Towed or Stowed

Towed or Stowed

Towing is the simplest and least expensive option, since you just tie off the painter, tilt the outboard clear of the water (or remove it and stow it onboard), and off you go. This isn’t a bad choice if you have a sailboat or slow trawler, since the towing resistance will be minimal at displacement speed, and chances are good–especially in the case of the sailboat–that there is no room on deck for the boat. It also saves you the expense and weight of a set of stern davits.
If you plan to tow, a tender with an air-filled collar is the way to go because the tender invariably will impact the mothership’s hull on a regular basis. An inflatable or RIB tender is also unsinkable, provided the collar isn’t punctured.
When towing any boat, utilize a tow eye low on the stem. The boat will tow better than if tied at the bow cleat since the higher tow point will tend to pull the bow down, increasing yaw and drag. Consult the builder to make sure the stern cleats on the tow boat are up to the task.
If you have a semi-planing boat that cruises at 20 knots or more, from a fuel-efficiency point of view, you’d do better carrying the boat onboard, since the tender will create much more resistance at those speeds and increase fuel burn. Also, higher speeds make impact damage to the tender more likely. Boats cruising above displacement speeds while towing their tender must pay out more line and set the tow farther astern so that it rides the wake aft of the rooster tail when on plane. Once you slow down to enter the confines of a channel or harbor, you’ll have to shorten the tow line to keep the tender under control and out of harm’s way.
From a launch-and-recovery point of view, the easiest place to carry a tender is on stern davits of some type. Stern davits allow the tender to stay low, which improves a yacht’s stability and makes the tender easier and safer to launch and recover. Stowing the tender low also prevents visibility problems from the helm (bow stowage) or from the flying bridge (hardtop stowage) and access to the tender and davits is easy if the boat has a cockpit or swim platform. However, if you have an express cruiser or lack a flying bridge, this location could a negatively impact your view astern.

On the other hand, adding weight aft, especially weight cantilevered out past the transom, makes it harder for the boat to get up on plane, and the minimum speed at which it will stay on plane might be a knot or two higher than usual. If your boat is borderline underpowered, an 800-pound tender hanging well off the stern might even prevent you from getting on plane. Adding or increasing the size of interceptors or trim tabs would be a good idea in this case, or you might consider a cockpit extension to increase buoyancy aft.
A trawler with a boat deck on top of the house presents a natural spot for your tender. However, adding the crane and the tender, motor and gear could have a substantial negative impact on the yacht’s center of gravity. CG moves in the direction of a weight addition; when CG moves up, stability decreases, and with it righting arm, which represents the energy that’s available to return your boat to an even keel. If you have a 70,000-pound, 55-foot, hard-chine trawler with a lot of metacentric height designed in, and your tender and davit are modest, then life is good. But if you put a 1,000-pound tender on the top of the deckhouse of a round-bilge, 40-foot displacement trawler that’s not designed for it, you will definitely feel the difference in the roll amplitude and period. Stowing a tender also increases your boat’s effective windage.
On a sportfisherman, the best place for a tender is usually on the foredeck for several reasons. First, it’s not in the way of the business end of the boat. It’s lower to the water than if it were at flybridge level, so the negative effect on the yacht’s center of gravity will be reduced. Being forward of the boat’s center of flotation, the tender might make the boat trim by the bow. This can cut both ways: It makes it easier for the yacht to get and stay on plane, but it also can make the boat behave poorly running down-sea, with both the weight and the inertia increasing the yacht’s tendency to yaw, or bow steer. Once again, a 2,000-pound tender and davit on a 136,000-pound, 76-foot Viking likely will have zero impact on handling, but the same tender on a 40-footer could be a problem running home in quartering seas.
The bottom line is that adding a tender to a yacht is not like adding a porch onto a house. The yacht’s stability and handling, visibility from the helm, impact on the mothership’s waterline, ease and safety of launch and recovery, and accessibility are all elements to consider. The builder, an engineer or even a qualified surveyor can guide you with stability issues. Consult with the builder before installing davits to find out if the yacht’s hull and deck structure can take the load.