How to Design a modern Yacht

The knife-sharp bows that were seen in the world of high competition until yesterday afternoon (-2015) make no sense: Upwind the sailboat is heeled and Downwind we want a spoon-shaped bow and even more so if the stem is vertical.

 

Note

JPK 1030 — JPK Composites https://www.jpk.fr/en/gamme/jpk-1030/

the last JPK

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Sorry

JPK 1085

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Sorry again

JPK 1050 — JPK Composites https://www.jpk.fr/gamme/jpk-1050/

JPK 1050

 

Transquadra 2017

Finish line

First we see Alex Ozon with a Plywood Epoxy "Bepox 900" and second JPK with a "JPK"

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Well no, in this video without sound you can only see Alex with the Bepox 990 that worried so many because it was unbeatable due to its contained wet surface compared to the then dominant trend. Less is more.

 

(1 Ton Plywood Epoxy Surfboard for an old fogey)

What are the differences in nuance with a "Bepox" 2015 or a new "JPK" 2025

LWL is smaller and therefore the D/L ratio (ca. 150) is higher, but it is much easier and more comfortable to hoist almost 30 square meters per Ton

And my Surfboard is not looking for speed or to win any race: the design is focused on Comfort and Safety which in the end translates into not using an autopilot or using a very cheap one

And the cockpit is more comfortable for an old fogey

 

and ...

it has two gears to stop safely:

plan A) hove-to like a yawl
plan B) hove-to without sails anchored in the sea with a sea anchor

and another detail is that the rudder and the centerboard are raised and so on the one hand they stay clean and, on the other hand, the small sailboat can rest on a nice sandy area

 

(I assure you with complete sincerity that I have been wanting to stop writing for months, and I almost managed it thanks to the magnificent ignore function of this forum but on the one hand I get distant echoes and on the other hand I obviously really like talking about my dream surfboard)

 

You appear to have the completely incorrect belief that there is only one "dominant trend". The wide, high wetted surface shapes are not really a dominant trend in world sailing - only in some of the most publicised events.

If you look at what people are really sailing you will learn that J/boats, TP52s and many others don't follow the "dominant trend", which isn't really dominant.

 

If you want a surfboard, why are you so obsessed with sailboats?

Is it that you haven't understood the difference between a surfboard and a sailboat?

 

This vice is worse than smoking and then trying to quit smoking

Last night I realized (Savitsky 1964) that instead of tilting the vector H towards the stern it is better to tilt the vector H1 towards the stern, the first way results in a resistance of 1218 Newtons and calculated in the second way it results in 1250 Newtons because H1 is more inclined towards the stern due to the fact that the Angle of Attack is greater than the trim (t) of the hull because it is the sum of the trim plus the shape of the hull

0.60 Froude
t = 2°

A) 3000 Newtons
H1) 3600 Newtons
H2) 6400 Newtons
B) 900 Newtons

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The sailboat in this still photograph is sailing in "young adventurer mode": 75kg + 25kg belongings, loaded with 90 days x 2000 kcal/day of food and 70 liters of fresh water

 

Jib: 9
StaySail: 7
MainSail: 14

I was 'sailing' a lot last night with Numbers

once again worried about whether a 9 square meter jib would be too little and maybe a 20-24-30 square meter gennaker

To my delight I see that the quest for speed pales in comparison to functional beauty

in 10-30 knots of wind, Downwind, the sailboat does 5 knots (0.35 Froude, which is "the real world hull speed") 6 knots (0.40 Froude, which is the theoretical hull speed) 7.5-8 knots (which is the "carene speed", "carene" around 150 D/L depending on the mode) and (StaySail+ MainSail second reef): 9 knots with 14-18 knot ... Surf

That is, in complete harmony with Force 7 waves that sail at 14-18 knots

 

With the sailboat anchored, the sailor sleeps under goose down in the bow in a enormous bed

And while sailing, the sailor sleeps in a sleeping bag on top of the 60 cm wide food cargo box and large chart table between the two closets without doors, one for dry clothes and another for wet clothes, that is, the sailor sleeps across so he doesn't roll with the roll of the sailboat

And who is in charge of the helm?

 

Autopilots

The cheap ones, supposedly cheap (ca. 500 Euros)* are actually very expensive for what they offer

Two autopilots have recently appeared, one in California and another in Germany, which for around 800 euros 950 dollars, compete with the 1.5-2 K Euro autopilots

Pelagic Autopilot Systems https://pelagicautopilot.com/

Pcnautic Tiller Autopilot https://pcnautic.com/en/product/pcnautic-autopilot-tiller-pilot

On the other hand, there are wind vane pilots between 1.5 and 6 K Euros

But the question is neither the price nor the electricity consumption in the case of autopilots, but the functional beauty

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*: OMG: 670

https://www.svb24.com/en/simrad-tiller-pilot-tp-22.html

 

With superb and exceptional Pitch control, and wonderful Yaw control... the sailboat almost sails alone

Let's not forget that Joshua Slocum sailed around the world without a windpilot or autopilot: simply by balancing the off-centre force of the mainsail with a jib on a bowsprit

if a sailboat almost sails alone (thanks to its stable hydrodynamic balance on the Pitch and Yaw axes) then it only needs to control the imbalance created by the force of the mainsail

 

Functional Beauty

Jib sheet to tiller

Simple Self Steering | Cruising World https://www.cruisingworld.com/simple-self-steering/

 

The staysail boom

The StaySail Boom serves a lot of functions and is one of the best inventions since cold beer

It is used to trim the sail upwind: we can adjust the angle of attack, the camber and the twist, that is, what they now pompously call "3D trimming"

On the other hand, it helps us to make the sail efficient downwind

It also allows us to install a reef and turn the staysail into a storm sail

And

It is a wind vane in charge of steering the helm



(Eric Hiscock, Cruising under Sail)

StaySail Boom to tiller