Repairing Your Ski Boat Floor: A Comprehensive Guide

Repairing the floor of a ski boat is a challenging task that requires caution and a basic understanding of the procedure. The first step is to stabilize the ski boat on a cradle, followed by checking the condition of the stringers and transom, which stabilize and hold the deck. The deck is then cleared of all elements and machines, with cables and connections noted for reassembly. The next step is to create a floor template by laying a plastic sheet and marking the outline, or simply referring to the existing flooring. The existing flooring is then carefully cut and removed, followed by measuring the deck to determine the number of plywood planks needed. The plywood is cut, painted with oil-based paint, and installed on the deck using epoxy resin and cleats. Finally, fiberglass sheets are laid on the plywood flooring and sealed with epoxy resin to protect the floor from water damage.

Removing the flooring

Before you start removing the flooring, you should have already stabilized the ski boat on a cradle, checked the condition of the stringers and transom, and cleared the deck of all elements, machines, and materials.

Now, you can start by creating a floor template (optional). Lay a plastic sheet flat on the deck, taping it tightly. Draw an outline from the bow to the stern and back again, marking the areas of overlapping, console, hinges, and holes. Take photos of the template and then gently remove the sheet.

Next, use a circular saw to cut through the flooring. Go across the length of the flooring, cutting ⅝ inch deep into it. Be careful not to cut too deep and damage the hull. After cutting, slowly pull out each section of the flooring and store it together. This will be useful for understanding the direction of the floor and the points for screwing when you install the new flooring.

If you don't want to create a template, you can simply refer to the old flooring when installing the new one.

Measuring the deck

Measuring the ski boat deck accurately is essential for installing the new flooring. Here is a detailed, step-by-step guide to help you through the process:

Firstly, tie a string across the length of the boat, ensuring it is straight from the centre of the bow to the centre of the stern. This string will serve as a reference point for your measurements. Starting from the bow, make a mark on the string every 16 inches until you reach the stern. These marks will divide the deck into manageable sections for measurement.

Now, for each 16-inch section, you will measure the width of the boat. Hold a measuring tape at each mark on the string and measure the width of the boat to one side, either the starboard or port side. Repeat this process for each mark, measuring the width of the boat consistently on the same side.

Next, divide the bow and stern into three sections each. From the centre of each section, measure the length by holding the measuring tape in the middle and extending it to the other end. This will give you the length of each section.

To ensure accuracy, it is recommended to create a floor template, especially if you are ordering a new boat floor. Lay a plastic sheet flat on the deck, taping it tightly to the surface. Trace an outline from the bow to the stern and back, marking any overlapping areas, console locations, hinges, and holes. Take photos of the template and make additional notes as needed. This template can be sent to manufacturers to create a custom-fit floor for your ski boat.

Alternatively, you can utilise modern technology to measure the deck without physical templates. Photogrammetry is a process where you can use your camera or mobile phone to capture images of the deck. Special targets are placed temporarily on the deck, and these photos are then loaded into photogrammetry software like PhotoModeler. The software calculates the position of the targets and deck surfaces in 3D space, allowing you to outline the deck regions accurately. The output is a 2D drawing that can be exported to CAD/CAM software for further adjustments and tool path planning.

Measuring the ski boat deck is a crucial step in the floor replacement process. Take your time, be precise, and don't hesitate to seek additional resources if needed.

Cutting and preparing the plywood

Now that the measurement is done, you can transfer the measurements onto the plywood board. You can also refer to the previous flooring or the floor template you have made. With that as a reference, cut the plywood planks one by one and see how many planks you would need to cover the ski boat deck.

After cutting the plywood planks, do paint them with oil-based paint. This leaves a waterproof layer on the plywood so that it can survive longer in marine conditions. If possible, you can lay a foam board before installing the plywood plank on the ski boat.

If your boat floor is wider than the standard 4 x 8-foot sheet of plywood, then you have a few options. The more expensive option is to buy an oversized sheet of marine plywood. Sometimes it’s difficult to find and you can expect to pay twice as much for a standard 4 x 8 sheet of marine plywood.

So, to keep the cost down, you can buy a 1/2”, 4 x 10 sheet of marine plywood and cut it in half, making two 4 x 5 pieces. Rotate both pieces and splice them together to make a 5 x 8-foot sheet.

This works well if the main support for your floor runs the full length of the boat keel (centre of the boat), providing good support in the middle. The outside edges of the plywood are attached to the hull cross members where they meet the sides of the boat.

For additional strength, reinforce the plywood seam with a 1/8” x 2” aluminium strap, secured with large flange pop rivets. The end result will be a very firm floor.

Helpful tip: If you need to cut plywood for your project, check out our article on “How to Cut Plywood with a Circular Saw”. It offers some great tips on how to make straight cuts safely on full sheets of plywood.

Putting on the planks

Once you have measured the deck, you can transfer these measurements to the plywood board. You can also refer to the previous flooring or the floor template you have made. Using this as a reference, cut the plywood planks one by one and see how many you will need to cover the ski boat deck.

After cutting the plywood planks, paint them with an oil-based paint. This will leave a waterproof layer on the plywood so that it can survive longer in marine conditions. If possible, you can lay a foam board before installing the plywood plank on the ski boat.

Before you put on the planks, apply a layer of epoxy resin to the deck. Epoxy resin is known for its water resistance. Applying it will stabilise the deck and increase the water-resistance of the plywood flooring. Let the epoxy resin dry and then install the planks one by one.

Take reference from the previous flooring to see where to nail the planks. Make holes with a drill machine and attach cleats for attaching the plywood planks to the deck. Slowly and carefully, install each plank on the deck. Do decide on the direction of laying the planks too. Ideally, they would go across the length of the boat.

Fiberglassing the flooring

To begin fiberglassing, you need to sand the plywood floor lightly. This smoothening process prepares the floor for caulking, which is done to seal any gaps or seams between the floor and the hull, posts, and stringers. Clear caulk is the best choice for caulking as it is less noticeable than white caulk.

After sanding and caulking, a primer coat of resin is applied to the floor. The correct proportion of hardener and resin, as recommended by the manufacturer, should be mixed, keeping in mind the working temperature—ideally between 60 and 90 degrees Fahrenheit. A small batch should be mixed first for testing, and then adjustments can be made as needed. The resin is then applied to the floor using a roller, ensuring adequate coverage on all sides.

The next step is to lay out the chopped strand mat (CSM) over the floor, ensuring it covers all the spaces intended for fiberglassing. The CSM should overlap by about one inch at the edges and on the walls, and any excess can be cut later.

Once the CSM is in place, resin is brushed and rolled onto it, making sure that the overlaps and joints are evenly coated. This step should be left overnight to dry.

After the resin has dried, two layers of gel coat are applied. The gel coat acts as a protective barrier and can be applied using a roller. Wax is added to the gel coat to harden it further. Alternatively, paint can be used instead of gel coat, offering more colour options and non-skid varieties.

By following these steps, you will achieve a high-quality fiberglass finish on your ski boat floor, ensuring its longevity and enhancing its appearance.

Frequently asked questions