DIY boat ladder: scroll down for a step-by-step guide

Wherever you sail your boat, from time to time she is going to spend some time out of water – in a boatyard or next to your home.

Sitting on the hard while supported with legs, or being on a trailer, your yacht will most likely be difficult to board without some kind of ladder.

In our yacht club I have seen all kind of ladders; some of them too short, most too long, too flimsy, too heavy… the majority of them having had a previous life at home and now ‘retired’ as a boatyard ladder.

For a while, every time I went to my club during the winter, I was hauling my aluminium 6ft A-ladder back and forth, because I needed it at home as well.

If I’d had a smaller car, that wouldn’t have been possible and maybe I would have done something about it much sooner.

I didn’t spend much time on my DIY boat ladder design. I knew it had to be cheap, quick to build and solid enough to support my 90kg+ weight.

Also, it had to be light and easy to stow.

As I enjoy working with wood the most, the choice was easy.

I excluded aluminium as a building material and steel would have been too heavy and would rust.

I decided to use a framing 2 x 3 timber available at any builder’s merchants. I selected the best pieces I could find in a pile.

I looked for minimal knots and them being as straight as possible.

They were not perfect, of course, but I didn’t want to pay a premium price for a high quality wood.

I figured that with some protection the ladder should last at least a few years.

As I write this, six years later, the ladder is still in excellent shape.

Measuring up for your DIY boat ladder

The first thing to do is to measure how high your deck is from the ground – or better still, the exact location on your boat where you want to board.

This might be a side deck near the cockpit, or stern, or whatever part of the boat you find the most secure to access when the boat is on hard or on a trailer.

Next you need to decide on the angle of your ladder when in use.

It’s much easier and safer to climb a ladder which is not completely vertical, but too much of a slope is uncomfortable and puts more strain on the ladder construction.

I have found that an angle of about 70° is ideal.

The bottom of each side rail should be cut at that angle so that when the ladder is in use the side rail foot is parallel with the ground.

You could attach some rubber pads on each foot to protect the wood and make the ladder less likely to slip on wet surfaces.

You also need to think about where you will attach the ladder.

It must be securely attached to the boat before use with a strong piece of rope, for example. I position my ladder to access the boat over the side decks into the cockpit, and I use my genoa winch as the securing point for the ladder.

It’s best to make your ladder side rails extend above the top rung so they provide some kind of handholds.

Don’t make them too long, however, as they’re not supported by rungs and may break if you lean too heavily on them or pull on them strongly.

If you make your side rails using 2 x 4 timber, they’ll be stronger but you might have difficulties holding onto them if your hands are on the small size.

I made my side rails extend for 24in after the top rung.

Materials

A mortise and tenon joint is used to connect the rungs to the side rails Based on your ladder dimensions, calculate how many pieces of 2 x 3
(or 2 x 4 ) timber you’ll need.

You need to know how wide your ladder will be, with the length of each rung increased by the amount needed to wedge it inside the rails with a mortise and tenon joint.

Joints of half an inch should be enough. Also, work out how many rungs you will make, the distance between them, and how high from the ground the first one will be.

The rungs on my ladder are 15in wide (not including the length inside the side rails) and the step distance between rungs is 12in.

Cut the two side rails to length. Clamp both side rails in position as they will be when the ladder is complete (inner faces of side rails are together) and secure them to the work bench.

Mark the positions for each rung on both side rails.

Now unclamp the rails and open them like a book – so the inside surface of the side rails is facing up. Clamp them together.

Mark the areas to be cut out – where the rungs will be let in to the side rails.

The angle is the same as the angle you marked to cut the bottom (foot).

This way all the rungs will be horizontal when you position the ladder to be used.

After marking the areas to be cut, unclamp the side rails. You should now cut out each section of side rails where the ends of the rungs will be inserted.

If you are good at using a circular saw, set the blade depth to ½in and make parallel cuts then use a chisel to remove the wood.

I used a hand saw because I was hoping to get a more precise shallow mortise into which my tenon (end of the rung) will nicely fit.

Next, try dry-fitting rungs into the side rails. Don’t attempt to assemble the whole ladder yet.

Most likely, the side rails and rungs are not perfectly straight, so even if you try, it won’t work.

Remember you are using construction grade timber, not perfect cabinetmaking wood.

Continues below…

The purpose of dry fitting at this stage is to make sure your rungs will fit into the side rails.

Ideally they should fit tightly, but if you did make some mortises too wide, you can always insert some shims to remedy the problem.

I suggest that you again clamp together your side rails with mortises pointing up and check that all mortises are the same depth.

It is also important that all rungs are cut to exactly the same length.

Once you have mortises on both side rails ready, drill two holes into each mortise. The size will depend on the screw size you will be using.

I used 3in-long No8 decking screws with ceramic coating, four for each rung.

Space them far enough from the mortise ends so they don’t split the rung ends when you drive screws into them.

Then, on each side rail, about 1in under the bottom rung and 1in under the top rung, drill a hole for a ¼in threaded rod.

Tip: First drill a bigger hole for the nut, big enough so you can put a socket on the nut, then drill the ¼in hole.

The larger hole for the nut should be deep enough to accommodate the height of the nut plus washer.

Before starting assembly, cut two pieces of ¼in threaded rod to the length equal to the maximum width of the assembled ladder, ie. the distance between the outer faces of the side rails when the rungs are inserted.

You’ll also need four nuts with flat washers. If possible use nuts with Nylock inserts, or apply some thread locking compound if using regular nuts.

Assembling the ladder

With side rails and rungs ready, you can start assembling the ladder. Each rung will be fixed using deck screws and exterior wood glue.

First, drive the deck screws into all the holes made through mortises; drive them just short of protruding into the mortise.

Clamp one side rail onto the work bench with mortises pointing away from you.

Apply glue to the mortise and to the end of the rung, insert the rung into the mortise and drive both deck screws in.

If you have a work table long enough, it’ll be easy to align each rung within the mortise, just push it down to the work table surface.

If you are working using a work bench – as I was – you could clamp a length of wood to the side rail so that you can align each rung to be flush with the side rail surface.

When all rungs are glued and screwed to one side rail, turn it so the rungs are pointing up.

Now, things will go easily or not, depending on how straight your timber was.

I had some difficulties aligning the second side rail with all rungs because my timber was not perfect and there was some twist in it.

If you run into a similar situation, here’s what you do: start with the bottom rung – align it with the mortise, but not the full depth, just enough so it will stay inside.

Apply glue and drive in both deck screws, but not too much – just enough to hold the rung in place.

Then work in the second rung, again just deep enough to stay inside the mortise.

As you go, you can go back and tighten the screws on previous rungs to make them go deeper into the mortise. That way you can slowly force everything in place without breaking anything.

Your ladder will most likely have 6 to 10 rungs, so you should be able to do this quickly enough before the glue sets.

Final assembly of your DIY boat ladder

If you need to force the side rails together because they’re not straight, use some rope (the Spanish windlass technique) or bar clamps.

Don’t try to force them just by tightening the screws because you’ll risk splitting the ends of the rungs.

When you have all the rungs glued and screwed in, install the threaded rods under the bottom and top rung.

If they’re a little too long, grind the excess so the ends will be flush with the side rail surfaces.

The following day, you can round the corners on the side rails tops.

If you feel like making your ladder even better looking, sand everything using 80-grit sandpaper and apply some wood sealant.

You can even paint it but then you will increase the chance of your ladder disappearing as it may start to look too fancy and expensive… which for sure it is not.

DIY boat ladder: Step by step guide