Yrvind

keep us posted.

 

Thoughts about Keels

SOME THOUGHTS ON KEELS

By writing this, I do not meant to denigrate anyone’s ideas or theories, but just to state my own.

For an AIT boat, I think a keel is the answer for three purposes: ballast placement, directional stability, and roll dampening.

The keel I drew for my “Football” design concept (see attachment) is a full length one with quite a bit of rake to the leading edge. The reason for this is to move the Center of Lateral Area (CLA) far enough aft, so the main sail alone would have its Center of Area (CA) properly placed so the boat could sail on all points on the wind, except downwind.

To sail downwind, the jib is raised and sheeted tightly. This gives the boat a lee helm that is very easy to get rid of. The jib will have a down haul which will lead to the mast.

The long keel is deep enough to have a rudder attached to its trailing edge. This rudder has considerable area and, due to the fact that it is attached to the keel and is of rather modest aspect ratio, it is far less likely to stall. It is also very firmly attached to the boat, so its far less likely to break or be lost.

The keel has a specific gravity that is about one and a half. The reason for this is to limit the roll speed. Weighing in at around 136 kg, it will provide a great deal more righting moment when it’s out of the water than when it’s in. This will provide a sudden increase in righting moment, once the boat is nearly on its Beam end. At this point, due to its high sides, the boat will be more likely to slide sideways, from a wave hit, than invert.

The mast will be stuffed with foam, so it cannot fill up with water. Originally, I drew it with square sections. Now, I’m inclined to make it round, so the boom and gaff will be easier to fit, and more likely to survive a wrenching rollover.

Sven has made much of the idea that a keel of any kind can trip a boat, causing it to capsize from a wave hit. I agree with him in principle.

With no keel underneath, the boat is far more likely to slide sideways, than flip, from a broadside wave hit. It is also more likely to slide down the side of the wave, when broadside to it, and not be caught in the curl of it, when it breaks.

A boat with a fixed keel is vulnerable to all these hazards.

However, with this particular design, that may be less true. The reason being that the boat will be less likely to get caught, broadside to the wave, in the first place.

This is because of three peculiar characterizes of the hull, keel, and rig design. The first is the hull itself. The stern transom is immersed by about 15cm. This creates drag, which slows the boat down somewhat, but also gives it a preference for going forward, rather than backward or sideways. Second is the keel. With its CLA so far aft of the boat’s CG, the boat will further prefer going forward, when sliding down a wave surface. Third is the mast placement. Stripped of all sail, its bulk being so far forward will further make the boat tend to point down wind.

I am not saying my approach is necessarily better than Sven’s. I’m just saying it is defensible.

Much of what I have learned about tiny offshore boat design, I have learned from Sven’s accounts. I’m sure his personal experience measures well against any theoretical knowledge I have.

However, having spent so many years acquiring this knowledge, I do enjoy trotting it out once in a while.

My “Football” design will probably never be built, and I will probably never sail out of sight of land, due to family issues and finances. But I do like to fantasize once in a while.

 

sharpii2 your post is good and we feel the same way about this issue. I am however making provision for alternatives, how, what and where I'm not sure, but if I wanted to remove the keel I should be able to do it without destroying the boat.
My group is very keen on this "full keel" experiment and I am of course holding thumbs that it will work as well as hoped for.

sharpii2 I will use this post of yours in my blog next week, please let me know if you are against this.

I want to publish (copy) posts from other people including Sven (eg Youtube links) just to help this endeavour and show the world that there are other people out there that support this challenge. I always post links to where I found my info I dont steal other peoples writings

 

This configuration of keel and rig has a lot going for it. A full keel which stretches further to the bow combined with a single sail rig would probably be more exposed to the dangers Yrvind warns about.

 

IMHO, sailing such a small (short) vessel around the world is indeed possible, but something that must be well thought out. For instance, my "Football" design is intended to do the trip in hops of around 2,000 nm each. Such would take an estimated 40 days, allowing for storms and calms. At its best, the boat will probably make 80 to 90 mile days. At its worst, it will just sit there, glued to the water, or be bashed backwards from storms.

I'd budget at least two years, more likely three, to complete the voyage, because, as Sven has pointed out, the seasons may move faster than the boat. I would not want to be in any boat during a great south ocean winter. I'd also like to leave and return to the equator, so there would be no disputing my circumnavigation claim.

For a non-stop voyage around the world, I'd go with a scaled up version of "Football", maybe 16 ft (4.88 m) . Such would be less stubby, carry vastly more stores, and have a faster top speed. It would have a 6.5 (1.98 m) Beam, and a top speed of around 5. 25 kts. It would displace over two metric tons. Even that may be a one or two stop boat.

 

The original idea of the AIT was to beat Serge Testa's "record" of 500 days to circumnavigate in a boat, 10 ft long.
Testa didn't want to set a record, he just sailed around the world trying to make it as enjoyable as possible,seeing as much as possible. I think the AIT was supposed to be in the same spirit, having fun....if that's possible in a 10 footer.
I have no doubt that in "near perfect" conditions it will be challanging to beat the time Testa needed for his voyage,be it alone for the hull speed of a tenner, compared to what Acrohc Australis was capable off.
Why Yrvindt added the "non-stop" sequence is a mystery,at least to me, and forces him to choose a route which is adapted to his needs but may be questionable as a record breaker for a "true" circumnavigation". "Bending the rules" as Yrvindt calls it and adding non removable structures to his ten footer, making it actually a 12 footer, or something like that, isn't going to help to give his record the spirit it should deserve, the "media" is a harsh animal.........

In my (unexperienced !!) opinion Yrvindt has shoveled himself a mountain of food on his platter which might be hard, very hard to finnish, perhaps even harder to digest.
Two to 3 storms a week,according Sven himself, and this 52 times in a row, at least, is possibly a bit too much for the brain.
No doubt that Sven's boat can stand up to it. No doubt that Sven's experience can stand up to it.No doubt that his body condition can stand up to it.....doubt that his grey matter will survive it....


I surely hope that Yrvindt makes it, he deserves this as a kind of "Lifetime Achievement Award" but at the same time I hope that Manie follows Testa's spirit and make a "many stops " circumnavigation and enjoy the beauty, food,fauna and flora, people and sun of the world and if there's still time left after all that, take the record of Serge Testa.

 

http://windraf.blogspot.it/

 

Am I the only one who (mis ?) judge the value of an ,even small, cockpit to spend a few hours a day "outside".
Sitting/standing in an open hatch doesn't look the same to me as sitting in a cockpit.......I think LOL !

 

Westel good point

That is why I feel even a tiny swim platform bolted to the transom is a must
that is where you can be "outside" and at least try and wash a bit from time to time
Sit in the hatch with your feet outside
My swim platform will have a sturdy handrail around that will also support the wind generator and it will be enclosed with nylon mesh to form a "cage"

 

"this is Tateo Ikao from Japan, we met him when he brought this 20 ft. sailboat that he built in japan and had it shipped to Newport Beach Ca.to the shipyard.we took him to the channel entrance and let him go, off to hawaii which will take him 3 months and than to japan another 4 months and there is no motor no sail only his rudder which he works by hand...incredible oh yeah he is 75 years young... good luck"

http://www.youtube.com/watch?v=6E_SX9gPJbM

 

‘‘LONG TIME NO SEE’’​

Good to hear from you Sven, nice to see the progress, thanks for the update

 

I have the feeling that Sven is getting caught in the "engineering labyrint", it looks that he's trying to overdo things on the "simplest" tasks like securing a hatch but that's obviously only my opinion.
Sealing off a hatch with, what looks to be Torx bolts, is probably the best way to get tension on the hatch to make it watertight but....you need "special" tools to undo these bolts. A wingnut style bolthead or a simple small "T" handle welded to the Torx bolt head would make it easier to undo the bolts without any tools.
I'm also not sure what the purpose of the washer under the Torx bolthead is.Usually a washer is placed to spread loads or to protect materials. With a washer hardly any bigger than the bolthead itself, it must be there to protect the material I assume. The idea of having a washer that can't fall off seems very appealing but, the washer is threaded and is free to rotate around the boltshank on the top of the bolt. The washer will rotate and the thread in the washer will be damaged which makes it very difficult to remove that washer if needed.
The less parts that can break or stop functioning, the better I guess but this is probably question to endless debate what and what not to use.

One thing is for sure, Sven thinks about every single part, no matter how small or "unimportant" it looks and this only can increase his chance of succeeding !!

 

Better alternative

I absolutely don't like that closing system. What about using a swing top hinged lid system and use the bolt system as a back up. To have to screw and unscrew everytime is just silly. This screw and unscrew system will most likely fail at some point due to metal fatigue or he may lose the tool to unscrew it. I cannot believe he will use that silly system. There are metal clasp lock system with tension on the market he could use.

 

Something like this

http://de.wikipedia.org/wiki/Bügelverschluss#mediaviewer/File:Kniehebel-Box.JPG

 

I agree but it could be that he hasn't enough room to have fully acces to the stowage with a hinged lift top. If you can remove the lid you have full acces to the compartment.
Sven will be "screwed" big time when he loose the Torx tool ....could allways have a vise grip as back-up....
Giving how good Sven is with rope and knots, I would have thought that he would go for a simple system which could be fixed all the time with some rope and his hands.

On the other hand, Sven doesn't mind to ditch a system on which he spended a lot of time, money and effort if in the end the system doesn't satisfy him. Many, if not most, people would carry on with a bad system because it consumed money,time and effort .....