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Several plastic sit-on-top kayaks are being marketed as "unsinkable" and "sea-worthy". However, I read that few people had to beach when the did not close the front hatch properly.

My question is: how difficult it is to close the front hatch "properly" and how safe are those "unsinkable" kayaks anyway? Does it help if a kayak has water-sealed bulkhead separating the front hatch and the rest of inside of the boat?

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    I am sure a famous ship was described as unsinkable once... – Venture2099 Feb 1 '17 at 13:20
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    This question can't really be answered in general because the design of hatches will change with make and model. Except to say that all hatches/bungs will let in some water - it shouldn't be a significant amount though, it should never be an issue during a single trip but they will need draining from time to time (after several trips). Partly this is also a function of the conditions it's used in and how much water pressure is applied to the seals. – Niall Feb 1 '17 at 13:32
  • @Venture2099: And in WWI, the brits fielded actual unsinkable Q ships against the U-Boats. While in fact filling the entire cargo hold with cork makes a ship unsinkable it does not protect it from being blasted in half. – Joshua Feb 2 '17 at 2:33
  • @Venture2099, actually it wasn't until after the event, but never let the truth get in the way of a good story ;) – Separatrix Feb 2 '17 at 8:40
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    I suspect topkayaker.net/Articles/Touring/LongDistance.html will answer you question. It argues sitons are safer than sitin's, especially for solo and inexperienced paddlers, hatch leaks are a bigger problem with sitin's and bulk heads in sitins create a problem if you take on a lot of water. – user5330 Feb 3 '17 at 20:47
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The boat itself is effectively unsinkable, it's a sealed plastic box. The hatches normally have bulkheads separating them from the rest of the boat. If the hatch sections become swamped it's not going to sink the boat, just make it very difficult to handle.

It should be noted that most properly set up kayaks are "unsinkable". All kayaks should have adequate buoyancy* to prevent them sinking. That doesn't stop them getting swamped when things go wrong. Here they're using "unsinkable" to say that it behaves like solid block buoyancy i.e. like a surfboard. You might be swimming but the boat is still floating.

Sea-worthy is an entirely different game. If you're thinking of using a SOT kayak at sea you shouldn't be straying away from lifeguarded beaches or organised groups. You're much more exposed, more likely to come adrift from the boat and probably inexperienced just because you're asking the question.

How "safe" is it? as safe as the person on board.

I'm yet to see a proper SOT sea kayak. They're mostly recreational toys or fishing platforms. If you're splashing about off balmy beaches in the Bahamas they're fine. If you want to cross the Pentland Firth, then you'll need proper boats and an experienced group.

*"buoyancy" in this case means foam blocks, sealed bulkheads, airbags, etc, design features or addons specifically designed to stop the boat from sinking.

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  • What about SOT kayaks which don't have bulkheads? Still "effectively unsinkable"? I mean, does it matter whether the kayak has bulkhead or not? – josep78 Feb 2 '17 at 9:05
  • @josep78, I'd be wary of one without bulkheads because that's lazy manufacturing and you don't know what else is wrong with it, but if you remember that they're summer toys not proper kayaks you should be ok. – Separatrix Feb 2 '17 at 9:08
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    -1: Although Sit ins have advantages over SOT, are the only option for many locations and my preference, there are a number of manufacturers of high end SOT kayaks that are more than sea worthy enough for long distance touring in moderate conditions, making it incorrect to assert all SOT are toys. – user5330 Feb 3 '17 at 2:36
  • refer : topkayaker.net/Articles/Touring/LongDistance.html – user5330 Feb 3 '17 at 2:44
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    @mattnz, you are entitled to your opinion and he is entitled to his, but what he's saying is they're slower, the hatches leak more and they're better for beginners who are out alone in places they shouldn't be. – Separatrix Feb 3 '17 at 7:58
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No they are not unsinkable.

There is a class of boats where the hull material itself is buoyant, like a surfboard. These sit on types are not of this caliber. They are plastic boats with a sealed (to varying degrees) hull which traps air creating buoyancy. Any break in the seal; either by way of an open drain plug, storage hatch ajar (if part of the buoyant hull), or puncture (disrepair, shark attack, slamming into rocky surf) will cause a loss of hull buoyancy. The severity of the mishap will depend on exposure and the size of the breach in the hull and what methods of evacuating water from the hull you have available.

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  • The polythene they're made of is slightly buoyant, but nothing to write home about. However, as mentioned in the comments to the question, being unsinkable is not protection against getting blown in half, you just end up with two floating halves of a boat. – Separatrix Feb 3 '17 at 9:16
  • A person is slightly buoyant as well but we don't consider people unsinkable. The boat doesn't provide nearly enough buoyancy to provide meaningful aide to a person a drift in a sea in relation to the OP's questions. – Glenn Feb 3 '17 at 14:27
  • Hence why they should have bulkheads and additional buoyancy. If you own a boat without adequate buoyancy, you haven't added any and it sinks, that's your lookout. However under normal operation, normal circumstances, not being eaten by a shark or smashed onto a reef, the boat would not become waterlogged where a normal sit-in kayak would. – Separatrix Feb 3 '17 at 14:42
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In regards to seaworthiness of SOT vs Sit In kayaks, it depends...

Typically a SOT, because you are sitting on top of a air cavity of some depth, will have a higher center of gravity and in that sense be more tippy than Sit inside. Initially the SOT will feel more stable because its like a big surfboard compared to a sit inside sea kayak, which is narrower, but when a sit-inside goes, it goes suddenly. It has little reserve stability.

If you do swamp or flip a sit-inside sea kayak, (and are unable to roll it back, which takes considerable strength and skill, )attempting re-entering a sit-inside, often full of water, can be difficult. A SOT can just be climbed back on (by most fit people anyway) like a surfboard

Some specific hull shapes, available only in sit in sea kayaks ( e.g. Icelandic) , seem tippy at first, but stiffen up when leaning, and have good reserve stability. This type of sea kayak can offer more control in terms of maneuvering it begins to become unstable.

So given a unexpected wave, I think you are more likely to find yourself in the water when you paddle a SOT, because of the higher center of gravity, the lack of secondary stability, and the less optimal hull shape of SOT in regards to controlling the kayak.

But given that you suddenly find your self in the water, I think you are a lot less likely to be able to get safely back into the Sit Inside than the SOT, especially if you paddle solo.

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  • I must correct you on one fact, it doesn't take strength to roll a kayak, only specific technique and skill. – Separatrix Jul 30 '18 at 17:24

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