ML Boatworks GP 400 Sports Hydro. - RC Groups
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Feb 26, 2013, 02:16 AM
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ML Boatworks GP 400 Sports Hydro.

I bought this kit from Mike at ML Boatworks to slowly build up for our EB (6s) Sports Hydro class. But because the weather has been holding up the painting of the U-95 1/8th Scale Hydro, & my Whiplash, I started on this one.

As you can see the same basic hull comes in different sizes. GP265, GP310, GP330, GP400 & he's working on a GP480.

Comes with all frames, stringers , skins, & fibre glass cowling. (2 types to choose from.)

The laser cutting is excellent & the whole thing just falls together if you follow the manual. I won't post many photos, because the manual is full of them with the instructions. I'll just highlight where I changed or added something to suit my building style.

This is the manual.

The two sponsons were put together on the coffee table in one evening while watching the TV. See photo 1.

The main tub was assembled the next day in about 4 hours. Photos 2, & 3.

I did add a bit of extra 1/4" stock around all the joins of the air break and around all the joins around the curved trailing section of the sponson. Photos 4, 5, & 6
In photo # 6, you will also see that I extended the stringer on the outside edge of the air break section, forward one more bulkhead than shown in the manual. Just for a bit of strength in that area as I'm not going to add any glass or carbon fibre to the inside of the sponsons.

I also added a 1/4" stringer, half way between the air break, & the non trip chine, from the transom to the second bulkhead. Unfortunately I didn't take a photo of that.

Installing the non trip skins was quite simple, following the manual.
The ride pads, however were a bit more difficult.

I used Jans' suggestion of heating up the skin with a heat gun & forming a bend in it while the glue in the ply cooled & reset. It was then an easy task of gluing on the section over the transom & the first two bulkheads. Once that was dry, I applied CA to the rest of the stringers & bulkheads & held the ply in place with tape and a couple of clamps. Photos 7 & 8..

After adding a piece of 1/4" ply to the inside of the heel of the right hand sponson, I coated the whole of the inside of both sponsons & the tub with epoxy resin.
Then I just filled the sponsons with two part Eco Foam. Also the two front sections of the hull. It only added 5 oz but it adds a lot of strength to the skins. Especially the top one when it goes on. Photo #10 shows one sponson with the foam sanded to shape (also the front sections of the tub) & the other one as the foam had grown out of it ready for cutting & sanding.

That's where she sits at the moment. Top skins go on next, & then glue the sponsons on to the tub.

For anyone who likes building hulls Mike has a huge range to choose from.

Last edited by 785boats; Feb 02, 2014 at 01:01 PM.
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Mar 05, 2013, 01:37 PM
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Hi Paul, very nice of you to do a build thread! Build looks GREAT! I will have to keep an eye out for more of the build! Mike,
Mar 06, 2013, 02:42 AM
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Nice of you to notice Mike.
I thought I'd do the build over here as there are a couple of build threads happening over on OSE. Scott from our race club here in the land of Oz is doing the GP335 there. And then there's your thread & the manual which is a great build thread in its own right.

Well I've added some coolite foam to the sections down the sides of the tub & added the top skin. Also the skins of the sponsons were epoxied on last night.

The way I do the top skins is to coat the underside of the skin with epoxy resin. Add 24 hr Araldite to the frames & stringers etc, & then tape, clamp & weight down the skin onto the sponson or hull. That way the resin bonds to the foam as it cures. Will hopefully stick the sponsons onto the tub tonight.

Mar 11, 2013, 03:14 PM
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Here's the pics with the sponsons all glued on.
Looks like a boat now.
Apr 25, 2013, 12:29 AM
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This ones been lying dormant for too long & a fellow club member has told me to get it finished & racing.
So I've had a bit of a crack at it over the last few days.
I've added the motor mount & strengthened it up with some 1/4"carbon fibre rod. The motor mount & motor are solid. No flex in the floor pan now.
The ESC tray was epoxied to the rods, & the battery trays were epoxied into the front of the tub.
The strut & rudder were drilled onto the transom with a piece of reinforcing aluminium epoxied to the inside of the transom.
Then the stuffing tube was bent & cut and epoxied into place. I'm not running a liner in this one. I added two pieces of carbon rod across the tub so the stuffing tube would not move around as the floor was very flexible where the tube entered the boat. Rock solid now.
The water outlet pipe of 4.5mm tube was then drilled through the side of the hull & epoxied into place.
I had bought a Tia-pan fin & wasn't happy with the foot print of the bracket. It was too narrow & only had two bolts. So I made a larger bracket with 4 bolts to bolt it to the heel of the sponson. Still not sure if the actual fin is big enough really.
It hangs down 2" below the ride plate of the sponson. Is that enough?
All I have to do now is drill the holes for the safety loop. Strip it down & prep it for paint.
Still trying to decide on a paint scheme. Something that will use up the paint that I have lying around.
Here's a few pics.
Apr 26, 2013, 07:50 PM
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carlnoki's Avatar


what motor and Kv is that in your pics?
Apr 27, 2013, 04:27 AM
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It's a TP Power 4060 1350kv .
Jun 02, 2013, 02:06 AM
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785boats's Avatar
Well after getting some paint on it & a couple of late nights getting it ready, she had her first run today. No testing & no practice. It's first run was it's first race.
Must have been lucky with the set up & prop choice (CNC 448) because in windy & choppy conditions she won the race. Mind you, she was the only boat running at the end, but was running as fast as the other boats. And handled beautifully, even though she tended to run wide in the turns because I didn't have enough rudder throw dialed in.

In the second race I flipped it at the first corner, into a strong wind trying an H-7 prop.
She won the third race, still with the H-7 on it but with the strut dropped just a smidge.

Extremely happy with this boat. There's more speed in it yet.

She's entered in the Queensland State Titles next weekend but there will be no chance to do any testing before then.
Race one at the Titles will be the next test session.
Jun 02, 2013, 07:51 AM
Registered User
Great looking build. I just clear coated mine yesterday. Hardware will go back in today and will begin testing next weekend.
Jun 02, 2013, 01:43 PM
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I hope you like the way she rides too John.
What set up do you have in yours ? How about a couple of pics for us all to see what she looks like.
Jun 02, 2013, 03:09 PM
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Watching H1 Unlimited live streaming at Big Wake weekend. Just finished heat 2A and setting up for the next one.

My setup:

Turnigy 4074 KV
Hitec servo
Zippy Flightmax 4s-2p 5000mah
Blazer marine turnfin

Will get some pics up after the next heat.
Jun 02, 2013, 03:52 PM
Registered User
Most recent pics. Still have to solder bullet connectors on load side of ESC and install push rod on the servo.
Jun 03, 2013, 03:49 AM
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Looking good there John. Love the paint scheme.We are only allowed to run 1P setups for racing here in Oz.
What was the KV rating of your motor?

Jun 03, 2013, 06:26 AM
Registered User
Thanks, Paul. I know there are guys who spend a lot more time and money on the paint. I am enjoying all aspects of the hobby given a limited budget.

Re: the kv rating on the motor. Thought I had included that info but because I was pr-occupied with the H1 Unlimited yesterday, I must have missed it. The motor is an HK 4074 B 2000 kv. I considered a 1 p set up but a buddy of mine is building a similar size Whiplash and using a 2p. He wanted longer run times. I wanted to set up the boat so I could run either.
Jun 05, 2013, 08:15 AM
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785boats's Avatar
I'm with you on the paint thing John.
I'm a 2 colour rattle can specialist myself.

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