UDI RC Boats: Every Model Explained and Which to Buy (2026)

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UDI's current boat range is six models, and the right one depends almost entirely on the water you have. The 13-inch UDI034 Skater is the pool boat, the 17-inch UDI009 Rapid is the simplest way into a hobby-grade prop hull, and the 25-inch UDI005 Arrow and UDI022 Tylosaurus are the open-water pair. If you are still comparing makers rather than models, our beginner boat picks run the same size classes across brands.

The split that matters most is brushed against brushless. The 13, 14 and 17-inch boats run brushed motors on 7.4 V packs and ask little of the owner. The 22 and 25-inch boats are brushless, with a stability receiver that corrects steering yaw and a marine ESC carrying low-voltage, thermal-overload and locked-rotor protection. The jet-driven Inkfish is the odd one out, sold in both brushed and brushless form on the same hull.

UDI publishes the boats on its trade pages rather than its US store front, and the retail listings are resold under several seller names, so the model number is the thing to check before anything else.

Every figure above is UDI's own, published on the product pages, and the pages carry a note that the numbers come from laboratory testing and are for reference.

How UDI's Range Is Put Together

The current line is the 25-inch Arrow (UDI005), the 25-inch Tylosaurus (UDI022), the 22-inch Mosasaurus (UDI018), the 17-inch Rapid (UDI009), the 13-inch Skater (UDI034) and the 14-inch Inkfish, which exists as UDI023 in brushed form and UDI023PRO in brushless form. UDI's US store front carries cars and trucks rather than boats, so the boat specifications sit on the trade pages and in the PDF manuals.

The numbering does not follow size or position. UDI005 and UDI022 carry the same 645 x 170 mm hull figures on UDI's pages, UDI034 is the smallest boat in the range, and the Inkfish splits one hull across two model numbers. Other numbers exist only in the manual set: UDI008 and UDI020 share a single guide headed for pond use, UDI017 and UDI021 have guides headed for larger water, UDI010 has a guide, and the UDI019 page carries no document at all. None of those has a product page, a specification table or a published name. Older numbers circulate in retail listings instead: UDI002 Tempo still appears on Amazon, while UDI001 Venom is not sold as a boat there today; neither is on the current range page.

UDI states no replacement history anywhere, so any claim that one model supersedes another is unverified. The narrower reading is the useful one: the two 645 mm boats are near-identical on paper, and everything else steps down in size together with its power system.

What all six share is a 14-and-over statement, a double boat cover, water cooling, a navigation rudder, high and low speed modes, low-battery and out-of-range alarms, and forward and reverse control. All six advertise a self-righting hull, and the UDI018, UDI022 and UDI023 manuals describe it as a procedure the driver triggers rather than a passive trait of the hull.

UDI034 Skater (13 in): The Pool Boat

At 345 mm long, 90 mm beam and 412 g, the Skater is the smallest and lightest boat UDI makes, on a 30° dead-V. It runs a 91 g water-cooled brushed motor on a 1,100 mAh 7.4 V pack, quotes 20-25 km/h and about 13 minutes of running, and takes about 170 minutes to charge. A 2-in-1 ESC and receiver box keeps the electronics in one unit.

Two things make it the small-water pick. It is the lightest hull in the range by a wide margin, and it has the longest stated runtime of the six. The trade is speed and capacity: 1,100 mAh is the smallest pack UDI ships in a boat, The stated runtime is per pack; check the listing for the number of batteries included.

It is sold as an ECHOBBY listing with dimensions close to UDI's, and as a Cheerwing listing labelled UDI001-SKATER, which is a seller label rather than UDI's number for this hull. For more small hulls across brands, see our pool boat round-up.

UDI023 and UDI023PRO Inkfish (14 in): The Jet Boat

The Inkfish is a 362 mm shallow-V jet hull at 32°, 653 g in brushed form and 659 g brushless. The drive is a spray pump with a hidden impeller, and UDI positions the boat for shallow and rocky water.

The brushed UDI023 runs a 390SM-5022-66D carbon-brush motor of 105 g, quotes about 14 km/h and about 8 minutes. The UDI023PRO swaps it for a 2812 KV3500 brushless motor of 49.4 g, quoting about 20 km/h and about 10 minutes. Both use a 2,000 mAh 7.4 V pack with roughly 230 minutes of charging, both carry front and tail lights and a four-channel receiver with a built-in gyroscope, and both offer a one-key capsize return that UDI says to trigger with a single press of the function key and not in a low-power state.

UDI quotes about 14 and 20 km/h for the Inkfish variants, below the Rapid's stated 25-30 km/h. Our jet drive versus prop breakdown covers where the trade pays off, and the jet boat round-up puts the PRO against other impeller hulls.

Inkfish listings: Cheerwing UDI023, UDI023PRO, and two Ssccgym variants (standard listing, Plus+ listing). The "Plus+" name on the second Ssccgym listing is the seller's, not UDI's.

UDI009 Rapid (17 in): The Brushed All-Rounder

The Rapid measures 424 x 114 x 119 mm, weighs 565 g and carries a 30° deadrise. Its 91 g brushed water-cooled motor runs on 7.4 V, with a 1,500 mAh pack, about 200 minutes of charging, a 25-30 km/h claim and about 8 minutes of running.

It is the middle of the brushed group and the most conventional boat in the range: a prop behind the transom, a sealed receiver and ESC box, a bow bumper fitted to take the first impacts, and the UA13 transmitter. UDI's page gives the radio range as about 120 m, while the manual's parameter table says 100 m, so plan around the shorter figure. That manual also lists a maximum sailing time of 8 minutes, a maximum speed of 30 km/h, an operating range of 0 to 40 °C and a charging range of 5 to 40 °C.

For a first hobby-grade boat with the battery and charger in the box, this is the one to examine first. It appears on Amazon as Cheerwing UDI009 and as ECHOBBY UDI009.

UDI018 Mosasaurus (22 in): The Light Brushless Boat

The Mosasaurus is 577 mm long, 135 mm wide and 137 mm tall at 900 g, with a 33° deadrise, the sharpest V in the range. The brushless water-cooled motor weighs 92 g and UDI's page copy mentions a KV3100 figure that its specification table does not carry, so treat the KV as soft. Input is 11.1 V, the pack is 2,500 mAh, charging runs to about 300 minutes, and UDI quotes about 40 km/h and about 8 minutes.

At 900 g it is 333 g lighter than either 645 mm boat while giving up one hull size and part of the top-speed claim. It adds navigation lights and a reduced ride pad area, and it uses the UA31 transmitter. Where the water is a medium pond and the boat has to be carried any distance, the lighter hull is the easier one to live with.

Capsize recovery is documented in the manual as a throttle gesture: push the trigger forward and back, then pull back at once. A low battery cancels it. Available on Amazon; read the package line to see what is in the box.

UDI005 Arrow (25 in): The 3S Big Hull

The Arrow is 645 x 170 x 110 mm at 1,233 g on a 23° deadrise. Its brushless water-cooled motor is a 192 g unit measuring 34.5 x 73 mm and quoted at KV1800, running on 3S 11.1 V through a 2,200 mAh pack, with about 190 minutes of charging, a 40-50 km/h claim and about 7 minutes of running.

This is the hull several retail listings describe as the 25-inch brushless boat, and it ships with the UA13 transmitter plus an AC/DC adaptor and a 3S balance charger rather than the USB charger used lower down the range. UDI does not publish a manual for the Arrow on its download page.

Listings are numerous: Cheerwing Arrow, a second Cheerwing listing, a YUCT package, and two Ssccgym listings (first listing, second listing). The YUCT package ships two 2,500 mAh packs where UDI's specification is a single 2,200 mAh, so check the contents before comparing offers. Our rough water picks cover this hull among other rough-water boats.

UDI022 Tylosaurus (25 in): The 4S Version of the Same Boat

The Tylosaurus shares the 645 mm hull and 170 mm beam, stands 115 mm tall instead of 110, weighs the same 1,233 g and uses the same KV1800 motor. What changes is the input rating, 3S and 4S from 11.1 to 14.8 V, and the pack, 2,500 mAh, with charging stretched to about 300 minutes. UDI quotes about 8 minutes and the same 40-50 km/h band, and fits the UA31 transmitter.

The rest of the difference is hardware rather than hull: an aluminium rudder, an aluminium support, dual trim tabs, turn fins and a strut, plus controllable navigation lights and a sticker set. For anyone who intends to adjust trim rather than run stock, those parts are the reason to take this hull over the identical-looking Arrow.

One inconsistency to know about, because it appears on UDI's own page: the copy under the battery heading says 40 km/h on 3S while the speed figure elsewhere on the page says 50 km/h. The 40-50 km/h band is the fair reading of both.

Listings: Cheerwing UDI022, Ssccgym, TOUCAN RC HOBBY and wheelfun. At least one of those titles mentions a 100 A ESC, which is not a figure UDI publishes for this boat.

UDI005 vs UDI022: One Hull, Two Packages

UDI publishes the same length, beam, weight, motor and speed band for the Arrow and the Tylosaurus. Published differences include height, input voltage, battery capacity, charge time, runtime and transmitter: the Arrow uses UA13, while the Tylosaurus uses UA31. Both list a 23° deadrise.

The differences that are not on the spec sheet are the ones that decide it. The Tylosaurus carries aluminium running gear and controllable lights; the Arrow carries the simpler hardware. Both ship with the AC/DC adaptor and 3S balance charger. UDI does not say the Tylosaurus replaces the Arrow, so both remain current.

If the plan is to run the boat as it arrives, the 4S rating and the aluminium trim tabs on the Tylosaurus are headroom bought upfront. If the boat will live on 3S in a medium pond, the Arrow does the same job.

What UDI's Manuals Require Before You Run

Salt water is the clearest rule in the documentation. Every UDI manual published on its download page carries the same instruction, to keep the boat out of salt water and dirty water and to avoid running where people are in the water. That applies to every boat with a manual, not just the jet boat, and our saltwater guide covers the wider question.

Capsize recovery is active, not passive. The Mosasaurus and Tylosaurus manuals describe pushing the throttle trigger forward and back and then pulling back at once, and the Inkfish manual uses a single press of the function key. Low battery cancels the sequence, which makes a partly discharged pack the worst time to flip. Our explainer on how self-righting works covers the difference between powered and passive systems.

Charging follows a fixed order: the pack comes out of the hull, cools first, is never charged unattended, and the charger goes to the mains before the balance board before the boat battery. Charge times across the range run from about 170 to about 300 minutes on UDI's pages, and the Rapid's manual rounds its own figure to about 4 hours. Our charger picks and battery guide cover the options.

Water cooling needs the boat to be in the water. The Tylosaurus manual asks for the cooling hose to stay unfolded, since the motor is cooled by water flowing around the can, and it asks for the battery to be removed after each run. Removing the battery after a run is also part of our after-run checklist.

Radio range is worth reading carefully. The Rapid's manual gives a maximum distance of 100 m in clear, interference-free conditions against the 120 m on UDI's page, and the Inkfish's transmitter is quoted at about 100 m. Treat those as ceilings, not averages, and read our range troubleshooting guide if the boat starts glitching before that.

Buying a UDI Boat on Amazon

Several Cheerwing and ECHOBBY listings name UDIRC or UDI RC as the manufacturer, but manufacturer fields and specifications vary by listing. Other sellers carry the same hulls under unrelated brand names, including Ssccgym, YUCT, TOUCAN RC HOBBY, wheelfun and yunchin. None of that makes one seller official: UDI makes no statement about authorised resellers, and its own Amazon storefront carries the old UDI002 Tempo, a 16.7-inch boat that is not on the current range page.

Labels are the main hazard. The Skater appears as UDI001-SKATER under one seller and as TUDI001 under another, whose listed 342 x 89 x 88 mm is close to UDI's 345 x 90 x 95 mm. The Arrow appears under a "3554A" motor code where UDI specifies KV1800, and the Tylosaurus appears with a 100 A ESC figure UDI does not publish.

The remaining numbers, UDI001, UDI008, UDI010, UDI017, UDI019, UDI020 and UDI021, are not sold as boats on Amazon US. Searches for them return parts only: servos, props, packs, flex shafts. Our guide to buying RC boats online covers the wider problem of reseller listings drifting from maker specs.

UDI vs Pro Boat and Traxxas

UDI's current range stops at 645 mm, so anyone shopping for a large fast electric boat is in a different market. Our Pro Boat brand guide and Traxxas model guide cover that end of the market.

Where UDI holds its ground is the small end. Every current model ships with a battery and a charger, the brushed half of the range is mechanically simple, and the hulls run in a pond a larger boat would outgrow. The TFL brand guide is another brand-level comparison.

The compromise is tuning depth. UDI specifically lists aluminium running gear on the Tylosaurus, and UDI names UA-series transmitters for most models, while the Skater's transmitter model is unspecified. None of that matters on a 13-inch pool boat and all of it matters once you want to chase setup changes.

Conclusion

UDI's six current boats cover a narrow, coherent band: 13 to 25 inches, brushed on 7.4 V, or brushless on 7.4 V (the Inkfish PRO) and 11.1 to 14.8 V, all with a pack and a charger in the box and with the available manuals warning against salt water. Within that band the choice is mostly about water. The Skater for a pool, the PRO Inkfish for shallow or rocky ground, the Rapid for a straightforward first hobby-grade hull, and the Mosasaurus, Arrow or Tylosaurus once the water opens up.

Between the two 645 mm hulls, the Tylosaurus is the better buy for anyone who wants 4S and aluminium running gear from the start, and the Arrow is the simpler and lighter-specced package of the same boat. UDI does not say either replaces the other, and both are on its current range page. Read the model number, check the pack count in the box, and ignore motor codes that differ from UDI's page.

For the boat that best balances size, hardware and power in this range, the UDI022 Tylosaurus on Amazon is the pick, with the UDI018 Mosasaurus the one to take if the pond is smaller than the boat.