§ 01 · The eleven items, ranked
| Rank | Item |
|---|---|
| 1 | Overcurrent within 7″ of the battery + terminal — ABYC E-11 §11.5. Found on 60% of walks. The cure is a marine-rated MRBF or T-class fuse properly installed. |
| 2 | Battery hold-down inadequate or missing — ABYC E-10 §10.6. Found on 40% of walks. Two stainless straps and a tie-down to a structural bulkhead. |
| 3 | Bonding-system continuity broken at one or more points — ABYC E-11 §11.16. Found on 35%. Megger from the bus to each connection. |
| 4 | Reverse polarity at the shore-power inlet — ABYC E-11 §11.18. Found on 25%. A 30-second fix and a routinely-missed finding. |
| 5 | Strain relief at shore-power inlet missing or inadequate — ABYC E-11 §11.18 / NEC 555. Found on 22%. |
| 6 | Wire gauge wrong for the load — ABYC E-11 §11.7. Found on 18%. The voltage drop reveals it. |
| 7 | Engine-room lighting on a single circuit (no redundancy) — ABYC A-30. Found on 16%. |
| 8 | Bilge-pump float-switch piggy-backed on the pump's circuit — ABYC H-22. Found on 12%. Should be a separate fused supply. |
| 9 | Galvanic isolator missing or failed — ABYC A-28. Found on 9%. |
| 10 | Fuel-tank bonding broken at the fill plate — ABYC E-11 §11.16. Found on 6%. |
| 11 | No as-built electrical drawing exists — ABYC E-11 §11.4. Found on 4%, but on those boats it is always a major finding. |
§ 02 · The walk process
A walk takes Dom four to six hours on a 50-foot boat. Saoirse or Luis takes notes on a printed checklist that we have evolved since 2009. We work from a printed copy keyed to ABYC E-11 with cross-references to NEC Articles 553/555 and 46 CFR §111.10/§111.60.[1]
We do not energize anything live during the walk. The measurements are with insulation testers (Megger MIT400), clamp meters (Fluke 376), reference cells (silver/silver-chloride), and a thermal imager (Fluke Ti200) on the running main board. The findings are photographed in place — never moved — and the photographs go onto the corrective sheet.
§ 03 · What you can do yourself before we walk
Eight of the eleven items above are within a competent captain's ability to find and fix without our help. The savings on hourly rate is real if you do the easy items first.
- Battery hold-down: visually inspect, replace any missing strap.
- Reverse-polarity test at the shore-power inlet: a $14 plug-in tester from a chandlery does this.
- Engine-room lighting: count the circuits on the panel; if there's one, add a second.
- Bilge-pump float-switch wiring: trace the wire to the panel; if it shares a fuse with the pump, separate.
- Strain relief at the shore-power inlet: visually inspect; if the cord pulls the inlet, fix.
- Galvanic isolator presence: open the inlet box and look. If there isn't one, that is a finding.
- As-built drawing: if you don't have one, you can sketch one yourself before the surveyor arrives. The surveyor will accept a hand-drawn sketch with the right detail.
- Fuel-tank bonding: visually inspect the bonding wire from the fill plate to the bonding bus.
The other three items are us-shaped work: overcurrent at the battery (gets done while the battery is disconnected), bonding-system continuity (megger required), and wire gauge (load test required).
Cross-references: Plate P-07, Standards.
Sources & further reading
- ABYC. E-11: Electrical Systems on Boats. ↩
- NFPA. NFPA 70 (NEC), Articles 553 / 555.
- USCG. 46 CFR Part 111.
- Society of Accredited Marine Surveyors. SAMS surveyor directory.
- National Association of Marine Surveyors. NAMS surveyor directory.
- BoatUS Foundation. Pre-survey checklist.
- USCG. CG-840 Drydock book.