Features November 1, 1998 Issue

Uninflatable Tenders:
Two Alternatives to RIBs & Roll-Ups

Indeflatable is a rigid dinghy for people who like inflatables; Porta-Bote is fast, portable—and flexible.

Once upon a time, tenders were essentially wooden or fiberglass rowboats. Then came inflatables, which are easier to stow, less likely to damage the boat they are tending, and more stable. True, inflatables are not a joy to row, but boat owners in this country have never been too fond of rowing, and inflatables, with their flat bottoms and wide beams, provide more scintillating performance, even with small, lightweight outboards.

When manufacturers noticed that many people didn’t deflate their inflatables, opting to stow or tow them, and that the lowly tender could be used successfully as a runabout or sportboat, the RIB (Rigid Inflatable Boat) was developed with a fiberglass bottom surrounded by inflatable tubes.

RIBs retain many of the advantages of stowable inflatables, except that they don’t deflate completely for stowage. They’re lightweight, ultra-stable, fast (the top speed of soft-bottom inflatables is limited by the drag of a flexingbottom) and still have soft sides, a blessing when you’re trying to tie up to a boat in a rolly anchorage.

RIBs also retain some of the disadvantages of inflatables. They’re not as rugged as a rigid dinghy and they will eventually deteriorate if subjected to long-term ultra-violet (UV) exposure. They generally provide poor stowage, although this situation is improving with some of the newer RIBs we’ve seen which feature bow storage lockers. Their basic configuration wastes interior space—the side tubes intrude into the cockpit so that usable space, even on an extremely beamy boat, is limited. And it’s very difficult to add things like cleats; with inflatables of any type you have to buy rubber cleats and fittings and glue them on.

What We Tested
The Indeflatable and the Porta-Bote were both introduced as alternatives to inflatables. The Indeflatable is an all-fiberglass dinghy that looks like, is designed like and acts like, a RIB. Its major advantages over a RIB are in durability and stowage. The molded- in side tanks of the Indeflatable, unlike the tubes on an inflatable, don’t have to hold air to provide a rigid structure, so it’s feasible to use the space for storage.

The Porta-Bote, a design concept that’s been around for the past quarter-century, provides a good measure of stowability in a boat that’s fast and roomy, if a bit odd looking. It’s made of semi-flexible polypropylene, with molded-in polypropylene hinges that allow it to be folded to the size of a large surfboard. Theoretically, one can then carry it on deck.

How We Tested
We ran these two boats through pretty much the same range of tests that we used in testing stowable inflatables (June 1, 1997) and RIBs (April 1, 1998). We noted things such as ease of assembly, time to assemble (in the case of the Porta-Bote), and quality of instructions. Then we attached an engine and tested them on the water.

Maximum engine size for boats that aren’t inflatable is controlled by the Coast Guard. They’re subject to a computation based on LOA, beam, transom height and total displacement. Inflatables, on the other hand, are free of such limitations, and can be powered up to any limit the manufacturer deems proper. The Indeflatable we tested was rated for a 7-hp. engine (maximum) with up to three people aboard. The manufacturer, Concept Marine, advised us that the boat can be labeled for 10-hp. if the maximum capacity is reduced to two people. We tested it with a 5-hp. engine provided by the manufacturer. The 10' Porta-Bote we tested is rated for 3.9-hp.; we cheated and tried it with a 4-hp. Suzuki.

We set up the same acceleration course we had used for inflatables. We laid out a string of floats on 50’ centers, and measured the time it took to pass each float with two people aboard. We then took each boat out into calm, open water and measured top speed, both with one and two persons aboard.

Lastly, we just ran each boat through a series of turns, tight and otherwise, headed for whatever chop we could find (including some fairly serious boat wakes), and generally wrung out each boat, having fun in the process.

Porta-Bote
The first Porta-Bote we ever saw was a double-ended skiff that was described to us as “sea-going origami.” That was a long time ago; more recently, Porta-Bote replaced the double-ender with a square-back model that makes much more sense with an outboard. This “Genesis III” series of boats comes in three sizes—8’, 10’, and 12’. We tested the 10’ model.

Porta-Botes are made of polypropylene, almost 1/4” thick. There are three chines running the length of the boat; each of these is actually a molded-in hinge. There are three more hinges in the transom. With the wooden seats and transom stiffener removed, you can fold the Porta-Bote’s center hinge up, its two side hinges in, and end up with a flat package measuring about 10’ 10” x 2’ x 4” that weighs in at 58 lbs.

The three seats and the transom stiffener are made of painted plywood, and bundle up nicely into a package about 5’ long x 9-1/2” wide x 6” thick, weighing an additional 23 lbs. The folded boat can be lashed to a rail or stored on a deck or cabin top while the seats fit easily into a good, large compartment.

Assembling the Porta-Bote is quick and easy. The entire operation, after a bit of practice, takes about six minutes, or about as long as it takes to inflate a comparably sized RIB with a good electric pump. The hardest part is keeping the sides spread open enough to insert the first seat. All fittings are stainless steel or anodized aluminum.

Once you put the Porta-Bote together, you have an open dinghy with a 5' beam and a somewhat flexible hull. The seats and gunwales carry enough foam flotation to keep the boat afloat and upright even if swamped.

Performance with a 4-hp. engine was, in a word, startling. The boat, even with a 200-pounder and some gear aboard, jumped up onto a plane in less than 50', with no movement nor other acrobatics required on the part of the driver. With a crew of two, we couldn’t get the boat on plane with the 4-hp. outboard, though it seems likely that two lighter people could. With only a driver, we reached a speed of 15.2 knots; with two aboard, we barely exceeded 5 knots. As a reference point, the easiest-planing RIB we tested, the Apex A10, could only achieve a partial plane and a top speed of 9.3 knots, with a 4- hp. motor and a solo driver.

The Porta-Bote’s ride was unusual. The entire hull tends to flex under the action of waves and power, so that our testers’ initial impressions were that the ride lacked solidity. After 20 minutes or so, we were assured that the boat wasn’t going to come apart, and began to appreciate its virtues.

The Porta-Bote has a soft ride, apparently because much of the force of waves hitting the boat is soaked up in the hull’s flexing. It’s a nimble boat, not surprising for a beamy, essentially flat-bottomed craft. What we found surprising was how accurately it steered, exhibiting very little of the skidding on turns that we’d expected. The handling of the Porta-Bote was very good. Accurate turns could be negotiated at speeds that were somewhat above our testers’ confidence levels.

Stability is excellent. You can stand almost anywhere in the boat without danger of tipping, although, once again, the hull flexibility takes getting used to. The Porta-Bote is roomier than a comparably sized inflatable; there’s no designated stowage area, but the entire interior of the boat, except for a couple of inches of flotation foam inboard of the gunwales, is available for loading gear.

The Porta-Bote’s polypropylene sides aren’t apt to damage a fiberglass or wood hull, even in a forcible meeting. The Porta-Bote isn’t likely to be damaged either. The hull material, which carries a 10-year warranty, is tough. Hulls are available in pearl white, olive drab, and aluminum colors, which are molded into the plastic so that they can’t come off. The hull requires no maintenance. About the only maintenance the boat requires is repainting or re-varnishing the wooden seats.

An important advantage of the Porta-Bote over a RIB is its price. A 10' Porta-Bote lists for $1,249. That’s about half of what you’d expect to pay for a comparably sized RIB. The fact that you can’t legally put a larger engine on a Porta-Bote could also be considered a money-saver. Incidentally, Porta-Bote’s pricing is a refreshing change from usual industry practice—its 12-footer costs only $50 more than the 10-footer. The 8-footer is $40 less.

Are there downsides to the Porta-Bote? Sure. The most severe knock against the Porta-Bote is its appearance, which is odd, to say the least. Compared to a RIB, or to the Indeflatable, which have a “factory-finished” look, the Porta-Bote has obviously been bolted together from a collection of parts. The flexing hull will probably discourage some. While the Porta-Bote stows more compactly than a RIB, it still requires more deck space than, say, a deflated inflatable boat. And you can’t just add horsepower to improve heavy-load performance.

Bottom Line: If you don’t mind the unusual, the Porta-Bote is a good-performing, low-cost alternative to an inflatable.

Indeflatable
With the Indeflatable, Concept Marine set out to make a rigid dinghy with the performance characteristics of a RIB. They accomplished this by the simple expedient of replacing a RIB’s inflatable tubes with molded fiberglass. The result is an attractive little boat with all-fiberglass construction (except for a removable wooden bench seat), squared-off side tubes, and a flat foredeck. The Indeflatable measures 9’ 6” LOA with a 4’ 6” beam and weighs in at 145 lbs.

The Indeflatable is made of three layers of hand-laid fiberglass (plus gelcoat)—two layers of mat, and one of cloth. There’s a white rubber rub rail around the boat, which is helpful, though not as foolproof as an inflatable’s side tubes or Porta-Bote’s flexible hull. There’s over 12' of watertight storage in the side tanks and under the foredeck. Consequently, the 6’ 3” x 3’ cockpit is apt to remain uncluttered (even the 6’ jointed oars stow away neatly). One bow and two stern cleats are provided; additional fittings are easy to attach. It also comes with a compass, an unusual, but welcome, addition.

Like the Porta-Bote, the Indeflatable’s power and capacity ratings are controlled by Coast Guard regulations. We tested the boat with a 5-hp. Nissan engine equipped with hydrofoils. Performance was good. The Indeflatable gave us a top speed of 13.7 knots. It planed easily, though not quite as easily as the Porta-Bote. With two people aboard, we couldn’t get the Indeflatable to plane. The manufacturer told us that the maximum load for planing is about 320 lbs., a figure which we exceeded by 75 lbs. or more.

The ride was much more conventional than the Porta-Bote’s. It felt controllable, stable and precise, if a bit harsher than the RIBs we tested previously. We got the feeling that, if it weren’t for regulations, the Indeflatable could easily handle a somewhat larger engine; we think moving up to a 7-hp. would have made a difference. Turns were predictable at any speed, with little skidding or heeling. We did encounter a bit more spray than with the Porta-Bote and most of the RIBs we tested.

From a maintenance standpoint, the Indeflatable is simply a fiberglass dinghy. It doesn’t require the care to avoid UV damage that inflatables do, and the hull, while it can be scratched, isn’t apt to be punctured. The seat will require periodic re-varnishing. Sitting on the gunwale is comfortable.

The Indeflatable is available in off-white or tan, to match the hull colors of some popular cruising boats. It comes complete. About the only option available is a depth sounder. Concept Marine can customize stowage to meet your specific needs. At $2,595, it is competitive with a RIB of this size.

Bottom Line: The Indeflatable is an attractive alternative to a RIB for people who don’t want to put up with a RIB’s inherent need for care. Its combination of a rigid hull and a rather thin rub rail means that you have to be more careful than you would in an inflatable coming up to your boat. And while it’s a sprightly performer with a light load, you can’t—as you can with an inflatable—compensate for a heavy load by putting on a bigger motor.

Recommendations
It’s difficult to make a direct comparison between two such different tenders. If you’re simply looking for a rigid replacement for an inflatable and are able to live with its power limitations, the Indeflatable is a good choice. It’s well-constructed and nicely finished. Its principal liability, of course, is the inability to carry it on the deck of most boats. In good weather, one can tow just about any dinghy, but even when coastal cruising, there comes a time when it must be brought aboard.

The inexpensive Porta-Bote, on the other hand, is something completely different. It’s somewhat stowable and somewhat quirky. We have seen people cruising with them stowed on deck, though they present a large surface to waves. While it performed very well in all our tests, one of our testers was not enthusiastic about its flexing. If you think that a Porta-Bote might fit your needs, first try getting a ride in one so that you can judge the ride and appearance for yourself.


Contacts- Porta-Bote, Porta-Bote International, 1074 Independence Ave., Mtn. View, CA 94043; 800/227-8882. Indeflatable, Concept Marine, Box 494, Belle Haven, VA 23306; 757/442-2276.

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