18′ Inflatable Boats SD518 Review

The 18' Inflatable Boats SD518 is a 17.8' inflatable boat from Saturn, built for boaters who want a real boat that still packs into the back of an SUV. It is rated for 10 people with a 2500 lbs load capacity, which covers a realistic day on the water for most buyers.

At 17.8', it is the 1st largest of the 26 inflatable boats in Saturn’s current range. At $1,799, it is the priciest of the 28 inflatable boats in the current range. If you want to skip ahead, check the current price here.

For this review I went through the full spec sheet line by line, so everything below comes from what the manufacturer actually publishes — dimensions, capacities, and construction — plus what those numbers mean once the SD518 is on the water.

Key Features

• 17.8' long × 6.6' wide
• 20" tubes
• 3+1 air chambers
• Rated for 10 people
• 2500 lbs maximum load
• Transom rated up to 50 HP (15" shaft / 175 lbs) Tube
• Weighs 140 lbs Floor
• Packs into 53x28x14"
• Anodized Aluminum Floor
• 1100 Denier Reinforced PVC Floor
• Listed speed: 30 mph (40HP w/2 adults)

On the Water

On the water, three numbers tell you most of what you need to know: length, beam, and tube diameter. At 17.8' long and 6.6' wide with 20" tubes, the SD518 is a full-size inflatable with a reassuring footprint. In inflatables, tube diameter and beam do most of the work keeping you level — wide tubes are why these boats feel so much more stable than their weight suggests.

The transom is rated for up to 50 HP (15" shaft / 175 lbs) Tube. That keeps you in small-outboard territory — light, affordable motors that one person can lift and mount. That is the whole point of a boat like this: enough power to get you to the spot without the cost, weight, and upkeep of a big rig.

Saturn lists a speed of 30 mph (40HP w/2 adults). Treat that as a realistic expectation with the stated setup rather than a promise — load, prop, and conditions move that number around.

Plan around the 2500 lbs load rating, not just the person count. Add up people, motor, fuel or battery, cooler, and gear before you buy. If that math lands close to the limit, size up — a boat that runs near its rating is slower, wetter, and less fun.

Build and Materials

The tubes are 1100 Denier Reinforced PVC Floor. That is the heavy-duty end of the PVC fabrics used on inflatables this size — thicker fabric resists abrasion and holds air pressure more consistently. Seams are Quadruple Overlap. More overlap at a seam means more glued surface holding the tube together, which is exactly what you want on a boat that lives in the sun and gets dragged up beaches.

The spec sheet lists 3+1 air chambers. Separate chambers are a safety feature, not a spec-sheet decoration: if one compartment is ever compromised, the others keep you afloat. The Recessed One-Way valves sit flush in the tubes, so there is nothing sticking out to snag on a dock, a truck bed, or your fishing line.

Floor: Anodized Aluminum Floor.

Weight, Portability, and Setup

The SD518 weighs 140 lbs Floor. Plan on two people or a dolly for the carry to the launch. It packs into a 53x28x14" package (149 lbs).

Listed setup time is 45 min. — that is inflation plus assembly, and it gets faster after the first few outings.

Who It's For — and Who Should Skip It

Who it is for: anglers, divers, and families who need a tender — or a standalone fishing boat — without owning a trailer, running up to a 50 HP (15" shaft / 175 lbs) Tube outboard. If your fishing looks like trailer-free launches, skinny water, and packing the whole rig into a vehicle, the SD518 fits the program.

Honest trade-offs: it is still an inflatable, so inflation and setup are part of every trip. Sharp shells, hooks, and rocky shorelines demand the same respect you would give any PVC boat. Rinse it after saltwater use and store it out of long-term direct sun — UV is the slow killer of every inflatable ever made.

Who should skip it: if you want to turn the key and go with zero setup, or you regularly run rocky rivers, a rotomolded or aluminum hull will make you happier.

How It Compares

Within Saturn’s current range, the next step down is the 16' Inflatable Boats SD488 (16 ') at $1,699 and the next step up is the 11' Saturn V-Keel Boat KM330D (130 in (around 11')) at $899. If you are torn between sizes, the usual advice holds: buy for the load you will actually carry most weekends, not the biggest crew you might take once a year. A smaller boat that runs light is faster, drier, and easier to handle than a bigger one loaded to its limit.

Care and Maintenance

An inflatable boat rewards basic care and punishes neglect — the good news is the care part is simple. Rinse it with fresh water after saltwater use, and let it dry before you roll it up; packing a damp boat away is how mildew starts.

Watch air pressure when temperatures swing. Air expands in the heat and contracts in the cold, so a boat inflated drum-tight on a cool morning can get very firm by midday. Bleed a little air if the tubes feel overly hard, and top up when evenings cool off.

For storage, keep it out of long-term direct sun — UV is the slow killer of every inflatable — and store it loosely rolled or partially inflated rather than folded tight on the same creases every time. Keep sand and grit out of the valves, and carry a small patch kit aboard. None of this is difficult; it is just the routine that keeps an SD518 going for years instead of seasons.

SD518 Specs

Frequently Asked Questions

Where to Buy

The 18' Inflatable Boats SD518 is listed at $1,799 on BoatsToGo‘s website. If it sounds like your kind of boat:

Check Current Price

Pricing and availability change, so confirm the current price on the product page before ordering.

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