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Hovercraft
By Mike Glanville
Hovercraft Buyers Guide
Buying a hovercraft? We hear many sad stories from people who have purchased hovercraft only to discover the hard way, what works well, and what doesn't. This guide was created by the manufacturers of the Hov Pod, a three person marine leisure hovercraft, for further details visit www.hovpod.com
See Buyers Guide at http://www.hovpod.com/ownership/buyersguide.html
Small hovercraft can be classified as race craft, kit-build or leisure.
1. Race craft focus on speed
2. Self-build focus on low cost
3. Leisure craft focus on safety and reliability
Cost versus Performance, Safety and Reliability.
For Race craft, speed is the key objective, so weight is reduced wherever possible. For example, to reduce weight, craft have very thin GRP, so safety can be compromised. Race craft are often designed for land rather than use on sea. Thin GRP is needed for racing but not in leisure use as any impact causes expensive damage. Safety features such as the fan cage may restrict airflow, so safety is often compromised by speed.
Self-build folk favour the low cost approach; this often can affect quality, safety and performance. People spend considerable hours building hovercraft, (200 to 400 hours) only to experience major disappointment on the first outing. The Hov Pod has taken years of development to eliminate the pitfalls associated with hovercraft design and manufacture. That said, some people love a challenge, and are happy to spend hundreds of hours creating their own craft. But at what cost? Too much work and not enough play can make Jack a dull boy!
The third type of craft appeals to people who just want to have fun. Leisure hovercraft demand safety, reliability, and ease of use.
Not all leisure craft are the same.
Some manufacturers sell new hovercraft with second-hand engines, purchased from local salvage yards. Some craft dig their nose into water and stop suddenly with dire consequences. Some craft do not contain enough buoyancy and sink! Some craft don't restart on water (a paddle could be useful) Many craft have one-piece skirts that cost megabucks to repair. Hulls that crack and let in water, craft you can't steer without throwing your weight violently into the corners!
Engine type. Hovercraft need high power-to-low-weight engines. Rotax are very popular, proven by many years use in the snowmobile and microlight industries.
Rotax offer intake silencers and exhaust mufflers to give excellent noise reduction. Some new craft have been sold with 'used' automobile engines or small commercial engines that need to be re-tuned and upgraded to generate sufficient power and therefore are prone to long term failure and overstressing of components.
One engine or two? Many hovercraft use two engines, one for thrust, one for lift. Hov Pods have only one engine for lift and thrust; reason being that it is easier and far safer to coordinate one set of controls, easier to service one engine, plus you get less noise from one engine. Thrust engines are often placed in front of the driver - yuck! All those fumes and noise coming at you, and the first wave that hits you may swamp the engine, causing lift failure.
We deliberately designed the Hov Pod without a gearbox assembly, this allows us to site the engine much lower in the craft, providing lower centre of gravity, reducing the tendency to roll (we have even seen other craft literally roll over in a simple low speed turn), and providing much greater ease of control. We also place the engine low down to ensure no airflow disturbance to the fan; clear airflow results in greater efficiency, and less noise. We only use new engines, whereas many new hovercraft have been sold with reconditioned engines
Stopping on land. Hovercraft should be considered as land-based vehicles as well as water-based; stopping on a small rock shouldn't cause the floor to crack, since cracks let-in water. Most hovercraft have a single skin or thin and weak double skin floor, whereas the Hov Pod has a thick double skin floor, between which runs a stiff marine grade buoyancy layer for greater safety and strength. We add Kevlar (as used in bullet proof applications) and aluminium runners and impact sheets to protect the craft from the inevitable knocks that occasionally occur.
Stopping on water? During demonstrations, a number of customers have panicked when we stop the Hov Pod on water, because other manufacturers have told them to avoid doing this! Many hovercraft have a problem with starting on water, and you will sometimes hear the expression "getting over the hump", that describes the problem in getting back up onto the cushion of air to start moving again. Hov Pods are designed to lift a payload of 250 kilos (HP52) or 310 Kilos (HP65) on water starts. (Add 25% more weight capability when starting from land) Other craft also have a very severe tendency to spin and throw occupants when stopped quickly on water; the Hov Pod has been designed to quickly yet safely and smoothly stop in a controlled straight line.
Buoyancy. Many hovercraft have poor buoyancy characteristics and can actually sink if swamped, whereas the Hov Pod has full buoyancy sandwiched between a rigid, double skin floor. Not only will the Hov Pod stop quite happily on water but it has also been independently tested for flooded buoyancy approval. Buying a professional designed and manufactured craft helps to overcome regulatory restrictions, where they apply.
Skirts Occasionally, hovercraft skirts may get damaged so you need to know how to replace a skirt, and how difficult the job will be. The Hov Pod has 65 different segments, (for damage limitation) so rather than having to replace the whole skirt if damaged, at great cost, you just replace the damaged segment. Naturally you will wish to go exploring with your hovercraft, but need to get home safely, so having a few spare skirt segments handy is a good idea, only takes a minute to change each segment; far easier than trying to recover a hovercraft with a damaged one-piece skirt. Hov Pods use a Hypalon/Nylon material (as used on all RIB's) for excellent wear, UV and salt-water protection. The Hov Pod in tests has operated with up to 25% of the skirts missing. The careful design of the skirts also means that in normal use the Hov Pod generates virtually no spray and the drive and passenger can stay virtually dry.
Hov Pods are designed to withstand accidents when they occur, protected by an aluminium plus rubber bumper strip to minimise damage to the craft. Vehicles not fitted with bumper bars suffer far greater damage during impact, reason why autos have them fitted as standard. Very few hovercraft have such protection, despite the fact that cracked GRP damage can be difficult and quite costly to repair. We also fit aluminium and Kevlar impact sheets, and aluminium runners on the underside of the Hov Pod for durability whilst coming to rest on firm ground. The design approach to incorporate a thick and rigid double skin hull and extensive impact protection is important because we have seen other craft where the hull has literally fallen apart after hitting a wave.
"Ploughing in" is a term to describe a problem where a hovercraft suddenly stops, due to the nose of the craft dipping into water - as anyone knows, sudden stopping or deceleration will cause passengers and driver to part company with a vehicle, so we have designed the Hov Pod to overcome this problem. The Hov Pod has never ploughed in, though we continue to hear of incidents where other hovercraft have suffered this problem, sometimes with quite serious consequences.
Transporting the Hov Pod. The Hov Pod can be supplied with a fully galvanised custom designed trailer made by an approved trailer manufacturer. For safety this trailer is designed for single person operation. Many cheaper trailers are available but require either two three or four people to back breakingly lift the craft off and on the trailer. The Hov Pod trailer utilises 4 rubber coated rollers (to protect the hull and stop that annoying banging when trailering) and a simple winch mechanism to gently unload or reload the Hov Pod in about a minute.
Good safety design is no accident; extensive development has gone into designing the Hov Pod. Safety is a very important aspect of design for the leisure market, and our designers have considered many factors not found on other craft. For example, we fit a front and rear guard to the fan assembly - who in their right mind wouldn't? (Actually, the majority of hovercraft manufacturers don't) Consider sealed batteries and ventilated fuel tanks for example. Or ease of use, the Hov Pod only needs fingertip control, no need to shift your weight to turn corners! Again the Hov Pod has gone through a full governmental certification.
Other considerations: Check craft quality, is the craft constructed of GRP, has GRP chop strand mat been used or as in the construction of the Hov Pod, quadraxial mat? A whack with a mallet shouldn't offend. GRP when new nearly always looks great but if not made by experts in a controlled environment it will soon suffer from many hidden problems. Ask to see an older model to check the quality of the GRP, which can crack and delaminate after 6 months. An immaculate looking craft on day one can, after 6 months, can look very forlorn. GRP repairs are costly. Does the craft have a really solid bumper protection system? Can you give the impact areas on the side and bottom of the craft good hard whacks with a mallet? Can you sit on the side quite happily without breaking it?
Ease of use: On Water - can the craft be used in the conditions you intend to use? On water, sit on the side, climb in, climb out, will it topple over? Does it plough in? Will it float? What weight can it lift in on water-starts? Has any government provided safety certification? Do an emergency stop; can you keep control? Does the craft travel in a straight line? Do you have to throw your weight when cornering? Many craft will not turn unless you move your weight to the side of the craft? Is driving instinctive to use, with handlebars and throttle, or are complex joysticks and elevator controls needed to use the craft?
We have deliberately focused on product quality, and to understand our marketing approach, you should read the Design Philosophy Document. http://www.hovpod.com/technical/designphilosophy.html .
Stretching the dollar, pound or euro is important for everyone, but so too is value for money, no one wants to spend thousands on a vehicle that is unsafe or difficult to repair.
Hov Pods are extremely easy to drive, similar to a motorcycle, and fantastic fun. In demonstrations, we can usually hand over the controls to a person after 15 minutes tuition. Hov Pods were specifically designed for marine leisure and commercial use, and have many features that you will not find on other hovercraft. Hov Pods are designed to be easy to use, easy to service, safe to operate, reliable, durable and fun. We hope you will soon arrange a demo so that we can show you the superior features of the Hov Pod so that you can see for yourself, why it remains probably the best leisure hovercraft available anywhere in the world today.
Contact us via our website www.hovpod.com Download the Hovercraft Buyers Guide from http://www.hovpod.com/download/Buying%20a%20Hovercraft%20Guide.PDF
About the Author
The Hov Pod is manufactured by Reaction International Ltd, in Southampton, UK
Telephone +44 (0) 7699 391 390
See website www.hovpod.com
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