Lake Amphibian Operational Tips – Part 8/10
Written by John Staber: Glassy Water Operation. This is the most dangerous operation with any seaplane, due to the fact that there is no depth perception over glassy water. This is exacerbated by opaque or overcast skies. Anytime these conditions occur a glassy water approach should be used. Quite often these conditions occur on only part of the surface you are landing or taking off from. It is possible when landing or taking off to experience the surface to go from ripples to glassy. Always use the glassy water approach and landing unless you are absolutely sure you will be down and stopped within the rippled area. The glassy water departure is just as dangerous as the landing and care must be taken not to fly back into the water after lift off.
The Lake operates the same off glassy water as rippled. The pilot is the one that can’t tell what is happening. I prefer to not wear headphones for most water operations and especially for glassy water. You need to be able to hear the sound of the water on the hull and sense the correct attitude, which is the same as any takeoff or landing when you can see the surface. You should be focused on a known point in the distance, hence the takeoff should not be made toward the middle of a large body of water, with absolutely no visual reference. Preferably, landings and takeoffs should be made parallel to shore where there is at least some visual reference.
We need two things. The correct attitude for landing and an acceptable rate of descent. There are variables like load, density altitude, horsepower. I prefer to set up the proper attitude at altitude where I have an horizon. From experience, most Buccaneers need between 15 to 16 inches of manifold pressure to give us no more than 200 feet per minute rate of descent. Flaps should be down. The attitude should be slightly nose-up as evidenced by visually sighting out the copilot’s window at the horizon. Trim to this attitude, and more than likely you will see an airspeed of around 58 mph and a rate of descent of 200 feet per minute. Minutely adjust the manifold pressure to change the rate of descent. When I designed the new panel for Skimmer One, I put the airspeed over the rate of climb, over the manifold pressure, knowing that those are the three major instruments used for a glassy water landing. After all, the glassy water landing is an instrument approach to touchdown.
Now for the landing itself. The object is to get as close to water as possible before we lose our last point of reference. This is where the shoreline comes in handy as we can see that we are about 10 or twenty feet above the water. Reeds growing out of the water are a help also and can get us even closer. At this point we add power to the known power setting and gently pull the nose up to the airspeed that we know to be correct…and wait, checking again for an acceptable rate of descent, and wings level…and wait, and wait, and wait until finally we hear, rather than feel, the hull parting the water below. Don’t do anything yet. Give yourself a few seconds to make sure that you really are on the water. At this point, retard the throttle as you relax some back-pressure on the yoke to compensate for the lack of nose-down thrust (remember that?). It is most important that you add power first during the level-off to prevent a high rate of descent when the nose is raised. Should you let the rate of descent get too high you may skip out of the water. Do not change anything since you do not know how high you are above the water, and keep your attitude correct and wait for the next contact whereupon you will probably stay on the surface. If you are not completely sure of anything during this most dangerous approach, go around and start all over, making sure you have a rate of climb after adding power to prevent flying back into the water, now in completely the wrong attitude.
The feeling of idling along on completely glassy water is like nothing else. One feels as if they are hovering in a vacuum bereft of any visual reference, except maybe the wake behind the floats and hull. Truly in-explainable, and you will know what I mean when it happens to you.
The glassy water takeoff is identical to the rippled water takeoff in attitude, but it is more difficult to get the correct attitude. It must be done by feel and the sound of water under the hull and sensing that “sweet spot”. Do not get over-anxious with the lift off with too much back-pressure, but allow the Lake to fly off of its own accord when it is ready. The last thing we want to do is lift off with insufficient airspeed since we need to stay in the air and climb away from the glassy water.
Since they are so dangerous, I highly recommend, that if you have a choice, always land on the ripples. However, that doesn’t mean you should not be proficient in glassy water landings. It goes without saying that one should get a proper check-out with a Lake qualified instructor before solo flight, especially in the above conditions.
Text and pictures courtesy and copyright of John Staber, Owner of Colonial Skimmer SN #1; John has flown and worked on Colonial Skimmers since 1964 and has accumulated more than 5000 hours in all different makes and models. In 2011 he published a book on the restoration of N6595K which can be purchased on his website. If you are interested to learn more about Skimmers and Lake Amphibian Aircraft, there will be one new article per week, dealing with a new topic.