ESI
Essential Shipyard UniversityTrailer Service · TS-1
TS-1 · Trailer Service · Day One

Trailer Service — the Job, Start to Finish

Everything you do to receive, service, and release a boat trailer to ESI standard — taught in the order the job actually happens: running gear first, then the boat sits right, then it's inspected, then the brakes. Every job has standard work, and every clocked minute is either building the boat owner's trust or costing us the next job.

Welcome back.
Pick up where you left off.
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The job flow

How a trailer moves through the bay

Not "bearings class, then brakes class." One job, in order, with standard work at every step.

1
Standard Work & the Job Card
Kaizen as ESI runs it — the system before the trailer
2
Bearings & Axles
Hub service, preload, marine grease, induction heat, the short-hub trap
3
Tires & Wheels
Load range, age-out, PSI, lug torque, wheel corrosion
4
Bunks & Positioning
Bunk/bow-stop set so the boat loads and sits right
5
Inspection & Report
Documented safety inspection, findings to part numbers
6
Brakes — 3 job types
Free-backing conversion · surge install · electric install & wiring

Corrosion failures and the nut induction heater run through every module — that's the marine reality here.

Module 1 · The system first

Standard Work & the Job Card

Kaizen here isn't a poster. It's four things you use on every trailer.

By the end you can
  • Pull the right job card and run the trailer through the bay in one-piece flow.
  • Work to the standard-work sheet — the documented best-known sequence for each job.
  • Stop and flag a defect found outside the job's scope instead of absorbing it.
  • Write an A3 on any comeback and update the standard work so it doesn't happen twice.
The four Kaizen tools you actually useKaizen 1. Standard work sheet — the documented best sequence for each job; your reference while working, not a test.
2. Visual control — the bay is set so a missed step is visible: parts staged in job order, torque-striped fasteners.
3. Stop and flag — a defect outside the job's scope stops the job and goes on the report; never quietly absorbed or ignored.
4. A3 on comebacks — every comeback gets a one-page root cause and a change to the standard work sheet. The sheet is a living document.

The job card travels with the trailer through the bay — receive → service → inspect → release — so anyone can see where it is and what's left. Time is the measure: a new tech should be producing billable trailer work within ten supervised days, and everything spent past making you productive is waste. Do it right the first time; a comeback costs the job twice.

Stop and flag — the rule that protects the customerESI standardYou're servicing bearings and you find a cracked frame cross-member. You do not "just do the bearings and hope." You stop, flag it on the report tied to a part/repair, and it becomes a quoted line — never a silent pass and never a silent free fix. "If it looks right, it flies right" — if it doesn't look or feel right, escalate to the lead.

Module 1 quiz

Module 2 · Running gear

Bearings & Axles

Bearings are where boat trailers die. A hot hub hits cold ramp water and drinks it in — this is the job that keeps a trailer off the shoulder of I-5.

By the end you can
  • Service a hub to standard: strip, inspect races & cones, replace seals, repack with marine grease, set preload by torque.
  • Identify a failing bearing by feel, sound, and grease color before it strands a customer.
  • Use the nut induction heater to break a corroded spindle nut or U-bolt without a flame near tires, grease, or brake lines.
  • Spot the EZ Loader / Load Rite short-hub trap and order axles to spec.
1Why marine bearings fail — water intrusion

The #1 killer isn't mileage, it's water. A wheel bearing runs hot from highway rolling; back it down the ramp and the hub plunges into cold water, the air inside contracts, and it sucks water past the seal. Water emulsifies the grease, rusts the races, and the bearing washes out and seizes — often far from the shop. That's why marine trailers run bearing protectors (Bearing Buddy and equivalents) that hold positive grease pressure to push water out, and water-resistant marine grease, never chassis grease.

Failure points to catchFailureWheel wobble/play (loose or worn) · a growl or roar that rises with speed · a hub too hot to hold after a road test · grease color: milky/tan = water intrusion, gray/metallic = the bearing is coming apart · a protector that won't take grease or has lost its spring pressure. Any one of these is a stop-and-flag.
2Hub service — the standard
  1. Strip and clean. Pull the hub, drive out the seal, remove cones. Solvent-clean and inspect the races (cups) and cones for pitting, bluing, brinelling, spalling.
  2. Replace as a set. On any rebuild, replace inner and outer races and cones together even if the cups look clean — mixing old and new destroys bearing tolerance (Eastern Marine practice). New seal every time.
  3. Repack with marine grease. Force grease fully into the cone from the wide side until it extrudes through — no air pockets. Light film in the cup and hub cavity.
  4. Set preload by torque, not by feel. Seat the bearings (snug the spindle nut while turning the hub), then back off and set to the spec/procedure, install the cotter pin, and confirm the hub turns free with no play.
  5. Fill the protector correctly. Install and grease the bearing protector to proper spring pressure — packed, not blown out past the seal.
Induction heater — the right tool for a seized nutWatch-outA corroded spindle nut, U-bolt, or hub fastener comes off with the nut induction heater, not a torch. Induction heats the fastener fast to break the rust bond with no open flame — critical on a trailer surrounded by tires, wheel-bearing grease, seals, brake fluid lines, and wiring that a flame would ignite or ruin. Watch-outs: keep the coil off brake lines and DOT fluid, off tires, off wiring insulation, and mind galvanized coatings (zinc fume) and nearby aluminum. It's faster and far safer than a torch in a wheel well.
3Axles & the short-hub trap

Axles are order-to-spec, never stock — matched to capacity, track, spring center, and brake flange per job (one spare only, matched to ESI's own fleet). Use the Dexter Index at the parts counter to configure and identify before ordering; Dexter now owns much of the shelf (UFP acquired 2013, Tie Down's axle/brake assets 2017, Redneck/Redline 2021), so four "brands" are often one supplier.

The stocking trapVendorEZ Loader and Load Rite use a SHORT hub on their 1" and 1-1/16" straight axles — shorter overall length than a standard boat-trailer hub. EZ Loader is the dominant trailer under the boats coming through Anacortes, so we stock short hubs, not just standard. Grab the wrong hub and the whole job stalls waiting on parts. Source: SeaWide/NTP-STAG (primary, next-day), Tuff Trailer Ferndale (~1 hr same-day backstop), Amazon for one-off fills.

Module 2 quiz

Sources: Dexter LIT-001-00 service manual & Dexter Index; Eastern Marine hub reference (replace races in pairs); marine bearing-maintenance practice (water intrusion, protectors, marine grease).

Module 3 · Running gear

Tires & Wheels

Trailer tires almost never wear out — they age out and blow out. Reading them is the skill.

By the end you can
  • Read a trailer tire's load range and DOT date and judge whether it's aged out.
  • Set cold pressure to the sidewall max and torque lug nuts to spec in the right pattern.
  • Catch wheel and stud corrosion before it strands a customer.
1Age, load range, pressure

Use ST (Special Trailer) tires, not passenger (P) tires. Trailer tires typically age out in ~5–6 years regardless of tread — the rubber cracks from UV and ozone while the boat sits. Read the DOT date code (last 4 digits = week/year) on every service; a deep-tread tire that's 7 years old still gets flagged. Match or exceed the load range for the trailer's GVWR, and set cold inflation to the tire's sidewall maximum — trailer tires carry their rating only at full pressure; an underinflated ST tire runs hot and fails.

Failure pointsFailureSidewall cracking / dry rot (age) · a flat spot from sitting loaded · underinflation heat failure · a mismatched or under-rated load range · corroded/rusted studs and wheels, especially steel wheels in saltwater. Aluminum wheels resist corrosion better but still need the mating faces cleaned.
Lug torque & re-torqueESI standardTorque lug nuts to spec in a star/cross pattern, and re-torque after the road test (and tell the customer to re-check after the first ~50 miles) — new or reseated wheels settle and loosen. Torque-stripe them as a visual control so a missed wheel is obvious.

Module 3 quiz

Module 4 · The boat sits right

Bunks & Positioning

A boat that loads crooked or sits on the wrong spot gets damaged on the trailer, not on the water.

By the end you can
  • Set bunks so the boat loads straight and its weight lands on hull structure, not between frames.
  • Set bow stop and winch height so the boat comes home to the same place every time.
  • Re-carpet and re-bracket bunks and set guide posts.
1Bunk placement & hull support

Bunks carry the boat, so they must sit under longitudinal hull structure (stringers/keel line) — not span an unsupported panel where they'll dent or oil-can the hull. On welded-aluminum boats especially, support runs under structure, with load shared between the bunks and the bow roller/keel support. Carpet the bunks (marine bunk carpet) so the hull slides and doesn't mar. Verify with the boat's weight actually on the trailer, and re-check after the first loaded road test.

Set it so it self-centersESI standardBow stop, winch post height, and guide posts are set so the boat drives on straight and stops in the same place every time — that repeatability is what makes a ramp launch fast and safe. Guide posts for low-light and current. Positioning is a real job outcome, not eyeballing.
The deep version — bunk geometry under structure on the lift, keel support, float-off depth — is ESI's proprietary differentiator and lives in the fabrication course (TS-3). TS-1 covers correct adjustment.

Module 4 quiz

Module 5 · Prove it's right

Inspection & Report

The report is the product. It's what the customer keeps and what protects ESI.

By the end you can
  • Run a complete documented safety inspection and produce the written, photo-capable report.
  • Tie every finding to a part number or repair line so it becomes a clear quote.
  • Catch the three failures that generate every comeback before the trailer leaves.
The three comeback failures — check these last, every timeRed lineGrounds — the #1 lighting fault is a bad ground, not a bulb; chase lights to root cause at the ground. Bearing preload — too tight cooks the bearing, too loose lets it hammer; set by torque and confirm free spin with no play. Brake bleed — air in the lines = no brakes; bleed to procedure. Get these three right and the trailer doesn't come back.
Findings tie to partsESI standardEvery finding on the report references a part number or repair so it converts straight to a quote — no vague "brakes worn." Photo the finding. A defect outside the current job's scope is flagged, not absorbed (stop-and-flag from Module 1). The clean written report is the customer handoff.

Module 5 quiz

Module 6 · Brakes — three job types

Brakes: Free-Backing Conversion, Surge Install, Electric Install & Wiring

Washington requires brakes on all wheels of a trailer over 3,000 lb GVWR, applied from the tow vehicle, plus automatic breakaway that holds ≥15 minutes (RCW 46.37.340). Three jobs cover the trailers we see.

By the end you can
  • Explain the reverse problem and pick the right reverse solution for the trailer.
  • Convert a surge trailer to free-backing brakes.
  • Install and bleed a surge actuator system, disc or drum, with the correct reverse solenoid where required.
  • Install and wire electric / electric-over-hydraulic braking components to a clean ground.
The reverse problem — why brakes need a reverse solutionSurge (hydraulic) brakes work by the trailer pushing against the tow vehicle when it slows — the coupler compresses and applies the brakes. Back up, and the trailer pushing forward looks exactly like braking, so the brakes lock and you can't reverse. Every surge trailer therefore needs one of three reverse solutions: free-backing (mechanical, in the drum), an electric reverse solenoid (blocks fluid on the reverse signal), or a manual lockout (a pin — old-school, easy to forget).
6aFree-backing conversion for surge

Free-backing brakes let the trailer roll backward without the drum grabbing — a one-way mechanism inside the drum releases in reverse, so no solenoid and no reverse wire are needed. Converting a lock-up surge trailer to free-backing means swapping to free-backing drum assemblies (backing plates/shoes designed for it). It's the clean fix for a customer who tows behind a vehicle with no reverse-signal wiring, or who's tired of the manual pin.

Free-backing is a DRUM solutionWatch-outFree-backing lives in the drum. Disc surge brakes do not free-back — a disc caliper has no reverse-release mechanism, so a disc surge trailer must use the electric reverse solenoid instead (see 6b). Know which system is on the trailer before you quote the conversion.
6bInstalling surge

A surge system is the actuator/coupler (master cylinder built into the tongue coupler — e.g., UFP/Dexter A-160, Titan), lines to each wheel, and the wheel brakes (drum or disc). Install to the actuator's service manual, then:

  1. Mount the actuator to the tongue, rated to the trailer's GVWR; connect the safety chains and the breakaway cable so a disconnect applies the brakes.
  2. Plumb the lines — DOT 3, tinned/coated fittings, routed clear of road hazards and the ramp; on tandem, tee to all braked wheels.
  3. Set the reverse solution. Drum → free-backing or solenoid. Disc → electric reverse solenoid is required (legacy UFP disc uses solenoid #27, part #34500; push-rod assemblies vary by braked-axle count — Pacific Trailers library). Wire the solenoid to the reverse-light circuit so backing up blocks brake fluid.
  4. Bleed the system to the actuator procedure — print and post Dexter 059-906-00 "Brake Bleeding of Surge Actuators" in the bay. Air in the lines is the #3 comeback.
  5. Breakaway: verify the breakaway applies the brakes and holds; replace a dead breakaway battery. Required to hold ≥15 min (RCW).
Surge failure pointsFailureBrakes drag/lock in reverse (dead solenoid, no reverse-wire signal, forgotten manual pin) · soft/no brakes (air in lines — bleed) · corroded master cylinder and brake lines from saltwater (the marine killer — flush after every saltwater dunk; use coated/stainless lines and fittings) · seized disc caliper · leaking actuator seals · corroded breakaway switch.
6cInstalling & wiring electric braking components

Electric brakes (and electric-over-hydraulic, common on heavier Class C tandem/triple) apply from an in-cab controller over the 7-way. Electric drum brakes use an electromagnet that grabs the drum; EOH uses an electric pump/actuator driving hydraulic disc/drum. Install the magnets/backing plates or the EOH unit to spec, then wire it:

  1. 7-way wiring with the brake circuit and reverse circuit; use tinned marine wire, sealed/heat-shrink terminations, supported and chafe-protected.
  2. Ground it right. The brake magnet/EOH ground must be clean bare metal, not a rusty frame bolt — a poor ground is the classic electric-brake and lighting failure. Run a dedicated ground where the frame is suspect.
  3. Breakaway switch and battery so a disconnect energizes the brakes; verify hold.
  4. Set the controller gain and test under tow; confirm even application across axles.
Electric-brake failure pointsFailureWeak/no braking from a bad ground or corroded connector (chase to the ground first) · worn magnets · a controller set wrong · a dead breakaway battery · corroded 7-way pins. In saltwater, corrosion at every connection is the enemy — dielectric grease and sealed terminations are standard, not optional.
Corrosion is the thread through all threeMarine realityEverything on a saltwater trailer is fighting corrosion: bearing washout, rusted brake lines and master cylinders, seized calipers, corroded grounds and 7-way pins, rusted studs and frames. The countermeasures are constant — flush after saltwater, marine grease and bearing protectors, coated/stainless lines and fasteners, tinned wire, sealed terminations, dielectric grease, cold-galv on welds — and the induction heater to break the fasteners corrosion has already seized.

Module 6 quiz

Sources: RCW 46.37.340 / 46.37.351 (WA brake requirements); Dexter/UFP surge actuator manuals + 059-906-00 bleeding; Pacific Trailers legacy UFP library (disc reverse solenoid #27 / #34500); surge & electric brake troubleshooting practice.

Assessment

TS-1 Final Exam

Pass at 80% to unlock your certificate. Progress and answers are saved on this device — stop and come back any time.

Credential

Certificate of Completion

This is half of TS-1ESI standardThe certificate below is the written half — the course quizzes and final at 80%. Full TS-1 credit also requires the in-house practical: a lead watches you do the real jobs on a real trailer and signs each one to ESI standard. An experienced tech may challenge the reading and go straight to the exam, but no one tests out of the practical.  Open the Practical Sign-Off sheet →
ESSENTIAL SHIPYARD UNIVERSITY
Certificate of Completion
This certifies that
has successfully completed ESI Trailer Service — TS-1, demonstrating the standard work to receive, service, inspect, and release a boat trailer: bearings & axles, tires & wheels, bunks & positioning, inspection, and brakes (free-backing, surge, and electric).
Date
ESI Training
Essential Shipyard University
Pass the final exam (80%) to unlock your certificate.