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Honesty Corner

 

     

The Honesty Corner - and hovercraft's experiences - of Marco Mastrangeli, MACP designer.

During my 25 years of activity with hovercrafts I have first been an enthusiastic user, then a frustrated one. I then saw the unexpressed compact hovercraft potentials and modified hulls and engines.

So I became a designer and a producer, user and teacher of advanced courses and now, after having promoted the project Hoverspill and having been the technical responsible, I am dedicating myself to the MACP being president of the Research Center ACTR and CEO of MACP Hovercraft LTD.

a young Marco - Moscow 1995 - Gepard Hovercraft (visit to Neptune)

The MACP - The NEW

My meeting with the "hovercrafts world" began in 1990, when I purchased a company that owned several american hovercrafts and in 1992 I bought other vehicles from the same firm, assuming the improvement of performances. Unfortunately these crafts proved to be very deficient in salt water with a negligible degree of reliability and the activities without failures did not exceed the 5 hours of use. The foam absorbed salt and humidity weighing down the whole craft. After several works including Alessandria 1994 flood and other works at Venice, I was beginning to hate the 2-stroke engines for reliability and high fuel consumption, resulting in a lack of autonomy.

On one of these hulls (about 4 meters) in 1994/5 I even managed to put a Lombardini 45 hp marine diesel engine, 3600 Rpm. managing to make it work decently (once even in a circuit racing). A test of high technology but with a penalizing weight and low power, without the possibility of following for lack of light and powerful diesel engine. But the reliability was exceptional.

Hoverguard diesel

1994/5 - "transplantation" of a diesel engine

In 1999, I devoted myself to the Hover4 project, a 4-stroke engine with 100 hp, bottom hull in carbon/kevlar and protective bow, a clear improvement in terms of performances and reliability, but substantially an improvement of the characteristics of the vehicles already in use, not a redesign of the basic concepts. (with criteria and skills that anyway at that time I did not have).
These Hover4 were produced in discrete quantities, but the real turning point came when, instead of testing the craft according to the criteria of the expected use (SAR missions of short duration), we began to perform specialized services with SOA company, for works in various months (river bathymetries in inaccessible areas, during the winter etc.) and sea 10 hours a day of intensive use, and with little time for a careful maintenance, maximum 1 h in the evening and on Saturdays.
Not so much the individual component, but whole technology adopted (and normally used by us and by our competitors) began to show serious operational limits, wear and unexpected difficulties, repair during missions etc etc..

Syn4

2004 torture of a Hover4 (Core drilling)

 

For about eight years this activity (fortunately made without serious accidents and injuries), has allowed a gradual improvement of the technology adopted, enabling both the fine-tuning of the mission logic (every day we had to go in and out the rivers several times, passing through forests, steep shores, measuring dams and waterfalls, etc.) and the reliability of the small Hover4, so that at the end the revisions time stretched up to 300 h.

But several problems were unsolved, such as the possibility of flooding and disruption of the fund, problems linked to the type of the hull and impossible to improve. At that point, after having exhausted the range of the potential uses, having operated at sea and in rivers, in the most inaccessible areas, became evident the need for a different technology, and consequently the choice not to enter in the market with a vehicle that, despite the improvements, could not be said to be apt to professional use.

2003 - After 700 h heavy duty work (Guzzi based propulsion unit, 1,0 vers.)

From all of these experiences, which then led to the successful realization of the MACP - which I consider to be the CHANGE and I am proud to be the main author - I drew my opinions. As far as my opinions can be considered subjectives or partial, these are nevertheless the product of a work dedicated to these vehicles, supported by an established activity in the field:

1) Hovercrafts are all different. Even in the same dimension, the techniques and materials that you can use are incredibly different, thus performances and reliability. Just like a car, there are off-roads and sport cars. Unfortunately, the success or the failure in the use of a single hovercraft is extended to the entire class, with very bad consequences. I've seen Hovercraft completely wrong for power and size (see Venice Fire Brigades) being sold from a bigger Company of Southampton, which have never worked even in a poor way, whose operational failure has closed the market for years. Instead, I successfully passed very difficult tests, but saw bids calling "3-seats Hovercraft" with no other indication seeing that were bought crafts at a very low cost which didn’t even float.
2) Hovercraft are not easy to drive. In optimal conditions, to be able to get on a vehicle light and powerful and get a nice ride, is easy for everybody. But with the increase of weights, dimensions, and adverse conditions difficulties increase exponentially. When the hovercraft is on cushion, detached from the surface, speed becomes immediately noticeable and you have to deal with the inertia and the difference in driving a mean that has no effective directional appendixes and can only act with the propeller thrust. The lack of feedback and of the usual and predictable reactions, lead to a constant feeling of uncertainty and lack of governability, a feeling that you delete only through practice and use. Professional activities must be carried out even in harsh environmental and weather conditions, and some dangers are imperceptible.
3) Hovercraft manufacturers generally do not tell the truth, or at least enhance performances that will not serve in practice and keep silent on operating limits. (3Wlaw) The problem is that the buyer for the 99% does not know hovercrafts, or applies criteria suitable to boats or cars.
4) Experts and consultants, engineers and naval architects are as much misleading as they are experts in boats. They refer to traditional boats not considering amphibious performances, or the power need to curve, the inertial effect, or simply the fact that a hovercraft goes on rocks and stones, where boats keep far away.
The consequence of these points is that very rarely I have seen hovercrafts responsive to the needs, purchased and used with continuity and expertise, but often they are semi-abandoned by frustrated crews, who are unable to get the best from the craft or are disappointed by the wrong purchase.
5) Trials and demos. Practice tests are fundamental to see if the vehicle is fit for the use. But the buyer should avoid to put unnecessary poles and let the producer (honest) with the task of suggesting the best technical solutions. But long-term tests have a significant cost, and two hours tests only show that the hovercraft can work for at least two hours, but does not consider all the essential aspects (maintenance, resistance to salt water, etc) Then the purchaser should make a tender of the performances required and a description of the work area and submit these to the manufacturer, with a guarantee of purchase once the performance requirements are met. Even better, should participate to work days with teams that use the means, or do a complete course. Or resign to pay the rent for several days.
6) Driving courses and training: unless these are related to recreational vehicles particularly simple and light, if concerning only driving techniques, courses are useless and dangerous. They only give a false sense of security. Drive is a matter of hours of experience, but the true difficulty comes from the mission management, which rarely occurs in areas of easy accessibility, with dangers to which no one is accustomed to recognize. Since a breakdown hovercraft can be reached just by another hovercraft or by an helicopter, it is good to have an in-depth knowledge on how to get out of trouble.
Going up and down from a trailer, perhaps several times a day, overcoming obstacles, the coming up from impervious and craggy shores, are all aspects to be considered. At sea an hovercraft stopped or broken down "clings" with the skirts to the water and stands still, on a river it is suddenly dragged away by the current, and sometimes it becomes unstoppable.
7) Hovercrafts (good designed) are not particularly noisy. The crew proximity to the engine and the propeller is undoubtedly a problem, a drawing-room conversation is difficult. Externally, and contrary to general belief, the propeller noise disappears after a few meters, and if the hovercraft is well designed, not overloaded and with intact skirts, after a while you hear a normal mechanical noise. The problem is that for starting a hovercraft needs to "take off" - or get out from Hump - and for this it is necessary to speed up to the maximum for 5/10 seconds. Any mechanical device set to maximum RPM and close to people has a tremendous effect and the fact that usually works are in the quiet nature makes the noise stand out. The air produced by the propeller can easily knock down a grown man, overturn tables and throw away umbrellas. At the end, it's just a matter of pilot education.
8) Hovercrafts do not disturb the wildlife. Although it may seem strange, birds adapt in a few minutes to the hovercraft presence, and the real problem is that birds don’t move to let you pass. I have personally used hover in parks and lakes, where lived flamingos and other birds, noting with surprise their indifference and, sometimes, we had to map the nests to avoid being attacked ...
9) Hovercrafts are perfect only where there are no alternatives. For how long one might fall in love with the concept, a hovercraft will always be more expensive in the purchase, in maintenance and more difficult to run than a boat.

 

My failures
If errors teach you something, here is a list of which I have been victim/author

January 1995: sucked into the roller under the waterfall at the Tiber Island in Rome.

Cause: incompetence and arrogance.
Lesson: be informed and aware of the potential hazards before
Consequences:
1 craft Hoverguard destruction and severe damage of 1 Hoverguard diesel engine, 2 propellers of rescue boat damaged.

August 97: sinking with a 5 mt. Ackerman hull, diesel powered.

Gela (CS)

Cause: lack of buoyancy and of preventive test.
Lesson: always test first in the shallow waters..

Before sinking


June 2001: Accident with Hover4 in a demo at Police Corps.

(Portovenere)

Cause: abrupt stop for the Guzzi engine seizing
Effects: cut on the forehead as I was bent to adjust the splitter
Lesson: helmet mandatory.
Consequences: for years there was the talk of a my fatal accident.
 

May 2003: Bumping into a "invisible wall" while coming up from a waterfall Bormida River

Cause: tow rope loose, loop in the water and hooking on a stone
Effects: immediate stop of the vehicle in the middle of the waterfall; feeling of having bumped into an invisible wall.
Consequences: destruction of the windshield and of part of the bow of Hover4
Lesson: a new way to get hurt.

 

July 2004: Hover4 impaled on a submerged pole

Lake Viverone

 

Cause: stop on the invisible pole to answer to the phone, with the vehicle overload -2 strong people, 100 l of anti-mosquito treatment, pump and engine, etc. for over 370 kg.
Lesson: be careful where you stop
June 2005: overturning and sinking Hover4 at Oglio River
Cause: breaking of the gas cable, with a strong current in the river; presence of an inclined tree that stopped the venturi duct, and the hull behaved as a“"spoon"
Effect: sinking and breaking of the venturi duct, propeller etc..
Lesson: in the rough river two accelerators control are better.