that. W..............................

There are several wave spectra that are really useful, even simplistic models. The energy spectra functions in common use are more than adequate to identify poor design attributes and where severe adverse motions are going to occur.

If the craft shows violent responses in the RAO to say JONSWAP that's indicative enough. You don't need to know exactly how bad, just that it's bad is enough to change the design.

As for fudge factors, the spectral models are refined to match actual data. Even the old simple PM spectra has been updated recently.

 

[TwoLegged]

This was, to me, one of the interesting results that came out of the Golden Globe Race.  Several cases where it seems as though these well-regarded "seaworthy" but heavy, full-keeled boats tripped over their own keels in a big, following sea.  They couldn't go fast enough to slow down the relative speed of the waves, but they weren't towing a drogue either, so they started surfing until they wiped out.  Would have been interesting if they had some similar era fin keels out there.

Heavy full-keeled boats have their merits.   They dry out nice and safely alongside, or on legs.  They heave to well.  They usually have deep bilges. They can be built with encapsulated ballast, which avoids a few maintenance headaches.

But even though the old-timers used to commend them for downwind work, they are actually a very poor choice.

A downwind boat basically wants a big, deep foil-sectioned rudder well aft, and no appendages forward of that.  Kinda like an arrow or a rocket: stuff at the back to control direction.  And it wants to be light enough to accelerate well, with low drag, and with drive from sails well fwd.

One of the best approaches to those goals is the Boreal centreboarders.  They don't have a huge rudder, but they do have  a daggerboard on each quarter, so with the centreboard raised they are almost unbroachable.

But the long keel boat has almost none of that.  Too heavy to accelerate and surf.  Rudder usually pulled or raked fwd a bit to reduce keel area.  Rudder usually barn door shaped rather than foiled, with its flow buggered up by the keel and the prop aperture.  And tons of keel area forward, in an unfoiled profile, which is a recipe for tripping over.

It would be interesting to test (somehow) whether a long keeler might be safer with a drogue.  But it does seem clear that they are unsafe to race in the Southern Ocean

 

[MikeJohns]

This was, to me, one of the interesting results that came out of the Golden Globe Race.  Several cases where it seems as though these well-regarded "seaworthy" but heavy, full-keeled boats tripped over their own keels in a big, following sea.  They couldn't go fast enough to slow down the relative speed of the waves, but they weren't towing a drogue either, so they started surfing until they wiped out.  Would have been interesting if they had some similar era fin keels out there.

I think tripping over a keel is urban myth. They don't develop enough drag for a boat to trip over and displacement boats always trim up with speed, even full keels with brutal frontal areas.

I suspect its more due to poor directional control.

 

[estarzinger]

Heavy full-keeled boats .....  they are unsafe to race in the Southern Ocean

I believe you are vastly underestimating the potential influence of the skipper.  

The seamanship demonstrated in this race was hmm . . pretty miserable.

These boats do have some distinctive traits, and do require specific handling (there is a reason that the Pardey's developed their specific/distinctive approach).

 

[maxstaylock]

Don't think the Golden Globe proved anything, except you need pretty big balls and a high tolerance to failure if you choose to go into the Southern Ocean in a 36' boat, with minimal righting moment.  Time will tell if it's even a half sensible idea in a Class 40.

While there are undoubtedly bad boats out there, if you discount the extremes of any design era, the median should be able to cope with most stuff, with vessels lost mostly coming down to luck, seamanship, maintenance, preparation, and damage history, rather than if the keel is a foot forward/back/deeper/shallower.

One man thinks a safe boat has a dry deck, plenty of stability, and a buoyant nature.  Another man thinks safety comes from easy motion and battleship strength, both will probably live to be old men anyway.  A third guy will probably do a lap in a boat with offset patio door, and think nothing of it.  A good allrounder cruising boat is by definition, 'good' at nothing, it's the ultimate compromise.

I hope I am never at sea in conditions that put my crazy notions of survival tactics to the test.  Have thumbed through most of the older books, 'The Elements of Seamanship' by Rodger Taylor is my favourite.

So if I had a new sailor friend who I wanted to give a book in the hope it might help them live longer, which would it be?

 

[estarzinger]

a book in the hope it might help them live longer, which would it be?

By a very large margin it would NOT be a book about boat characteristics and design.  It would be directed at the skipper - maintaining situational awareness, fatigue management, being pro-active rather than reactive, etc etc.  There is a whole category of such books dealing with risk/emergency/crisis/stress response.  . . . the whole "Long periods of boredom punctuated by moments of sheer terror" skill set.  However, not all of them deal with the fatigue management issues, which is distinctive to a few such situations, including being short handed in the S ocean.

 

[kent_island_sailor]

This was, to me, one of the interesting results that came out of the Golden Globe Race.  Several cases where it seems as though these well-regarded "seaworthy" but heavy, full-keeled boats tripped over their own keels in a big, following sea.  They couldn't go fast enough to slow down the relative speed of the waves, but they weren't towing a drogue either, so they started surfing until they wiped out.  Would have been interesting if they had some similar era fin keels out there.

My boat doesn't do that, she'll put on a burst of speed and get out in front of the breaking wave. The challenge is not to stuff yourself into the wave in front of you. The issue we had was it was very hard to work to steer, an hour wore you out. It would not have been doable for a cruising couple for long, at some point they would have needed a drogue to slow down and take it easy.

 

[TwoLegged]

I believe you are vastly underestimating the potential influence of the skipper.  

The seamanship demonstrated in this race was hmm . . pretty miserable.

These boats do have some distinctive traits, and do require specific handling (there is a reason that the Pardey's developed their specific/distinctive approach).

Hmm.  I am torn between on one hand bowing to your huge expertise, and on the other hand the low probability that so many experienced skippers were so incompetent.    The only way I can see to resolve this gap is to consider that what little I know of the Pardey techniques is that they mostly involved slowing down, lying ahull or using sea anchors.  Both approaches amount to taking a break from racing, and that would be counterintuitive .... but it may well be that like IOR boats, these long-keeled hulls are unsuitable to being driven hard in difficult conditions.  

 

[kent_island_sailor]

By a very large margin it would NOT be a book about boat characteristics and design.  It would be directed at the skipper - maintaining situational awareness, fatigue management, being pro-active rather than reactive, etc etc.  There is a whole category of such books dealing with risk/emergency/crisis/stress response.  . . . the whole "Long periods of boredom punctuated by moments of sheer terror" skill set.  However, not all of them deal with the fatigue management issues, which is distinctive to a few such situations, including being short handed in the S ocean.

Before my first offshore trip as skipper I read through all the Fastnet reports and got this out of it:

The boat will take it if you can, do not EVER get off the boat unless it is a step up. Remember the guy left for dead on a boat "about to sink" who eventually came home not dead in that very boat?

Fatigue and seasickness will turn a minor problem into a disaster too, or at least you will think it is with the minimal brain function you have left.

 

[estarzinger]

Hmm.  I am torn between on one hand bowing to your huge expertise, and on the other hand the low probability that so many experienced skippers were so incompetent.    The only way I can see to resolve this gap is to consider that what little I know of the Pardey techniques is that they mostly involved slowing down, lying ahull or using sea anchors.  Both approaches amount to taking a break from racing, and that would be counterintuitive .... but it may well be that like IOR boats, these long-keeled hulls are unsuitable to being driven hard in difficult conditions.  

Go back some years . .  .and take a look at how Moitessier drove his boat (and a few others from that generation).  He was by no means timid.  But he had a sensitivity for the design which these recent skippers did not seem to have at all.

Some long-keeled hulls are plainly bad designs; as are some fin keeled boats and some lift keel boats, and some IOR's and some IMS's, etc etc.   But you are painting with way too broad a brush to say that all long keeled hulls are unsuitable.