ABYC A-16 — Electric Bilge Pump Standards

ABYC's voluntary consensus standard for powered dewatering on recreational boats. Insurers, surveyors, and builders all lean on it. Here's how to size, wire, and install a bilge-pump system that won't flag on survey day.

Publisher

ABYC

Companion std.

E-11ISO 15083

Federal overlap

33 CFR 183

Real output

50–70% of rated GPH

Voluntary, but effectively required ABYC standards aren't federal law — but three forces make compliance real: marine insurers underwrite to ABYC, marine surveyors cite A-16 deficiencies on pre-purchase and insurance surveys, and builders face increased product-liability exposure for deviation. USCG 33 CFR 183 is the binding federal rule for powerboats under 20 ft; A-16 goes beyond that floor.

Capacity by Vessel Length

Rule-of-thumb minimum aggregate capacity, synthesized from ABYC guidance plus manufacturer charts (Rule, Attwood, Johnson, Jabsco, Whale). GPH figures are open-flow rated; real-world output through typical hose runs and 3–4 ft of head drops 30–50%.

Vessel length	Min aggregate GPH (open flow)	Configuration	Typical 12 V draw
< 20 ft	500 – 750	Single automatic pump	2.0 – 3.0 A
20 – 26 ft	1 000 – 1 500	Primary + manual backup	3.0 – 5.0 A
26 – 35 ft	2 000 – 2 500	Primary + high-capacity backup	5.0 – 8.0 A / pump
35 – 45 ft	3 500 – 4 000	Multiple pumps, zoned	8.0 – 15.0 A / pump
> 45 ft	6 000+	Zoned + engine-driven emergency	15.0 – 20.0 A / pump

Representative models: Rule 500/750 (small craft), Rule 1100 or Attwood Sahara 1100 (mid-size), Rule 2000 or Johnson Ultima 2200 (cruisers), Rule 3700 banks (larger), Rule 4000 + engine-driven emergency (offshore).

Wiring — ABYC E-11 Gauge Table

Minimum conductor AWG for 12 V DC bilge-pump circuits at 3% voltage drop (the critical-load criterion). "Length" below is round-trip; confirm convention with your installation guide.

Pump current	10 ft	20 ft	30 ft	40 ft	50 ft
5 A	16 AWG	14 AWG	12 AWG	12 AWG	10 AWG
10 A	14 AWG	12 AWG	10 AWG	10 AWG	8 AWG
15 A	12 AWG	10 AWG	8 AWG	8 AWG	6 AWG
20 A	12 AWG	10 AWG	8 AWG	6 AWG	6 AWG

Wiring requirements (A-16 / E-11)

Circuit protection at 125–150% of pump max draw, within 7 inches of the power source (or 40 in if in a sheathed run). An 1100 GPH pump → 7.5 A or 10 A fuse.
Tinned marine-grade copper, stranded — bare copper or solid wire is non-compliant.
Auto circuit separate from the panel switch — turning off the "bilge pump" at the panel must not kill the automatic float circuit.
No wire nuts, no tape-only splices — required splices are heat-shrink crimp butt connectors. Keep splices out of the bilge if at all possible.
Negative to the DC negative bus, not the engine block. Bilge pumps are ungrounded to the hull but share the boat's DC negative.
Connections above max bilge-water level wherever routing allows.

Installation Checklist

Discharge thru-hull ≥ 8 in above static waterline at maximum heeled/loaded condition.
Anti-siphon (vented) loop where the discharge apex could submerge under heel or sit below waterline.
No check valves in the primary discharge line — they fail closed (disables pump) or open (back-floods). Use a vented loop.
Strum box / strainer on intake, sized so partial fouling doesn't starve the pump.
Float switch on its own dedicated circuit, mounted so debris can't jam it.
Manual override at helm with pilot light — crew must know when the pump is cycling.
High-water alarm 2–3 in above normal float-switch cycle height; audible at helm.
Separate compartments need separate pumps on vessels > 30 ft — a midships pump can't dewater a flooded forward or aft compartment once the boat trims.
Reinforced or wire-reinforced marine bilge hose, double-clamped with 300-series stainless below waterline.
Pump mounted on a base (not directly on hull) for serviceability; clearance for float swing.

Rated GPH ≠ real flow The number on the box is open-flow at 0 ft head. Through 4 ft of head and typical hose runs, most pumps deliver 50–70% of the rated value. Size the aggregate capacity at the high end of the table above and plan for one pump to fail.

Common Compliance Mistakes

Undersized aggregate capacity — a single 500 GPH on a 28 ft boat. Rated output after head loss is less than half the box number.
No backup pump. A-16 anticipates pump failure; primary + backup with independent float switches is the baseline above daysailer size.
No high-water alarm. Float switches stick, hoses pop, thru-hulls fail. Without an alarm, the first notice is water over the sole.
Undersized wire. 16 AWG on a 30 ft run to an 1100 GPH pump sags voltage enough to drop flow 20–30% and overheat the conductor.
Check valve instead of anti-siphon loop. Check valves fail closed or open — either mode floods the boat. Vented loops are the standard.
Float circuit tied to panel breaker. Panel off = auto off. Must be separated.
Non-marine connectors. Wire nuts, solid wire, and electrical tape die in a bilge within a season.
Discharge thru-hull too low — submerges under heel and back-floods both pump and boat.

Sources

ABYC Standards A-16 & E-11 USCG 33 CFR Part 183 Rule / Xylem Installation & sizing guides Practical Sailor Real-world pump output testing

FAQ

What minimum bilge pump capacity does ABYC A-16 guidance suggest for a 30 ft boat?

For a 26-35 ft vessel, CalcSpec's ABYC A-16 synthesis lists a minimum aggregate 2,000-2,500 GPH (open flow), configured as a primary plus high-capacity backup pump. Note these open-flow ratings drop 30-50% through typical hose runs and 3-4 ft of head, so size at the high end.

What wire gauge does ABYC E-11 require for a 15 A bilge pump on a 30 ft round-trip run?

Per the ABYC E-11 gauge table for 12 V DC bilge circuits at 3% voltage drop, a 15 A pump on a 30 ft round-trip run requires a minimum 8 AWG conductor. At 50 ft it steps up to 6 AWG; at 10 ft, 12 AWG.

Where must bilge pump circuit protection be placed and how is it sized under A-16/E-11?

ABYC A-16/E-11 require circuit protection at 125-150% of the pump's maximum draw, located within 7 inches of the power source (or 40 inches if in a sheathed run). An 1100 GPH pump takes a 7.5 A or 10 A fuse.

How high must a bilge pump discharge thru-hull be mounted per the A-16 installation checklist?

The CalcSpec ABYC A-16 checklist places the discharge thru-hull at least 8 inches above the static waterline at maximum heeled or loaded condition, with an anti-siphon vented loop where the apex could submerge. It specifies no check valves in the primary discharge line.

No bars in the engine room, none past the breakwater

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ABYC A-16 and E-11 are copyrighted and sold separately. Capacity-by-length figures above are industry rule-of-thumb synthesis — not a quotation from the standard. For installations subject to survey, insurance underwriting, or builder liability, consult the current edition of A-16 / E-11 directly or an ABYC-certified marine technician. 33 CFR 183 is federal law for covered vessels and its requirements are binding; ABYC guidance exceeds that floor.