Friday, April 14, 2017

Call Me Crazy

Today I'm going to try and complete the wiring aboard Autarkia.  We have bought solar panels, a controller, a satellite receiver for Sirius music, and the battery box has been built and installed.  I will detail all of this in a post as soon as the  work is complete - probably in the next few days.

The fact is - Autarkia is just about ready for sea trials - sans a sailing rig.

But I have been thinking crazy thoughts.

Consider the following:

1) .  Autarkia has a very reliable and pretty much brand new engine, that is quite fuel efficient (Evinrude Etec 30hp).

2).  Autarkia also has large, uncluttered and unencumbered decks, that we are very fond of.

3).  She is low, stealthy, and sleek looking in her present state.

Given the above, you may think that we are considering abandoning wind power altogether and simply using Autarkia strictly as a power boat.  But that is not the case.

But we have long considered how we would actually SAIL Autarkia given who and what we are, our skill-sets at this stage of life, and how much effort and bother we want to put in to powering the boat with the wind.  And I have always said - probably in the blog previously, that most of our SAILING would be downwind in ideal conditions.

If that's the case (and getting closer to being sure of it) then a rethink of how we might harness the wind is in order.

Firstly, since we would sail only with the wind say - 30 degrees either side of aft - then the lateral resistance of that honkingly big and heavy off-center board I built is not required.  What IS required would be a a couple of smaller skegs (say about 2 sq.ft. each below the waterline) that I could make up with 3/4 inch engineered plastic sheet held in place against her sides with a through bolt and large wingnut to allow them to give way upon striking the bottom.  Also, a smaller rudder could be made up from the same material and of course be designed to kick up as well.  I could make all three items in very short order.

And what then would be capturing the wind in these ideal conditions?

Why THIS of course!


Or Something Like It

A pilot-lifter kite, appropriately sized, is very stable in a range of wind conditions, has a LOT of pull, and is inflatable without any solid spars.  In other words, it packs in to a little bag when not in use.  They can be readily purchased ready-made, or can be sewn up by yours truly from many proven plans that are free online.

Those of you who are so inclined, can do some research on kite-powered sailing, but in a nutshell you will find that most efforts so far employ parafoil designs that are very powerful, but are very unstable as well and must be controlled constantly.  The surfboard crowd who use them for example, fly across the water with these kites way out in front of them at a low angle - not high up - so that the force is in the direction they want to go.  Forward as oppose to up, although there are many examples of people flying up in the air with them.  But to get that forward pull, they must constantly weave the foil in a figure eight pattern ahead of them.

There are also efforts being made by a German company to use kites on cargo ships to reduce fuel consumption.  But again, these are parafoil designs that in this case are controlled with servos and computers.

Which brings us to our very stable and hands-off pilot lifter kite.  It pulls, but as the name implies, it is lifting more than pulling.  The force applied is in most cases at an angle greater than 45 degrees straight up.  A waste of effort in that direction.

But there is a low tech solution I have come up with, though I do not claim to have thought of it first, though as of yet I have not found an example.

It is best explained with this horrible schematic sketch:


Launching large kites can be challenging - especially from a boat.  However, Autarkia with her large fore deck, flat and without the clutter of lines or rigging, would certainly have an advantage over other boats.

I would also have a short mast - say ten feet or so - that could be used in some way to assist in inflating the kite (the mast could also accommodate the anchor and steaming lights).  Three inch aluminum pipe would be more than adequate, and it would be low enough that it could be fixed in place.

Let the controversy begin!

10 comments:

  1. I assume you have read this paper on kite sailing? http://www.peterlynnhimself.com/Kites_For_Yachts.php
    Has quite a bit of information on the issues facing kite-sailing.

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    1. Thanks Andrew, I have. In fact I emailed Peter asking him to comment on the weighted line idea, but as yet have not heard back.

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  2. IMHO: worth the effort to build a sail rig. A chinese lugsail is a mess of lashings and ropes but worth the effort once done. So easy and convenient to use. It will pay for itself many times over in fuel and convenience. Use a really discount fabric of 2nds from Rochford Supply, or even polytarp if need be but, of course, good fabric will serve you well. Super easy to learn it's use too. My first big build turned into a motor boat due to a number of reasons but I wish I'd done a bit more work and made it into a sail vessel. But.... IMHO!!!

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    1. Thanks Robert - and good to hear from you too! I'm in a fit of whimsy right now. Who knows what will come of it. But thanks for those grounding thoughts...

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  3. I never did do the proper vector mathematics. There is no advantage to add a weight to the kite line. But I'm not bitter...

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  4. I think it its your boat and if you want to try it. Then go for it. I have see kites used on a few small craft before mostly to get more wind. Really some jib sails look much the same or similar to a parachute on the front of a boat. There are also some using no masts with just jibs successfully. I for one would love to see it and know your progress. At least from the stand point of knowing that in an emergency without any major jury rigging. I could employ the sail if I lost my mast(s) to make it home or somewhere safe. They used to put sailing kites in life boats at one time. I am anxious to see your progress and wish you the best with the project.

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    1. Thanks for your comments Samuel! One thing we know know for sure is THIS year at least, we won't have a sailing rig. We want to enjoy the boat. But as we do, playing with kites will be fun. We'll vet the idea and either abandon it, or be inspired to pursue it further. I am really anxious to try it anyway, and will will be cheap and easy to do, and will satisfy my inner tinkerer to the max!

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  5. Good on you for thinking outside the box. If the experimentation would be fun for you, I say go for it! You'd be the only kid on your block (of course you already are, in many ways)

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  6. Hi Alan,

    Kites have an advantage in being relatively cheap and easy to test... one can sew up the sail for few $$ and no hardware, try it out (even on land) and just see.

    I was going to comment on vector analysis, but I see you been there.

    One thought... you might consider floating line... a situation I could see is that the kite goes into the water on retrieval (for whatever reason), spilling a long length of string into water shared with the (now essential prop).

    For other directions along the lines of easily handled, downwind sailing, might consider a short mast (under bridge clearances)flying a Ljungstrom sail (twin, triangular sails fixed along their 'luff' to a rotating mast. Sets like a small delta kite and roller furls around the maast. Doubles as a riding sail.

    Or one or two offset triangular sprit-boomed mizzens near the aft quarter.

    We had easy rides in a little box sharpie yawl, squaring the (offset) mizzen across the transom... good visibility, and not tendency to broach and round up. Kind of like having a sail kicker.

    SO many ways to skin a cat(yawl). 8)

    Dave Z

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    1. Thanks Dave! Well, getting the boat out on the river and seeing how she behaves is going to give me a better feel for what to do wind power wise.

      Anyway, something that I will detail in an upcoming post is the little off-center boards I made for motoring. I don't intend to incorporate them into a sailing rig unless they pleasantly surprise me in the motoring tests. They are made of HDPE marine board 3/4inch thick, and I'm simply through bolting them to the sides above the waterline with a single SS bolt so they can pivot up upon striking anything. They will bear loads in either direction, and have a submerged area of a couple of s.f. each. I'm quite impressed with the strength.

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