Gut feeling on boat sizes.

[GILow]

Great story and it really captures the essence of how I see the smaller boat thing. Sure it was less comfortable but it just sort of soaked up the punishment over three days. (As did the crew).

[Kenomac]

There are so many speculations on this thread that are just plain wrong. People with smaller size boats will always cheerlead for their size and model. We’ve owned boats of all sizes down to an 11ft kite, bigger is safer and more comfortable which translates to less fatigue; it’ll also get you to where you want to go much quicker and is therefore able to avoid bad weather. Larger boats have systems onboard to make things easier to singlehand, which I’ve been doing for much of the season.

I’d upsize to an 80 footer if and when I can afford it.

Other boats we’ve owned include an O’Day 20 and a Hunter 450.

[Dan GB]

Originally Posted by Kenomac

There are so many speculations on this thread that are just plain wrong. People with smaller size boats will always cheerlead for their size and model. We’ve owned boats of all sizes down to an 11ft kite, bigger is safer and more comfortable which translates to less fatigue; it’ll also get you to where you want to go much quicker and is therefore able to avoid bad weather. Larger boats have systems onboard to make things easier to singlehand, which I’ve been doing for much of the season.

I’d upsize to an 80 footer if and when I can afford it.

Other boats we’ve owned include an O’Day 20 and a Hunter 450.

Originator of thread was posting about a feeling looking at a smaller boat than his own. The theme was sense of robustness, not 'real' safety.

I don't think anyone is arguing that your observations of size are wrong in any way - speed and comfort is obviously greater the larger your boat is. Duh

[Terra Nova]

Originally Posted by hamburking

...although a smaller boat may be less comfortable, IMHO it is inherently safer, structurally.

Oh boy!

[NormanMartin]

Interesting discussion. I, too, follow the GGR2. Good to have a real time study of the argument in favor of old fashion designs and long range sailing. The final analysis of the vessels and their skippers will keep us reading and discussing for years.

I have a lot of offshore experience in other people's boats. I am a sailing professional. So, I sail boats that are sometimes sub-optimally prepared. (Not negligently, just not to the level of detail I prefer as a sailing snob.) I notice the details such as hand holds, sink drainage, clear access to gear, etc. is what really matters. It is exhausting to struggle to perform an operation. With exhaustion come mistakes.

My curiosity is how well do these GGR2 vessels take care of their sailors.

On another note. I am reading Ron Holland's book and he discusses a 33 foot S&S design, Spirit of San Francisco, that did some notable offshore sailing. Preparation and crew are a big factor. I'd like to use my 33 foot Aphrodite for some offshore voyages... after a few modifications. All the loads and the comforts are perfect for me. And, I love to sail her.

Norm
Cape Cod

[Adelie]

Originally Posted by GILow

Now this boat I have been walking past is a very tidy Roberts 36. A handsome boat in good condition.

And as I walk past her, I increasingly feel that she is more robust and seaworthy than my significantly larger Swanson 42. And when I say larger, I mean MUCH larger. The Swanson is beamier and taller and massively more heavily rigged.

So WHY do I feel the little Roberts is more seaworthy? Is it watching similar sized boats plying their way around the world in the Golden Globe, or am I picking up something that the legendary Pardey's were trying to convey with their preference, I understand, for a boat around 35 feet?

Curious to what people feel makes a seaworthy boat. Am I picking something up about boats that are TOO big to be as seaworthy? Is there something about a compact and contained boat that makes it more robust. Or am I missing the point completely?

Matt'

The Swanson is "massively more heavily rigged." because it has massively greater loads on it. The question is whether the factor of safely higher (ratio between loads and strength) is better or worse on the Swanson or Roberts?

The Pardey's point is that the effort involved in working a boat goes up as the boat size increases. Additional labor saving devices can help alleviate this problem as long as you can afford them, can maintain them and they don't break at very inopportune times. The Pardeys came to their size preference based on the outcome of the Xmas 1982 debacle at Cabo San Lucas. 29 of 45 sailboat were driven ashore during an unexpected gale. The observation of the Pardeys and several folks that were there during the event was that boats 37' and over with a couple aboard were more likely to have been driven ashore. You can read about this in their book "Capable Cruiser"

Originally Posted by Wotname

Dunno the answers to your questions but I remember the Hiscocks progressively got larger boats and at some time, they realised their boats were getting too big and reflected that smaller was better. Their first circumnavigation was in Wanderer III which was 30' (Sir Laurent Giles design).

Wanderer-III was 30'
Wanderer-IV was 49'
Wanderer-V was 39'

Originally Posted by hamburking

A large boat experiences FLEX in the hull as it rides the waves. The hull does actually bend and move, which affects all the rig and structure below.

The larger the boat, the greater the flex.

A smaller boat is much more rigid. The forces smaller. A small boat is like a cork on the ocean. A cork can survive anything. A big boat breaks apart under the strain.

So although a smaller boat may be less comfortable, IMHO it is inherently safer, structurally.

Scale effects.

[a64pilot]

There is something called the square cube ratio that explains to some extent why spiders can walk on water, and elephants can’t jump.
It also explains how a 40’ Boat can be twice as big as a 30’ Boat.
However it also explains the forces that act on the bigger Boat, the bigger Boat has to be much stronger to withstand the same external forces.
It’s why a Piper Cub looks like it does and 747 isn’t just a big Cub
People have tried scaling up airplanes, and it doesn’t work pretty quickly.

Same I’m sure with boats. Take a good, strong 30’ Boat and simply scale it to 50’ and I’m sure you would have a weak hull, perhaps dangerously so.
https://en.m.wikipedia.org/wiki/Square–cube_law

For whatever it’s worth, the larger Boat due to the square cube rule will need proportionally more sail area to achieve the same results as a smaller boat.

[Kenomac]

Originally Posted by a64pilot

There is something called the square cube ratio that explains to some extent why spiders can walk on water, and elephants can’t jump.
It also explains how a 40’ Boat can be twice as big as a 30’ Boat.
However it also explains the forces that act on the bigger Boat, the bigger Boat has to be much stronger to withstand the same external forces.
It’s why a Piper Cub looks like it does and 747 isn’t just a big Cub
People have tried scaling up airplanes, and it doesn’t work pretty quickly.

Same I’m sure with boats. Take a good, strong 30’ Boat and simply scale it to 50’ and I’m sure you would have a weak hull, perhaps dangerously so.
https://en.m.wikipedia.org/wiki/Square–cube_law

For whatever it’s worth, the larger Boat due to the square cube rule will need proportionally more sail area to achieve the same results as a smaller boat.

Your last sentence makes no logical sense.

[atmartin]

Originally Posted by a64pilot

For whatever it’s worth, the larger Boat due to the square cube rule will need proportionally more sail area to achieve the same results as a smaller boat.

I'm not an NA, but longer boats tend to have lower displacement to length (D/L) ratios. One reason for this is beam/length ratio becoming much lower.

Longer boats usually carry less sail and therefore less ballast proportional to smaller boats.

Just look at ballast ratios on sailboats over 60'. Generally less than 30%, often close to 20%.

If by "larger" you meant heavier (more displacement), the SA/D ratio remains the same. If you meant longer, you've got it reversed.

[a64pilot]

Originally Posted by Kenomac

Your last sentence makes no logical sense.

OK the interior volume and therefore weight and displacement go up not in a linear relationship to length.
To drive the heavier greater displacement Boat will require more than twice the sail area of a boat half the length, significantly more.

There is a realistic size limit to a sailing vessel due to the square cube ratio and the ability to carry enough sail to drive one, the larger sailing ships of times past carried so much sail, cause they had to.

These concept drawings of large cargo ships with sails, are fantasies.

[Don C L]

So I have chartered boats up to a Peterson 44, which I really liked. I could sail upwind in a LOT more wind in far more comfort and speed than my 29 footer. And that speed does make a difference in comfort too I confess! But I still love my little boat for many of its particular virtues too. That bigger boat was not set up to singlehand, I needed crew, and the forces are exponentially greater as we all know, but if the hull and rig are exponentially greater in strength to match it, then no problem. It's just that if something breaks on a bigger boat my fear is exponentially greater too A bigger boat FEELS safer (and that reassuring feeling can keep one calm and perhaps a little more rational when it's nasty out,) but if a smaller boat is built well and you trust it and you don't mind being bounced around more, a good small boat can get you there too... except upwind on a really windy day

[charliehows]

I think the basic tension is between sailing the boat vs liveaboard space; a smaller boat is easier to manage under way, a bigger boat is easier to live on.
My boat fits the small category and has some distinct advantages; small sails and a ketch rig are easy to manage in rough conditions, I can reach the prop to clean it whilst keeping my head above water, I can manage the anchors with a manual winch...I'm sure there are many other things I can't think of immediately
But...although I find her comfortable, you wouldn't describe her as spacious...
The size of the boat is not really much of an issue – the difference between a 36' and a 50' doesn't amount to much when something goes wrong; both rely on a certain amount of machinery to manage what is, once you get beyond the basic sailing dinghy, a heavy vessel; it's the skippers skill, experience and resourcefulness that makes the difference.

[sailorboy1]

Oh the ever perfert offshore sailboat compared to a good cruising boat.

Will it never end?

[thomm225]

So I was watching this old boat motoring out today while standing on my 27 foot boat and thinking Geez!?

That boat has sat unused in a slip for at least 8 years and now someone has brought it back to life

It had a small outboard on it and then I realized that boats of the same type have circumnavigated several times.

It was an old Albin Vega 27.

VEGA 27 (ALBIN) sailboat specifications and details on sailboatdata.com

[atmartin]

Originally Posted by a64pilot

OK the interior volume and therefore weight and displacement go up not in a linear relationship to length.
To drive the heavier greater displacement Boat will require more than twice the sail area of a boat half the length, significantly more.

There is a realistic size limit to a sailing vessel due to the square cube ratio and the ability to carry enough sail to drive one, the larger sailing ships of times past carried so much sail, cause they had to.

These concept drawings of large cargo ships with sails, are fantasies.

In thinking only of the square cube ratio, you're missing beam to length ratio. Larger boats/ships have significantly lower beam/length ratios than the small boats most of us own.

Originally Posted by Wikipedia

The beam of many monohull vessels can be calculated using the following formula:



Where LOA is Length Overall and all units are in feet.

Some examples:

For a standard 27 ft (8.2 m) yacht: the cube root of 27 is 3, 3 squared is 9 plus 1 = 10. The beam of many 27 ft monohulls is 10 ft (3.05 m).

For a Volvo Open 70 yacht: 70.5 to the power of 2/3 = 17 plus 1 = 18. The beam is often around 18 ft (5.5 m).

For a 741 ft (226 m) long ship: the cube root is 9, and 9 squared is 81, plus 1. The beam will usually be around 82 ft (25 m), e.g. Seawaymax.

Larger boats don't scale evenly in all directions. Mostly, it's length that's added.

The SA/D ratios don't change dramatically, even in huge yachts.

Maltese Falcon 289 ft

Sail Area: 25,791 sq ft
Displacement: ~2,480,000 Lbs
SA/D: 22.5

Tenacious 213 ft

Sail Area: 13,100 sq ft
Displacement: ~1,172,000 Lbs
SA/D: 18.9

Alexander von Humboldt 213 ft

Sail Area: 14,640 sq ft
Displacement: ~1,984,000 Lbs
SA/D: 14.8

At this size, the displacement figures are probably not that accurate, but going off the data I could find, you can see that the ratios don't scale into absurdity.

Didn't the last windjammers/clippers sail with crews of a dozen or so? Handling 50,000+ square feet of sail? I'm not suggesting over-canvassed boats are wise for shorthanded crews, but this is a limitation imposed by the crew, not physics.