4G Sprint Boat Build Part 1: Moulding the Carbon Fiber Hull

[@thatformanet]

Wow, awesome progress. Great stuff!!

[@3dm4rk]

Brilliant as always Stepan, I appreciate the way you show the whole process, warts and all! Looking forward to your next installment! 😎

[@mjetdevelopment]

Thanks, I am glad you like it! Maybe I could show the whole build this way.

[@gwlith1578]

Pretty impressive how light it is. Edited to see how the rest of the build turns out ceap up the great work👌

[@YOUNGSTERS-JETS]

if you wax the mould again after applying the pva-release agent you might get a better parting, first coat of wax has to be pretty liberal and given a bit of time to harden off before buffing to reduce porosity, looking good :) putting the half's together, I used tape to align them , super-glue and some thumb-pressure to tack to together, then resin and ribbon on the inside, hope that helps mate, Mark

[@mjetdevelopment]

Oh the wax over pva is a good idea, I did not think of that! Also probably I did not wait enough for the wax to harden as you are saying. And yeah I will use tape to align the parts. Thank you for all the tips!

[@sl66ggehrubt]

@@mjetdevelopment It's actually the other way around... wax, buff, wax, buff... then PVA the wax layer. In my PLA/PETG molds it goes: sanding -> gap filling primer -> sanding -> more gap filling primer -> sanding -> cleaning -> waxing -> buffing/waxing again -> PVA. Then splash some water into the mold to release the part.

[@mjetdevelopment]

@@sl66ggehrubt You use water as an additional release agent?

[@sl66ggehrubt]

@@mjetdevelopment no I splash water down the edges of it after the glue have cured to release the part 😀

[@mjetdevelopment]

@@sl66ggehrubt Ah ok then:)

[@MrDesperadus]

Awesome Steve! I am planning to user your design on Vlatva river for crack/meth delivery system. Do you think this boat could work on wavy nature of river with backstream or only on calm lakes? Thanks!

[@louis_sckr42]

Hey there, i think we should team up for meth and crack delivery routes over rivers! This is a great plan. We should consider cocaine as well. The boats will definetly be able to do that. We should equally split between Mjets and KwikJets and make a big business out of it! Cheers!

[@ScumfuckMcDoucheface]

@@louis_sckr42 haha Hey, I live right on the Detroit River seperating Canada and the US, better yet I live on the safer side (Canada) haha I'm totally in, I've got the work shop and very useful connections. =)

[@Ghosty-RC]

Thank you soo much!!! Will there be an updated version of this for the supersprint?

[@mjetdevelopment]

Glad ti hear you like it! Do you mean a mould to make the Supersprint from carbon fiber? So far I am not planning to do this, there is a bigger chance that the Ragnarok will get a mould design. We will see in the future, for now it is not a priority.

[@Ghosty-RC]

@@mjetdevelopment sweet. Is there a chance for a smaler boat? We only have small streams around here and a smaller boat would suit it better. Thx for your answer! Regards from Germany

[@mjetdevelopment]

@@Ghosty-RC Even smaller boat than the Supersprint is totally possible, it's just that it's not on the list for close future. Too many projects in mind:)

[@clappedadventures]

I just finished printing the mj sprint jet at 2x bigger than the original and it actually runs better with more weight and a bigger motor

[@mjetdevelopment]

Wow cool! Great that you solved the issues with component sizes. I would be interested to see how it runs!

[@clappedadventures]

@@mjetdevelopment yeah it was a bit of a mission finding hardware bearing and shafts were easy to find but bolts long enough to hold the impeller housing the the hull was a problem

[@OTWRC]

Awesome! 👍👍👍

[@mjetdevelopment]

Thanks!

[@maxoppmn5381]

I sent you a message on CGTrader, regarding the M-Jet 30. I need advice on improving the print of the first impeller, so that it is not out of round/out of balance when on the shaft! Thanks!

[@mjetdevelopment]

👍

[@burner8126]

Hi Stepan, a common width of carbon fiber cloth is 300mm. Is that wide enough?

[@mjetdevelopment]

@@burner8126 It's barely enough for the full width of the hull. The hull itself is 20cm wide at the widest point. For more comfort I would recommend a wider cloth, alternatively you can use 2 overlapping pieces.

[@ericbrockhus2518]

Hi Stefan, Can you tell me the size for the threaded rods for the joining of the moulds for the 4g jetboat hull? M4 or M5? Don't think it was mentioned in the video or somewhere else? or did I overlook? And a question about the water cooling channel in the m-jet 35 housing. There is no seal in between the two housing parts for the cooling water. will it just spill a bit from between those two housing parts or is that tight enough nothing is needed? or maybe it will spill but does not matter since there is enough water supply to circulate? and last question. Can you tell me what you payed for the stainless intake grating to get it lasercut? pcb ways wanted 45 or 50 dollars extra for it while I ordered two aluminium laser sintered impellers for a good price. The intake grating would be in the same package so no extra shipping costs. I was surprised thst was so expensive compared to laser sintering. cutting the grating would take maybe 2 minutes? and printing two impellers would be more like a few hours I imagine? So I only ordered the impellers and just ordered a little raw 2mm stainless plate at Aliexpress to cut one myself with the dremmel. It is halfway and it is hard work and will not be so pretty compared to laser cut but it is at the underside of the boat and the price they asked was not ok to me. did you had the same? Maybe you have a 90% similar mail I tried to send a few minutes back via cgtrader but there was a few times a warning it did not work and then all was blank so needed to write it again. Best regards, Eric Brockhus

[@mjetdevelopment]

Hi, the threaded rods are M5. Regarding the intake grate, it definitely should be cheaper. I got mine from a local manufacturer and price was around 6$ per piece, there was just a requirement that the whole order must be over 20$ so I got more of them. Often if you order more of them, price per one decreases rapidly. I did not receive any CGTrader messages from you, probably something went wrong, but you can just ask me here:) Good luck with your build.

[@meckarelis3235]

Is it possible to build a full size carbon fibre boat whitout a vacum bag. Just like this but with some extra layers.

[@mjetdevelopment]

Yes, vacuum bagging is not necessary.

[@meckarelis3235]

I want to build a about 4 meter hull. And have made some paper templates. I noticed here on youtube that most people tend to lay carbon fibre whit vacum. But not so often vacum when laying glass fibre. Therefore i thought of making the hull of glass fibre couse i do not have a vacum pump or enything. But if it is possible to lay it whithout vacum i will shoose carbon fibre.

[@mjetdevelopment]

@@meckarelis3235 Wow... I cant really give advice with this size. At 4m length, shrinkage of the epoxy might become a problem. But I dont know.. What will you use the hull for?

[@meckarelis3235]

@@mjetdevelopment a fun projekt. Just a little higher apeed boat that i could bounce around a bit on. I live near a coastline where i can drag a boat of that size down to a river and then drive like half a km to the coast line. And why not use that easy acces to a whole ocean by having a new hobby

[@meckarelis3235]

And i thought. Why not build a boat of dense foam and cover it in carbon fiber. Like a surf board.

[@jiriprotiva9321]

Čau Štěpánejá jsem DOMINIK

[@mjetdevelopment]

Nazdaar:)

[@dextersxxxxlab]

Stefan, I have a question about joining the two hull halfs. you use fibreglass tape. Is that real tape with self adhesion? does it have open stucture so epoxy resin will soak into it and bond it to the hull? Why did you use this stuff and not a strip of carbon fibre?

[@mjetdevelopment]

The fibreglass "tape" has no self adhesion. It is just a strip of fibreglass around 30mm wide, and needs to be laminated with epoxy just as the carbon fibre cloth. The advantage of the tape aganist a cloth is the ease of use - no need for long cuts, you just cut it like a tape. Also, the tape all holds together, unlike the cloth, where the borders tend to separate and leave the cloth's structure. Furthermore, the tape I used was much thinner than my cf cloth, so it was easier to bend it around the joint.

[@dextersxxxxlab]

@@mjetdevelopment Thank you for the fast reply. Great support. I am thinking about smoothening my hull moulds with epoxy. You think that is a good idea?

[@mjetdevelopment]

@@dextersxxxxlab Yes, I heard some people had success with that.