Savitsky 1973

Resistance of transom-stern craft in the pre-planing regime





This

This is exactly what I was looking for, the missing piece

(A) Up to 0.45 Froude we have Delft and "the main part of Michell"

https://www.mdpi.com/2077-1312/8/6/400

(B) From 0.45 to 0.75 we have this Savitsky-2 (1973) to have bifocal vision with other estimates, and beyond that

(C) the classic Savitsky-1 (1964)

Problem solved, And everything fits together by adapting Savitsky to the profile of a sailboat hull, an adaptation I call Savitsky 2025

 

With bifocal vision from two points of view... the suspicion of being trapped in a tunnel is dispelled, and the beautiful sensation of feeling reality emerges; how wonderful scientific knowledge is!

 

1 Ton WindSurf Board Plywood Epoxy, Total R @ 0.60 Froude

- Delft: 1304 Newtons
- the clue that Dolfiman gave us: 0.7 Delft: 1048 Newtons
- my model: 994 Newtons
- Savitsky 1973: 975 Newtons

 

The effect of raising the bow out of the water combined with a gigantic wide stern is spectacular.

i) By raising the bow out of the water, drag (Froude => 0.60) is greatly reduced.

ii) The wide stern also reduces drag

iii) The wide stern eliminates the destabilizing low lateral pressures at the stern, which, combined with a bow out of the water, means we can send Mr. Max Michael Munk to a peaceful nap, much to the delight of the autopilot.

iv) The large, wide, and difficult-to-sink stern interacts hydrostatically with the angle of attack, controlling it like the flaps or interceptors on a motorboat.

The enormous difference that is often forgotten between a motorboat and a Surf-glider is that the propeller raises the bow, while the sails, with their enormous leverage, sink the bow.

And the major difference in the hull design of a 1-3 ton sport sailboat and a dinghy is that the dinghy sails upwind at 0.40 Froude instead of 0.35 Froude And ... And that Downwind the crew can trim the hull, in a 1-3 ton sport sailboat the hull trim must be hydro-Dynamic

 

+ A deep cockpit offers safety, comfort, and functional pleasure. Furthermore, the ballast tanks are located below, above the chine, and drain through simple plugs in the cockpit floor

+ The mast is 40 cm from the cockpit

Climbing on deck is strictly forbidden; it's madness on a small light sport sailboat.

+ And since there are no cables or stainless steel on deck, the bowsprit rotates aft to launch and retrieve a beautiful small A5 gennaker

Of course, the sailor has to get off his confortable seat. A cruelty by the designer.

And the magic carpet sails away on the Wave, Surf-gliding at the speed of the Wave: 12-14-16-18-20 knots

 

Note

Note how the same research can be interpreted in two ways:

It is evident that those who read Savitsky (1973), when translating from motorboats to sailboats, said: "Let's make light sailboats with very sharp bows."

And now we read it as saying: "Let's make light sailboats that quickly lift their bows out of the water, taking into account the force of the sails and their enormous leverage."

 

Note, 2

JPK 1050 - IRC racing machine https://www.jpk.fr/en/gamme/jpk-1050/

"Carène scow, déplacement très léger et grande surface de voile"

(maybe 300 K Euros)

Note how we now have to cite the now ubiquitous "scow" that is: wider bows



The pencil marks the first chine position in S1.

A lower chine and a wider nose allow for the construction of a larger, more efficient wing.

To quickly get the bow out of the water in a fast transition in the 0.50-0.60 Froude zone

 

And

And a high chine at the stern and very very low chine at the bow, along with the reconciled longitudinal positions of the fundamental centers (CF, CB, CG), allows us a semi-classical longitudinal balance, and ...

even that when heeling, the center of Flotation moves forward as if was designed by Herreshoff

https://herreshoff.org/explore/

 

2025

JPK 1050

A fully equipped one might cost perhaps around 400,000 Euros

 

Let's suppose the genie in the lamp gave me that 400,000 Euros sailboat, question: - would i enjoy hoisting a gigantic A3 gennaker all by myself?

Nah, 3-3.5 ton sports boats are for two-person racing.

And the scientific thing is 1 sailboat, 1 man.

What is the essential founding for the success of a fishing rod among the male tribe?

Nothing.

or everything: Zen contemplation, cave/hut, freedom, ease of mind ... and the beauty and functional pleasure of seeing and feeling a machine working well in harmony with nature

 

3.5-ton 300K sports sailboat (the first estimate was better) with a gigantic 120-square-meter gennaker, and we assume a Displacement of 3.75 tons = 43 square meters per ton

0.85-ton 60-70K sports sailboat with a small 24-square-meter A5 gennaker on a swiveling bowsprit, and we assume a displacement of 0.95 tons = 47 square meters per ton

I mean, the Savitsky-64-73-25 Surfboard can carry food and drink for 90 days for 1

---

For example, for a 20-day Atlantic crossing east to west

+ 850 kg (= 375 Hull + 270 keel + 200 kg)
+ 100 kg, 1 man and things
+ 75 kg, food for 90 d
+ 90 l, fluids
= 1.115 tons

40 sqm per ton

 

Aqua Quorum

https://www.histoiredeshalfs.com/50' monos/C10 Aqua.htm

On a modern sailboat, the optimal position of the keel-ballast, both to avoid a violent pitch upwind and for good downwind surfing, is aft because the sailboat's primary center, the center of flotation, is also aft.

The enormous advantage of a small, 1-ton sailboat is that, to begin with, it doesn't need a backstay, and to finish, a 3/4 fractional rig fits perfectly: the keel is the centerboard for upwind sailing.

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Demolition Derby 1997

I can't find it, but something like 4-5 yachts capsized or disappeared at sea while Aqua Quorum was surfing brilliantly and then turned upwind to rescue a sailor.

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Pete Goss. Sailor, adventurer, international speaker. What next? Find out here https://petegoss.com/blog

Pete Goss new/last boat

Pete Goss: a new mini-exploration yacht that’s a bit different - Yachting World https://www.yachtingworld.com/cruising/pete-goss-a-new-mini-exploration-yacht-thats-a-bit-different-143376



Outside the crazy world of seeing who can pee the farthest, we only owe obedience to three gods: Functionality, Comfort, Safety