Fishbox Improvement, 101: Closed-Cell Foam, Gaskets, and Pumps

If you are anything like me – and since your eyes are seeing this you probably are – fishing is the number-one mission on the agenda most of the time your boat leaves the dock, and you will be putting the fish you catch into an integrated fishbox. Some built-in fishboxes are great, while others leave a lot to be desired. Unfortunately, it isn’t easy to alter them and you’re more or less stuck with what the boat comes with… right? Wrong! A little work and some creative thinking is all it takes to improve the integrated fishboxes on your boat.

Most fishing boats have an integrated fishbox or two – and most of us wish they looked like this one does right now.

The biggest problem with most integrated boxes is a lack of insulation. Some builders pump foam in around the box, some add coring into the laminate and call it “insulated,” and some do nothing at all. On one boat I ran for a season, the box was nothing but a fiberglass shell located directly above a pair of diesel engines. The first time I went fishing, 120 pounds of ice melted away before I arrived at the hotspot. Luckily, in most cases you can address this issue exactly as I did: get a can of spray-able closed cell foam, and blow the foam in all over the back and sides of the box. This is often, however, easier said than done. You’ll probably have very poor, limited access to get under the deck. The soultion? Get a few feet of aquarium air-line tubing. It’ll slide right over the nozzle on the can of foam, and you can thread it deep into the boat’s belly to reach those un-reachable areas. One word of caution: this stuff expands as it dries, to the tune of 60 or 70 percent. Be careful not to over-do it, or the expanding foam could end up far from where you intended and could potentially cause damage.  

Water leaking into fishboxes in the deck is another leading cause of premature ice melt-off, which is commonly seen on modern fishboats. The cure here is simple: get one of those sticky-back gaskets they have at the marine supply store, and add it to the seal or lip on the fishbox hatch. These gaskets only last for a couple of years before the glue fails or the gasket deteriorates, so you should expect to replace it with some regularity. On the bright side, the job only takes 10 minutes and the gaskets are cheap.

Another common problem with integrated fishboxes is evacuating the water, scales, and slime. Boxes with the best design drain directly overboard, but those that don’t need to be pumped out. Macerater pumps are the most common, but these tend to clog, seize, or fail with seasonal regularly. Occasionally you’ll see mere bilge pumps used to drain a fishbox – these tend to clog, seize, or fail with weekly regularity. The solution? Swap them out for the noisier and more expensive but far more reliable diaphgrahm pumps. Although this is a pricy and labor-intensive move, these things can pump wet sand out of the fishbox without being damaged, much less slime and scales.

Using these improvements, your integrated fishboxes will be better than ever. Now get out there and fill ’em.