Features May 1, 2004 Issue

Airdeck Rollup Boats

In a test of seven roll-up boats with inflatable decks and keels, the Zodiac Cadet 310FR ACTI-V was the top choice. Best Buy honors go to the Mercury 310 Airdeck Hypalon.

So, you need a blow-up boat to use as a tender for people and gear between shore and anchor, or for checking out the harbor, or for gunkholing up shallow creeks, or for increased safety when cruising—or for all of the above, and more. 

Testers ran each of the seven boats with both a 5-hp two-stroke Mercury and an 8-hp four-stroke Tohatsu.

You have several styles to choose from. At one extreme there's the old-fashioned flat-bottomed inflatable with slat floors of wood or aluminum. It's light, inexpensive, fairly easy to set up, but not made for speed or comfort. At the other extreme is the full rigid-bottom (RIB) inflatable with a fiberglass or sometimes metal hull and inflatable tubes above—stiff, and therefore fast; expensive, heavy to carry, not really stowable. There are several construction styles in between, but the style with which we'll concern ourselves here consists (with the exception of transom and mounted hardware) entirely of inflatable elements—two or three inflation tubes, an inflatable deck, and an inflatable keel section to give shape to the bottom of the boat. Sometimes the deck and keel chambers are combined.

These boats go by different generic and trade names, but they all endeavor to achieve efficient underwater shapes, like their cousins, the RIBs, by means of inflated parts that create V-sections. They all have decks that are inflated to quite a high pressure, generally around 11 psi. You wouldn't think of that as high pressure, but consider that the tubes on an inflatable are usually pumped to a pressure of around 3.5 psi. And they all roll up and stow in the space taken up by a medium-sized sailbag or large duffel. Since there seems to be no agreement on a generic name for this kind of boat, we'll call them airdeck rollups.

There are several advantages to this kind of boat. First, they're light. All of the boats in this review can be carried easily by two people, and with some difficulty by one person, for a short distance, either in their stowage bags or on the back, turtle-style. When in their bags, they can be stowed in a cockpit locker, or lashed on deck like a liferaft. Second, their bottoms are shaped so that they track straighter in all conditions—rowing, towing, and motoring—than their flat-bottomed siblings. In fact they're on a par, in many cases, with their RIB cousins in terms of performance and stiffness, although their light weight and lack of absolute rigidity in chop or at high speed can take them down a notch. They're also very comfortable at higher speeds if you sit on the airdeck itself. They absorb much of the jarring.

The main disadvantage is the flip-side of the advantage: Inflatable keels and decks can be punctured, ripped, and chafed through, perhaps no more easily than the inflation tubes above them, but common sense would suggest that you not drag them repeatedly up and down a shale beach or launching ramp. And no running in them with scissors.

What We Tested
The test was limited to 10-foot boats with high-pressure air floors—three Hypalon boats and four PVC boats. The floors of all of the boats are made of PVC, except the Achilles.

There are pros and cons to both Hypalon (the Dupont trade name for chlorosulfonated polyethylene, a durable synthetic rubber) and PVC (poly-vinyl chloride, a thermoplastic resin).

Hypalon is more expensive, but generally resists ultraviolet rays better. It therefore has a longer lifespan, and is particularly recommended for duty in warmer climates.

However, Hypalon seams need to be glued together manually, while PVC seams are "thermo-bonded," which makes for a good, airtight seam out of the factory. PVC fabric is somewhat easier for an owner to patch and repair, but it's also more susceptible to degradation from chemicals and oils.

All the boats have 5-year limited warranties except for the Mercury 310 Hypalon version and the Avon Rover, which come with 10-year limited warranties. See the individual boat listings for other key specs, including maximum horsepower and maximum engine weight. Due to the influx of four-stroke outboards, the American Boat and Yacht Council (ABYC) now recommends that boat companies list maximum engine weight on the transom plate. Four-strokes weigh more than two-strokes, which means a boat might be rated for a 10-hp motor but might not be able to handle the weight of a 10-hp four-stroke.

All prices listed are from Defender Industries (www.defender.com), with the exception of the West Marine RU-310 HP, whose price is quoted from West (www.westmarine.com).

Performance Testing
Testing took place in Sarasota Bay in calm conditions with very little current. Testers ran each of the seven boats with two engines, a 5-hp two-stroke weighing 44 lbs., and an 8-hp four-stroke weighing 81.5 lbs. Three-gallon fuel tanks were used.

We ran each boat/engine combination with one and two people, usually more than once with different people, but combining the crew combinations so that all boats carried about the same weight for each test. For the two-person tests the combined weight was about 400 lbs., give or take 15 lbs.

The manufacturers made a point that the boats must be inflated to their exact specifications in order to perform as designed. Accordingly, we were very careful with pumps and pressures.

These boats are weight-sensitive, so for each test we tried to sit in the most comfortable or "natural" helmsman's position to take our GPS readings. However, we also moved around the boats to see what we could do to help or hinder tracking, time-to-plane, sideways crabbing, spray, and safety. Suffice it to say that there are ways to operate these boats safely and efficiently—and every other way is no good. We were glad that both engines had dead-man's lanyards to clip to our belts.

Because of the calm conditions, we couldn't get much of a feel for how dry or wet these boats would be in chop. We did run them through passing boat wakes when we could, and tried occasionally to sit in places and goose the engines in ways that would encourage water to come aboard. There's not much to report here. They were all essentially dry.

The results of the performance testing are shown in the chart (see "Test Results: Airdeck Rollups" sidebar). GPS speeds (in miles per hour) are averages resulting from at least two full-throttle runs in opposite directions, with ample time for the GPS to settle. Even so, differences in speed shouldn't be over-valued. In the first place, a difference of even a knot or two is pretty meaningless in boats like this (unless you happen to be racing them). Rather, the whole procedure gave the four testers a chance to put all the boats through the same paces, methodically.

Other Factors
We also assessed the ease of assembly (including the quality of the air pump and the air valves), disassembly, and pack-up of each.

Testers also checked the placement and type of handholds, lifelines, and lifting rings, as well as the construction of the transoms.

We checked rubrail thickness and whether each boat had a protective keel strake.

Mercury 310 Airdeck (Hypalon and PVC versions)
Both Mercurys came with a dual-action hand pump and a good gauge—far superior to the foot pumps supplied with the other boats. This will make a big difference if the owner plans to inflate and deflate the boat more than a few times per season; for instance, if the boat is blown up for a harbor visit and deflated for the passage to the next harbor.

We also like the three-chamber layout for the tubes. It adds a valve, but also a safety factor in case one of the chambers is punctured. (Note: The PVC boat's pressure gauge was stuck at 2.5 PSI, so we used the gauge that came with the Mercury Hypalon.)

In addition to the three buoyancy chambers, the boat has an airdeck and a keel. The keel valve on the Hypalon version was difficult to center in the airdeck's circular opening. The Mercurys had the most secure oar arrangement of the seven boats tested. They're locked inside a sleeve that's attached to a swiveling T joint. Bungee cords also hold the oars just forward of the blades. The only downside is that you can't feather the oar blades while rowing (meaning that you can't rotate them parallel to the water on the return part of the stroke). This can make a big performance difference when rowing into a headwind, especially in a light inflatable boat with lots of windage.

The seat cannot be moved when the boat is inflated. The rope lifelines are not great handholds for the driver. The Hypalon version has a beefier rubrail than the Mercury PVC version. Both Mercurys have one-way drain plugs accessed from inside the boat—more convenient and safer than plugs that must be pulled from outside.

We found the Mercury boats the best balanced of all seven for rowing.

The Mercurys are the only boats with a protective keel strake.

The PVC version comes with a 5-year warranty, while the Hypalon boat comes with an impressive 10-year warranty.

Achilles LSI-104 Air Floor
The Achilles instructions were not exclusive to this model; they covered several different boats.

The oar arrangement was secure, but you cannot feather the oars. We like the lifelines, which provide security all along the tops of the inflation tubes.

There are two seat positions, but you cannot move the seat when the boat is inflated. There's an exterior drain plug with one-way valve. The air valves are conveniently located in one area, forward.

The Achilles has a Hypalon floor, which should be good at resisting UV degradation. It also has a fiberglass transom, which seems to us a better option than wood in this application.

Avon Rover R310 Air Floor
The Avon's inflation gauge does not mount in-line with the pump, as do all the others, making it more difficult to monitor the pressure while inflating. This boat took a long time to inflate, and does not pack as easily as the others, in our experience.

The Rover comes with light, two-piece wooden oars that Avon says have been used successfully for 20 years on their boats. The oars didn't feel as strong and rugged to us as the aluminum and plastic ones that came with the other boats. The oars are well-secured around their blades, but the looms rely on bungy cords for security. The Rover was the only boat that had an effective way to hold the oars on the inboard sides of the tubes.

The boat had no lifelines aft, but did have excellent handholds for the helmsman. It did not have a one-way drain plug, as on the others, nor did it have an aft seat position. The rubrail was the beefiest of the bunch, and the 10-year limited warranty (matched only by the Hypalon-version Mercury) earns the Avon boat big points.

Zodiac Bombard 305 Typhoon
The Bombard is both the lightest and least expensive boat in our test group, and it compresses, folds, and packs easier than the rest, too.

The Bombard is 5 cm shorter than the other boats, and the transom is set farther forward, which makes for a smaller cockpit area—and a shorter running surface. The buoyancy tubes forward are narrower, and the bow is more pointed and upswept.

Oar storage is not good, in our opinion. The oars can pop out of their aft keepers if the helmsman sits on them, and they can be dislodged by water sweeping up in a hard turn. Rowing, however, is very good.

The Bombard Typhoon's air valves are grouped conveniently in one location, forward. It has excellent webbing straps for handholds, and on the bow.

This boat was fast with two people, or with one person and the heavier engine to hold the transom down. The ride was rougher than the better performing boats, like the Cadet and Mercurys, however. The Typhoon has a clever optional bow stowage bag, but no aft seat position.

Zodiac FR310 ACTI-V Cadet
We had no problems with the instructions, assembly or packing of this boat. Ease of packing was second only to the Bombard.

The Cadet has the same oar stowage arrangement as the Bombard—quite secure forward, somewhat less so aft. It also rows nicely.

Inboard D-rings serve as tie-downs and can be used to lift the boat. Sitting on the tubes was uncomfortable for the helmsman because of the oar arrangement. But the boat does come with an aft seat location. Like the others, the seat cannot be switched when boat is inflated.

The Cadet was not the fastest boat in the test, but we considered it the best all-around performer. It was the only boat with skegs on its bottom—and they worked, helping it track well and giving the driver greater control. The ACTI-V inflatable deck/keel (combined in one chamber) makes a fairly pronounced "V" underwater forward, adding smoothness to the ride.

Not only is the drain valve inside the boat, but it's designed with a nifty open-close lever that's easy to operate.

West Marine RU-310
Zodiac makes this model for West Marine. Our test boat came with no instructions (it's supposed to, said West Marine), and the inflation pump had a kink in its line.

The boat, unlike all of the others, has a blow-up seat cushion that can be moved about. At first we were skeptical of this "pillow," but grew to like it. The testers placed it against the starboard tube and sat on it. The only downside is that it can blow away.

The 310 has a single lifeline around the top of the tubes. The oar arrangement is the same as on the Cadet and Typhoon. The inflation valves are not recessed, and can dig into your back when you're seated forward.

The boat felt light and was fast, topping out well over 20 mph with one person and the 8-hp motor. We noticed very slight transom and floor flex with two persons aboard and with the 8-hp pushing the boat. Turning and control was average.

Rowing was fine. You can feather the oars, but they're a little hard to turn. The bottom of the boat is flattish, with only a slight V-shape forward.

Conclusions
Our four testers were unanimous in picking the Zodiac FR310 ACTI-V Cadet as top boat. The Cadet's stability, tracking, and general feeling of seaworthiness really separated it from the other boats, despite the fact that it wasn't particularly fast, and has less-than-ideal oar stowage. The skegs and the ACTI-V inflatable keel really work.

For the second choice, three of four testers liked the Mercury 310 Airdeck Hypalon, and one dissenter liked the Avon 310 Rover. For the third choice, the dissenter went for the Mercury Hypalon, and the other three for the Mercury PVC. Obviously, we were impressed with both Mercs. They're very good all-around boats, from the superior pumps to construction to rowing balance. A Best Buy rating goes to the Mercury 310 Air-deck Hypalon, which Defender sells for $1,440, about $600 less than the Zodiac Cadet.

Our thanks to Stephan Lance of Defender Industries, Waterford, CT, for loaning us the Mercury boats, as well as for good advice on inflatables in general. Thanks also to Bob Kurmin of Sarasota's West Marine for the use of his RU-310 and loaning us the Mercury 5 outboard.

 

Also With This Article
"Test Results: Airdeck Rollups"
"Pictures and Specs"

Contacts
• Achilles, 201/438-6400, www.achillesusa.com
• Defender Industries, 800/628-8225, www.defender.com
• Mercury, 920/929-5040, www.mercurymarine.com
• West Marine, 800/BOATING, www.westmarine.com
• Zodiac/Bombard/Avon, 410/643-4141, www.zodiac.com

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