Logic in different length hulls

Why? Where is the evidence that even given those factors, a scow is better overall (to the extent such a subjective judgement is possible)?

Is a scow bow "better" at a Fn of .7 than a normal bow if the boat has a "normal" size rig and is doing the sailing that most boats do? How many boats spend a significant proportion of their time sailing downwind at speed in the ocean in big waves? Is it better for the typical sailor to go for a scow to maximise performance in such conditions, or is it better for them to go for a pointy bow that will get them upwind without slamming the rest of the time?

In what ways is it better? Does it give more room for the same cost as a sharp bow? Does the extra wetted surface potentially slow the boat in light to medium winds (surely it is likely to a lot of the time) and if so, how much does the larger rig and equipment required to keep the same WSA/SA ratio cost in cash and crew work?

Are the advantages it has when the boat is heeled worth the disadvantages when the boat is not heeled?

Where is the evidence that at normal speeds sailed at by most yachts, a scow bow is better downwind in the ocean? Yes, a scow bow may be better for Open type yachts racing downwind, but does that mean that it is better overall?

 

On a rational world somewhere far away in this galaxy ... sailing boats with Oceanic pretensions would be well balanced in longitudinal direction, among other things.

Planet of the Apes | Scientific American https://www.scientificamerican.com/article/planet-of-the-apes-2006-06/

But let's be realistic in this beautiful asteroid and painful world, planet of the apes of the Miocene, very wide bows are welcome.

 

Where is the evidence that (1) a scow doesn't also have its C of G forward of the CF; and (2) that having the C of G forward of the CF is inferior overall?

Where is the evidence that a 4o0K conventional cruiser/racer is slower than a 400k scow cruiser/racer?

In fact one thing that's interesting is that I can't find any race results for the new scow racer/cruisers. If they have not been proven to be faster then why does it seem that some people assume they are?

 

What does that mean in reasoned discussion? Where is the actual reasoned evidence that cruiser/racer scows are better balanced in longitudinal direction? Secondly, where is the actual reasoned evidence that the trade-offs for that (alleged) better balance create a better craft overall?

What seems to be getting ignored is that downwind balance in the ocean is merely one factor in design. Many boats spend little time going downwind in the ocean in conditions where longitudinal balance is a significant problem. Many boats spend far more time going upwind in flat water and light winds, for instance. So why make such a big deal about alleged improvements in specific conditions?

By the way, how many scows have you had? I've had three.

 

I can find results for the Ace 30, a scow designed for IRC racing and costing 250,000 Euros which is a lot for a 30 footer - the First 36 is claimed to be at around the same price. A J/99 is around 160,000 Euros and the JPK 1010 is similar.

The Ace 30 ran last in the UNCL championship in 2022. In 2022 she did the Armen race, finishing in 20h 37m. Two JPK 101os finished in 19h 20 and 19h 24 m to win and place second. JPK 10.30s and a Sunfast 3300 finished an hour ahead of the 1010s for third, fourth and fifth. All these boats cost dramatically less than the Ace.

In 2023 in the same race the Armen finished a respectable 16th out of about 60. She was over 90 mins behind the winning JPK 1030 and was beaten over the line by three JPK 1010s.

So there seems to be no evidence that even in this doublehanded racing in the ocean, the scow cruiser/racer is as fast as conventional boats that seem to be cheaper and to carry smaller sails.

The Ace is rated 1.001 on IRC, which is certainly NOT a penal rating considering the Ace's sail area and other measurements. The J/99s, 33' JPKs and Sunfasts are rated significantly faster and still beat Ace on corrected time even doublehanded in ocean races.

Nor is there apparently any evidence that the scow type is a better cruiser for its price. A conventional boat for the same general cost, like a First 36, will probably be faster AND roomier. And as scow expert Sam Maynard says "the scow comes with negatives, the slamming is really difficult to bear" so it's unlikely to be comfortable.

 

CT249 your observations are fine, but ultimately irrelevant. Scows aren't the apex of sailboat design and they aren't even mainstream, otherwise Beneteau would offer you one. However fashion is a driver in boat sales, so it's possible that foredecks will become wider in future.

Scows have one big advantage, more inside room for less lenght. This is important to those who feel their marina charges to much per foot and want a cheaper berth without feeling cramped.
The big disadvantage is that efficient upwind sailing has to be done at 30° heel, wich often isn't conductive to family peace. Combine this two factors and it's clear that it takes a specific type of sailor or a specific location for the scow to be a good option. Hence why Beneteau hasn't hired Raison to design them one for the masses.

To win races you buy the sailboat that's optimized as much as possible for the prevailing condition under the applicable rules restrictions. What's technically possible and "best" is not important, only what is allowed matters.

 

I'm sure it's relevant to in a boat design forum to try to find out how a certain design is performing. I was surprised because I thought the Ace 30, being so expensive and having a big rig, would be much faster than it seems to be even on a pure speed for LOA basis.

I agree that racing means optimisation for the rules and conditions - that's what seems to be ignored when people claim that because scows win in some races they must be more efficient overall.

 

-I think it is more or less understood from my words that i see very wide bows as a kind of lesser wrong:

If you don't want to give up a gigantic Stern there are two ways to regain Balance:

A) move everything (Center of Gravity, position of the Mast and rigging, and the Daggerboard) aft, as the center of the sailboat has gone aft.

B) make the bow wider and thus balance the wide stern.

I prefer way A

 

LCB = LCF

Longitudinal position of Center of Buoyancy = Longitudinal position of Center of Flotation

It's really not that complicated

In this demolition derby (Vendee Globe 1996-1997) a good handful of sailboats capsized downwind with big waves, and Aqua Quorum showed a magnificent performance.

To make a Longitudinally Balanced sailboat like Aqua Quorum we only need to move the Mast aft, and so the appendage that holds the ballast becomes the Centerboard.

 

Evidently my idea (2025) will not leave the slightest trace in the course of this story of trying to reconcile a modern (1970-) sailboat with well-balanced old classics.

And in the future (2070-) scow-like forms will dominate the Oceans.

 

"Surf is the Way"

Yaw Control: sum of Lateral forces aft of center of gravity

Pitch Control: sum of Vertical forces forward of the center of gravity

 

"Surf riding"

I propose that, together with this expression, "Surf riding", well established as a concept in the hydrodynamic literature on ships ... we also use the concept and expression ...

"Surf gliding"

---

"Surf riding" is the more humble version of surfing

(on a cargo ship it can be problematic: New Surf-riding & Broaching JIP | MARIN https://www.marin.nl/en/news/new-surf-riding--broaching-jip)

a small sailboat can enjoy surf riding in small waves, which is the beginning of surfing in big waves: "Surf gliding"

 

I sailed an E Class scow a fair bit, and when the going went strange, it was nearly always sailing upwind in > 1 metre chop- a puff at the same time as a larger wave slapping the heeled flat hull could (did) knock her over. How did you control that sailing your scows? (Started sheets? How does a modern ballasted scow do that sailing short handed in the ocean? Multihull auto sheet release systems?) I have no doubt about downwind performance of Scows, but upwind, it can get dicey, quick and violent. I guess the old saw about ‘winning boats start looking better’ rules over detached retinas and other sundry injuries. Did any windsurfers not pound? (Besides the Serenity.) My CRIT 650 & D2 pounded enough that I inspected them after every sail….

 

The problem of Ocean navigation on a relatively slow cruising yacht

Waves sail very fast in relation to the speed of a relatively slow cruising sailboat hoisting (Jib + Mainsail) about 10-15 square meters per Ton.

The sum of the Wind force, the force of the Earth forward of the Center of Flotation (CF) and the force of the Sea push the sailboat with for example ...

2 degrees bow down, Pitch
6 degrees Yaw and
15 degrees Heel/Roll

This (-2 Pitch, +6 Yaw, +15 Roll) creates a large Munk Moment which can be even huge depending on how the Bow is designed.

The sailing is then uncomfortable for the autopilot or for the helmsman, the yacht even knock down ominously, and in the worst case capsizes and rolls over.

 

A Munk moment only applies to a fully submerged body.
A yacht hull, is not fully submerged!