Should I leave the outboard mounted to the raft for the trailer shuttle?

Depends on the motor weight and the shuttle distance. Under 50 lbs and under 60 miles of pavement, leave it mounted with proper bracing. Over 60 lbs or over 100 miles or any washboard road — remove it. Transom flex over hours of vibration is the most common cause of motor failure between trips.

What's the most common transport failure?

Throttle cable chafe. The tiller flops in transit, the throttle grip swings, the cable inside the tiller arm wears at the bend point. Six months of this and the cable is half-strands. The motor still runs, but at random throttle positions. Always immobilize the tiller during transport.

Tilt up or tilt down for trailer transport?

Tilt up — fully — and lock with a strap or pin. Tilt-down lets the prop hang in the airstream and bounce. Tilt-up gets the prop out of the road-debris zone and reduces leverage on the transom mount. Locked tilt is non-negotiable. The tilt mechanism's hydraulics aren't designed for sustained vibration.

Do I need a special bracket to support the motor in transit?

Yes if the motor stays mounted. A simple plywood block wedged between the cavitation plate and a frame crossbar takes the bouncing load off the transom mount. Without it, the motor's full weight + vibration concentrates at the clamp screws — over hundreds of hours that's how clamp threads strip and transom mounts crack.

How do I prevent theft of the outboard at a take-out?

A locking bar through the clamp screws (cable and padlock through the pivot point) deters opportunistic theft. Locked storage in a vehicle or shop is better. The take-out parking lot at Hite or Sand Wash is the most exposed point in the trip — a motor visible on a trailer for 24 hours is a theft target.

Raft Trailer + Outboard Transport System (Don't Let the Shuttle Kill the Motor)

I rebuilt a Yamaha 6 hp tiller in 2019 because I'd let it ride 400 miles of washboard mounted to the transom with no support. The carb was loose on its mounting bolts. The throttle cable was at half-strands. The tilt mechanism had developed slop. The motor still ran. Barely. Two pulls became seven. That kind of seven. The rebuild cost me $280 and three evenings of garage work I should have spent on something else.

The motor wasn't broken by the river. It was broken by the road.

I keep coming back to that detail. The trips I'd run that motor on were modest — a few Cataract take-outs, a couple of Deso assists. The damage was almost all from the transport. Every shuttle from Salt Lake to Sand Wash, from Sand Wash to Swaseys, from Hite back to Moab — vibration at frequencies and durations the motor's mounts weren't designed for. Outboards are designed to run in water and ride in calm air. The trailer is the environment they hate.

This article is the system that keeps that from happening. It applies to any outboard between 25 and 100 lbs — the Honda 2.3, the 5–6 hp class, and most of the 8 hp range. Above 100 lbs you're into trailer-bracket-system territory, which is a different problem.

What the trailer actually does to a mounted outboard

Three forces concentrate at the transom mount during transport:

1. Sustained vibration. A road vibration spectrum from 5 to 30 Hz, 4–8 hours per shuttle. The motor's mounts and internal components were never designed for this — they're designed for running vibration, which is higher-frequency and shorter-duration. Loose bolts work loose. Solder joints crack. The carb on my Yamaha shook off its mounts. That's not metaphorical.

2. Leverage from the tiller arm. The tiller is a long lever. At highway speeds with wind buffeting, the tiller swings. Each swing concentrates rotational stress at the clamp screws and the steering pivot. Over 400 miles of swinging, the pivot bushings wear and the throttle cable chafes at its routing point.

3. Transom flex. A raft transom plate or frame crossbar isn't rigid the way a fiberglass boat transom is. Frame straps loosen under vibration. The plywood plate flexes. The motor weight, multiplied by vibration g-forces, exceeds the static load the transom is rated for.

Mitigation requires three different solutions:

Reduce the load (remove the motor, or partially support it).
Reduce the leverage (immobilize the tiller).
Reduce the flex (back-brace the transom).

The decision: mount or remove

Before you build the transport system, decide whether the motor rides mounted or removed.

Remove the motor when:

The motor weighs more than 50 lbs.
The shuttle is over 100 miles or includes washboard road.
The trailer has soft suspension (older boat trailers without urethane bushings).
The shuttle includes overnight on the trailer in an unsecured location (theft risk).
You're driving more than 60 mph for sustained periods.

Mount the motor when:

It weighs under 50 lbs (Honda 2.3 territory).
The shuttle is under 100 miles, mostly paved.
The trailer has shock absorption (newer trailers with proper suspension).
The shuttle is direct (put-in to take-out, no overnight).
You have a real bracing system, not just clamp screws.

For my own Honda 2.3: it stays mounted on shuttles under 200 miles of pavement. Anything longer or any washboard, off it comes.

For the Mercury 5 hp: removed for almost everything. 60 lbs is too much for the transom plate to handle in transit without significant bracing.

The mistake the system runs on

Beyond the Yamaha rebuild, the failures I've seen on other people's motors are remarkably consistent:

A friend's Tohatsu 3.5 with a hairline crack in the cavitation plate from a shuttle bounce.
A guide's Yamaha 8 hp with the steering bracket bolts backed out three turns mid-shuttle.
A crew member's Honda 2.3 with the throttle cable wearing through right at the tiller pivot — three weeks of partial throttle on the river before we figured it out.
A dealer-owned demo Mercury with the tilt mechanism's lock pin sheared from extended down-position vibration.

Every one of those failures was preventable. Every one took 5 minutes of pre-shuttle setup that didn't happen.

The lesson: the shuttle is part of the trip. Treat the transport setup like rigging.

The mounted-motor transport system

If the motor stays on, the system has five elements.

1. Tilt up and lock.

Tilt the motor up to its full upper position. Engage the tilt lock pin or strap. Verify the lock holds — push the powerhead toward the boat to confirm. The tilt mechanism's hydraulic cylinders and small mechanical locks aren't rated for sustained transport vibration. The locked-up position takes load off the cylinders entirely.

2. Tiller immobilization.

The tiller swings if not strapped. The throttle grip rotates if not strapped. Both create chafe points and concentrate force at the steering pivot.

The fix:

Strap the tiller to a frame crossbar with a 1-inch nylon strap. Snug but not bone-tight.
Tape or strap the throttle grip in the closed position. The throttle that creeps to half-open during transport is the throttle that's wearing the cable.
For motors with a separate kill-switch lanyard, secure the lanyard. Don't let it whip in airstream.

3. Transom support block.

The single most important piece of the system. A wood block wedged between the cavitation plate (the horizontal fin above the prop) and a frame crossbar.

Build:

4x4 block of pine or fir, sized to fit between the cavitation plate and the nearest crossbar.
Cap the ends with rubber pads (an old yoga mat works, or a piece of wetsuit material).
Wedge in place. The block takes the motor's weight off the clamp screws and transfers it to the frame.

For a Honda 2.3, the block is short (~6 inches) and light. For a 5–6 hp motor, the block is taller (~10–12 inches) and shaped to the cavitation plate.

Without the block, the entire motor weight cantilevers off the clamp screws during vibration. With the block, the load distributes between the screws and the frame.

4. Back-brace the transom.

If the motor mounts to a plywood transom plate (most raft setups), the plate can flex during transport. A simple back-brace — a 2x4 or aluminum stock running across the back of the plate, secured with cam straps to the frame — eliminates the flex.

For frame-mounted motors (no separate plywood plate), the brace runs between the motor's mount points and the frame's main longitudinal rails.

5. Cover the motor.

A motor cover or even a heavy-duty trash bag over the powerhead and tiller does three things:

Keeps road debris out of the air intake and carburetor.
Reduces UV exposure to plastic components during overnight transport.
Discourages opportunistic theft (a covered motor doesn't advertise itself in a parking lot).

The factory motor cover is fine. A custom canvas cover is better. On a 90-degree day in the Moab parking lot, a black rubber cover heats to 140°F. A canvas cover doesn't.

The removed-motor transport system

If the motor comes off, the system has three elements.

1. Motor stand or rack.

A dedicated motor stand in the truck bed or a rack on the trailer holds the motor in its operating-orientation (powerhead up, prop down). Plywood and 2x4 builds are fine. Commercial racks ($60–120) are nicer.

The stand needs to:

Hold the motor upright (cooling-fluid orientation matters for water-cooled motors).
Restrain it against tipping in vehicle braking and turning.
Allow tie-downs at multiple points.

2. Tie-downs.

Two minimum. One around the powerhead (between the cooling intake and the tiller pivot). One at the lower-unit (above the prop, below the cavitation plate). 1-inch cam straps. Snug. Bone-tight tie-downs crush plastic shrouds. Snug-and-checked is right.

3. Drainage.

Water-cooled motors store some water in the lower-unit cooling passages. After running, hold the motor vertical for 15 minutes to let it drain before stowing. Storing wet means rust at the impeller and the lower-unit gearbox.

For air-cooled (Honda 2.3): no drainage required. Wipe the prop shaft, stow.

The pre-shuttle field check

Before every shuttle, run this. Five minutes. Not optional.

Tilt locked. Push the powerhead toward the boat. No movement.
Tiller strapped. No swing in any direction.
Throttle grip secure. Tape, strap, or zip-tie. No rotation.
Transom support block in place. Wedged tight, rubber pads contacting cavitation plate.
Clamp screws torqued. Hand-tight + a quarter turn with the screwdriver. Not gorilla-tight. The threads strip.
Cooling intake clear. Visual check on water-cooled motors. No mud, no leaves, no plastic bag.
Fuel valve closed. Internal-tank motors leak fuel during vibration if the valve is on. External-tank motors are fine, but unhook the line.
Cover on, secured. No flapping in wind.
Theft deterrent in place. Cable lock through the clamp screws if leaving the rig overnight in an exposed location.

The check takes longer to read than to do.

Storage between trips

The motor that sits between trips is the motor that fails on launch morning.

Drain or run dry. Modern carbs gum up with ethanol fuel in 30 days. Drain the carb bowl or run the motor dry of fuel before storing more than a month.
Fog the cylinder. A spray of fogging oil through the spark plug hole prevents internal corrosion. Standard practice on water-cooled motors. Optional on the Honda 2.3 (smaller engine, lower risk).
Battery off (electric start). Disconnect or remove the battery if your motor has electric start.
Cover, in shade, off the floor. A motor on a concrete garage floor gets condensation in the cylinder. Stand or hang.

Theft considerations

The take-out parking lot is the most exposed point in the trip. A motor on a trailer at Hite or the Swaseys lot or the Sand Island ramp can sit overnight while shuttles run. Opportunistic theft happens.

Mitigations:

Cable lock through the clamp screws. A 1/4-inch steel cable + padlock through the clamp pivot points is the basic deterrent.
Take the motor off the boat at the take-out, store in the truck. Better than the cable lock.
Cover the motor. Out-of-sight is out-of-mind. A covered motor in a Hite parking lot gets ignored. An uncovered Yamaha 8 looks like a $3,000 motor that someone could lift in 90 seconds.
Take a photo of the motor's serial number before the trip. If it gets stolen, the report needs the number.

I've never had a motor stolen. I know two people who have. Both were exposed motors at unsecured ramps overnight.

What gets you on the river

The motor that runs is the motor that earned its transport. Five minutes of bracing before the shuttle saves a $280 carb rebuild, an embarrassing pull-cord scene at the put-in, or a stranded-on-Lake-Powell trip.

For the motor itself, see Honda 2.3 Outboard Review for the lightweight pick and Best Lightweight Outboard for Raft Support for the broader decision frame.

Plan the shuttle. Then plan the trip.

The shuttle is the trip's most boring leg and the most damaging to gear. A working transport system is what lets the same motor run trip after trip, season after season, without the rebuild bill that turns a $1,200 motor into a $2,000 motor over five years.

Set up the system once. Run the field check every shuttle. The motor lasts.