I'm just starting out, getting interested in hovercraft, what sort of things should I look out for?
If you are buying a manufactured hovercraft, around 4 metres long then most manufacturers, having been in the business for years well know their designs capabilities, they will guide you. They also want to sell you a hovercraft.
The Turbo hovercraft and the ones made in NSW (Australia) by Nell Fabrications perform well in this size of craft. For hovercraft over 4 metres the game changes dramatically and for 5.5 metres plus in length there are few designers and/or builders in Australia who have done the research, it's hard to get information or informed oponions.
If you are looking at, and want to buy a used hovercraft, 'one that works because you have seen it perform then I suggest the following:
Check the hull underneath for damage, particularly between the skirts. I saw a hovercraft which had just been purchased by a beginer, it had a large piece of tree branch sticking out of the hull under the skirts where it could not be seen easily, apparently the previous young owner had crashed into a submerged tree. Part of the fibreglass hull had to be rebuilt when the branch was removed.
I owned an aluminium hull hovercraft in which the buoyancy foam had absorbed water making the hull twice the weight, it was difficult to lift the craft by hand. I could not get rid of the water without replacing the buoyancy foam and the chemical reaction between the wet foam and the hull material started to corrode the aluminium. Also, the foam deteriorates with vibration.
Remember also that Electrolysis between dissimilar metals in a hovercraft will cause pit marks in the aluminium and corrode the copper wiring. When you check the wiring, you will find that the multistrand copper wire has gone black, it cannot be soldered and it can be brittle.
To slow the deterioration I paint the new wire joints and fittings with old type not thinned oil based house paint, it soaks into the wires and joints and dries to a skin but not where it touches the metal. when I need to re make the joint, I just wash the oip paint off with turps or petrol and clean with Methylated spirits before re soldering. you can get paint on your hands so be careful or it will be spread everywhere you touch, including your clothes.
Some things to check.
Check the skirt system and fingers for damage, are they attached firmly to the hull, are the attachment screw holes firm or loose. Happens in fibreglass hulls. I have seen several instances where the screws came loose over the water and the skirt loosened losing air pressure in mid flight over a lake.
Check the engine and pulley bearing mountings for vibration damage, check the engine mounts for damage, is the engine loose, are there any cracks in the mountings, are the mountings or thrust frame distorted.
Check the seams and the edges of the hull where water can enter. Any crazing or cracking will let moisture in to the fibreglass or in the case of an aluminium hull water can seep in and build up behind bulkheads and stiffeners.
Check the duct for prop wear and vibration damage. The fan moves because of a combination of cyclic forces and it will wear against the inside of the duct, Water/moisture can get into the fibreglass of the duct making it difficult to repair
Check the thrust fan blades for chips and damage, If it has a multiwing fan, are the blade tips and duct worn, if it has a thrust prop, are the tips chipped or waterlogged, is the guarding strong and not rusted away.
Check rudders and steering mechanisms for wear. (Self explanatory)
Check the electrical system, do the switches, lights work., do the motor/s shut down and start easily, does the battery charger work. Do you get a shock from the charger, 'it has happened to me'.
Is the seating firm or flattened and uncomfortable, upholstery cracked or worn.
Is the fuel tank firmly mounted and no fuel leaks, is the fuel hand bulb soft and pliable or is it hard and cracked, are the hose clips firm.
Does the craft hover Ok - loaded and unloaded, over land, water, grass, etc; are the skirt fingers damaged, is the bag sun damaged.
Is there any vibration with the motors running, is it normal vibration or is somehting out of balance, is the drive belt loose and vibrating.
Is the craft easy to get on and off the trailer, are the rollers working or worn. If it is a fly on trailer, is the floor in good order, no holes or jagged edges to catch skirts or fingers.
If you are looking at a commercial hovercraft, is the survey current, is the equipment in good order, Life jackets, fire extinguisher, paddles, torch, other.
Any way you get the idea ---- and don't hesitate to ask if you are unsure.
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