Swartkat is a Stealth Evolution Duo two-man spearfishing kayak.
This page shares some details of how we equipped the kayak for spearfishing and mentions problems and dangers we have overcome and survived.
The Stealth Evolution Duo is sold as a fishing kayak. Although it does work well also for spearfishing, there are various little things which need to be carefully addressed and managed.
My first spearfishing kayak was a Fluid Synergy, a plastic two-man general-purpose kayak---I still have it. It is a lovely seaworhty boat, extremely durable, very stable, very safe and it handles very well in the surf. What makes it less than ideal for spearfishing is that it is a bit slow, and it has no hatch, so everything, equipment and fish, has to be stowed in bag lashed to the deck. This only really leaves enough space for a single spearfisherman.
An important question that I had to answer was whether it would be better to use two similar one-man kayaks, rather than a single two-man kayak. I have done both and the answer is clear---if one of the paddlers/divers is inexperienced, you want to use the double boat.
Although I list several issues with the kayak below, taking everything into account, this kayak works very well for a father and son spearfishing solution.
The kayak has an overall length of 5m and is made of fibreglass. It has a large fish box along about 60% of its length, making it effectively double-hulled, with two separate buoyant cavities, the fish box and the main hull.
The fish box is fitted with a bung on top of the bow---it can be drained via this bung if the kayak is tilted on its side or inverted, but it can also be bailed via the hatches.
The fish box is accessed through two hatches with hinged lids, one in front of each seat. The lids are equipped with rubber seals and can be tied down. Nevertheless, if you roll in the surf, several liters of water do get forced past the seals into the fish box. It helps a lot if you tighten the lid straps properly, but still, some water will get in. If you roll multple times, more water gets in. Water makes the boat heavier, more difficult to paddle and steer and more likely to roll again. Lots of water makes the boat impossible to carry once you have landed. Try to stay upright.
Even if you stay upright, if you spend a long day at sea and you often have to open the hatches to stow fish and retrieve equipment, then some water will splash into the hatches, no matter how careful you are.
The main hull cavity drains through a separate bung (also on top of the bow). Before I fitted the inspection cover for the echo transponder (see below), the bung was the only access to the main hull cavity and the only place where you could drain it. If you're at sea, draining the hull through the bung will be very difficult. It is best to avoid water in the main hull cavity. But as we found out, water can and does get in there.
The worst leak was caused by a spear tip. Although the total length of the fish box is about 3m, it is partially obstructed by the two seat wells. Short spearguns can be inserted into the box through the rear hatch, but longer ones have to go in front. If your spear is longer than about 1.5m, you have to remove the spear from the gun and insert is separately.
In any event, at some stage of trying to fit long spears through the front hatch, we must have perforated the thin fibreglass bulkhead at the forward end of the fish box, allowing water to pass from the fish box into the main hull. This hole was difficult to find, but was then readily repaired with a blob of epoxy on a long stick. This solved about 80% of the leakage. Now we are more careful when stowing guns and spears---we always try to put a protective cap (a short length of speargun rubber) on the spear tips before stowage.
Another way that water enters the main hull is via the two rudder cables. These cables enter the main hull cavity near the pedals and exit into a small, frequently flooded cavity, that is hidden under small lid, directly above the rudder. Although the cables run inside thin plastic tubes all the way through the hull cavity, there is some leakage where these tubes pass through the fibreglass hull. This leakage is slow, but we found if we spent 4 or 5 hours out at sea, we shipped a few liters of water in this way. I later applied silicone sealant to the cable entry points and that seems to have reduced the leakage.
In summary, some water can and does get into the boat, into both hull cavities and you have to have a way to bail out this water at sea if it should become too heavy. We always go to sea with a small hand pump, with a long flexible inlet tube, as well as a 500ml hand-held container for scooping. We have only occasionally had to use the pump out at sea (and never the scoop), but we do routinely pump out some water after landing to make the kayak easier to transport.
An anchor is essential. It is a safety device that can be used to arrest drift caused by currents and wind when you are too tired to paddle. It also allows you to stay in a chosen location where you want to dive, especially if both paddlers leave the boat to dive.
There is an important difference between anchor requirements for fishing and for spearfishing. When fishing, you usually do not leave the boat, but when diving, you always do.
When spearfishing, you often find the situation where one person is on the anchored boat, while the other is in the water some distance away. The diver could then call the person on the boat, sometimes urgently, for example when a shark wants to take his fish. Then you want to be able to quickly detach the anchor, without losing it. Our anchor is therefore rigged with a float, which can be unclipped from the boat instantly.
For several reasons, it is better to attach the anchor to the bow of the kayak, rather than the stern.
If you anchor in a new spot, before leaving the boat:
This photo shows: flotation jacket, battery for sounder, pencil flares, water bottle, cell-phone in waterproof pouch, pump and container for bailing, flag alpha, anchor with float and snap clip.
If you go to sea, you should already know what safety equipment to take. I'd like to add the following:
You may or may not want to use a GPS. These days almost every telephone and even some watches have them. Just make sure your device is sturdy and waterproof.
A compass, however, is cheap, robust and simple. I glued a small one to the hatch lid. If you are caught in the mist, you will be happy to have it.
Clips and things
I have fitted multiple additional clips and bungees onto the deck in various places. These come in very handy to temporarily secure various things on the deck, especially fins, gloves, diving masks, spearguns and floats. But of course, in the surf, you must stow everything more securely in the hatch.
Currents can make anchoring impractical when both divers want to be in the water. This can be managed by not anchoring the kayak, but rather to tie it to the floatline of one of the divers.
Even wind from the side can be a problem. The rudder is ineffective unless you build up enough speed. If the chop is high and you are tired, it is hard to build up speed. If you can't rely on the rudder, it can be very diffult to turn the bow against a cross-wind to maintain the bearing you need to reach your destination.
Surf is scary! Probably scarier than most sharks. As I'm writing this I still have a bad limp from a surf-related injury more than a week ago. What I learnt from this experience: Do not tie up your paddles with a strong leash---it is the leash that injured me and if it had not snapped, I would have been injured even worse. I have subsequently inserted thin triplines in both leashes.
That said, the paddle leashes are essential. You do not want to leave the boat to dive if your paddles are not secured to the boat.
Handling the kayak in the surf requires skills acquired through experience. The paddlers have to work together.
Some tips for heading out through the surf:
When returning through the surf:
I have equipped Swartkat with a simple Garmin Echo 100 fish finder.
I'm happy with this sounder and would recommend it for this purpose. It is small and light enough for the kayak and it is waterproof (it even floats). It has a modest energy budget (lead-acid batteries are heavy), yet it delivers good quality images of both the bottom profile and fish in the water column. During a recent outing in False Bay, I could clearly distinguish on the echo the difference between schools of anchovy and shad.
The echo sounder itself is removable. It clips into a sturdy rotating mount. I fastened the mount on the rear fish box lid, where it is close enough to reach and to read, but far enough to allow my paddle shaft to swing through. I can rotate the echo if I want to show something to the front paddler. The two cables to the transducer and battery pass through (now sealed) holes in the deck underneath the canvas hinge of the lid.
The transducer is glued onto the inside of the bottom of the main hull, with silicone adhesive. I was told by the Garmin vendor to avoid air bubbles in the silicone adhesive. Apparently I managed this---the sounder works very nicely. Since the kayak has a double hull (the fish box is a separate enclosure inside the main hull), I had to cut a port into the side of the fish box, just behind the rear foot wells, through which I could reach the main hull to place the transducer. Cutting a neat circular hole inside the confined space of the fish box was a pain. Glueing the transducer down was easy.
I closed the hole by fitting an inspection port with a threaded lid. The transducer cable passes through the lid, via a grommet made from speargun rubber. The inspection port would allow me to reach the transducer again if needed---and also to bail the main hull at sea if it should flood.
The sounder is powered by a 12V, 2.4 amp-hour sealed lead-acid battery. I chose a small battery to conserve space and weight. I think it has adequate capacity: on its first excursion it was able to power the echo for a total 4 or 5 hours over two days, after which it still maintained a voltage above 12V.
The battery is mounted inside the fish box, in a small home-made galvanized steel plate bracket suspended below the deck, just forward of the rear hatch and snug behind the front seat well. In this position, the battery does not obstruct the stowage of long objects (fins, yellowtail, spearguns, etc.) into the fish box.
The battery is recharged while driving to and from the sea, by connecting it directly to the car's cigarette lighter, i.e. directly parallel to the car's battery and alternator. The alternator regulates the voltage at just over 14V. I measured the charging current, after the above-mentioned 5 hour discharge, at about 0.5A. This is still below the 0.72A maximum charging current, as specified by the battery manufacturer.
For a severly depleted battery this simple recharging setup may result in excessive current. If this turns out to be the case, I may have to modify the charging setup to limit the current. An excessive current can cause hydrogen to escape from the battery, shortening its life.
It is important to recharge any lead-acid battery as soon as possible after use and also to periodically top up the charge when not in use. If left depleted for too long, a lead-acid battery suffers irreversible damage.
The kayak is heavy. It weighs a few kilos more (maybe 3 or 4 kilos more) than the specification on the manufacturer's website (32kg). When it has stuff in the fish box (spearguns, wetsuits, anchor, fish, weightbelt!) it becomes even heavier. It is not a pleasure to carry, even for two people. You need a trolley.
I cobbled together (some welding of square-tubing and angle-iron was required) a collapsible trolley, with nice fat wheels for traversing soft sand. The plastic wheels were scavenged from a large toy quad-bike.
When assembled, the trolley is large (100cm long, 70cm wide, 50cm high), but when dismantled everything folds flat (except the wheels) and it fits easily into my vehicle.
The kayak rests on the parallel planks. The outside edges of the planks are 38cm apart. This spacing gave the best fit to the hull curvature.
The 70cm long cross-bars match the width of the kayak. They make it easier to properly position the kayak on the trolley and also provide conveniently positioned attachment points for the tie-down cords.
Obviously the boat has to be rinsed with fresh water, but the fish box has to be cleaned properly. I fill it with a few liters of water while it sits on the trolley and add a dash of chlorine bleach (Jik). Then I rock the boat forwards and backwards on the trolley to wash. Then I drain it through the bung with the hand pump. The pump only needs to be started and then it siphons the rest out by itself.