What's a spin anyway

Boat talk. I've always liked boat talk. In RL is is usually about sailing faster or repairing something. In SL it is often about making the sailing experience better. Right now sunshine is on the top of my list, but having both sunshine and boat talk at the same time... Doesn't get much better. I caught Craig "J-man" Ktaba tuning his lovely Ktaba 20 Teleri somewhere in the North Sea. It wasn't exactly a clear blue sky, but a piece of blue is also good.

Clear blue sky and boat talk

I wasn't really looking for blog-stuff, but I just had to snatch the picture above. Especially as february carries on with the sunless days we saw in january. As mentioned in the former post: January 2014 was  the darkest month in 45 years.

The North Sea is a pretty sailing area, but this won't be a sightseeing post. Craig had a really interesting issue to discuss: How does the spin-trim - or lack hereof - affect the boatspeed at different windangles. Now, Craig knows perfectly well what a spin is. The real question is: How to make a good approximation of all the wonders of spin-trim in SL. That's a question that won't fit into a short happy-go-lucky post.

Let's delve into it. Say you already have a boat that sails pretty much according to a polar. How does the spin then affect performance? Easy. Compare two polars from the same boat; One made without spin and one made with spin. The only real challenge is to get polars from a J-Class, but we can take a spin from a smaller similar boat and check that out. The IOM for instance. In low winds, going close to the wind, the spin can double the boatspeed. In strong winds most boats will be doing max hull speed. Unless the boat can plane or foil - and a J-Boat can't - it is impossible to cross the max hull speed. (See this for details. Scroll down).

Gulls and seals

Then there's the matter of trim. The polar may show boatspeed at certain wind angles, but usually the polar assumes optimum trim. This makes it a bit tricky. On a dead run you'd have a pretty rounded spin; Not too round cause it should also be wide enough to catch as much wind as possible. Not too wide though, cause then the wind would just glide off. Let's call that medium round trim. It's easy to find on a dead run. When the log maxes out you'r there. But... How do you graph that?

On a reach the spin works entirely different. Reaching means getting the wind from the side at some angle less than 180, and that means the boat will heel. If you heel too much, the keel will have less effect and the spin will just drag you sideways. So max speed on a reach doesn't neccesarily mean max power. You may very well need to depower in order to reach max speed. Not only is the position of the spin important. You'll also need to change the shape.

On a dead run you'll want a nice round spin. The airflow is kinda like a bag on a stick. We all did that as kids, right? Bamboo-stick, piece of string and a plastic grocery-bag. Now, on a reach you'd want to stretch the spin - flatten it - to make it work more or less like a giant genoa. The airflow gradually changes (with the apparent wind angle) from kite-like to wing-like. (See my post on telltails).

Let's go for a swim

The smaller the windangle the more flat you need the spin to be, or it'll just heel you over and drag you sideways. At around 100 AWA a normal spin stops working. A little less in low winds, a little more in strong winds. That's why real racers have many spins for different angles and windforces. So the boost from the spin depends on windspeed, boatspeed, windangle apparent windspeed and trim and some of these parameters are (very) interdependant. Now, all we need to do is to convert this gibberish into math - et voila - we'll have a great simulation of the spinakker.

In other words: We're looking for a formula that takes windangle, windspeed and leeward and windward sheet positions and produce a power factor which we can convert into speed and add to the speed coming from main and jib. I think that's what they call a VPP. Have a great weekend...

PS: More on the Ktaba 20 updates in a future post. Here's a hint...

Ktaba updates

A few days back I met Craig at TYC. I was planning to go tune my Fizz, but Craig was quite excited about his latest work on the Ktaba20. We talked boats for a while, but those updates really sounded interesting. I simply had so see them, so I hopped on board the beautiful Ktaba20. I can always do some more fizzin...

Boat talk 

Some of the new things had to do with the sails. That's why I sat on the front deck; To see those sail details. I like being up there. It's one of my favourites in RL, because you are even more immersed in the sailing whilst sitting up there - in the middle of everything. Perhaps my attitude up there is not very speedy, but it sure is a great place to sit while cruising. You could have an autopilot handling the steering for total relaxation, but that's more of an RL-thing. The waters in SL rarely offers hours of sailing in a straight line.

Take off

Besides, it's always nice to have someone like Craig at the helm. Then you know it's a smooth ride. No running aground and stuff. Lotsa nice boat talk too. We sailed north to have a peek at new Seychelles up there. As usual, the Ktaba20 sails like a charm. The sailing engine is Craigs own. It's very stable, and it comes with full WWC support. Make no mistake. We may look very relaxed, but the Ktaba20 is not meant for cruising only. Inside the Ktaba20 there's a racing heart.

Peeking

It turns out there's not much space in between those Seychelles, - more on that in a future post. We choose another route with more open sea to better test the new features. And they work great those telltails, - for that's what it was: Telltails enabling the cruiser to sail by visual - and the racer to find optimum speed without using huds and pocket calculater-like displays.

Open sea

We talked a bit about telltails. How to use them, where they go and why they work. Lots can be said about that, but in reality it's dead simple. The jib has a couple of telltails not far from the headstay. They indicate the flow coming on to the sails, and they are the ones by which you steer on an upwind and trim in any other case. The main has leech tails and they are the ones by which you trim the main. I better prepare a post on that subject.

It's very nice to see more telltails in virtual sailing. The Ktaba20 is now part of an exclusive club with only a few members still: The Flying Fizz, the Laser, the Cotton Blossom II, the Bolero and the virtual optimist aka the Shelly Fizz. Did I forget anyone? Ahh, yes... Manul made a tri-thingy with a fizzkit engine. I think it has telltails too.

PS: Why are there no closeups of those telltails? Good question. They need just a little bit of tweaking before they are perfect, and when they are, I'll post them.

Ktaba Wauw

I rarely get my hands on a boat that really makes me go wauw! It happened a few days back with another update of the Ktaba 20. Yes, Craig Ktaba is still working on the already beautiful Ktaba20. It's a long journey towards perfection, but it is so worth the wait.

Jib sheets

This version is much improved on both sailing engine and the graphics details. The graphics details are top notch. Just check the image above. Not only does it come with a main sheet. There are jib sheets too, and they actually run around the winches and back to a cleat; And they only do that to leeward.

Windex

Looking up there's more fun. This is probably the first time I've seen a keeler with windex that works; Meaning two things: It turns with the apparent wind, and it can be seen from the cockpit. Not a big deal, as many boatbuilders would say. Wrong. The windex is one of the key components of creating that feel, the illusion of being in a real boat. It's been on the Shelly Fizz, built by a racer and loved by racers, for years.

Smooth sailing

Question: What's the first thing a sailor looks for, - before setting sail? The wind direction. Why? You simply cannot sail (or even set sails) without knowing the wind direction. And where can it be seen? Look up, and there it is. Craig even modeled a windex that looks pretty much like a real one. It only misses the screaming orange colour on the bottom side; Makes it easier to see from the cockpit.

Sheets and boat

Here's one more shot of the sheets. Note how they run through the sheet traveller and around shrouds. The loose sheet just hanging round the mast. Totally realistic. I just love lying on the foredeck, half asleep, listening to the bow wake, having an occasional peek at the windex, the sails and sheets; Just to make sure the autopilot is on course.

Tiny details

There's just one tiny detail about those sheets; Probably noone will notice, but it is visible on the picture right above here; I'll let you figure it out, and then I'll send Craig an email about it.

The feel? The sailing? It's delicious. The sails look like sails, and they luff when they're supposed to. The boat moves like a boat; It supports realistic waves from the WWC windsetter. It heels over and accellerates as a real boat. It has nice sounds, though the winches are kinda silent.

La Deliciuse

One obvious thing gone missing though: There's no telltales. However, there is a pretty good hud in the form of a compass that includes wind angle, real and apparent. This means it is perfectly possible to sail the boat without that (f)ugly floating text hud, which so many boatbuilders seem to find sufficient. Oh, and there is a trimmable spin; And if you aren't really comfortable hoisting the spin, then you can always just wing the jib.

Taking a break in a lagoon

Cruisers will probably prefer that winging jib, as it is easier to handle. Requires less attention. In many ways the Ktaba is in fact perfect for a cruise around the virtual oceans. So many lagoons begging you to sail there, to moore and explore. It has room for a few friends too, and if they aren't just there to tan, they can even take part in the trimming.

Moored

That's when it starts to get really interesting. This lovely cruising vessel is built to race too. It has crewed  trimming, and there's several sail configurations to choose from. All this is run by a pretty lean and mean sailing engine, - built specifically for this boat. Low lag, easy sim crossing and WWC support, so there's shadowing, windbending, shifts, gusts, currents and more. A total dream machine. Wauv. Sail simulation? Oh yes! Much more on that in a later post.

Between the sheets

This is not a post about Craig and me being naughty. Nor is it a post about a cocktail inspired by boatly devices or weird liquids such as the Windex. Incidentally, that is an interesting question: What would be in a drink called "Between The Sheets, sailors edition"?

Tight sheets

Anyway, here we are, - all relaxed and between the sheets. Oh, I don't mean in the sense of being physically entangled in the sheets. Let's leave that to real life sailing, hehe; The important thing is, there is a sheet. A working sheet.

Loose sheets

See the stretching? In, out... Tight sheets, loose sheets. What a pleasure. If you check the other virtual boats in SL, very few of them actually have sheets. The boom and the jib might rotate, but there's no ropes to make them do so. The Flying Fizz is the exception.

Sheets on wheels

On the KTaba 20 there's even a set of blocks, one at either end of the sheet. All we're missing now is a twofold fiddle block configuration. Not entirely sure if that's the correct english term. In any case, it is very nice.

Since it is friday, it might also be nice with a drink... How about composing a "Between The Sheets, sailors  edition" !! I suppose you'd start by gently pouring some boat-rubbing, but... then what?

Distinguished class

Craig of the Ktaba tribe has gone and done something very nice and very extraordinary. Something seen only on a few very special virtual boats sailing the SL waters.

Wooohoooo

The Ktaba 20 now enters the distinguished class of boats with... Can you spot it?

(Hint: Even the brand new and super delicious Melges 24 hasn't got this feature. Naahnee naanee naanaa ;-)

Ktaba platinum

It's not really a Ktaba 20 Platinum, but it is a Ktaba with a few improvements over the last edition. Last time  the Spinnaker had autotrim. It still does autotrim, but now I can tweak it. Here's me watching the spin as Craig trims it.

Trimmable autotrimming spinnaker !?

Trimmable autotrim spinnaker? Sounds a bit weird, but it seems to work pretty well. Another thing is the flotation height. On the photo above you cannot see the bottom paint. On the next shot you see it.

Blue bottom paint

What you cannot see is that the other side "sinks" down correctly, as if the boat "sits" in the water, - not on the water. Dunno what the blue stuff is though. It sure isn't VC17m.

Gybing with boom

What also works now is gybing. Now the spinnaker boom will actually switch side. What's left to work with is the spinnaker shape. This is reportedly one of those very special and difficult things to adjust.

Poses

There's also a couple of nice poses available. Not only will the boat make you feel good because it sails nicely, - it will also make you look good. I like. All in all there are lots of small improvements. Small but vital for the overall impression. Oh, and it is stable. Good sim crossing, low lag and very few  crashes.

Cruising

What's still missing is the vane. In the picture above it seems ok, but it still flaps aftwards on a downwind course. A couple of telltales in the jib  would also be very nice.

My favourite spot on a cruise

About the windsystems... We tried switching back and forth from BWind to WWC a couple of times. It works well, but more testing is needed in order to determine if the boat has full WWC support. Wind, waves and currents. Right now it seems to not support waves. We didn't have time to check the currents. More on that in a post near you...

Here's more on the Ktaba 20.

Ktaba-time

The Ktaba 20 continues to evolve in the hands of its builder, Craig Ktaba. Last time I wrote about it, it wasn't quite ready for primetime; Now it's getting close. Let's see what's new...

Relaxing

There is a new and improved spinnaker pole. The spinnaker itself is also much improved, and it now has autotrim. I am sure some people like that. I know I do. It's perfect for cruising. For racing I will most definately want a spinnaker I can tweak for max performance.

Moored at Tradewinds

As you can see, the boat still looks great. In my last post about the Ktaba 20 I didn't show the mast in detail. Why? Because it wasn't really finished. It was just a stick with a set of spreaders and that was it. It was also a little too short.

The much improved mast

That has been fixed. Now, it is a pleasure to look up, when sailing the Ktaba 20. Thank you Craig. It makes the experience much better. However, there's still a few details. For one thing, the vane up there always points backwards when sailing, - even on a downwind course... Looks kinda silly and makes the vane useless.

The Ktaba 20 under sail

Here she is under sails. Not sure what kind of monster it is, that I see down south, but luckily the virtual world has no smells or scents. If only we could have a few buttons to click and select only the good ones. Flowers, the ocean, freshly cut grass and freshly baked bread. Wouldn't that be wonderful? Then guys could activate diesel, whiskey, tobacco and maybe also channel no. 5 and similar. Anyway, I can easily imagine the roar of the huge engine - and also the smell of burnt fuel. Eeew.

Top down look

A few minutes later Craig joined me. Nice guy. His conversation quickly made me forget all about the stinkpotter. We talked about the boat... lotsa little details, and I won't repeat them all here, but one thing deserves mentioning. The Ktaba - like many of her virtual sisters - she floats a little too high. It is easy to fix.

Starboard?

Especially when heeling it is obvious. The waterline comes up on the windward side, but it doesn't really dive down on the leeward side. Like I said... easy to fix. I am glad to report that Craig said that too. In the shot above the waterline is hardly present, but that multihull monster is. He slammed right into us...  Virtual sailing is great... we didn't break anything.

Back home...

Oh, one other truly wonderful thing... This baby has both BWind and WWC support. Two windsystems in one boat! Why is that so great? More on that in a later post. This is really it for now. Can't wait to sail the next version. It's already close to perfect, but as Craig says: We aim to please. That must mean the next version is even better. Aim high...

More on the Ktaba 20.

The virtual IOD collection

This is a fun contrast to the AC spacebug, I recently wrote about. For a while now, I've been watching a brand new oldtimer moored at Tradewinds. It seems virtual oldtimers are hot these days. Good things last... Probably because there is virtually no maintenance.

Left to right: Jim, Craig and me.

Here's the builder, Craig, and Jim and me talking virtual IODs, and there is definately something to talk about. They are so alike, yet so different. For starters the Trudeau One on the left is too big. It is almost 10 meters long. On the right we have the Bolero, which is also a little too big. The Ktaba 20 in the middle matches the size more accurately.

Spreaders

Then there's the rig and mast. Note how different the spreaders look. The Trudeau One has the most accurate mast. It is the only one of these three with a strut above the spreaders to support the top of the mast. Right now, it seems to me the Ktaba 20 mast is a little too short. The Bolero sports an interior setup with beds, lamps and what nuts plus live telltales.

Details

The Trudeau One and the Ktaba 20 have spinnaker poles lying on deck. However, they all come with spinnakers. Then there's the sailing engine. The Ktaba and the Bolero use modified BWind. The One uses a Trudeau engine, and it is the only one of these three to support crewed balancing. I suppose that's why the One is popular for racing.

Motoring, Craig in the back with sails set

Hmm... This could be lengthy, so I better stop. Suffice to say it is interesting to watch how different these virtual IODs really are. Naturally, we took the Ktaba 20 to sea. It sails nicely, but it is work in progress. Iit would not be fair to go into details now, so laters... When Craig tells me it is ready. 

PS: If you can't wait, then check Orca's Ktaba20 sailing pics.