Tender choices

You may have thought that anchors were a wellspring of alternative choices, but you haven’t seen anything until you start shopping for a tender for your boat.

Anchors have only one job to perform whereas tenders have a multiplicity of activities to support, from simple transportation, to sailing, to zipping around on river exploration jaunts. Tenders are an extension of your yacht for sport and for service as a shore boat. Versatile they must be, but also safe and manageable in all waters in which you plan to operate your boat.

Tender is a sophisticated name for a small and versatile boat attached temporarily to a yacht for general harbor duties. It is usually propelled by an outboard motor, but generally uses oars as a back-up. They differ from dinghies in size, being larger and outboard-propelled, and in their main use as a support vessel for a voyaging boat. Name differences aside, these small boats are vital to any larger vessel cruising inland, coastal or the blue waters of the world. They give the voyager an independence when anchored to conduct his business ashore without dependence on unreliable and expensive water taxis, to visit other boats in his anchorage or to seek out points of interest ashore and often up rivers. But any small boat will not do the job since size, seaworthiness and handling convenience are all critical to its acceptance. Tenders in the eight-, 10-, and 12-foot LOA size are by far the most popular, with the 10-foot LOA dominant in the voyaging field.The hard-hull tender

Tender concepts have evolved over the years in consonance with material development. The first tenders were wood and followed designs perfected for rowing or sailing. These traditional (and often classic) designs still exist and have a following with those who also like to row or sail around a harbor. To the majority of voyagers, however, outboard-powered inflatable models made possible through the development of plastics offer advantages of more convenient storage and inherent safety. With them, however, comes the lost of opportunity for exercise and the challenge of sailing that comes with the hard-hull tenders. There are some fine examples in the marketplace of hard-hull tenders made in both wood and fiberglass. It has been my fun experience to have owned three different models. The first was a fiberglass Sabot (similar to the El Toro) with a pram bow and hard chine. The size, eight feet LOA, seemed a bit small for adults, and the pram bow was wet to say the least, but it rowed and sailed remarkably well. Unfortunately, it was lost while being towed between Catalina and Santa Cruz Islands one dark and peaceful night. I never towed a dinghy any distance after that; I had realized the chore of stowing it on deck was a small price compared to being without a dinghy on arrival at an anticipated destination.

At another time I had an eight-foot LOA fiberglass Dyer Dhow that had a pointy bow but retained the hard chine like the Sabot with its typical hard-chine stability and excellent rowing and sailing qualities. It was great even without an outboard motor, but it had to be stowed on the foredeck, obstructing easy access to some ground tackle gear. The fact that it was a dream to row countered part of the stowage problem, and I had many days of pleasure with it in Pacific anchorages.

My third experience with a hard hull (these weren’t necessarily in chronological order, but more in market availability) was a Ranger nine-foot LOA fiberglass simulated-lapstrake round-bottom hull. It was an absolute delight for sailing and rowing but exceeded the available stowage space on the foredeck. Its round bottom also lacked appeal as a voyaging tender.

There are quite a number of quality hard-hull tenders on the market today in both wood and fiberglass. We can look at the Bruce Bingham and Bruce Kirby-designed Trinka rowing and sailing dinghy line as good examples of hard-hull tenders for those devoted to the more traditional ways of seafaring life. They have all the appeal of classic appearance, easy rowing and sailing, and good performance under power.

The major drawback to using a hard-hull design for a tender is its weight. Even the smallest Trinka at eight feet LOA weighs more than one person can handle without mechanical help. If I had to set a weight maximum for manually bringing a tender on deck, it would be about 50 lbs. Boats weighing much more than that have to be “craned” in and out. (I learned to hoist my Dyer Dhow aboard my sailboat with a spare halyard, but it still took the services of a second person to guide it into the chocks.) Davits appear to be a real convenience, almost a necessity, for handling a hard-hull tender, and that makes it somewhat unattractive for use on most sailboats of today’s voyaging genre. For the powerboat, however, with a broad, uncluttered transom or a clear swim platform, davits are a reasonable solution, and the hard-hull tender would supply to the powerboat crew an excellent opportunity to enjoy sailing in harbors after they have shut down their mechanical propulsion.

An outboard motor is a necessary convenience to make any tender into a real shore boat. Besides the good looks of the hard-hull tender and the ease of propelling it through the water, the hard-hull tender provides “inside” seating for those persons not inclined to enjoy “sitting on the tubes” of an inflatablesomething that shouldn’t be overlooked by the senior generation.

Opinion polls (and manufacturers’ market shares) indicate that few voyagers, power or sail, are so taken with tradition that they will put up with the shortcomings of a hard-hulled tender when they can have all the benefits of an inflatable tender at nearly the same cost. Price may be part of the reason, but handling inconvenience seems to be the basic problem.The inflatable tender

When I really got serious about blue-water cruising, I turned willingly to an inflatable boat, an Avon Redcrest to be exact, and found out quickly that the inflatable’s value was in stowage, stability and non-marking of the topsides. I also found out it was impossible to row an inflatable even with the longer oars I purchased, and never would it row willingly into any kind of a wind. I can recall many instances in far-flung Pacific anchorages where local work boats would offer me a tow to windward when my obstinate struggle with the oars doomed me to no progress.

The Redcrest, known as a “doughnut concept” inflatable because of the buoyancy tubes entirely surrounding it, could mount a small outboard on its stern buoyancy tube, but the mounting and handling process left so much to be desired that I stuck doggedly with the oars. The outboard motor was just another item to handle, feed, and maintain, and its performance wasn’t all that great. I had been there and done that.

The inflatable boat scene changed quite drastically when the “sport boat” design concept first showed up in the 1970s. It seemed to have some real merit for the voyager who was willing to accept its own brand of problems (greater weight and the need to carry gasoline) in exchange for increased freedom of movement in anchorages. They were still not rowable except under duress, but they showed promising performance with small outboards. Today the market abounds with inflatable “sport boat” tenders; actually, there are so many that it is impossible to make a quick choice.

Inflatable boats broadly invaded the recreational boating field in the 1960s after having proven themselves so ably in World War II military action. French and British companies were the pioneers in developing inflatables and have stayed heavily involved in the market for these boats’ commercial, military and recreational uses ever since. But many other firms later entered the field, and the competition today is intense. This should be your clue to do a lot of shopping around before committing to a purchase.

What made the inflatable successful, besides the original idea, was the timely development of fabric materials and reliable joining procedures. There is a whole class of inflatables made for fun purposes in safe home areas (like swimming pools) that are tempting to buy because of price. They do not, however, have the requisite durability and seaworthiness needed for serious voyagingeven on a relatively protected lake. Most of them are constructed of polyvinylchloride (PVC) non-reinforced sheet plastic, are heat-bonded, and are not designed for use offshore in any large body of water. While PVC and thermal bonding are not necessarily bad, those sold in drug stores are hardly of offshore quality. Do not let these colorful yellow bargains take your eye.

A good inflatable boat for offshore use will have buoyancy tubes, usually two, made of a sophisticated high-tech composite fabric called a laminate. Materials in this laminate consist of an outside layer (not just a coating) to resist chafing, UV deterioration, and petroleum product attacks; a sandwiched middle layer of close-weave polyester or nylon fabric for strength; and an inner layer (again not just a coating) to assure good air retention as well as to provide reliable bonding of adjoining sheets. The laminate materials are products of modern high-tech chemistry and several laminate formulations are vying for the trade. Among the more popular are PVC inner and outer layers bonded to a dense polyester-core fabric (this is a superior PVC formulation to that used in swimming pool toys). Another is the well-known, rubber-based Hypalon, which makes up the inner and outer layers of a laminate cored with a woven nylon fabric. Strong competition (principally by Avon and Zodiac) has fostered extensive development of these two particular fabrics and their related assembly techniques, and there is no clear “better” or “best” at the present.

Before a user blames a tube fabric or assembly technique for his troubles, he should be certain that he has given the inflatable product its requisite tender loving care. Inflatables are not indestructible, but they are almost bullet proof in normal voyaging use.

In searching the market you will find arguments as to the best way to assemble the many fabric pieces that make up an inflatable boat. Two assembly techniques are in current use: gluing and thermal bonding. The former is commonly used with sandwich fabrics having Hypalon surface layers, and the latter is used with fabrics having PVC surface layers. These assembly techniques are not interchangeable; each has been well developed for its own specific fabric applicationthe Hypalon/gluing technique by Avon and the PVC/thermal bonding by Zodiac. Other inflatable manufacturers use techniques similar to these. Success lies in the quality control of the joining process, not just the materials used. Inflatable boat designs

The number of designs of inflatable boat suitable for use as tenders is as varied as the number of manufacturers in the business. They range from the original Redcrest doughnut shape to sport boats that are designed to emulate the performance of hard-hull outboard motor-powered “speed boats.” Indeed, some of these designs can match the performance of many hard-hulled boats. Speed, though, is of secondary value in inflatable boats, following stability, which is what made the inflatable boat so popular in the first place.

Inflatable boat designs can be viewed in three general categories based more on marketing hype than on discreet design schemes. There are the fully collapsible doughnut shapes with removable floorboards; roll-up sport boats with segmented hard or pneumatic floorboards; and rigid inflatable boats (RIBs). These categories are useful for discussion but are non-exclusive, since definitions cannot keep up with the rapidity of design improvements made to these craft.

The in-the-water stability of inflatable boats is what has made them so popular, and the huge buoyancy tubes, ranging from one foot three inches to one foot six inches in diameter, are behind that stability. You can stand on one tube without tipping the boat over, making it ideal as a shore boat, with people often getting in and out and awkward provision and liquid containers being passed on and off under difficult conditions in a rolling sea. The inflatable’s ability to take a grounding on a sandy shore for purposes of loading/off-loading crew and provisions makes it far safer than with a hard-hull design and those high gunwales (the tubes) offer spray protection to stores being carried. You just can’t beat inflatables as shore boats.

The performance of the sport boat (basically the RIB, but also some of the roll-ups) is a direct result of stiffening and shaping the floorboards to make the inflatable behave more like a hard-hull boat. Early inflatable boats, like my Redcrest, had single-layer fabric floors, which rippled when being propelled and sagged when loaded with containers of any kind. This led to the use of plywood floorboard inserts, which were a great improvement for both rowing and low-horsepower motoring. Stowage of these boards, though, created its own problem reducing their appeal and leading to the creation of interesting segmented floor board designs in plastic and wood. These segmented boards can be rolled up with the rest of the boat as part of the stowage procedure.

The roll-up solution solved one problem but created another. The now-integrated floorboards increased the inflatable’s single-piece weight by about 15 lbs, and lifting it aboard the yacht as a unit became more difficult. The pneumatic experts, however, came up with several design alternatives to the weight problem while retaining the fully collapsible feature. One was the “high pressure inflatable floor” (HPIF) made of two separated layers of fabric tied together with thousands of threads (a take-off on the air mattress.) The space between the flat layers (measuring an inch or two) is pressurized to between eight and 10 psi. This makes the floor into a pneumatic plank with the stiffness of a piece of plywood but at a much lighter weight, and makes it capable of being deflated and rolled up with the rest of the boat. (Note that buoyancy tubes are normally inflated to less than three psi.)

While stiffened floors by themselves helped these early inflatables move better under power, it was the incorporation of the “vee-shaped” bottom that really made them into practical power boats. In its simplest form, a smaller fore and aft third inflatable tube acting as an inside keel pushes the flexible lower floor outward, creating a vee bottom for the boat. This gives it some of the advantages of a hard-hull powerboat in performance and tracking without adding too much weight or adding significantly to the stowage problem.

The final design iteration in inflatable boats (at least for the moment) is the substitution of a hard vee bottom in place of the fabric bottom. This is the rigid inflatable boat (RIB)the bottom is hard while the topsides are still inflatable. The vee bottom is made of fiberglass or aluminum, and the buoyancy tubes are attached to it, providing the stability of the inflatable boat concept with the performance of a rigid-hulled boat. Alas, though, it has now lost the convenience of easy stowage: although the buoyancy tubes can be deflated, the hard bottom remains rigid. It now takes halyard or crane lifting or a set of davits to bring it aboard, suggesting that only larger yachts can benefit from its special design. This has not deterred owners of large yachts who are willing to pay whatever price is necessary to equip their vessels with a performance tender.

It is not feasible, of course, to define the ultimate tender since its characteristics lie in the mind of the voyager and his or her intended use of it. The market offers a panoply of design, size, and price choices. However, don’t be too hasty in making a choiceyour later voyaging efforts will be greatly influenced by the tender you finally choose.

By Ocean Navigator