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Hang Gliding Water Towing

Postby Bill Cummings » Tue Feb 07, 2012 4:37 pm

Starting out hang gliding by water towing is best done in smooth glassy conditions for a beginning student. As the student advances, gradually, more wind can be dealt with.

At some point the wind will upset the hang glider on a lake and unless you know how to right the hang glider in a wind it can seem like an impossible, frustrating situation.

A single surface training glider, once upset, will only be showing the base tube floats and the tail float. The nose will be out of reach about five to six feet below the surface.

Keeping the boat motor’s propeller away from the sail cloth and wires is the first consideration. With this in mind, one person should be doing the glider handling off of the bow of the boat.

The boat driver should position the bow of the boat at the tail float of the hang glider.

The person at the bow should hold onto the tail float while the boat driver, in idle speed, reverses pulling the tail of the submerged glider so that the tail of the keel is pointing into the wind.

The boat driver will then align the boat with the keel tube and idle speed the boat backing straight into the wind.

The person on the bow lifts the tail float up as the boat is backing up into the wind.

When the person on the bow can grab the wire between the keel’s tail and the kingpost, he then can work hand over hand toward the kingpost.

With the kingpost in the hands of the bow person, the boat driver puts the motor in neutral and allows the wind to assist in blowing the raised rear half of the glider downwind. (At this point the glider’s tail is pointing straight up then moving downwind toward an upright position.)

The bow person goes hand over hand from the kingpost to the nose plate.

As the bow person lifts the nose plate out of the water, the boat driver must keep the front of the boat from touching the leading edge sail cloth on the wing tubes.
This is a critical part because the boat will tear the sailcloth if it comes in contact with the glider. The glider will not move easily in the water until the floats are on the surface. It is unbelievably easy to tear the sail cloth with the boat if it comes in contact with the glider when the hang glider is partially submerged.

The floats will now help raise the hang glider to the surface. The driver should be in idle reverse so that the wind will help bring the floats to the surface.

With the help of the wind, while the boat is backing into the wind, the bow person should be holding the nose flying wires and fly the glider up onto the front of the boat.

Next pull the glider nose-down to drain all of the tubes. All tube caps should have drain holes drilled in them so that lowering the nose will drain all tubes.
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Re: Hang Gliding Water Towing

Postby Bob Kuczewski » Sun Feb 26, 2012 10:15 pm

Hi Bill!!!!

Thanks for that great description. I've taken a first cut at an animation to go with your description. Here it is:

Flip_001c.gif
Flip_001c.gif (1.1 MiB) Viewed 3744 times


I built the animation in Blender, and it took me most of the day. But I'd say most of that time was just building the glider model and learning how to use Blender. After I had the model (and a better understanding of Blender), it took less than an hour to build the water scene and do the animation itself. So future animations should be much easier now.

I'm pretty happy with how it turned out, but it could use some additional features. At a minimum, I'd like to add the wind direction (maybe with a flag or a wind sock) to show that it's blowing from left to right. It would also be nice to show how the boat manuvers the glider into position. But it's a pretty good start to go along with your description above.
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Re: Hang Gliding Water Towing

Postby Bill Cummings » Mon Feb 27, 2012 1:05 pm

Hey Bob,
Very good animation. Wind blowing from left to right is correct and a sock or ripple lines on the water would show the wind direction.

I’m working on the next piece about how to next turn the recovered glider around on the boat (with the wind blowing) so that it is facing forward for quick transport or to start the next tow.
Also what a pilot can do to keep the glider from upsetting on the lake surface in the first place.

These animations will really help since finding a video or old film about this recovery method is something I have never come across before.
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Re: Hang Gliding Water Towing

Postby Bob Kuczewski » Mon Feb 27, 2012 1:32 pm

Thanks Bill!!

I think we can do a lot with animation since we can make it show specifically what we want to show. In some ways that can be better than actual footage. Of course both are useful, and that's the great thing about a multi-media training manual.

I'm very optimistic about what we can do. So if you have a specific animation that you'd like to see, just let me know and I'll give it a try. I suspect that the first draft of wording will be a rough cut, then the words and animations/videos will feed on one another until we end up with a really good and clear result.
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Re: Hang Gliding Water Towing

Postby Bill Cummings » Thu Apr 12, 2012 1:45 pm

An earlier posting explained how to recover an upset hang glider equipped with floats. In other words, only the floats were showing above the surface of the water. Such a scenario has the hang glider upside down in the water and completely submerged. After following the previous described recovery method, there are several ways to get the glider correctly headed, on the boat, in order to allow the boat to get up on plane and quickly move to your next location.

Boat static-towing and platform launch-towing each have slightly different ways of setting up for the next flight.
Boat towing and platform launching require you to get the glider’s basetube back on the launching chocks (yokes), with the glider headed the correct way, of course.
Just after recovering the upset hang glider, it will be in the front of the boat and headed into the wind, but the boat will be backing into the wind with it‘s bow pointing downwind.
Let’s come back to this problem a little later after first addressing the method of not upsetting the glider in the first place.

In this scenario, as a student of water towing, at some point you will find yourself waiting for the boat to return to you while you are drifting downwind and backwards, on the water’s surface, due to the wind.
If one wing tip is lifted by the wind, the opposite wing tip may dig into the water. Once this happens, your only concern should be to unhook yourself from the glider, because it is guaranteed to completely upset in this situation, and you will be helplessly powerless to prevent it.
Being blown backwards, while your glider’s wingtip is dragging in the water, is literally the “tipping point” beyond which you will have little or no control over preventing the glider’s upset.
Stopping a low wingtip from digging into the water is your goal, but your action will feel counter intuitive. Since you are surface handling, and not really “ground handling,” the rules are completely opposite of what most students would expect.

In the situation, described above, most students will actually accelerate the upsetting of the hang glider with their assumed control input which is in direct opposition to what should be done.
While drifting backwards on the water’s surface, you must move your body in the direction of the LOWER wingtip, but only if your body is partially submerged.

Some smaller glider floats require the pilot to go from prone to vertical in their special water harness. This allows them to reduce the weight, that the glider’s floats have to bear, by lowering the pilot into the lake.

If big floats are used, and they support the total pilot and the glider weight, this surface handling tip is not for you.

With smaller floats, though, you don’t want to sink them with too much pilot weight since that will allow your wing tips to dig, even more, into the water. Such action is guaranteed to back flip your glider into an upside down position, all thanks to the wind. This slow back flip will actually give you ample time to unhook from the hang strap. Because of the glider’s slow rotation upside down, unhooking when your glider is beginning its roll is extremely important, considering what the end result would be if you didn‘t unhook.

If you are using a prone harness your head, while flying, will be positioned just inches above the base tube. If you don’t unhook, once you and your glider are completely upside down in the water, your head will be mere inches from reaching the surface of the water and those essential gulps of air! A quick release, for situations like this, is a very good idea, while a Hook knife, taped to the down tubes, is another good idea.
Returning, now, to preventing a glider’s low wingtip from digging into the water and causing an upset in the first place. This is how it works.
As the wind is blowing you and your glider backwards in the water, you see that your left wing is getting close to the water because the wind is lifting your right wing.
Before your glider flips upside down, you have to respond, quickly, by simply doing the following:
MOVE YOUR BODY CLOSER TO THE LOWER WING!
Since your body is creating the most drag in the water, you want to place that drag close to the low wing. By taking that action, the opposite wing can move down wind easier and faster, reducing the lift on the right wing and increasing the lift on the left wing. This wing action will lift the left tip away from the surface of the water allowing the glider to pivot around your body.
Where you place this pivot point is what makes this reverse steering work consistently.
Again, while being blown backwards on the water, move your body closer to the low wing allowing the glider to pivot around your body and blow the high right wing downwind. The high wing will blow downwind and create less lift while the lower wing will now be creating more lift since its position is more forward into the wind.

A new student, trying to pull his glider’s high wing down with just his body weight, will continue to drift backwards in the water and will be quickly hastening his glider’s upside down flip because he is moving the pivot point of his body in completely the wrong direction.

Righting an upside down glider is a slow process that cuts into the precious available daylight time that you should be using for flying. Sensibility indicates that every water-tow pilot take necessary measures that will assure the avoidance of flipping his/her glider in favor of that flying time!

Once the glider is right-side-up and recovered, a process described in an earlier posting, there are several ways to align the glider, in a wind, toward the same direction as that of the boat.

If you are close to the shore, and upwind, the boat driver can simply pace the wind as far into shore as possible. Pacing the wind just means traveling down wind at the same speed as the wind. A piece of yarn or ribbon on the glider’s nose wire or the boat’s antenna will help you determine the correct speed to get to shore.
If you don’t need to land the boat, but only need to get the glider turned around, to cradle its basetube in the launching chocks, the driver can back into the wind and the bow person can fly the glider, by its nose wires, from the boat’s bow and settle the glider back onto its floats on the water’s surface.

In a 4 - 7 mph wind, with no pilot to muck things up, you can actually let go of the glider and let it drift downwind. At that point, the boat driver can then do a 180 degree turn and, in reverse, catch up to the glider by backing the boat up to the nose of the glider.
The bow person now can go to the boat’s stern and grab the glider’s nose wires . The boat’s driver should shift the craft into forward and the bow/stern person will be able to fly the glider, by the nose wires, into the launching chocks.
In a stronger breeze, after settling the glider back onto the water’s surface from the boat’s bow, a 75 -100 foot length of rope can be clipped to the top of the nose wires. Some of the clipped line length can be let out, as the boat turns its bow into the wind, so that the glider can be pulled up near the boat’s stern. Next, the glider can be flown onto the launching yokes by the nose wires and its basetube secured into its launching chocks. Remember, if the glider was underwater, its tubes are water-filled, so its nose must be pulled down to drain all water from its tubes. It is most helpful if the glider’s plastic tube-caps have holes drilled into them to speed up drainage.
If you are not doing platform launches, but are doing deepwater or beach-running launches, you may only need to motor to the downwind end of the lake. If you have a long distance to get to that end of the lake, you will want the glider’s nose and the boat’s bow headed in the same direction, so that you can speed to your destination.
To position a freshly recovered glider in the same direction as the boat’s bow can be either a simple, or impossible, task when dealing with a wind. A good situation about water-towing is that the wind blowing over the water is laminar, as compared to its equal velocity over hard ground or inland. Over a lake’s surface, for instance, there is far less mechanically-induced wind turbulence.

Tying a piece of yarn onto a glider’s nose wire or a boat’s antenna helps the boat driver “pace the wind”, successfully accomplished when the yarn is actually hanging straight down while the boat is moving forward. Once the wind-neutralizing “pacing” is accomplished, there will be little, or no, wind to create problems with turning the glider 180 degrees while it is at the bow of the boat.
The act of turning a glider 180 degrees, while standing on the bow of a moving boat, has a certain disconcerting element to it, especially if you make the mistake of using the water moving past the boat as a reference point to maintain your balance. So, for those of you feeling uneasy turning your glider on a moving boat, a slow power to the downwind end may be a better fit with your comfort zone. If you do attempt the moving 180 turn of the glider, it is most helpful to maintain your focus on a spot on the boat in order to keep your balance.
As the boat is pacing the wind, the pilot will be turning the glider around in zero wind.
When you get the glider turned around, all you have to do is sit, backwards, on the basetube, holding onto the downtubes and leaning backward toward the nose of the glider and boat. With the glider and you in that position, the boat driver can get the boat up on plane and move quickly toward the downwind end of the lake.

While the wind is blowing, the pilot and boat driver may find that they are about to lose the glider over the side of the boat. Should that occur, for any reason, the best course of action is: DO NOT struggle to prevent it! You should actually help the glider separate from the boat to prevent any possible damage. Next, you will have to start from scratch with the glider-recovery process. If you have a wingtip in the water, while the boat is idling in the wind, you will more than likely cause damage to the glider if you attempt to stop its further plunge into the water.
Should that situation occur, I must, once again, repeat: Move the boat clear of the glider if it is progressing overboard.
If it must be assisted overboard, to prevent damage, then push is away from the boat. The glider has floats, it will be alright. If it’s going, it’s going, and your fight to stop it will only lead to glider damage. Though frustrating, such action is the best course for the glider’s benefit.
So, now your glider is back in the water, again. OK.

All you have to do is start the recovery process from its beginning. This is usually the best course of action while you work to position your operation to allow the wind to assist you. Yes, let the wind help you. Why fight against what Mother Nature has provided for your glider’s water-recovery assistance AND to help you get back in the air?
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What boat should I buy to water tow?

Postby Bill Cummings » Tue Feb 12, 2013 8:50 pm

What boat should I buy to water tow?

If you are going to buy a small boat, 16 feet or under, there are several things that you should consider before your purchase.

Will you be towing mostly on small inland lakes or on big lakes or maybe the ocean?

For small inland lakes, it is hard to beat a tri-hull boat which promotes "rolling" stability. It is just about impossible to roll a tri-hull boat over and upside down.
It would be much easier to roll over in a V-hull boat of the same length.

Where a tri- hull boat does not shine would be in big waves, especially if you are up on plane and running fast into the wind. In big waves, a tri-hull boat will pound over the waves and rattle your fillings loose. A V-hull would be the boat of choice for cutting through the waves and producing a much smoother ride. Just be careful you don’t tip over in your less stable V-hull boat. With a bigger V-hull boat, you gain back some of the needed roll stability. However, your horsepower requirement will be greater.

Remember that, at times, your boat, with a glider secured into the launching chocks, will have you crossways to the wind and waves. Additionally, if a passenger is also moving around in the boat, with the wind and waves, the weight shift might roll the boat enough to get a wing tip in the water. This could develop into a serious situation.

A fiberglass tri-hull boat of 14-15 feet in length will require about 85 HP to keep you happy. The down wind run will make you wish you had some more speed.

A lighter aluminum V-hull will give you the same performance with even less horsepower. I would guess 65 to 75 HP would be acceptable.

Things a boat owner can do to peak boat towing performance is to trim the motor back to lift the bow farther out of the water, so that the back 2/3rds of the boat is in the water. At some point, the boat will start to porpoise. Should that be experienced, trim the motor back inward until the boat will no longer porpoise. Better yet, trim the motor back until the boat starts to porpoise then move weight in the boat farther forward until the boat will no longer porpoise. Another boat-speed-enhancing trick is to shim, or raise, the motor vertically to get the prop closer to the bottom of the boat. Too high will cause the prop to cavitate and race the motors RPM past red-line and also lose speed in turns due to prop cavitation. Each adjustment has a balance point. In other words adjust for speed, but not too much.

Boat motor propeller blades come with different pitches. You can move toward a power prop for getting onto plane faster at the cost of top-end speed, or you can go the other way to get more top-end speed which will make it harder to quickly plane your boat.

There are cheap plastic horizontal fins that you can bolt to your motor's lower unit to quickly help assist your boat's planing. These work wonders. Using the lower unit horizontal fin and a speed prop will improve both ends of performance.

The single most effective method of regaining lost performance speed is to fill in the gouges and scratches in the bottom of the boat, sand it down to a 600 grit sandpaper, then wax it. You can regain 5 mph on your top-end speed.

If your boat will be pulled up onto the beach, lay down some rubber belting, first, to protect the boat's hull from rocking on the beach's sand/rocks due to the motion of wind and waves.

Adding a glider and pilot to the back of your boat may require the relocation of heavy items, like battery and gas cans, farther ahead in the boat.
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