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How To Add A Swim Platform And Ladder To Your Boat

A swim step and boarding ladder combo makes getting back aboard easier and safer. Here's how to do this simple weekend project.

Swim platform

We do a fair amount of swimming and snorkeling from our outboard-powered 20-foot center-console and wanted more than the portable sport diver-style ladder that came with the boat to allow easy access to and from the water. While there are many quality boarding ladders on the market, after researching several styles of boarding ladders and combination swim platform/boarding ladders, we decided on a popular model from Garelick EEz-In that includes an integrated small platform with a telescoping ladder.

Garelick offers models featuring one or two steps, which can be stowed either on top or below the platform, and all the stainless-steel hardware for assembling the platform and mounting the ladders is included. The company's 19000 series of transom boarding ladders is designed for DIY installation on either side of an outboard or sterndrive engine. Models are offered with handrails and telescoping ladders. The platforms are made of 3/4-inch high-density polyethylene that measures 18x15 inches, are predrilled with pilot holes for hardware, and are supported by 1-inch-diameter stainless-steel rails to mount on the transom at a standard 10-degree angle.


Visit "Ladder Lessons Learned" to find out which boarding ladders worked best for self-rescue during a BoatUS Foundation test.

For our application, the Garelick Outboard Transom Platform & Telescoping Ladder model 19536 best suited our purpose. The ladder/platform combo is small enough to mount on the transom on either side of the outboard motor, yet large enough to serve as an over-water seat for donning or removing mask, snorkel, and fins. We selected the under-platform ladder-stowing option to keep the topside of the platform clear in the event we wanted to use it to stand on while inspecting the outboard's lower unit or to remove the cowling while the boat is in the water.

Selection Tip

According to a Garelick customer-service representative, boaters with outboard applications often choose a single-handrail 19536 model swim platform such as ours only to find that their transoms are not high enough to offer suitable thru-hull mounting points for both the strut below and the handrail above the platform (a distance of approximately 22 inches on our project boat). These customers end up ordering a second handrail to support the platform and forgo the underside strut and short support rail that are required with the single-handrail model. In such cases, a double-handrail model such as the 19546, designed for sterndrive use, may be a better choice if there is still enough clearance with the inside rail to turn the outboard all the way to the side on which the platform is installed.

We chose to mount the platform on the port side of the transom, which is a common location aboard outboard-powered boats as it avoids swimmers having to step over cables between the engine and starboard side of the boat on the inside of the transom.

We spent a little more than one hour to complete the installation, which includes mounting the platform to the transom, followed by attaching the telescoping ladder to the platform after it is secured to the boat. Here are the major steps in the installation process.

Tech Support

Degree Of Difficulty: Easy to moderate

Tools and Materials:
  • Tape measure
  • Wrenches
  • Screwdrivers
  • Drill
  • Sealant
  • Stainless steel nuts, bolts and washers
  • Platform and ladder

Time: 1 to 2 hours.

Cost: Approximately $200, depending on model.

Resource: Garelick Eez-In

Mounting handrail on swim step

1. Determine which side of the transom is best suited for installing the swim platform. Mount the platform's single handrail on the side of the platform opposite the outboard. In our case, with the platform located on the port side, the handrail support was mounted on the port side of the platform.

Securing support rail to platform

2. Secure the short underside support rail and angled underside strut to the starboard side of the platform.

Holding platform against transom

3. Hold the assembled platform against the transom to determine its location, making sure it's level with and above the waterline with room to thru-bolt both the handrail support above and the angled rail support below to the transom. Check to make sure the outboard can swing fully to port without contacting the platform.

Marking locations for thru-transom holes

4. Mark the locations of the thru-transom holes to be drilled for the bolts (customer supplied) to mount the strut and support rails on the transom.

Driilling mounting holes

5. Drill the mounting holes, starting with the bit in reverse so as not to chip the surface of the gelcoat.

Sealing holews and bolts

6. Seal the holes, and bed each bolt with marine-grade sealant. Transoms are often wood-cored so it's important the hardware is sealed correctly, or water can begin to rot the wood and weaken the structure. In many applications, backing plates will be required on the inside of the transom to spread the loads and prevent possible issues with the fasteners compressing the core materials.

Attaching strut and support rails

7. Attach the strut and support rails using thru-bolts with adequately oversized washers or backing plates. If the transom is less than 2 inches thick, Garelick recommends that a backing plate (not included) be mounted on the inside of the transom.

Attaching ladder

8. Attach the telescoping ladder, which comes preassembled, to the platform using the pilot holes and fasteners supplied.

Attaching ladder security strap

9. Attach the ladder's security strap mounting tab to the underside of the platform with stainless-steel bolts. Then secure the stowed ladder with the touch-tape strap beneath the platform, and check operation of the strap and ladder.

Swim Ladder Safety

Most people have the greatest strength in their legs, not their arms, making it difficult to pull themselves up a ladder, particularly if their legs can't assist. Steps that do not extend far enough down into the water can make getting up onto the swim platform difficult. Steps must extend far enough into the water to suit your abilities, and any handles for climbing out must be in the right location and high enough to work properly. Even the best platform and ladder arrangement may not work well for all people.

Practice using your ladder at a safe place, such as off a gently sloping beach, with help around, to be sure it suits your abilities and those of your family and crew. You may need to provide additional steps or handholds on the boat's transom or elsewhere at the stern to make getting out of the water easier. These can be bought from chandlery shops or online. Ensure that any hardware is securely installed using stainless-steel nuts, thru-bolts, and backing plates.

Two other important safety notes: To avoid serious injury, turn off your engine when using a swim ladder. And always be aware of the dangers of carbon monoxide when in the water or near the water's surface around boats. This silent killer, which has no noticeable smell, can come from running engines, especially gasoline, as well as other sources on your boat or on nearby boats. It can quickly disable and kill.

— Tom Neale

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Dan Armitage

Contributing Editor, BoatUS Magazine

A full-time travel and outdoors writer based in Ohio, Dan is in his 20th season hosting the popular syndicated radio show Buckeye Sportsman. He gets around on a pontoon boat and an Aquasport center-console, which he uses for all his DIY editorial projects and fishing features. A USCG Captain (Master 50-ton), he’s a popular speaker at boat and sport shows.