Length vs Beating, course vs pounding

[Sailor 99]

In MY Opinion if your boat can't go to weather then you bought the wrong boat plan and simple.



Now do you want to go to weather is another thing. Must racers want to go to weather because that's were the skill displayed.


Most cruisers want to reach or go down wind.



Beating 900 nm's up wind is tough and few would like to do.


Almost all of the round the world boats go round the world down wind.

[FranklinGray]

In my opinion, it is not the length/displacement ratio, but the displacement and speed of the boat that effects how she feels when the wave hits. Heavier boats move less to the wave; add in the extra speed you get from longer water line and you have a lot more kinetic energy to plow thru the wave which makes the ride smoother. Example: those long but very light weight offshore racing boats that just remain flat and waves washing overboard. They have the speed to create a lot of KE and even though they are very light displacement boats for their size, they do have decent displacement compared to say a 20'er. Remember, it is just the front part of the boat hitting the wave when beating, not the whole boat.

Also gotta keep in mind that the true wind moves aft the faster you go, so the waves do too. The farther aft the waves, the less impact you have.

Here is the formula for KE = 0.5 x mv2

So speed if squared, giving speed a big factor. Take two boats weighing about 9 tons, one is going 6 knots and the other going 9 knots. The first will have a KE of about 36,000 and the second will have a KE about 87,000. That is a lot more energy the boat is representing to the wave with just a 3 knot increase in speed.

The first boat represents my old 37' Hunter 376. My new boat, can carry a KE of 262,000 due to the 27 tons and extra speed, that is a 700% increase energy being thrown at the wave.

[FranklinGray]

Originally Posted by svsonora

I think displacement for the LWL ratio is more important than pure displacement, and so is hull design. A boat designed to plane and to be very lightweight for its size will never be as comfortable as say, a westsail 32. Even if shes a 60 footer.....

I totally disagree. Speed is a huge factor and the extra waterline allows you to go faster easily. A hull shape that allows you to plane allows you to exceed hull speed making the difference even greater. See my previous post about the formulas for KE to measure the different in energy smacking into a wave at different speeds.

Want a visual, look at videos of the offshore race boats where they are going at like 20+ knots and the boat is not rocking or rolling much at all, but the water is being push out of it's way and therefore, all the deck wash. It is a wet ride and intense, but smooth.

Now of course, a heavy boat going fast is pretty comfortable too Speed is the key.

[Sailor 99]

Originally Posted by FranklinGray

I totally disagree. Speed is a huge factor and the extra waterline allows you to go faster easily. A hull shape that allows you to plane allows you to exceed hull speed making the difference even greater. See my previous post about the formulas for KE to measure the different in energy smacking into a wave at different speeds.

Want a visual, look at videos of the offshore race boats where they are going at like 20+ knots and the boat is not rocking or rolling much at all, but the water is being push out of it's way and therefore, all the deck wash. It is a wet ride and intense, but smooth.

Now of course, a heavy boat going fast is pretty comfortable too Speed is the key.

Agree speed is very important. If your going slow up wind in a westsail 32 its going to be over all a crappy ride. Up and down and down and up for hours and hours and hours,.... Going nowhere. On the other hand if your in a big 45 to 55 footer with a big sail plan that can make 7 or 8 knots to weather then it will really nice ride.



A boat that gets up on a plane can be as long as you want, its still going to ride like a dinghy and going 900 miles up wind in a dinghy does not sound like much fun.

[FranklinGray]

Originally Posted by Dark Horse

...
A boat that gets up on a plane can be as long as you want, its still going to ride like a dinghy and going 900 miles up wind in a dinghy does not sound like much fun.

Well, weight is part of the equation of KE. A dinghy just isn't going to have much weight, but a 80' offshore racing yatch that is doing 30 knots is not going to be all over the place. True, there will be a lot of vibrations and noise that will keep you tense, but the movement will not be so much.

[secrabtree]

Originally Posted by StuM

> First, is that in general, a 50' boat may simply ride better than say a 35' or 40' boa

That's it in a nutshell.

The operable word in the quote is MAY. And what that word ALWAyS also includes is "may not". Things like hull design, sails (amount and cut and quality), and sailing ability of the skipper all have major effect upon comfort. On the return trip from Hawaii I had a friend crew on my fairly light displacement Cal 39 that had previously made that trip on a heavy displacement boat. Before the trip he told me that he wouldn't choose to make that trip on such a light displacement boat except as a friend of mine. After the trip he said my boat sailed more comfortably (and fster) than on his previous trip on the heavier displacement boat.

[markbarendt]

Originally Posted by peter loveridge

gentlemen do not sail to windward, at least not in boats whose length in feet is less than their age

Giggle, dang that's a big boat...

But, I'm not necessarily a gentleman so...

[Don C L]

Is there a monohull that can do 20kts to windward? And have a smooth ride? That’s my next boat!

[Stu Jackson]

Originally Posted by markbarendt

>>>>>>>>>>>>>>>>>
That’s the inspiration for this thread. Having the skills to make the upwind journey as smooth as possible is important.>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>

Good inspiration concept. You are aware that the skills come from the doing, not the reading, albeit boat choice input is helpful. Good luck, happy hunting.

[markbarendt]

Originally Posted by secrabtree

The operable word in the quote is MAY. And what that word ALWAyS also includes is "may not". Things like hull design, sails (amount and cut and quality), and sailing ability of the skipper all have major effect upon comfort. On the return trip from Hawaii I had a friend crew on my fairly light displacement Cal 39 that had previously made that trip on a heavy displacement boat. Before the trip he told me that he wouldn't choose to make that trip on such a light displacement boat except as a friend of mine. After the trip he said my boat sailed more comfortably (and fster) than on his previous trip on the heavier displacement boat.

That interesting.

[ancor]

BVI, seastate is the factor, not the wind strength, especially if the breeze only just came up.

[MartinR]

25 knots apparent or true, real wind or from masthead instrument? If from masthead instrument, reduce by 15 or 20% unless the instrument is calibrated for height. Yes, sometimes beating can be comfortable and sometimes not, depending mostly on wave period. Correct reefing helps, in choppy sea though, more sail area is needed to push through, though. Longer boats are generally of course more comfortable beating up, though not every time. Narrow boats are at a disadvantage, as they heel more, but the positive is that they roll less. This is a complicated equation, giving different results each time,-).

Actually, long keeled traditional boats tend to give a more comfortable ride "uphill", although slower. So, on a modern boat you will have less comfort, but for shorter time.

[MartinR]

Originally Posted by FranklinGray

I totally disagree. Speed is a huge factor and the extra waterline allows you to go faster easily. A hull shape that allows you to plane allows you to exceed hull speed making the difference even greater. See my previous post about the formulas for KE to measure the different in energy smacking into a wave at different speeds.

Want a visual, look at videos of the offshore race boats where they are going at like 20+ knots and the boat is not rocking or rolling much at all, but the water is being push out of it's way and therefore, all the deck wash. It is a wet ride and intense, but smooth.

Now of course, a heavy boat going fast is pretty comfortable too Speed is the key.

We talk about beating here.......

[MartinR]

Originally Posted by FranklinGray

Well, weight is part of the equation of KE. A dinghy just isn't going to have much weight, but a 80' offshore racing yatch that is doing 30 knots is not going to be all over the place. True, there will be a lot of vibrations and noise that will keep you tense, but the movement will not be so much.

You mean if you drive a car at high speed, high kinetic energy, and hit a bump in the road, it will be more comfortable? In my experience, the car goes flying.
The reason modern racers are not moving so much downwind is because they can stay on a wave for longer. Upwind, though they have kind of dismal motion comfort. The high kinetic energy is rapidly transformed into potential energy when you hit a wave...... .I agree with you, downwind, speed is the key. Upwind you have to adjust speed and angle to optimise the behaviour of the boat.

[Dave_S]

I've posted about this on here before but it doesn't get much support from the crowd.

I like the idea of T foiling rudders for my cruise boat.

They are almost always used to provide foil assist... i.e. lift. Most outcomes for this end with cruising catamarans not having the power to weight ratio to allow the foils lift to overcome drag and end up with a net loss.

My plan is to have 0 lift when the boat is at it's no sea state sailing level. However if the boat chages from level by X degrees the T foil will change by the same amount, this moves the pivot point of the boat backwards so it will behave similar to a much longer boat.

This should result in a number of benefits with smaller losses. This is not my idea it has been used before successfully on a smallish number of boats, most smaller and lighter. I have yet to see a flaw in the idea.

I'll let you know over the next year or so.