Desirable and Undesirable Characteristics of Offshore Yachts

[Steam Flyer]

I own it and love it.  I don't care anything about, and generally loathe, modern boats so it's right up my alley.  For me one of the most interesting takeaways was that a heavier rig was much more stable and less likely to be knocked down than a light one, all other things being equal.  So if you've been looking for a justification for switching over to a solid timber mast with galvanized shrouds and stays, you can point to this.

High inertia in roll. Easy to do, hoist something heavy up your mast.

FB- Doug

 

[low bum]

High inertia in roll. Easy to do, hoist something heavy up your mast.

FB- Doug

Well I guess, in theory, but I've never known this to be a storm tactic.

 

[estarzinger]

I own it and love it.  

That is awesome   It is rather the attitude that cruisers out in remote anchorages away from internet forums take.  I actually don't remember EVER having a debate about anchors or boat design with fellow distant cruisers.  There was a decently high base level of knowledge and then we all pretty much just did ourselves and did not much worry about other  people's choices or justifying our own.

We did occasionally have discussions about techniques and best practices - but honestly even those were rare and they may have only been because both Beth and I are curious  'process people' by nature.

 

[estarzinger]

High inertia in roll. Easy to do, hoist something heavy up your mast.

FB- Doug

are you volunteering?

if so, we hope you don't have a heart attack up there half way across the tropical pacific (lol).

sorry - just felt like being childish for a moment there

 

[Steam Flyer]

are you volunteering?

if so, we hope you don't have a heart attack up there half way across the tropical pacific (lol).

sorry - just felt like being childish for a moment there

Hey jump right in the pool, here

Just having fun, the boundaries of where theory meets practice are a good place to lighten up IMHO

High inertia in roll. Easy to do, hoist something heavy up your mast.

Well I guess, in theory, but I've never known this to be a storm tactic.

Me neither. But that's what a heavy mast or rigging is doing, increasing roll inertia. Obviously it's not a simple case of "more is better."

Part of the challenge in studying yacht design is to pick out the common elements, on the basic level that the laws of physics 'see' your boat, and trying to apply them in general to boats of differing configuration. A lot of times, it's confusing or even misleading. It's amazing we don't argue more.......

FB- Doug

 

[estarzinger]

Well I guess, in theory, but I've never known this to be a storm tactic.

In the square rig days, they actually did the opposite - bringing bits of the rig down to deck in preparation for a storm.

That's because the 'all things being equal' in your original post is a bit of a trap.  If you add weight to a rig, you do increase roll inertia which is good, but you also (almost inevitably) also decrease RM (and AVS) which is bad and (usually) the net effect is bad. 

It shows the challenge of pulling isolated bits of completed dynamics out and singling them out.

 

[low bum]

Me neither. But that's what a heavy mast or rigging is doing, increasing roll inertia. Obviously it's not a simple case of "more is better."

Part of the challenge in studying yacht design is to pick out the common elements, on the basic level that the laws of physics 'see' your boat, and trying to apply them in general to boats of differing configuration. A lot of times, it's confusing or even misleading. It's amazing we don't argue more.......

FB- Doug

The "argument" in so much of this stems from that period where boats transitioned from wood construction (with it's form defining limitations) to fiberglass (which freed designers up amazingly and liberated the underbody from basically any restrictions).  It's a spaghetti junction where aesthetics and intended uses crash together at rush hour.  Witness the hostility that the Valiant 40 was met with.  "That's not what a safe cruising boat looks like!"

The whole race rating scam/scandal nonsense that led to so many lousy boats laying on their beam ends never to return is on one end of the spectrum, in opposition to cruising oriented boats that are comically heavy and slow and built based largely on nostalgia and aesthetics rather than common sense - the "character" boats that come to mind. The retro-grouches of course crowed and said "See?  Next time will you listen?"  But the famous survivor of the Fastnet was not a pilot cutter but a Contessa 32 with a very non traditional underbody that was made possible by new materials and new thinking.

There's plenty to learn, and has been learned, from both ends of that spectrum and prudence lies in the middle.   "Desirable Characteristics" tries to take a look at this and I think if you're interested in that subject, it's an important work.  But if you're a total modern and play with carbon fiber this, and foiling that, then it's not particularly pertinent.  There really is no argument any more - modern boat design has simply moved on.  People that point at this book, and this time, and chuckle sagely to themselves about those dim witted ancients do not cover themselves with glory.

 

[low bum]

In the square rig days, they actually did the opposite - bringing bits of the rig down to deck in preparation for a storm.

That's because the 'all things being equal' in your original post is a bit of a trap.  If you add weight to a rig, you do increase roll inertia which is good, but you also (almost inevitably) also decrease RM (and AVS) which is bad and (usually) the net effect is bad. 

Yes you're right - strike the topmasts down on deck.  I wonder how much of this was tradition and standing orders, how much was hard learned experience, and how much was fear of the fidded mast junctions that could twist and splinter across the grain.  

 

[Steam Flyer]

The "argument" in so much of this stems from that period where boats transitioned from wood construction (with it's form defining limitations) to fiberglass (which freed designers up amazingly and liberated the underbody from basically any restrictions).  It's a spaghetti junction where aesthetics and intended uses crash together at rush hour.  Witness the hostility that the Valiant 40 was met with.  "That's not what a safe cruising boat looks like!"

The whole race rating scam/scandal nonsense that led to so many lousy boats laying on their beam ends never to return is on one end of the spectrum, in opposition to cruising oriented boats that are comically heavy and slow and built based largely on nostalgia and aesthetics rather than common sense - the "character" boats that come to mind. The retro-grouches of course crowed and said "See?  Next time will you listen?"  But the famous survivor of the Fastnet was not a pilot cutter but a Contessa 32 with a very non traditional underbody that was made possible by new materials and new thinking.

There's plenty to learn, and has been learned, from both ends of that spectrum and prudence lies in the middle.   "Desirable Characteristics" tries to take a look at this and I think if you're interested in that subject, it's an important work.  But if you're a total modern and play with carbon fiber this, and foiling that, then it's not particularly pertinent.  There really is no argument any more - modern boat design has simply moved on.  People that point at this book, and this time, and chuckle sagely to themselves about those dim witted ancients do not cover themselves with glory.

Very well put, thank you

FB- Doug

 

[estarzinger]

On a tangent . . . good wood is a truly marvelous material.  If it were 'invented' today it would be hailed as a wonder material. And careful wood construction is quite awesome.  

 

[low bum]

It's amazing.  And building boats in wood leads to the most beautiful shapes imaginable.  It's like how trout fishing necessarily takes you to the most beautiful places in the world.  Serendipity.  But this isn't good enough for a lot of people.  Smith wants to beat Jones and money is no object, the materials seem to have no strength or weight limitations, so you get the twisted shapes we see now in sailing.  

 

[Panoramix]

On a tangent . . . good wood is a truly marvelous material.  If it were 'invented' today it would be hailed as a wonder material. And careful wood construction is quite awesome.  

The only real default of wood is that it is time consuming (thus expensive) to build.

 

[slug zitski]

The only real default of wood is that it is time consuming (thus expensive) to build.

The defect with wood is the countless secondary bonds 

 

[low bum]

The defect with wood is the countless secondary bonds 

Yep.  Fiberglass becomes all one thing.  A wooden boat, however well made, is still a whole lot of small things held tightly together.  And sometimes not very tightly.  And apparently it's delicious.

 

[MFH125]

Yep.  Fiberglass becomes all one thing.  A wooden boat, however well made, is still a whole lot of small things held tightly together.  And sometimes not very tightly.  And apparently it's delicious.

Wood epoxy boats are just as much monocoque structures as any fiberglass boat.  Sometimes more so depending on how interior liners are installed and hull-to-deck-joints are done.

The defect with wood is the countless secondary bonds 

Really? I've never heard of wood epoxy boats having delamination issues.  Most damage I've seen has been the wood splintering or giving way, not the glue joint.

Wood has its "limitations" as a material:

• it burns
  
• material properties vary from tree to tree
  
• it's hard to work with in very small or thin geometries
  
• it's very bulky for its strength
  
• it's not isotropic, i.e. it has a grain.
  
• its very soft
  
• it rots
  
• it's not dimensionally stable with changes in moisture content
  

Most of these are either non-issues, or are easily managed/mitigated for hull construction.

 

[mookiesurfs]

That would depend on who you ask, on any particular day. I once thought I knew a lot more than I probably do. Ironically, thinking you know a lot can get you started in the direction to understand how much more there is to learn.

I take some things as truths, others as guidelines, some as absolute BS. The trick is differentiating between them. Experience can help in that regard, provided you survive and learn from your mistakes.

"Ah, but I was so much older then, I'm younger than that now."

The more I learn, the less I know.

 

[CapDave]

The only real default of wood is that it is time consuming (thus expensive) to build.

And time consuming (thus expensive) to maintain - at least ordinary timber construction is. I've owned a wood boat...and sailed on and cared for other wood boats. It's just an entire extra bucket of time/money on top of everything else on a similar fiberglass boat. Some people sail to mess about with boats - I prefer to mess about with boats to sail. 

 

[Panoramix]

And time consuming (thus expensive) to maintain - at least ordinary timber construction is. I've owned a wood boat...and sailed on and cared for other wood boats. It's just an entire extra bucket of time/money on top of everything else on a similar fiberglass boat. Some people sail to mess about with boats - I prefer to mess about with boats to sail. 

Traditional wood construction but a modern wood epoxy isn't that bad, I think purchase price aside the minimal extra hassle makes sense to get a light, rigid and solid boat. Solid GRP boats are a bit heavy and flexible and a cored boat probably needs as much attention as a wood epoxy boat.

 

[Fah Kiew Tu]

As to the expedition centerboards - that feature is primarily for the important task of being able to sneek into shallow enough water that truck size ice bergs can't follow you.  They ground outside you.  And for being able to take the ground well.

FWIW I am quite a fan of these sorts of hulls for the reasons you state. I've been in the pack with a disabled engine and seen icebergs carving their way through and knowing there was nothing we could do should their course intersect ours. The ability to get into shoal water to avoid them & big floes/bergy bits is essential if you want to go far south.

In fact were I to build 2 more boats, the second one would be a hull of this type. Unfortunately due to age I doubt I'll build even one more boat, but who knows...

And as a point of interest Mike Johns currently owns 2 ocean capable cruising boats, both in steel, and neither are of the 'crab crusher' hull form. Both by 2 different Australian naval architects.

But also neither are of the modern lightweight 'skimming dish' form made possible by modern composites. They're heavy displacement cruising boats with the ability to carry tonnes of stores.

And my own boat is a relatively light/medium displacement shoal draft hull in steel with a heavy junk rig for simplicity of handling. I have absolutely zero plans to take her further south than we already are though.

FKT

 

[estarzinger]

In fact were I to build 2 more boats, the second one would be a hull of this type. Unfortunately due to age I doubt I'll build even one more boat, but who knows...

I have 6 boats (with various stages of designs) I would like to build.  I hope we get the opportunity to build one of them. I doubt we will go south again, but I have some unfinished business north.