Hobbyking Marine Series - Scott Free and Relentless V2 - RCGroups Review

The Hobbyking Marine series has started off on the right foot with the Scott Free Deep Vee and the Relentless V2 Catamaran.


A Pair of Affordable, High Performance Race Boats

The all new Hobbyking Marine series has just debuted with a pair of ABS-hulled electric boats that look great, perform even better, and are quite easy on the wallet - a trifecta rarely seen in our hobby. The Relentless V2 and Scott Free both feature identical power systems and similar running gear, but it's their hull designs that set them apart. Available separately, each boat is powered with a pair of 2s 4000mAh LiPo packs wired in series (4s 4000mAh), identical alloy propellers.

In this review, I'll test each one and give you the run down on performance, reliability, and value. Whether you chose the Relentless V2, the Scott Free, or both is up to you! Let's get started.

Hobbyking Marine Series - Relentless V2 and Scott Free - RCGroups Review (8 min 17 sec)

Scott Free

Product:Scott Free
Hull type:Deep Vee
Hull material:ABS plastic
Length:28.7" (730mm)
Beam:7.08" (180mm)
Motor:Water cooled 2815 brushless outrunner
ESC:60A water cooled
Steering servo:High-torque standard
Required LiPo:2x 2s 4000mAh
Product link:CLICK HERE

The Scott Free is a deep vee hull designed after the full-scale offshore race boat of the same name. The hull is an updated version of Hobbyking's Quanum Aquaholic electric boat, with the main differences being found inside the waterproof hatch. Inside the Scott Free's hull resides a potent 2815 electric outrunner, 60a watercooled ESC, and cradles on each side of the hull for a 2s 4000mAh LiPo.

What's Included - Fit and Finish

The Scott Free ships safely in the box with foam protecting the bow and stern. The propeller and rudder are not installed, and radio great is not included. Aside from bolting the rudder on and installing the propeller, the only additional assembly step is to put together the plastic stand.

All decals are pre-applied and they look very scale. The ABS hull is actually clearcoated over the graphics to seal them in and provide a much cleaner look. On the bottom of the hull are four strakes that are designed to keep the hull nice and stable in the water, and prevent sliding during turns.

The rudder is constructed of machined aluminum while the rudder stand-off bracket and propeller strut are injection molded plastic. The water pickup is known as a prop-blast pickup, and forces water from the propeller through the motor and esc cooling jackets. Prop angle and depth are not adjustable on the Scott Free.

Its difficult to see in the above photo, but there's a ride pad built in to the right rear of the hull (left side of the above picture since the hull is flipped). The ride pad counteracts some of the torque of the motor and prop, allowing the Scott Free to ride straight in the water at speed.

The hatch is made of plastic and attaches at the front with a stainless steel bolt that acts as a dowel, and a plastic rotating latch at the rear. When secured on the hull, the hatch clamps down on the foam ring around the opening, making the hull virtually watertight.

The interior tray holds the electronics in place, and is glued into the hull, unlike the Relentless V2 catamaran, which has the tray screwed in. I see no problems with the glue holding well.

The drive system consists of a 4mm flex shaft that attaches to the motor with a collet-style coupler; it grips the flex shaft by tightening the nut, and attaches to the motor shaft with a grub screw. The flex shaft travels out the stuffing tube through a plastic sleeve, and then through the strut. The strut contains a bearing on the end, followed by a strut bushing, and then the drive dog that attaches to the propeller. This system works well as long as you keep a small but of space (usually 1-2mm) between the drive dog and the strut. This is because the flex shaft contracts when under power and can push against the strut if there's no space between the drive dog and the strut housing.

Relentless V2

Product:Relentless V2
Pricing:$131.88 (International warehouse)
Hull type:Catamaran
Hull material:ABS plastic
Length:28.7" (730mm)
Beam:8.2" (209mm)
Motor:Water cooled 2815 brushless outrunner
ESC:60A water cooled
Steering servo:High-torque standard
Required LiPo:2x 2s 4000mAh
Product link:CLICK HERE

The Relentless V2 is the second hull in the Hobbyking Marine series and shares all the same electronics and running gear as the Scott Free deep vee. This offshore catamaran features an abs hull and hatch, with decals applied and clear coated over for a great finished look. Power comes from a pair of 2s 4000mAh LiPo batteries in series, for 4s 4000mAh.

What's Included - Fit and Finish

Just like the Scott Free deep vee, the Relentless V2 comes with the rudder and prop removed; a pair of hex wrenches are included to make the installation easier. The only tasks left to complete are putting together the plastic stand and installing the radio receiver of your choice.

All aspects of the running gear and electronics are virtually the same for both boats, but the Relentless V2 does have a different method of attaching the interior plastic electronics tray. Unlike the glued-in tray on the Scott Free, the Relentless V2 takes advantage of the open tunnel style of the catamaran; screws are used to attach the tray inside the hull.

Batteries Used

Both boats require a pair of 2s 4000mAh Lipos. I chose the Turnigy nano-tech 2s 4000mAh 35-70c packs. They have great punch and minimal voltage sag under load. It's important to use a pack that's up to the task of powering a boat and operating inside a hull with no ventilation. The Turnigy nano-tech packs deliver without getting too warm, post-run.


Scott Free Deep Vee

The Hobbyking Marine Scott Free deep vee has a top speed in the mid 30's, and a run time of around 8-10 minutes depending on throttle. Handling is on par with what you would expect from a mono of this size; it's can turn extremely tight at full throttle without rolling over, but too much input and it will just spin out. Spinning out isn't really a problem because you have to really try to make it happen by turning full lock. The Scott Free is much more sensitive when turning right than left, and it's easy to over steer. I ended up tuning the steering end point way down and the expo way up for right turning, which helped quite a bit. Turning left is much more progressive, and the boat doesn't have the tendency to dart as it does when turning right with too much input. Nevertheless, with the expo and end points set to my liking, she became precise and easy to handle when turning left and right.

Unlike the Relentless V2, getting the batteries into their trays and secured with the hook and loop straps is a little difficult. You have to snake both packs through the cooling hoses and over the motor wires. Once they are in, reaching under the deck lid to grab the hook and loop strap is a pain; it's just a tight fit in there! However, with the packs secured, there's no chance of them moving, and their location is perfect for balancing the hull just right.

Relentless V2

This catamaran caught me off guard with it's impressive handling at speed. Most cats in this size range with a beam that's not overly wide tend to roll to the outside and flip while turning. That was definitely not the case with the Relentless V2. It holds a line nicely in the turns and can change directions quickly without rolling. Granted, there's a limit to what a catamaran can take, and if it's choppy, she may catch a sponson and roll.

Unlike the Scott Free, the rudder on the Relentless V2 is offset to the right, a common practice in heat racing boats that go fast and only turn right. This usually means great right hand turning performance and a mushy feeling when turning left. But I noticed great performance when turning either way. The battery packs are also easier to put into the hull, thanks to the wider beam. You still have to snake them through the cooling tubes, but there's more room to get your fingers in there. As with the Scott Free, run times were around 10 minutes, and estimated top speed was the mid 30's.


Both boats suffer from cavitation at the prop when starting out. The props are not sharpened and are pitched high, which causes the prop not to bite and hook up until it gets enough forward momentum. You can see in the video portion of the review that both boats cavitate until then get up enough speed, and then instantly hook up. Since my usual boat running routine involves no stop and go driving, I don't see this as a problem.

Action Photos


Hobbyking nailed the opening of their Marine Series with the Scott Free and Relentless V2. Both boats are fast, they handle well, and they are priced right for what you get. The use of the 4mm flex shaft, a true collet-style motor coupler, and a metal prop shows that Hobbyking wants these boats to last. Shoehorning a pair of 2s 4000mAh LiPos in the ABS hulls makes for great top-end power, and having a pack placed on each side of the hull helps with turning performance as well.

The only change I would make would be to sharpen the propeller, which should help with the cavitation I experience at takeoff. Other than that, both are perfect examples of what performance boating looks like on a budget.

Last edited by Matt Gunn; Dec 17, 2015 at 02:13 PM..
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Dec 17, 2015, 02:09 PM
Registered User
When I got mine it had a plastic prop should have waited....
Dec 17, 2015, 04:15 PM
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ApexpredatorGT's Avatar
Nice write up!

Looks like a lot of bang for the buck on this one
Dec 20, 2015, 07:05 PM
Registered User
Panhead5496's Avatar
These look awesome! I think I might get the relentless!!! How much were the batteries each?
Dec 28, 2015, 08:45 PM
Registered User

Scott Free Prop

Great Review! My Scott Free's prop will move up or down about 5 mm by loosening the 2 allen head screws nearest the hull. I'm not sure if that counts as adjustable or not
One more thing, the outrunner motor has a fan type thing on top that will chew into your battery if the lipo strap gets loose. Its really cool to see smoke billowing from an electric boat
Dec 28, 2015, 08:55 PM
Registered User
I found the stock 3 Blade prop to be too big for the boat. The ESC would cut out on fresh batteries at WOT after about 50 feet. I switched to a X438 and the boat turned into a bullet. I plan on putting a GPS in it tomorrow to see how fast it is.
Dec 28, 2015, 09:59 PM
Matt Gunn's Avatar
Thread OP
Originally Posted by routhier11
I found the stock 3 Blade prop to be too big for the boat. The ESC would cut out on fresh batteries at WOT after about 50 feet. I switched to a X438 and the boat turned into a bullet. I plan on putting a GPS in it tomorrow to see how fast it is.
I never had that problem on either boat. You could have had a faulty ESC in some manner.
Latest blog entry: www.gunnphotoservices.com
Dec 29, 2015, 09:09 PM
Registered User
GPS was 36 MPH on a short body of water. I believe you are right the ESC timing was set at 15 on the stock SeaKing ESC, I changed it to 3.5 when I put the X438 prop on. I will test the stock prop in the AM with the lower ESC timing.
Dec 31, 2015, 05:26 AM
Registered User
I have a V1 and even with the prop lowered all the way down, and the Two 2s lipo's wired in series, all the way to the rear, the boat still runs too wet. Which eats alot of speed. Also have tried a few props. last prop used was a x438
Dec 31, 2015, 06:57 AM
Boaters are nice people.
Originally Posted by Xcessive Carts
with the prop lowered all the way down, and the Two 2s lipo's wired in series, all the way to the rear, the boat still runs too wet.
If the prop sits too low (or/and angled down), the bow will be pressed down, making the boat run wet.

Have you tried raising the prop and having just a smidge of downward angle?

On a side note; as it's an ABS hull, the trailing edge of the transom will be rounded, water will pull up the transom, instead of the flow breaking off, this causes drag.

If you sharpen the trailing edge, you'll gain speed.

Regards, Jan.
Dec 31, 2015, 07:35 AM
Registered User


Sorry. it was way too early in the morning to make that post, the Strut and prop are RAISED to the max allowed by the strut support.
I know it isnt a race boat, and it will never be a 50mph + boat. I have other boats for that, but I just want it to run higher and dryer like it should.
It is a fun boat to run.
Dec 31, 2015, 07:37 AM
Registered User
I really want to try the 3 blade prop that comes on the V2. Spent some time on HK website, but couldnt find a part number.
Dec 31, 2015, 08:46 PM
Registered User

3 blade Scott Free prop

This prop has a 5 MM bore. Only available from the Global Warehouse.

https://www.hobbyking.com/hobbyking/...dProduct=63648 I order this on 12/12 and got it and a few other items on 12/28.
Dec 31, 2015, 08:53 PM
Registered User
Relentless, My motor tray came loose so before I re-glued I move moved the battery tray back one set of holes. Mine runs dry.
Feb 05, 2016, 02:57 PM
Registered User
250Flyer's Avatar
Just bought the Relentless v2.

Will post some pics up when it arrives.

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