Boat Trailer Guide | SJ AI Studio

📐 Trailer Sizing & Tow Vehicle Calculator

Boat Length (feet)

Dry Weight (lbs)

Gear / Equipment (lbs)

Fuel Weight (lbs)

Total Boat + Gear Weight–

Recommended Trailer Capacity (GVWR, +20% margin)–

Combined Rig Weight (boat + trailer, est.)–

Recommended Tongue Weight (10–15%)–

Minimum Hitch Class Needed–

Minimum Tow Vehicle GVWR / Towing Capacity–

Estimates only — always confirm against your boat manufacturer specs, trailer VIN plate, and vehicle owner's manual towing charts.

Photo by Csaba Nagy / Pexels
🔗 Hitch Class Reference Chart

Class	Receiver Size	Max Gross Trailer Weight	Max Tongue Weight	Typical Use
Class I	1.25"	up to 2,000 lbs	200 lbs	Small jon boats, kayaks
Class II	1.25"	2,000–3,500 lbs	350 lbs	Small aluminum/bass boats
Class III	2"	3,500–8,000 lbs	800 lbs	Most fishing & pontoon boats
Class IV	2"	8,000–10,000 lbs	1,000 lbs	Larger pontoons, mid cabin cruisers
Class V	2" / 2.5"	10,000–20,000+ lbs	1,700–2,700 lbs	Large cruisers, heavy dual-axle trailers

Weight ratings are for the receiver hitch itself — your tow vehicle's frame-rated towing capacity and rear axle GVWR can still be the limiting factor. Match the lowest number in the chain.

Photo by Anastasia Shuraeva / Pexels
🛞 Tire Pressure & Bearing Maintenance

Before every trip

Check tire pressure cold — match trailer tire sidewall PSI (usually 50–65 psi, not vehicle tire PSI)
Inspect tires for cracking, dry rot, or uneven wear (trailer tires age out even with low mileage)
Check lug nut torque on all wheels
Spin each wheel — listen/feel for grinding or excess play in bearings
Check bearing hub temperature after towing (should not be hot to touch)

Every 1,000 miles / seasonally

Repack or grease wheel bearings (or top off Bearing Buddy / EZ Lube fittings)
Inspect grease seals for leaks or damage
Check brake components (if equipped) — pads, actuator, breakaway cable
Inspect frame, bunks/rollers, and winch strap for wear or rust
Rinse trailer with fresh water after any saltwater launch

⚓ Launch Ramp Checklist

Remove tie-down straps and transom straps (keep bow strap/winch attached)
Install drain plug
Load gear, coolers, and passengers' items (not passengers yet)
Disconnect trailer wiring harness from tow vehicle
Attach bow and stern dock lines, have fenders ready
Start engine on muffs/hose beforehand if possible to confirm it runs
Do prep off to the side, not blocking the ramp lane

Back down slowly, trailer wheels to about hub-deep or per ramp markings
Set parking brake, keep tow vehicle in park with wheels chocked if needed
Release winch strap, walk boat off with bow/stern lines
Move boat to dock, tie off securely
Pull tow vehicle and trailer out of the launch lane immediately, park in lot
Load passengers at the dock, not on the ramp

Stage trailer and back down only when the lane is clear
Drive/winch boat onto trailer straight and centered on bunks/rollers
Attach winch strap/safety chain and pull tight
Pull forward clear of the ramp before doing anything else
Remove drain plug, drain live wells/bilge
Reconnect trailer wiring, test lights (brake, turn, running)
Install transom and bow tie-down straps for the road
Rinse trailer and boat, stow fenders/lines

Photo by Robert So / Pexels
💡 Trailer Light Wiring Guide

Photo by Erkan Utu / Pexels
4-Pin Flat Connector

Standard on most small/mid utility and boat trailers. Handles basic lighting only — no auxiliary power.

WhiteGround
Red / BrownTail / running lights
YellowLeft turn / brake
GreenRight turn / brake

7-Pin Round (RV) Connector

Used on larger trailers with electric brakes, backup lights, or a charge line for a battery/livewell pump.

Pin 1 – WhiteGround
Pin 2 – BlueElectric brakes
Pin 3 – BlackAuxiliary / battery charge
Pin 4 – GreenRight turn / brake light
Pin 5 – YellowLeft turn / brake light
Pin 6 – RedTail / running lights
Pin 7 – BrownBackup lights

Before every tow: plug in the connector, then have a helper confirm running lights, both turn signals, and brake lights. Corrosion at the pins is the #1 cause of trailer light failure — dielectric grease helps.

🚤 Boat Trailer Guide

📐 Trailer Sizing & Tow Vehicle Calculator

Photo by Csaba Nagy / Pexels 🔗 Hitch Class Reference Chart

Photo by Anastasia Shuraeva / Pexels 🛞 Tire Pressure & Bearing Maintenance