Picking the Correct Boat Hose

If you were to ask a group of boaters which type of marine hardware causes the worst case of sticker shock, most of them would probably think of electronics or engine parts. Well, they’d be wrong. In my 10-plus year career in working with marine supplies, it wasn’t a new radar system or engine thermostat that made my customers feel as if their wallets were spontaneously combusting. Nope, it was boat hose.

Imagine pulling a three- or four-foot section of one-inch engine water intake hose out of your boat and then taking it to your local marine shop for a match. Next, imagine nearly $30 vanishing from your back pocket. While per-foot hose pricing can take your breath away, don’t let it tempt you into skimping or misplacing frugality. When it comes to boats, selecting and installing the right hose for the job is absolutely essential to system functionality, as well as safety. Let’s take a look at the types you’ll likely encounter.

Pro tip: When measuring for hose, always find out what the inside diameter (ID) of the hose you’re replacing is, not the outside diameter (OD).

This is the good stuff and the best to use in marine sanitation systems. Look for the black or white, wire-reinforced, rubber hose marked specifically as "Sanitation.

This is the good stuff and the best to use in marine sanitation systems. Look for the black or white, wire-reinforced, rubber hose marked specifically as “Sanitation.”

Sanitation Hose
If you’ve been on a lot of boats with toilets that have been in service for more than a couple of seasons, you know “that smell.” It’s very common, and can be hard to prevent and hard to eliminate.  Aside from tedious head maintenance, the best way to help keep those odors at bay is by using the proper sanitation hose, which is engineered to not absorb odiferous effluent.

Unfortunately, this hose comes with that aforementioned sticker shock. Be prepared to spend as much as $10 a foot for the good wire-reinforced vulcanized rubber stuff (comes in black and white). And be sure it is classified as “sanitation hose” on the outside. It’s generally sold in 1-1/2-inch diameter, but can also be found in 3/4- and one-inch sizes for use with macerator pumps.

You will also likely find white PVC sanitation hose with stiff, somewhat inflexible characteristics. Yes, it will certainly look better where it is exposed in head compartments, and it is cheaper than the “black stuff,” but it does not resist odors nearly as well in the long run.

Uses: Head discharges, holding tank lines, macerator pumps, and vented loops.

Raw water/exhaust hose is tough stuff, made up of layers of cloth- and wire-reinforced rubber.

Raw water/exhaust hose is tough stuff, made up of layers of cloth- and wire-reinforced rubber.

Raw Water/Exhaust Hose
Typically among the most expensive hose you’ll find in any marine supply shop, exhaust hose is usually comprised of several layers of tough, cloth-reinforced, vulcanized rubber with a stiff length of wire running through it. It’s designed to make bends without collapsing, and it’s extremely abrasion- and heat-resistant, making it an ideal candidate for connections to through-hulls under the waterline, and for carrying hot exhaust gases and cooling water overboard.

Some exhaust hose has no wire reinforcement, especially the big stuff over four inches in diameter. That’s because larger exhaust line runs don’t usually encounter any bends.

Uses: Raw water engine intakes, hot water exhaust, raw water intakes for heads, washdown pumps, or other bits of plumbing that connect to a below-the-waterline through-hull.

"Red tracer" PVC potable water hose. Note the wound nylon reinforcement threads throughout.

“Red tracer” PVC potable water hose. Note the wound nylon reinforcement threads throughout.

Potable Water Hose
This stuff doesn’t usually fall into the “sticker shock” category, but it’s an area where boaters often are tempted to use the wrong stuff, such as clear PVC hose. Proper water hose is reinforced with nylon threads to not only strengthen it against the pressure of fresh and raw water systems, but also to help prevent it from collapsing on the suction side of pumps. If you want to really show an attention to detail, use hose with a red tracer for hot feeds, and with blue for cold feeds. Also, look for “FDA Approved” in the specifications.

Uses: Freshwater systems (manual and pressurized), raw-water washdown systems (above the waterline connections), water tank vents, ice box drains, scupper drains (above the waterline), and more. A good general-purpose hose.

Marine fuel hose. Note the "Type A2" rating on the side of the hose.

Marine fuel hose. Note the “Type A2″ rating on the side of the hose.

Fuel Hose
Fuel hose can be confusing, and that’s mainly because of all the different classifications it is sold under. What you’ll usually find are types A1, A2, B1, and B2. Generally speaking, A-type hose has a thicker wall than B-type hoses, and must also not leak during a two-and a-half-minute fire. The number classifications in those letter ratings (e.g. “A1”) refer to the permeability of the hose. Type A1 hose, for example, will be less permeable to fuel than Type A2.

If you’re working with gasoline, it’s really difficult for me to recommend anything but Type A1, and I don’t think I ever sold a foot of B1 or B2 hose to anyone for this purpose, except for fuel tank vent lines. Diesel fuel is obviously less volatile, but that never stopped me from encouraging my customers to go with A1 hose for those applications.

Uses: Engine fuel feeds, fuel fill lines, fuel tank lines, and fuel vents.

Smooth-walled bilge hose is always the better bet if you don't need lot of flexibility.

Smooth-walled bilge hose is always the better bet if you don’t need a lot of flexibility.

Bilge Hose
Bilge hose is designed to work with bilge pumps, as the name suggests. What usually sets bilge pump hose apart from other hoses is its flexibility. This is an advantage, since bilge pump discharge lines are often weaved and routed through some tight areas. In fact some bilge hose is sold under the trade name, “bilge flex.”

But I wouldn’t use it. This corrugated (ridged) hose is certainly flexible, but it also is cheap and flimsy. It’s a dirt and grime magnet, too,  thanks to all the tiny ridges in its surface. Those ridges also create friction inside the hose, which reduces the efficiency of your bilge pump.

For bilge pumps I like smooth-walled, white PVC hose with nylon reinforcement. It’s much more durable, and with a smooth exterior, it doesn’t attract fuel, oil, dirt, or any of the other nasty stuff in your bilge. It’s also smooth-walled inside, which means its effect on pump efficiency is minimal. It’s unfortunately not as flexible as other bilge pump hose, and may require some work to route through your boat.

Uses: Bilge pump pickups and discharges.

 

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