Installing a Shower Drain in a Head

This article shows how I installed a simple, inexpensive drain into the floor of the head (bathroom) so that I could install a shower.

boat head shower

The head on my boat has plenty of room for a shower, even it’s hard to show it here.

I’m beginning to seriously considering moving aboard full time in April. One of the main drawbacks to the idea is that my boat doesn’t have a shower. There is plenty of room for it, there’s just no drain or pump to handle the water. I researched several different options, originally hoping to install a filter-and-bilge-pump-in-a-box kit that West Marine sells. However, the dimensions and layout of my boat called for a simpler approach.

Upon inspection, the main challenge I had facing me was the fact that there was no apparent way to access the underside of the shower floor without doing serious structural re-work. Although a thru-hull for the sink was close at hand, I needed to have sufficient volume and drop below the shower to install a pump to pump the water up to it.

Since the bilge was close at hand, a clear option was to drain into the bilge and let the bilge-pump pump it out. I consulted several sailors in my area and it turns out that despite the fear of getting hair stuck in the bilge pump, this is a fairly common setup. Because of its ubiquity and simplicity, I decided to document my installation here for the benefit of others.

Prep Work

head drain

Site is prepped, the first layer of fiberglass mat is down, and ready to push the drain into place.

An hour spent surfing the web did not turn up any manufactured drains that would work for my setup. I had approximately 3/4 inch clearance from the bottom of the fiberglass floor to the hull – barely enough to stick a finger under, let alone do any crazy routing of plumbing hoses. Because the shower was fiberglass, I decided to fiberglass in my own simple hose. There is always a hesitation taking on a new project with fiberglass because it’s so permanent, but I felt very confident about this approach.

The first step was to punch a hole and verify the hose I got would snake through to the bilge. Easy enough. The second was to rough up the gelcoat on the existing floor fiberglass. I have a picture at the bottom of this post of the grinding bit I use for this. I have gotten a lot of mileage out of this sucker. It’s perfect for roughing up a surface to ensure good adhesion with new fiberglass.

Installing the Drain

IMG_2433The drain I created was just a piece of 1/2 inch hose with three short pieces of stainless steel welding rod poked through it. The welding rod creates a strainer and also gives the fiberglass a scaffolding to bind to. This makes the anchoring of the hose much more mechanically solid.

After the prep work was done, I cut some fiberglass mat into one inch strips. I then cut these strips into alternating lengths and fiberglassed them up against the interface where the hose goes through the floor. I wanted this interface to be water tights and there was also a gap between the corner and the edge of the welding rod that I needed to fill in. Once my initial layer of fiberglass was down, I pulled the hose through and added another layer of fiberglass mat over the top of the welding rods. Once everything was in place and the mat had wetted-out, I then molded the edges and cleaned up any smears.

I was also careful to thicken my epoxy before applying it, to eliminate the risk of a runny mess.

Detail work

Head Shower Drain Hose

I use conduit clamps to route the drain hose the short distance to the bilge.

Once the fiberglass finished curing, I used conduit hangers to route the hose into the bilge. Now that the basic functionality is in place, I will probably sand down a bit of the fiberglass and apply a gelcoat. This will protect the epoxy from ultraviolet exposure and also help it to blend in better with the floor of the head. The basic fiberglass mat is pretty rough, so gelcoating and sanding will also reduce the edges available for mold and soap scum to collect on.

I also plan to install a filter on the end of the drain hose to catch hair and other stuff like that. I may document this part in a future article, as I’m not sure what I’m going to use yet for a filter. Please leave any suggestions in the comments.

As I talked to other sailors about how to approach the installation of a shower, I found out that many people shower in their cabin and let the water run into the bilge. Since many have come before, I’m sure many will come after. This is an inexpensive and easy upgrade to that basic idea. Hopefully this article will give someone the confidence to do a similar modification to their boat.

Fiberglass Grinder

This is the drill big that I use to grind surfaces in preparation for fiberglassing. It’s very aggressive and works great to rough up gelcoat.

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