bulkeads vs. float bags

-- Last Updated: Sep-06-11 10:30 AM EST --

I often hear that 2 sealed bulkheads are needed for safety purposes (and I have a couple of boats like that). Is there really a good reason why the sealed bulkhead may be safer than float bags or has it become just a shorthand for saying that bow and stern flotation are an important safety feature?
BTW, I just got (as a present !!!) a Liquidlogic XP10 which has a stern bulkhead, and I put float bags in the bow in front of the foot pegs. Simple enough.

(I can see why boats with bow and stern bulkheads might be "better" (vs. safer) in some instances, but it might not be about their bulkheads. For example, those boats with bulkheads tend to be day touring boats (or full on sea kayaks) rather than rec boats, and those boats have advantages over rec boats for some/many purposes.)

Six of one, and a half dozen of the …

If your float bags are taking up the same amount of space as compartments than it would be the same in my estimation, but they seldom do.

In a capsize, the water is going to find every vacant space with the air bags, so I would much prefer the compartments

jack L

Maintenance and related features
First, two sealed bulkheads are usually also associated with full perimeter rigging - static line around the edge. I am guessing that you haven’t worked much with self-rescues yet, or are quite athletic and limber. I find that the lack of perimeter line makes solo re-entry other than one involving a roll to be quite difficult, or nearly impossible.

Second, you don’t have to pay much attention to bulkheads as long as they are good to start. And like JackL says they do displace more water - it’ll get inbetween float bags and you still risk having a heavy front end.

The LL X10 is intended to be used in situations where you would always be able to swim it to a nearby shore. A full out sea kayak is intended to go places where that is not going to be an option. So a float bag failure or unnecessary water in the boat makes a lot more diff in the reliability of a self-rescue out in open water than it does a short swim to shore or the nearest eddy.

I have a stern bulkhead so I don’t feel that I have to buy a special float-bag and shove it in and blow it up and worry about it popping on me.

" Is there really a good reason why the sealed bulkhead may be safer than float bags or has it become just a shorthand for saying that bow and stern flotation are an important safety feature? "

Yes, a bulkheaded compartment encloses more air. It’s not shorthand because not all kayaks can have bulkheads, ie. your XP10 and other whitewater boats can’t practically have bulkheads and it’s assumed the paddler can roll and the river bank is nearby.

Longer kayaks used far from shore can have a larger percentage of flotation to shipped water than a whitewater boat and bulkheaded compartments secure that flotation more effectively than airbags. Speaking as one who had a Mariner Express without bulkheads and eventually added them.

I have two boats that have no bulkheads, but are not rec boats. One is a 17’ mahogany Struer flat water boat. I put a set of sea kayak float bags in it, but I have to say when it capsizes it is a real pain to deal with. The cockpit is big, and the boat really fills up, much more so than a 17’ boat with bulkheads would.

Also, because the interior volume is open, lifting a boat like this with even a small amount of water in it is asking for injury, as the water is free to run all the way to the bow or stern, around the float bags. Even a smallish amount of water all the way at the stem turns the boat into an awkward load that is hard to control.

The other boat with no bulkheads is a 14’ SOF. This one is not such a problem, as the bags are quite big, and the boat doesn’t take on a great deal of water when capsized, which hasn’t happened anyway (except intentionally).

It is really important to have the bags reliably secured, otherwise the water will just pop them out. This is easy in a SOF, as there is framework everywhere to connect to. The front of the Struer is easy, as the footboard holds the bag in place. The rear bag is fairly secure, but does move around when it’s flooded back there.

Thanks, Celia
I always appreciate your detailed replies to posts here. Your noting that bow and stern bulkheads are often “associated with” decklines is part of my questioning – that is, that it isn’t necessarily the bulkheads themselves (assuming one does have bow and stern flotation), but that they are associated with other features like decklines that may provide an advantage safety or otherwise.

(And, yes,I have certainly appreciated the decklines when practicing self-rescue in my dual bulkhead boat.)

And, I do hear you and Jack regarding the water getting around/between the float bags. I’ll have to make a point of testing that out soon! But you are right regarding the XP10; I was not planning to use it where on-water re-entry was necessary. The float bags in this case are more to keep the boat lighter and level swimming it to shore/eddy.

It gets cool fast in the evenings here, and that’s usually when I can get out so I don’t spend as much time swimming as I should!

Just keep checking them
I find that about 1 in 4 float bags I get tend to get rubbed open or otherwise fail sooner than their companions. Bulkheads often have the good grace to start leaking more slowly, giving you warning by making the sandwich soggy.

That said, when I am out on the ocean there are usually inflated float bags inside the bulkheads, just in case.

My Necky lacked a front bulkhead.
I set it up for 3 point ties on a large float bag that fills the bow. The front tie is attached via a swivel to a Harmony drain plug. I felt that if much water got up in the bow, I would want a better way to drain it out rather than tipping a boat that could have a stern full of gear.

Removing the drain plug also allows for detaching the nose loop of the bag. The bow can then be used for one or two of my old slide closure Voyageur inflating storage bags.

Good idea
I like the drain plug idea - that would solve a lot of problems. Mariner kayaks used to do something similar, putting 4" Beckson hatches near the bow of their boats to allow efficient packing of boats with no front bulkhead.

Having said that, and maybe it’s my background as a carpenter, but I could never attack this boat with a drill to install a humble drain plug, no matter how much sense it makes:


Draining a boat with no rear bulkhead is much more difficult. A bow air bag isn’t as much of a problem, but still allows more water in than a well-placed bulkhead.

But I’d strongly prioritize at least a stern bulkhead.

took the words
out of my mouth. You really want to have both in case one fails. The best reasoning for air bags and no bulkheads I’ve ever seen is that if the boat leaks behind a bulkhead there isnt a damn thing you can do about it on the water, and you probably wont even realize it until its well advanced. With no bulkheads that water will find the cockpit where you can pump it out. Even so I prefer bulkheads, and always use bags inside them for serious paddling. It provides a back up, and a way to keep loose gear from flopping around.

my $.02 is that Mariner was lazy and didn’t want to spend the labor/engineering/cost to outfit their boats with bulkhead/hatches because there’s nothing advantageous to passing floatbags and dry bags through the cockpit for a touring kayak to say nothing of the extra amount of water that comes through float bags.

I think the no bulkhead/hatch design was more in line with their design philosophy of no moving or removable parts. They felt that there was simply less to go wrong with a shell-only approach.

I have an Express with rear bulkhead only (which I installed – I don’t agree with every aspect of the Mariner design philosophy). In the bow, I use large airbags secured by a strap and lash-tab. The airbags fill up so much volume that I brace off them with my feet, which is very comfortable over a long paddle. In rough water, I back up this system with a seasock, which gives me huge floatation reserves and makes draining simple.

I still prefer hatches/bulkheads (way more versatile).

Can add a seasock
as well. Keeps water, sand, dirt out of the boat and adds warmth

you’re both right!
I think the issue many manufacturers site is the stress point a bulkhead creates on the hull, some use foam or plastic bulkheads in fiberglass boats to avoid this.

I think it’s different design theories as well as a cost/work issue.

btw. My ancient Mariner I has bulkheads and hatches!

As far as the no moving parts theory the Mariner sliding seat is one really big moving part :slight_smile:

My bad…
Forgot that tiny detail. My boat has a foam seat.

seems to me a flotation bag is a significant moving part with a fatal failure mode. I used two float bags in the bow of the Express and it still would take on more water than when it was bulkheaded later on. After having built a few s&g kayaks I can understand the motivation to go with a bare deck/no bulkheads. Installing hatches takes time. Less time more profit. There are plenty of adequate hatches out there.

Float bags are a distant 2nd choice
My WW kayak lacks sealed bulkheads, so I have two float bags in the rear. Not enough room in front for any. It is only 6’7" long total, total volume 50 gallons.

It always amazes me how much water gets in there WITHOUT wet-exiting. Just cumulative amounts infiltrating through sprayskirt (which is a tight, full-neoprene model) add up to a lot of water sloshing around. When I get out to empty it, the shape of the deck and where the drain holes are make this boat much slower and more difficult to empty than my 17-ft sea kayak with bulkheads.

Wherever possible, I would definitely choose sealed BHs over float bags.