Bulkhead install with hull reinforcement & uncut hatch

Hi there, a lake/river newbie here. Have just bought a cheap poly Perception Spectrum to get started with, which has a couple of curious features that I can’t find any reference to in web searches so coming to the forums!

The first is a factory-sealed hatch in the stern section, ie. there’s everything for a hatch, just need to actually cut out the top and install a cover. There’s no bulkheads, only a couple of small bits of foam at each end, so I’ll probably need to install a rear one at least to create a bit of extra flotation as I wouldn’t trust heavily loaded drybags and the old styrofoam to keep it afloat.

Which brings me to the second feature - an oval frame behind the seat that appears to reinforce the shape, plus a tube that runs along the bottom of the hull from end to end of the 'yak, on the inside. This will clearly complicate installing a bulkhead but is probably manageable.

Any advice on dealing with these two features around a) when “adding” a hatch is it fine to simply cut into the hatch template and add a retail hatch over? and b) any tips on installing a bulkhead around the tube/brace?

Also, are these common features? I haven’t been able to find ANYTHING on the net about them, but perhaps I’m using the wrong search terms of tube, rod, bracing, strut, reinforced hulls, etc. etc.?

TIA for any help

I had a Spectrum kayak as you described. It had the two plastic ribs that served to stiffen the hull (one behind the cockpit and one in front), and the aluminum tube (the keelson) running along the length of the hull. You can remove seat, ribs and keelson if you want while working on the kayak, but they do need to be there for the structural integrity.

You could fit a foam bulkhead either in front of or behind the rear rib. Just make a cutout on the bottom to clear the keelson and use lots of sealant around the cutout. Or you could fit your bulkhead inside the rear rib and then seal the bulkhead and rib in place.

If it were me though, I’d skip the hatch and just go with a float bag in the bow and stern. For a hatch, you’ll need to make a hatch cover and find a way to seal it. Or, cut a smaller circular hole in the closed-off hatch space and then install a round rigid hatch with its own rim. It’s all a fair amount of work that might still not be ideal.

Have you paddled the Spectrum yet? I found that the flat bottomed hull resulted in poor tracking. You may want to see if you like the way it paddles before investing a lot of time and money into modifications.


Check the archives. There may be more out there. Perception Aquaterra Spectrum

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If the goal is to add flotation, then I would just go with float bags (as mentioned above). Putting one in the back is easy, as you pretty much just slide it back and inflate it and the seat will hold it in place.

In the front, though, you would be best to find something to attach it to, as otherwise and inflated float bag in a flooded boat may just slide out (and when it does that, not give the kayak any flotation).

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Fantastic comments & suggestions all - thanks! Especially the terms - keelson, I had not heard that one yet.

Yes, it’s certainly an oldie but looks in decent shape (no oil canning or fading). And yes it doesn’t track fantastically, but after a couple of hours to get to know what strokes work and what doesn’t I managed to make peace and grow to like my first 'yak. For a hundred bucks (Au) it hasn’t cost much and I would happily put the same in again to improve its function. Plus it’s good to get to know the details of modifying using a cheap boat rather than a $$$ one!

I do want to carry gear for camping hence the hatch/bulkhead desire, so I’ll do a bit of work and see how it all pans out, although finding the right materials for that has been tricky in regional Australia. I’ll do some documenting & follow up via this post.