Small Powerboats & RIBs
The dinghy is the charter yacht's runabout — the run to the beach, the trip to the fuel dock, the shuttle for guests and stores. It is also where many charter injuries happen. This module covers the full IYT Module 13 syllabus at Working depth: dinghy and engine types, starting drills, prop-walk, stability, beaching, trailer work, crash stops and towing — with a prop-walk simulator and a step-through beaching sequence.
Dinghy Types & Their Trade-offs
"Dinghy" covers the whole family of small tenders — rigid hulls, pure inflatables, and the RIB (rigid inflatable boat: a solid hull with inflatable tubes). Don't confuse them with sailing dinghies. Their job is short hops: harbour to anchorage, boat to beach, guests back and forth. Each construction buys you something and costs you something:
- + Largely puncture-proof; rows and tows well
- − Hard edges scratch and chip topsides when coming alongside
- + Soft tubes are kind to hulls alongside; light and stowable
- − Easily punctured by reef, rock or anything sharp
- + Best of both: solid planing hull, forgiving tubes, seakeeping
- − Heavier, pricier, needs davits or a crane on smaller yachts
Engines & Drives
A dinghy is driven one of three ways. The transom — the flat vertical panel across the back (stern) of the boat — is where most of them mount.
The engine sits inside the hull, driving a propeller under the boat. Found only on big tenders (ten-plus passengers): heavy and expensive, so mostly a superyacht item, lifted aboard by crane onto davits (small deck cranes that hold a dinghy).
Sucks water in and pumps it out through a nozzle — the same system as a jet-ski. No propeller, so much safer around swimmers. The downside: the intake sucks in plastic bags, weed and jellyfish, which stalls the motor.
The whole engine hangs on the transom — the most common tender engine. Clamped or bolted on with a safety cable to a strong point in case a clamp fails, and a tilt mechanism (manual or electric) to lift the propeller clear in shallow water and for beaching.
Most outboards burn petrol/gasoline as either 2-stroke or 4-stroke:
| 2-stroke | 4-stroke | |
|---|---|---|
| Lubrication | Oil mixed with the fuel (newer models inject it from a separate reservoir) | Separate oil system, like a car |
| Character | Cheaper, simpler, lighter | Smoother, quieter, cleaner-running |
| Fuelling caution | Know which you have before you fuel. No naked flames, extinguisher to hand, don't overfill, ventilate well — and stow dinghy fuel on deck or in a vented locker, never below. | |
Propellers, Ventilation & Prop-Walk
A propeller pushes the boat ahead or astern — but it also paddles sideways. That side-thrust, the "paddle-wheel effect" or prop-walk, swings the stern one way and the bow the other. Which way depends on the hand of the propeller — which way it spins. Looking from behind the boat, a right-handed propeller turns clockwise in forward gear, a left-handed one anticlockwise; most single-engine boats have a right-handed one. It also depends on whether you're driving ahead or astern. Try every combination:
Two faults can make a propeller lose its grip on the water. They feel similar — the engine suddenly races while the boat stops accelerating — but they have different causes:
A propeller works by gripping solid water and pushing it back. If air reaches the blades — sucked down from the surface in a hard, fast turn, or because the engine is tilted up too high in shallow water — the propeller spins in a froth of air and water instead of solid water. It loses its grip, so the engine races (the revs jump) while the boat slows down. The fix: ease the throttle, straighten up, and let the propeller get back into solid water.
At very high revs, the water rushing over the back of each blade can have its pressure drop so low that it briefly boils into vapour bubbles — even though the water is cold. Those bubbles collapse violently against the blade: you feel it as noise and vibration, and over time it pits and eats away the metal. The cure is the same — less throttle, and keep the propeller clean and undamaged.
Start-Up, Shut-Down & Fault-Finding
The first rule, in IYT's own words: "Do not start the motor unless you know how to stop it." Find the stop — usually a red push-and-hold button, sometimes a key — before you touch the starter. It's always backed by the kill cord: a short lanyard that clips to the driver at one end and to a cut-out switch on the engine at the other, so that if the driver is thrown from the helm or falls overboard, the cord pulls out and the engine stops instantly.
- Fuel tank full — shake to mix (2-stroke premix)
- Fuel line connected; breather vent open
- Prime with the bulb until it firms up
- Engine firmly secured; water intake submerged
- Tilt locked in the run position
- Kill cord connected — to the engine and to you
- Gear shift in neutral
- Cold engine: choke — but don't flood it
- Throttle to the start position
- Pull the cord firmly (mind the elbow — brief the crew behind you) or turn the key
- No fire after a few pulls? Open the choke and try again
- Once it fires: choke in, throttle eased
- Check cooling water is circulating — the tell-tale, a small stream of water squirting from the engine that shows the cooling pump is working
- Never engage gear at high revs
- Slow right down before shifting; never slam from full ahead into astern
When it won't start, work the simple causes before blaming electronics (modern engines beyond these basics are a mechanic's job):
| Symptom | Check first |
|---|---|
| No fuel flow | Fuel in the tank · line connected and primed · breather open · clean the fuel filter at the power head (the engine unit at the top of the outboard) |
| Dead on the button | Kill cord actually in place · battery and battery switch · connections · fuses |
| Turns over, won't fire | Pull and inspect the spark plugs · choke technique (flooded?) |
Stability, Trim & What to Carry
A dinghy is at its most dangerous during boarding and un-boarding — weight placed high or off-centre tips it fast. The helmsman owns the load plan: spread people and gear evenly side-to-side and fore-and-aft (four passengers sit two-and-two, helmsman aft at the engine), everyone seated and holding on before casting off, and a safety brief covering lifejacket locations and what to do if things go wrong.
- Accelerate smoothly; match speed to conditions
- Planing may need weight shifted forward to help her up
- Sitting low, your sightlines are poor — keep passengers out of your view
- One hand on wheel, one on throttle on console boats
- Come off the plane gently; slow before neutral
Lifejackets · flashlight (doubles as the night navigation light under 7 m — check local rules) · oars or paddles · bailer (something to scoop water out) · compass · a painter (the dinghy's bow line) of decent length · whistle · first aid kit · boat hook · knife · fire extinguisher · flares · anchor and line · handheld VHF · GPS · tools · binoculars
Beaching & Trailer Work
Beaching is easy in calm water and genuinely dangerous in surf — big breakers or a deep swell mean don't try. Read the shoreline too: smooth sand forgives, rock and coral puncture. Step through the approach:
- Practise reversing somewhere empty first — ramps have an audience
- Bungs in, transit damage checked, trailer lights unplugged
- Let the bearings cool before they go under water
- Boat's stern needs to float free; keep the car's wheels out of the water (jockey wheel + rope extension on shallow ramps)
- Winch cable stays attached until you're ready; launch slowly; painter on so she can't drift off
- Footwear on — ramps are slippery and strewn with glass
- Drive on to the partially-submerged trailer, or float her on by hand in the shallows
- Tilt the engine on approach — protect the prop
- Hook the winch to the D-ring and crank up — beware spinning winch handles, they break bones
- Flush the cooling system with fresh water; rinse boat and trailer after salt
- Lights reconnected and tested, cover on, load secured, hitch checked before you tow
Crash Stops & Towing
A crash stop is an emergency-only manoeuvre — think man overboard — and the crew get a warning shout first, because the boat's own wake is about to catch up with the transom. IYT gives two methods:
Throttle back to neutral and turn hard to port or starboard, presenting the boat's beam to the overtaking wake so it rolls under you rather than over the transom.
Throttle back to neutral watching astern; as the wake arrives, a burst of throttle ahead lifts the stern over it.
Towing another dinghy calls for care and communication. The tow steers poorly or not at all, so every turn is gentle — turn tight and you'll turn inside your tow, collide with it, or drag the towline into your own prop. Coming alongside a wall, remember the tow can't kick astern to stop; let wind and tide do the braking.
- Towline made fast on the casualty
- Approach across her bow at ~90° (or 45°, as conditions allow)
- Line to a strong point on the tow boat — ideally a bridle
- Set the scope: short in enclosed waters, lengthened offshore to match the seas
- Take up the strain gently
- One crew watches the tow the whole time
- Casualty keeps weight aft and steers if she has a rudder
- At night, show the correct towing lights
A line from each aft cleat meeting at a centre point spreads the load, stops the tow's weight slewing your stern side-to-side, and keeps the towline away from the propeller.
For close-quarters work at the destination: bow line, stern line, and fore-and-aft springs onto the casualty, rigged while she's still on the stern tow — then manoeuvre dead slow.
Small Powerboats & RIBs — Knowledge Check
11 questions at IYT exam standard (75% to pass), drawn from the IYT Module 13 knowledge review.