Broadly speaking, 3-panel FDS IKs are assembled by gluing the three DS planks into a wrap-around envelope of more PVC which holds the panels in a boat-like shape. Some floors are removable, a bit like a footbed slips into a shoe. This makes the hull skin’s inner floor accessible for easy cleaning, rinsing and drying before storage: an important part of IK care.
Not everyone may see drying as the deal breaker I make it out to be. Much depends on where you live in terms of climate and storage space.
Less good but almost universal with three-panels is a DS floor permanently glued to the floor skin but not fully sealed to the side panels. See the two images above: at the bow and stern where the tape stops, water and debris run down into the side cavities.
A drain valve helps water to run out when flushing before deflating. Some boats feature several capped drains along the sides, which is either odd or a ‘more-looks-better’ marketing gimmick. After all, unless you’re an oligarch, your bath has only one plug hole.
Don’t mistake these multiple drains as self-bailing ports, no matter what clueless vendors may claim or owners may think. Open the drains when afloat and the boat will part-fill with water. Until I realised this, I was baffled by these drains. So it seems were actual owners.
Such a boat is nearly as much of a pain to dry properly as the bladdered IKs I go on about. There will always be moisture in the long, inaccessible side cavities along the floor edge which you’ll struggle to dry properly. Proper rinsing and drying matter if you want your IK to last a long time, especially after you’ve been at sea when sand and other debris can get in the boat. Seawater causes mildew, staining, slime and odours. So does trapped organic matter, while in the long term, trapped grit might rub unseen against the soft PVC until it wears right through (this will probably take years).
A theoretical way to eliminate these issues is by fully sealing or ‘wallpapering over’ the floor gaps the bow and the stern as shown in green above. To drain and dry such fully sealed boats, you simply flip them over to shed the excess water, then deflate, spread out and wipe dry, just like the round-tube Grabner on the left.
A boat modified like this would have no crud-trapping, moisture-retaining cavities. The flaw with this idea would be the air trapped in this sealed-off cavity would make the boat impossible to pack compactly: like trying to roll up a partially deflated inner tube. It needs a breather hole: a simple plug would work. Pull out the plug when deflating, plug up once inflated to keep water out.
Fyi: this is all hypothetical but an Italian chap with a BIC FDS told me he had just this problem: gravel and grit collecting in the cavities. One solution of his was to stuff the openings each end with a dense sponge. Water may still get in but bigger grit won’t. Good idea.
For the moment it seems most manufacturers are happy to settle on fitted floors with drains, just as some buyers are either oblivious to- or not bothered by this issue.
Actually there is a worse option: supposedly ‘self-bailing’ 3-panel FDS IKs which have little side cavities on the edge of the fitted floor and simple drain holes in the outer skin. There are no closable drain valves.
A tellingly unused and unbranded FDS IK (left) I saw on eBay was like this. I had to check with the seller as there were no photos of the floor. Within an hour it sold for £700, but once on the water the new owner will find their boat filling up from below. It may only be a couple of inches, but that water will slosh back and forth as you paddle along, adding several kilos of weight and upsetting stability. You could easily tape up the holes in the outer skin, but this is why what look like FDS bargains come unbranded, badly designed and without guarantees.
As said above: not everyone may see drying as the deal breaker I make it out to be. Much depends on where you live in terms of climate and storage space.