What made Pilot Cutter so fast? Just rumors?

[NewAlexandria]

You are tiring me out, but I'll answer in order:

1. How exactly are your formulas "10 times better?" Or better in any way?
The answer is in my post, but I'll go step by step here. Speed to Length Ratio 1.25 is what I used across tons of boats. Some of them I lump together, some of them I chose on purpose and I ended up with boats and their speeds. I came to WS32 and some other boats with similar water line length. It confused me why using the formula fat WS32 had same speed as a skinny boat of same length. Then I realized MAX HULL speed is the same no matter how fat the object is as long as you have the power to overcome the resistance. So something else is at play then and it has to be calculable. Then I realized the STL 1.25 ratio is useless,and there has to be a better way. I contradicted the STL 1.25 ratio with the the 1.34 theory and assumed to completely abandon the STL formula in favor of a formula that will allow me to see which boat shape is easier to make TOP Speed. That way my formulas will be able to distinguish between fat and skinny boats, or verses more or less displacement. I wrote them and they were good enough to reclassify the boats I had on the list. That's when the original pilot cutter to me became a different boat than WS32 or some other known boat. Which answers my original question for this thread. And I was able to do this with numbers. STL 1.25 has no meaning for displacements sailboats but it does have meaning for other boats (planing). It does not solve anything, neither does it show MAX HULL speed for the boats I'm working with. Read more in Answer 2.

2. ON your 1.34 question
I really have no idea what you want me to answer here. In the beginning I said the 1.34 is the only thing that makes logical sense to me, and that 1.25 rule is contradicting the 1.34 theory, and that I will stick with 1.34 idea. Btw, if you search long enough, other sailboat forums use the 1.34 theory and completely don't really on 1.25 but they have no idea why. I explained why I selected it in my post before.
How it came about? Only what I read in the book, who invented it, and how it is used. Me and you are beating a dead horse at this point.

3. Stability
My answer is diplomatic maybe because I dont' have full understanding of it, I did not get deep enough into it, and I don't want to calculate the full stability of a sailboat just yet. I'm only interested in the stability gained from momentum + initial stability, and how those 2 create the compromise with the speed of the boat and it's RATIO. This is the most important part to me. I have no idea what you want from me, if I'm telling you where my limit is. Also, I haven't started talking about boat stability here yet, so you could not have WTF going in your head because of that. I avoided the topic.

Anyway, I'm done with your posts for now. It takes too much energy. Unnecessary back and forth between us and it takes away from the thread. Best advise for you would be to assume I know nothing and tell me. That way I will know for sure.

P.S. Just realized the stability post was not for me. oh well, too late.

[Lee Jerry]

Originally Posted by NewAlexandria

You are tiring me out, but I'll answer in order:

1. How exactly are your formulas "10 times better?" Or better in any way?
The answer is in my post, but I'll go step by step here. Speed to Length Ratio 1.25 is what I used across tons of boats. Some of them I lump together, some of them I chose on purpose and I ended up with boats and their speeds. I came to WS32 and some other boats with similar water line length. It confused me why using the formula fat WS32 had same speed as a skinny boat of same length. Then I realized MAX HULL speed is the same no matter how fat the object is as long as you have the power to overcome the resistance. So something else is at play then and it has to be calculable. Then I realized the STL 1.25 ratio is useless,and there has to be a better way. I contradicted the STL 1.25 ratio with the the 1.34 theory and assumed to completely abandon the STL formula in favor of a formula that will allow me to see which boat shape is easier to make TOP Speed. That way my formulas will be able to distinguish between fat and skinny boats, or verses more or less displacement. I wrote them and they were good enough to reclassify the boats I had on the list. That's when the original pilot cutter to me became a different boat than WS32 or some other known boat. Which answers my original question for this thread. And I was able to do this with numbers. STL 1.25 has no meaning for displacements sailboats but it does have meaning for other boats (planing). It does not solve anything, neither does it show MAX HULL speed for the boats I'm working with. Read more in Answer 2.

2. ON your 1.34 question
I really have no idea what you want me to answer here. In the beginning I said the 1.34 is the only thing that makes logical sense to me, and that 1.25 rule is contradicting the 1.34 theory, and that I will stick with 1.34 idea. Btw, if you search long enough, other sailboat forums use the 1.34 theory and completely don't really on 1.25 but they have no idea why. I explained why I selected it in my post before.
How it came about? Only what I read in the book, who invented it, and how it is used. Me and you are beating a dead horse at this point.

3. Stability
My answer is diplomatic maybe because I dont' have full understanding of it, I did not get deep enough into it, and I don't want to calculate the full stability of a sailboat just yet. I'm only interested in the stability gained from momentum + initial stability, and how those 2 create the compromise with the speed of the boat and it's RATIO. This is the most important part to me. I have no idea what you want from me, if I'm telling you where my limit is. Also, I haven't started talking about boat stability here yet, so you could not have WTF going in your head because of that. I avoided the topic.

Anyway, I'm done with your posts for now. It takes too much energy. Unnecessary back and forth between us and it takes away from the thread. Best advise for you would be to assume I know nothing and tell me. That way I will know for sure.

P.S. Just realized the stability post was not for me. oh well, too late.

2. The fact that you don't know what I'm asking is quite telling. (Didn't your book tell you?) The 1.34 is not "a theory." Here's the answer:

Hull speed is when the length of the bow wave equals the waterline length. The speed of a deep water gravity wave (surface wave) is:

C = sqrt(gλ/2π)

where 'C' is wave celerity, 'λ' is wavelength and 'g' is gravity. 'g,' '2' and 'π' are constants and can be brought out of the radical. So:

sqrt(g/2π) = 2.2628856

Of course, this doesn't equal 1.34, but we haven't considered the units. The units of 'g' are ft/s^2, and the root of them are ft^1/2/s. '2' and 'π' are both dimensionless. The units of wavelength are feet, and when the root is taken becomes ft^1/2. When combined we have ft/s. But we want velocity in knots, so we have to multiply by 3600 s/hr and divide by 6076 ft/nm. Thus we get:

sqrt(g/2π) * 3600 / 6076 = 1.3406860 ≈ 1.34 nm/hr

Replace celerity with boat speed and λ with LWL, and thus the hull speed formula:

V = 1.34 sqrt(LWL)

with V in kt and LWL in ft.


1. Experienced naval architects and designers use that experience by looking at not just hull speed but also other factors, such as displacement - length ratio, sail area - displacement ratio, ballast ratio, and other things, to modify the hull speed formula. This may include the lines plan (if their design) or pictures of the hull. They may include the ability to plane, if applicable, to whatever extent. Thus, they use S-L ratios that differ from 1.34 to predict performance, lower or higher as required. That's where the 1.25 to 1.5 range (or greater) comes from. Lower for fat, round, heavy boats; higher for skinny, flat, light boats. It's not random. (Oh, and it's not a top speed, but rather a design speed for the expected "power;" if power is higher speed could be higher.) Just because you don't understand, doesn't make the numbers wrong.


3. Your concept of stability (that you haven't defined) is too whacked to deal with. I wouldn't know where to start.

[Chris 249]

Well done, Jerry.

I notice that our new resident legend in his own basement hasn't got the honesty to address the fact that he is completely wrong with his astonishingly silly claim that sailboats can't plane.

Trolls are so dishonest and cowardly that it's rather astonishing.

[Don C L]

Just for fun check out this example of something very old but very advanced. The ratio of simplicity to speed is off the charts.
Shunting a crab claw sail. No rudder, a paddle. (OK second one has a rudder) Those who lived, and live, on the sea, considered this optimal. The image is from Marchaj's book "Sail Performance," page 159.

https://www.youtube.com/watch?v=yV3R_U7KYpw

https://www.youtube.com/watch?v=esvihQymZWI

[NewAlexandria]

I figured it out. I found the freaking Compromise Ratio. It was in front of us all along, in mathematics (geometry), but no one put the 2 + 2 together on paper, but humans were doing this all along from experience, from feel. I found boats that support my theory and are only off by 0.04 without calculations. I will eventually write it all up. I had a feeling the Sweet Spot is based on 2 numbers, but was not sure which one. Now I know.

Going through boat data and looking what others did I realized the answer.

[Chris 249]

Is "the answer" something to do with you admitting that your claim that sailboats can't plane is completely false?

How many people do you expect to convince when we all know that you are denying the reality we see and experience?

[Lee Jerry]

NewAlexander, do you remember when I said this:

Originally Posted by Lee Jerry

No one can disprove what you say because you talk nonsense. When they do make a point to demonstrate that you're wrong you just ignore it and go on as if the post doesn't exist. Requests for clarification go unanswered.

And you responded with this:

Originally Posted by NewAlexandria

Show me exactly where I did that and I will reply...

I gave just a couple examples (of many more cases). And now you've done it again. Did you see post #107? Any comments? Questions? Corrections to your previous statements? Or are you just going to ignore it?

[Chris 249]

I think he'll just ignore it, LJ, just as he ignores the reality that he lied when he said that sailboats don't plane.

[Lee Jerry]

Originally Posted by NewAlexandria

I figured it out. I found the freaking Compromise Ratio. It was in front of us all along, in mathematics (geometry), but no one put the 2 + 2 together on paper, but humans were doing this all along from experience, from feel. I found boats that support my theory and are only off by 0.04 without calculations. I will eventually write it all up. I had a feeling the Sweet Spot is based on 2 numbers, but was not sure which one. Now I know.

Going through boat data and looking what others did I realized the answer.

"I found the freaking Compromise Ratio."
I do hope it is as profound as your last revelation.


"I found boats that support my theory ..."
And how many did not support your theory? You're not cherry picking data are you?


"... and are only off by 0.04 without calculations."
How do you know how far off they are without calculations? Didn't you have to do a calculation(s) to get that 0.04? Further, what does that 0.04 mean? Does it have units? The answer is: it's meaningless without context. (But thanks for sharing your success.)


"I had a feeling the Sweet Spot is based on 2 numbers, but was not sure which one."
Before, you said it was going to be one number to get your "optimal" boat. Now it's two...

[NewAlexandria]

I did not forget about you or this thread. Be patient. I'm compiling more data to show you. It's beautiful. You will like it. I need to be patient with this to be fair and accurate.

Also, I did get Marchaj book. I hope his English flows nice since he is my old country man
Book was $10 shipped. People have no idea on this planet how worth these books are these days. World went into "money" direction, but you can take advantage of what people abandoned. In Manhattan at Barnes and Nobles they have less books about sailboats then me now.

P.S. Whenever I search something about sailboats, this thread is on the main page of Google often.

P.S. 2. Skene's book is good, especially those 2 last chapters where he actually shows every calculation. Not as deep though, but his English flows smooth not like the other I read. You need both though. The Sea Bright Skiffs book was also very good, because it showed me how to build something in a simple way, and it was very interesting in terms of my Perfect Ratio hunt. Stay tuned.

[Chris 249]

I'm patient, but when are you going to be "fair and accurate" and admit that you were wrong to claim that sailboats can't plane?

I t's not just that you can't understand that the fact that you don't admit you were wrong proves that you can't be objective or reasonable. It's also that you missed such an obvious fact, which proves that you don't even know the most basic facts about the area you are claiming to be an expert in.

Here's a hint - when you don't tell the truth, other people know you're not trustworthy and therefore it's logical to disbelieve what you say. The other issue of course is that what you say is unscientific and doen't chime with reality.

[MicHughV]

A lot of boats will list "xx" feet of LWL, but as soon as the boat is on the move, even slowly, the LWL will increase.

What about a beamy, deep draft boat of say 30' LWL and another one with planing hull also with a LWL of 30'...the same speed....I don't think so...

[Bowdrie]

Originally Posted by MicHughV

A lot of boats will list "xx" feet of LWL, but as soon as the boat is on the move, even slowly, the LWL will increase.

What about a beamy, deep draft boat of say 30' LWL and another one with planing hull also with a LWL of 30'...the same speed....I don't think so...

This is a broad generalization, but we can also have a situation with shall we say, a "want's to but can't quite make it" regarding planeing.
An example might be some of the 1st. generation IOR boats with their fine stern sections that were optimized for up-wind work.
On some the steering could become squirrely when pushed hard downwind.
As they tried to "get over the hump" in the S/L ratio, the sterns would settle, the bow would rise-up and climbing the hill of the bow wave was just about a lost cause.
The designers added "blisters/bumps and humps" to the stern sections, this gave more buoyancy in the stern, it helped the steering and helped to keep the bow down and with the boat more level more sail power translated into "go" instead of "climb".
By suppressing the stern wave, the boat could "fool" the water just a little into acting like the WL was longer than actually measured.
The reverse of that might be our Westsail 32. When it's pushed hard the stern wave gets up where you could surf on it and additional sail just sinks the boat deeper into the hole it's digging.

[NewAlexandria]

Can you help me get the beam of the Grimalkin Yacht?
Was it 10 feet and 3 inches?

[NewAlexandria]

Chris, give me your definition of planing for a sailboat,and give me your definition of a sailboat as related to this thread and I'll answer.

Big heavy sailboats do have LIFT as well, and due to that lift and big waves they can appear to be on top of that water for a moment, but that's not planning. Not even semi planning. Planning starts at about 20 to 24 mph. No heavy displacement sailboat can do that. Stern wave gets disconnected from the stern. That's planning.

"Grimalkin's beam is 10.25 ft according to published data and it's very likely to be right because that was common for such designs - but so what?"

Thanks. You will be nicely surprised so what.