Dinghy Towing Basics
February 10, 2012
Filed under Dinghy Towing
Traveling with a dinghy vehicle is almost a given with today’s larger motorhomes. Although the trend to bigger coaches has injected “camping” with more creature comforts than a luxury hotel room, it’s not without its drawbacks. Even rigs with a 60-degree wheel cut will encounter some difficulty negotiating narrow roads in smaller towns during sightseeing tours — and it’s just not fun trying to park a 40-footer at local markets when replacing perishables.
A dinghy simplifies such tasks, and eliminates the need to break camp and stow everything each time you need (or want) to venture away from the campground. Additionally, the dinghy can stow gear securely when motorhome storage is filled (within weight restrictions), and there is the security of having a spare set of wheels in the event of an emergency.
It’s not without consequences; dinghy towing will affect the acceleration, fuel economy and braking of any motorhome, to some degree. However, proper selection of a dinghy and towing equipment will enable you to safely and conveniently enjoy the benefits of auxiliary transportation.
Calculating Towing Capacity
To calculate your motorhome’s available capacity for towing, subtract the fully loaded weight (passengers and cargo) of the coach from its rated GCWR (gross combined weight rating). Then weigh the dinghy (with full fuel) and see if that is less than the amount you just calculated. If you are using a dolly to tow, weigh the dinghy and the dolly together.
The first and most essential step in selecting a dinghy vehicle is to make sure it is approved by its manufacturer for flat towing. While you do have other options —many passenger cars or light trucks can safely be used as a dinghy, provided a towing accessory (such as a transmission lube pump) is available for that specific model as an aftermarket add-on, or towing on a dolly or trailer is planned — these vehicles have been certified for four-wheels-down towing without affecting their warranties. However, buyers should always first confirm flat-towability by consulting the vehicle owner’s manual before the purchase is finalized.
When selecting a dinghy, first find out the maximum towing limit of your motorhome and then determine which vehicles fall within that limit. Towing limits aren’t the only factor to consider, but they help to eliminate many choices based on weight alone. The weight rating of the motorhome’s hitch receiver is another concern, although most are adequate, and receivers can be upgraded. Keep in mind, however, that an upgraded hitch receiver cannot increase the specified towing limit set by the chassis manufacturer.
An economical four-passenger compact car can double as a family’s second car when not traveling, but even a larger SUV or sport truck can be towed, providing its weight is within the towing limit of your chassis.
Most flat-towed dinghies track so well that many motor- home drivers have commented,“You don’t even know it’s there.” Front-wheel-drive (FWD) vehicles with manual transmissions and most 4WD vehicles with manual transfer cases are among the easiest and most economical to tow. Plus, they tend to rank among the lightest vehicles.
Some auto manufacturers also produce FWD vehicles equipped with automatic transmissions that are flat-towable. They are popular because the expense of towing equipment is minimal, and readying for towing involves fewer steps.
But some vehicles do require special procedures, such as starting the engine every 200 miles to circulate transmission fluid. Note that this cannot simply be circumvented by overfilling the transmission before towing, because the problem isn’t caused by lack of sufficient fluid but rather by lack of oil circulation. Such practices, although inconvenient, are designed to prevent drive train damage and must be incorporated into the towing routine.
Another vehicle-specific consideration is that towing some dinghies with the ignition switch in a position that allows the steering column to remain unlocked also leaves power applied to various electrical circuits. Over the course of a full day of towing, this can lead to significant battery drain. While strategies for dealing with this vary considerably by model, most fixes involve temporarily unplugging one or more fuses from the vehicle’s fuse box before towing. A more involved alternative is to connect the offending circuit through an owner-added switch, allowing these circuits to be made tow-ready by the mere flip of a switch.
The Motorhome/Dinghy Link
An essential ingredient in safe dinghy towing involves a solid, properly designed- and-installed mechanical linkage between the motorhome and the towed vehicle. Hitch receivers, tow bars and baseplates must all be in good working order, rated for the weight you intend to pull and, when applicable, designed for the specific application.
Hitch receivers: Check the rating of your hitch receiver to ensure that it is rated for the heaviest load you intend to pull. If a receiver is already in- stalled on your coach, the weight limits and class should be clearly visible on it.
However, the riding height of a motorhome rarely matches up with that of the chosen dinghy, oftentimes necessitating the use of an adjustable- height drop receiver to allow the tow bar to ride level. Receivers should be bolted (not welded) in place, using at least Grade 5 bolts and lock washers, locking nuts and thread-locking sealer.
Tow bars are available in two basic styles: A-frame or self-aligning. A-frame tow bars (offered as “solid” or “folding”), while the most economical, are designed to fit a limited number of base- plates (the mounting brackets affixed to the dinghy) or specific applications; however, the folding design will fit a wider range than the solid design. These types of tow bars are strong, but heavy, and require storage space when not in use. Hitching is easier with a helper to guide alignment.
Self-aligning tow bars are available in two styles: dinghy-mounted and coach-mounted. Coach-mounted units are the most desirable, as there is less chance of damage when not in use — and hitching is a one-person operation. Highly adaptable, self-aligning tow bars fit a broad range of vehicles by attaching to model-specific base- plates: Class III (5,000-lb.) or Class IV (10,000-lb.) models are available. Contact tow-bar manufacturers to find out if baseplates are offered for the dinghy you plan to tow.
Baseplates are perhaps the most critical variable in this link. While tow bars and, obviously, hitch receivers are intended for mass fitment, different brands, models and years of dinghy vehicles require different baseplates and installation procedures, so proper selection and installation are essential.
Installing a baseplate typically entails very specific procedures.
On some vehicles the bumper covering (fascia) must be temporarily removed. Some minor drilling may be required and the bumper covering and/or grille may also require some trimming.
Installing the baseplate can even be more involved, requiring temporary removal of the bumper covering, front fascia panels and some minor trimming of the grille inserts and shock absorption pads.
On some vehicles, the baseplate installation process can be even more intricate. For example, the air dam may need to be trimmed or the factory-installed belly pan may require either trimming or permanent removal. Such requirements are described in the manufacturer’s fitment charts — hopefully eliminating any unpleasant surprises at installation time. Today’s baseplates do a good job of blending into the exterior lines of the dinghy vehicle.
Remember, too, that all 50 states require properly rated safety chains or cables to keep the dinghy from separating from the motorhome if the tow bar or ball fails. Safety chains or cables should be connected securely to the dinghy and crossed under the tow bar, then secured to the hitch receiver. They should be long enough to allow full turning without binding, but not drag when slack.
Other Towing Equipment
Should you choose (or already own) a vehicle that is not flat-towable as produced, there are retrofit kits for many models. One retrofitter, Remco Manufacturing (www.remcotowing.com) estimates 80 percent of passenger vehicles can be modified to serve as dinghies with its line of retrofit products.
For rear-wheel-drive (RWD) and some 4WD applications, couplers enable the driveshaft to be easily disconnected from the transmission or differential by a cable or lever mounted near the driver’s seat. These kits run about $650 and can be installed in about three hours.
A transmission-lube pump can be mount- ed and plumbed into some automatic transmissions to keep fluid circulating while the vehicle is in tow. Other FWD vehicles can be adapted using a Remco axle-lock disengagement device. Check with your dealer to make sure a specific modification does not affect the dinghy’s warranty.
Tow dollies also offer an alternative to flat-towing, although they take up space in camp. Remember that the dolly weight must be figured in with the total weight of the dinghy.
Trailers track better than dollies, but they take up even more precious space in camp.
Also, the weight of the trailer drastically cuts into the total weight that can be pulled behind a motorhome, thereby making this method a distant third choice.
There are a number of other accessories for dinghy towing. Some, like dinghy braking devices, should be considered mandatory, while others (such as rock guards and RV underskirts) protect against road debris. These components are addressed in “Towing Accessories”, along with dinghy wiring and lighting.