Too short, wide, puffy and flexible for what you are considering. It is more raft like than kayak like and will be slow and hard to keep on track in windy coastal waters. You could easily get swept out far from shore where you would have a great deal of trouble getting back to land. Most of these cheap inflatables do not have multiple inflation chambers meaning that if one seam goes, you get a puncture or one valve fails, you are going to sink. Not safe for anything but a small stream or pond with warm water. And with 2 adults and a dog it is going to sag in the middle, which further slows things down.
There are better inflatables for a bit more money (as others have suggested, look at the used market). Sea Eagle’s Razorlite line would be more rigid and reliable and is 8" narrower, which can make a huge difference paddling forward in wind and currents. The thin high pressure walls also give you more cargo room. I have a friend who paddles coastal areas all around Europe in an Itiwit Strenfit X500 solo (they do make a tandem), but he is very experienced and my understanding is that these can feel unstable to people who are beginners.
Folding kayaks are as light or lighter than many inflatables and because of the metal frames, they are more rigid and perform better in coastal conditions. If I was going to take the kind of trip you are planning I would bring my Feathercraft Java , which is a hybrid inflatable and frame sit on top tandem that is 16’ long, 28" wide and has both a drop down skeg and a full rudder, plus cargo mesh nets. (photo below, set up as a solo with the rudder removed). It can even be rigged with a sail. It only weighs 34 pounds and fits in a duffel bag about the size of a standard Army duffel and sets up in about 20 minutes – likely faster with two people working on it. It can be converted to a solo as well by moving one seat to the middle. lots of room on a 16’ kayak for camping gear and any size dog. The inflatable side and floor tubes are encased in sturdy dacron canvas sleeves so they are protected from damage and punctures. Even if you damage one (which can happen if you forget to open the valves to release some pressure when the boat is out of the water in hot weather – the air expands and can pop a seam) they are easily repaired in the field with a glue and patches kit, which come with the boat or can be bought at sporting goods stores.
The Java model is no longer made but used ones do turn up. I only paid $650 for the one I bought used – it was $4000 when it was new. Feathercraft was a very high end product and even older ones tend to be in good shape since people that pay that much for one tend to care for them well. I have another Feathercraft (sit inside solo model) and both are 15 years old with no problems.
Advanced Elements does make some similar models, with aluminum “back bone” frames that make them more rigid, but only the more costly ones would have the features you need. Note that a lot of inflatable manufacturers recommend they only be used on calm lakes and rivers, not coastal use. Brands like Longhaul and Nautiraid make folding kayaks suitable for sea use but they are costly.
I would also suggest you consider getting a pair of solo kayaks rather than a tandem if you are considering this kind of exposed paddling in rather remote locations with just the two of you. If you run into troubles, like an unexpected capsize or problem with the boat, having the other person still in their boat gives you the safety option of being able to assist the dumped person recover their boat. if you capsize in a tandem and also have to deal with keeping track of the dog, it could be a real mess.
You didn’t mention your paddling experience – that would also be important to consider in making your choice of what to paddle and where. Whatever you get, make sure you know how to get back into the boat in deep water if you get dumped BEFORE taking it out in coastal conditions.
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