All A-Boarding Ladder

The only thing better than hopping into the water for a swim while anchored in that secluded cove is being able to get back on board when you're done.

Spend time at any yacht club tiki bar and you’re bound to hear the tale: a cruising couple, an impulsive mid-ocean swim, the inability to climb back onboard, and the telltale fingernail scratches sighted along the transom waterline of the unmanned vessel when found. In an effort to keep you from becoming the fodder of such sea stories, here’s the scoop on choosing and installing a boarding ladder.

Boarding Ladder Basics

A boarding ladder provides a means to safely enter and exit the water from either a boat’s deck or a swim platform. It can also make it easier to board a dinghy or assist in retrieval of personnel in a MOB (man overboard) situation in calmer waters.

American Boat and Yacht Council (ABYC) standards state all boats must have a means of unassisted reboarding, one accessible to and deployable by a person in the water. The rungs or steps of the ladder must be 12 inches apart, and the top surface of the lowest step of the ladder must extend at least 22 inches below the waterline with the boat in its normal static floating position. While 22 inches (roughly two rungs) is the minimum, keep in mind that the farther a ladder extends into the water, the easier it will be to use – particularly for older or less agile passengers or crew.

Types & Styles

Boarding ladders should be constructed of corrosion-resistant materials such as plastic, aluminum, or stainless steel. However, each material has its pros and cons. Aluminum is lighter and cheaper, while stainless steel is stronger and more durable but also more expensive. Plastic ladders (typically polyethylene) are the least expensive, but not as durable as aluminum or stainless-steel units.

Boarding ladders can be fixed or portable and come in a variety of styles and price points. For the purpose of this article, we’ll concentrate on four types: portable ladders, swim step ladders, transom ladders, and detachable or removable ladders.

• Portable ladders are normally stowed aboard until needed. The most common type found aboard smaller powerboats is the gunwale-mount unit, which simply hooks over the side of the boat. Gunwale-mounted ladders are handy and relatively inexpensive (one reason for their popularity), however, they can also be flimsy. Another possible downside is that they tend to move about when in use, making them harder to climb. An even worse problem is that you must be in the boat to mount them … problematic if you were the only one aboard and fell overboard.
• Swim step ladders are typically mounted to a powerboat’s swim platform. Installing a combination swim platform stepladder is also an option for smaller vessels (i.e., those powered by outboards or I/O drives) that may not have space for a full transom swim platform. Due to their proximity to the water, both types of units normally require no more than three steps to meet the ABYC requirement regarding extension into the water. When not in use, the ladder can either fold up onto the swim platform itself or telescope out of the way underneath.
• Transom ladders are hinged units typically found on sailboats. Many are constructed so that they become an integral part of the stern railing when raised and secured in place. When lowered, they provide an opening in the stern railing and a means of entering and exiting the water. Transom ladders designed as part of the stern pulpit are generally factory installations, however aftermarket units can often be easily installed (depending on the vessel’s transom configuration).
• Removable ladders (as opposed to portable ladders) are attached using permanently mounted brackets, typically bolted to the gunwales or deck of a vessel. They employ keyhole slots, cotter pins, or some similar arrangement that allows them to be easily installed and removed for stowage when not in use. Some units are rigid, one-piece ladders; others are hinged (so they can be folded up rather than removed when not in use), telescoping, or even accordion-style units, which can be adjusted to facilitate boarding a dingy or fully extended for water entry or exit.

Mounting Considerations

Ladders should be located at a spot that’s easy to board the vessel (the side of a sailboat adjacent to the lifeline gate, for example). If stern-mounted, they should be installed as far away as practical from the propeller(s) and exhaust.

Installation Tips

Before you start, thoroughly read and understand the ladder manufacturer’s instructions. Next, visualize the installation and do a “dry run” to identify and address potential problems beforehand. Does the location you’ve chosen for the ladder meet manufacturer and ABYC recommendations? Are the mounting hardware, backing plates, and so on, sufficiently robust? Can they be reached from both sides for tightening? Can you, your family, guests, and others whom you might have aboard easily use it?

Although the thought of drilling holes in your boat can be unnerving, installing a boarding ladder is well within the ability of most DIYers. Here are the basic steps for installing a typical transom swim platform ladder:

1. Select the best side of the transom to mount the ladder. The side you choose should provide easy boarding and not interfere with previously mounted equipment. Stern ladders should be mounted as far as practical from the boat’s centerline (and propellers).

2. For outboard or sterndrive vessels, turn the outboard or sterndrive as far as possible toward the selected side, then mark the transom with a grease pencil to show how far the unit extends. Next, position the swim step or ladder outboard of the mark, keeping it above and parallel with the waterline. The exact height above waterline called for by the manufacturer may vary, but 6 inches is a good general rule if not otherwise specified.

3. Mark the holes for the mounting bolts with a grease pencil. Verify you’ll be able to access each from the inside once drilled (in order to install and tighten the mounting hardware) and that you won’t be drilling into anything, such as equipment, wire runs, plumbing, and so on.

4. Drill the holes using appropriately sized bits. Start by making an indentation at the center of each hole with a punch or other suitably sharp object to prevent your drill bit from wandering. Next, drill a small pilot hole, then redrill with the correct sized bit. To avoid chipping the gelcoat, use sharp bits and drill at slow speed using minimal pressure on the drill, allowing the bit to do the work. Another trick is running the bit in reverse until through the gelcoat, then switching to forward and continuing to drill as normal.

5. Dry fit the ladder and mount to verify everything is properly aligned, then remove the ladder and thoroughly seal the edges of any exposed coring with epoxy (to prevent water intrusion into the coring).

6. Once the epoxy has dried, install the ladder, thoroughly bedding (caulking) the mounting hardware with a suitable marine-grade sealant. Use only marine-grade stainless steel mounting hardware, and install backing plates or large washers to spread the load evenly.

7. Check and tighten the mounting hardware periodically.

Safety At The Dock

Another place to consider installing a ladder is at your home dock or marina slip (if they allow it). This ensures you always have access to a ladder and the ability to enter and exit the water while swimming or in the event of an emergency, such as accidentally falling in the water.

Dock ladders come in various styles, from fixed or stationary ladders to lifting or swing-up ladders, allowing you to choose a design that aligns with your type of dock and specific needs. The ladder should extend several feet into the water and have at least two to three rungs submerged, regardless of tides or water levels. Wide, flat steps make entry and exit safer and easier on feet.

When planning your dock ladder installation, choose a location where the water is deep enough for safe entry and exit, but protected from prevailing winds, waves, and heavy boat traffic. — F.L.