Taxiing with Fib
Foreword
Everything that sails can, if conditions help and mistake are made, capsize and this is very true for the Fib.
In fact capsizing in taxiing is practically the only accident we experience on this machine.
Taking off and landing is mainly made against the wind and in any case with a speed that keeps the relative wind in front that is the conditions in which Fib is stable.
Things change when you are taxiing in the water to reach the taking off place or back to the beach or dock when you have landed. Those operations are generally done at much lower speed.
The Fib has such a big sail on top of it that, with relatively slow airflow, can lift the boat with two pilots, and is easy to understand that if this airflow (wind), also much lighter than the one needed to take off, is not coming from the right directions and invest a great part of the sail, this can result in a capsizing.
This chapter wants to point out some very important notions and tricks to avoid this happening. Obviously you risk that when there is some wind but is very important that you study, understand, apply and practice those suggestions also with light wind if you do not want to soon or later go swimming instead of flying!!!!
1)Weight-shift system and our sensations implications
The wing in Fib moves separately from the rest of the machine and this pose the main problem from which the capsizing can occur.
In fact the boat can move laterally quite a lot in the water due to turns or waves but the wing needs in taxiing to stay perfectly horizontal on the water to expose less possible surface to the wind. Unfortunately this is a little unnatural for the pilot. In fact all our reflexes are conditioned from our standing position and we perfected them from when we started learning to walk. Those reflexes work the same when we are seated and is automatic for us to think that is horizontal what is parallel to our bottom.
For the reasons said above, this is not true with the Fib in the water. The boat tilts one side for some reason, but if we want the wing to stay horizontal on the water surface the bar will not be parallel to our bottom.
Is important to remember and train yourself to this “switching” the position of the steering bar from your sensations. It can help to look at the bar herself in rapport to the horizon or look often laterally alternately to the tip of the left and right wing to check that the wing is parallel to the water surface..
2)Relative wind
The wind you feel in a moving vehicle is different in strength and direction form the real wind that is the one you feel when the vehicle is stopped.
We call this wind:”relative wind” .
The strength of it is the sum of your speed and the wind speed if you are moving with the wind in front. Is the difference between the wind speed and your speed if you moving in the opposite direction and in fact if you go faster than the wind speed in this situation you will feel the relative wind in front of you. (I.e. If there is a wind of 10mph from your back and you move at 15mph you will feel a wind in front of you of 5mph).
In direction between those the relative wind speed increase from back to front wind.
The direction of the relative wind is a component of the two strength; speed and wind and the faster you go more from the front you will have it.
On the front cable of the Fib wing there is a wind direction indicator made with a piece of sail. If you do not have it or it was broken be sure to put one on. It can be advisable to put one on both the front cables and lower them to a position where you see them easily when in the pilot seat. Those indicators give you the directions of relative wind.
ALWAYS IN TAXIING LOOK AT THE WIND INDICATORS AND MOOVE YOUR STEERING BAR CONSEQUENTLY; TILT SLIGTLY DOWN, IN RAPPORT TO THE HORIZON THE WING TIP OPPOSITE OF WHERE THE INDICATOR IS FLOWING!!
3)Efficiency of the rudder
The rudder of the boat works proportionally better faster you go. If you are slow you will have to move the ruder more to turn than if you are moving faster. And if the boat is nearly stopped the boat will not turn no matter how you move the rudder.
4) Torque effect of the prop
The propeller of the Fib turns clockwise and due to its mass it produces a torque that tilts the boat on the left.
When a boat is tilted to the left it turns on the right.
For those two reasons you have (like in take off) to move your steering bar on the left to keep the wing horizontal and correct the direction pushing your right foot on the rudder bar.
The amount of those movements depends on the speed of the boat (see par.3&5)
5)Good speed: slow, plowing and planing
We have in the Fib like in all fast boats 3 progressive kind of speed
1) Slow: the boat is flat in the water, the rudder works not very efficiently
2) Plowing : the boat has the bow up, the stern is deep in the water and moves a lot of it and is quite instable and, due to the torque of the propeller (see par.4), is tilted on the left. The rudder works but not very well.
3) Planing: the boat is fast and flat in the water and the rudder is very efficient
The better speed for taxiing is a low or planing speed: the boat is flat in the water and the movement needed to keep the wing horizontal is limited. Of the two the planning is the better one because the rudder is more efficient.
Beginner are normally quite scared to go fast but they have to force themselves on that remembering that if obstacle are around maneuverability is very good and if you have to stop, releasing the power stops the boat immediately.
6) Starting from the beach or dock
It seems strange, but a lot of capsizing with the Fib is experienced just in this situation.
The pilot is busy pulling the rudder down or doing other preparations and he forgets the position of the wing (see par.1) The wing is tilted, and the wind has a big surface to push.
ALWAYS IN TAXIING TAKE CARE OF THE WING POSITION. EVERYTHING ELSE CAN WAIT! ALWAYS KEEP MINIMUM ONE HAND STRONGLY ON THE STEERING BAR AND LOOK AT THE WING POSITION AND NOT AT YOUR FEET OR ANYWHERE ELSE.
There is no big advantage in having a Fib capsized but with rudder down or intercom connected!!
Try to start with the wind more in front that you can. If you have to go in some other direction you will turn after, when you are moving faster.
If the wind is coming from the back just go as fast as you can, possibly faster than the wind speed so (see par.2) you will have front wind conditions that as we said are a stable condition for the wing and you will also have a good maneuverability (see par.3)
7) Taxiing cross wind
The main thing to be remembered when taxiing in cross wind is obviously to keep the wing nearly horizontal on the surface. Nearly because you have to tilt it a little (not to much that will make difficult keeping the direction) on the wind side.
Especially at low speed look mainly, if not only, to that wing tip. You do not need to look forward very often: normally you sail in a wide open area.
With the wind on your right remember that the torque effect, specially at plowing speed, tilts a lot your boat and you will have to move your steering bar quite a lot on your left.
For what said at par.2) is advisable to taxi cross wind at high speed: in this way you will move your relative wind in front of you, but remember that, if you have to reduce speed abruptly, the direction of your relative wind will veer back obliging you to correct the bar position in order to maintain the wing horizontal.
8) Taxiing downwind
At low speed this is the other (see par.6) most common cause of capsizing the Fib.
The wind that hit the trailing edge of the wing, that is not rigid like the leading edge, can lift it on one or both sides making the Fib turn and swivel in a situation in which your rudder is very inefficient and waves in the stern can even make the sailing more critical.
Only one suggestion: Always taxi downwind at high speed!
9) Wide turns
At low speed no problem if you look at your wing tip upwind and move it consequently slightly tilted down.
Remember in any case that a boat in a turn tilts inside it .This means that if you turn left the torque effect (see par.4) is added to this tilting and you will have to move your steering bar to the left quite a lot to maintain it horizontal on the water. When you turn on the right the two effects elide themselves and you will have to tilt the wing much less.
With that in mind, there is no problem and in fact is advisable to make wide turns at high speed for the reasons explained in par.2).
10) Narrow turns
If you have to make a turn of approx 180 degrees there are two different maneuvers depending from where you come.
1) Taxing downwind and turning 180degres to be in front windconditions.(better on the left)
As said before we advise that you are taxiing at good speed in this situation. To turn is preferable to do it on the left. You just start the turn and slow down after tilting the left wing tip down. The torque effect and the natural movement of the boat in turns (see par.9) will augment this tilting and keep the boat in a safe situation. Just remember to level the wing when you are with the wind in front and do not let the boat turn away from front wind
2) Taxing front wind and turning 180degrees (better on the right). Is a much more critical turn and in fact with strong wind is preferable to avoid it and if needed use the old seaplane trick of stopping the motor and letting the wind push you back explained in other part of the manual and that has to be part of a proper training by your instructor.
If you have to do it, do it slowly and turn on the right: in this way the torque effect elide the tilting of the boat on a turn (see par.4) and you will have to move the bar less.
No problem from 0 to approx 100 degrees of turns because obviously you have your upwind tip of the wing slightly down in rapport of the horizon.
After that can start the problem. You have slow speed (rudder not very efficient) possibly waves that swivel the boat and wind that start pushing on the trailing edge. All that can, quickly and unrealized by you, turn the Fib well over the intended 180 degrees (190-200-220 degrees) and you will have the wrong side of the wing tilted down!
Suggestion to avoid all that: When you have turned approximately 100/110 degrees gain speed as quick as you can (remembering that the torque of the prop will tilt the boat and you will have to move more the steering bar). Your rudder will work efficiently and your relative wind will move in front or will be light. After, that as suggested before with back wind, keep going fast.
11) Choosing where to land in function of the taxing to make.
As is clear from all what said above we consider taxiing quite a critical maneuver of the Fib in strong wind. (We do not define strong wind because is a term only relative to the pilot experience).
We have the advantage on Fib that we generally fly in a very big landing surface and we can easily choose place and direction (advisable mainly with front wind) where to land.
For those reasons a competent Fib pilot chooses the landing place in a way to minimize the risks of taxiing. That means that he lands more downwind possible from the final stopping place minimizing the need to do narrow turns or cross wind or downwind runs or on the left of the final directions if is obliged to do a 180 degrees turn to go back to the beach or dock so can make that on the right as suggested.
For this reason if his evaluation was wrong (i.e. landing more forward or on the right than intended) he does not hesitate to take off again and repeat the operation. And after he has landed does not stop the boat but keep taxiing at if possible at planing speed to have the advantage of a more frontal possible relative wind.