New Scratch built fibreglass/carbon mono build

[minigazz]

I have done a reasonable amount of research on them and from what I gather they are to help shed water from under the boat on turns which is why they end before the transom because the boat is generally going straight while planeing. They also help bite into the water to stop it sliding like the centreboard on a sailing boat. They can also create lift by trapping air and forcing it under the hull which isnt also desirable!

[martno1fan]

They are mainly to create lift,most older designs had strakes all the way to the transom especially ones with submerged drive but with todays modern designs with surface drive and more powerfull motors the lift at the transom isnt needed especially on a model,in fact having them all the way to the back could cause issues at the higher speeds these modern powerplants produce.I have a small 40" cig hull with strakes all the way to the transom and becuse im expecting this hull to go well over 50 mph im going to possibly remove some of the strakes.
Mart
ps Gaz the plug looks great.

[minigazz]

I got back off holiday on saturday and began work again on sunday. I finished sanding the filler in the strakes and then gave the whole hull 2 coats of varnish followed by a coat of durabuild primer. I wasn't too happy with how the durabuild went on as it showed brush strokes horrifically! I now have the job of sanding it all down flat! My problem is going to come when i flat it back to the varnish/wood and then need to reapply leaving more brush strokes! I don't know if any of you have any tips for this?

Alongside all this I made a mold for a hatch off of an old boat which i have as practice. I think the gelcoat reacted with the HIPS that the original hatch was made from as it left it with a poor surface finish and locked in the mold quite badly. When I got the original out it had loads of weird bubbling on the surface too. Other than this it was quite successful! I managed to pull a new part from it, although it didn't release as easily as I had hoped! Is there a good amount of wax coats to aim for and a time between each coats application/buff?

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[minigazz]

I pushed on today and despite my initial disappointment with the durabuild primer I can now see how good it is for its sanding properties. I flatted the majority of the hull back with 180 grit and then found in places I had hit the varnish/wood, so I reapplied the durabuild. I then repeated this step, only now I only had to reapply to a few areas. Do I need to worry about areas being up to the varnish layer? I'm away again for a few days, but I may take the boat with me with a pack of sandpaper and continue tidying this thing up!

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[d3lap]

Man this thing is coming along really nicely! Cant wait to start on mine!

[minigazz]

Thanks, haven't managed to get any more done in the last few days because I am working for my aunty. The primer really is a pain because just as I start getting a nice finish on the boat I sand through to the wood and have to start recoating with the treacle like stuff! And I ruin a brush every time!

[minigazz]

I did a bit of sanding the other day, I am still away from home so theres not a lot else I can do. I went through the grits, 120 240 400 600 1200 2000, on the top deck but yet again I have hit the wood again. I am not sure what to do, possibly give it two coats and have another go - although I am worried about loosing all the definition on the bottom of the hull.

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[minigazz]

Finally back home and able to work! Only today I was interrupted by a scumbag breaking into my student home! I have finally started on the hatch, initially i tried lining the hatch recess on the hull with film and putting car body filler in it and adding a foam core to take and exact copy of the recess. Unfortunately this didn't work so I cut out a piece of wood, covered it in car body filler and then started sanding it down. I also sanded much more on the hull. I have bought some acetone which has allowed me to spray the durabuild onto it more evenly rather than brushing it on. I can now see the appeal of the stuff - its fantastic! I wouldn't recommend it though if you don't have access to spraying equipment. Another day or so and I should be well on my way to getting some moulding done. As a practice/test run I have tried duplicating some old hulls I have which are the ones you see alongside in the pictures.

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[larryrose11]

minigazz,
awsome work dude! you hare quite a craftsman.

I can tell ya some things from my experience with a mini rio (350 mm), heavy mod:
-Transom. Put a piece of aluminum or marine ply as the transom under the CF when you lay it down.
-Motor mount: Make it flexable, and use a flex shaft. Mount the motor towards the rear. so the heavy batteries can go up front. The mount is in the front on my Mini Rio, and if I used a lighter motor (oversized, my first build) I would have had a lot of problems with balance, as I could not have been able to get the weight far enough up front.
Strut: use a strut so you can carefully adjust the angle. The mini ones sold here work great. I have an extra I can sell ya if you want.
Batteries: Put the batteries up front, velcroed down so you can get the ballance you want.
-Flotation: You piled a lot of effort into this thing, make sure you but enough flotation that it wont sink if it is totally full of water. On my Rio, I ran it on 3S lippo, a 3600 KV motor, 30 A esc, and a Octura -y531 prop. It is a bit unstable it is so fast. probaslly about 30 MPH a x431 or smaller would be a better choice

http://www.youtube.com/watch?v=3Lz6FH4jO3E

same boat on 2S

http://www.youtube.com/watch?v=0SqZBlOe860

[minigazz]

Thanks Larry.

I am definitely going to go for a strut, I least the hard way with an old boat that this is a definite requirement! Im thinking of having two smaller batteries in the edges to give a nice weight distribution and to allow them to be moved up and down the hull into any position I require. That little thing is brilliant! especially on that kind of water.

Im hoping to get on with the build a little over the next few days as I am home from uni for the holidays, but unfortunately it is freezing cold so Im not sure if Im brave enough!

[larryrose11]

Thanks for the compliment. It was running with an engine way too bic in the vid, and a small 30 A ESC. it was my first build. The motor was greatly limited by the ESC, but that was fine as anything more would have been too much.
I just orederd a new motor for it, so Ill see how it goes:
http://www.hobbyking.com/hobbyking/s...tor_Boat_.html
it is a little lower KV (3300) than the one in the vid(3600) Cooling was never an issue with any of it.

I'm rebuilding it currently with the new knowledge I have gained from that boat, basically what I listed above.
A final note about final build with an unknown hull:
Don't commit the motor and servo placement with Epoxe. I just spent some time gently sanding with a dremel to remove the stuffing tube and servo mount which I had epoxied down. Use Goop, or Shoe Goo. It is tough enough when cured to work, ut softer than the fiberglass and so you can remove it.

[minigazz]

Thanks for the advice! I'll be sure to take it on board when i come to hardware installation! I made a similar boat in the past which you can find here

http://www.youtube.com/watch?v=oecj6fFaSAA

http://www.youtube.com/watch?v=QECW8HCfiFA

http://www.youtube.com/watch?v=cJSpn-4BwxA

It had the problem of having too much power. It also suffered from having a very basic hull design. I found using an in runner motor could help stop the boat from rolling so much as the initial inertia of the motor starting up is less.

Today I finally got some work done on my new boat! It consisted of another re-spray of the bottom of the hull and the canopy and then sanding the canopy to a shine. I am struggling to get the shine as high as I would like though, I have gone through all the sand paper grits up to 2000 grade and tried using T-cut scratch remover, but I would maybe benefit from using a more purpose made polishing compound?

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I am also wondering what the best way of joining the two hull halves together will be. I am thinking of building the upper edges around the join flange up with some of the chopped-strand-resin paste and then sanding it to a completely flat edge using sand paper mounted on a board, then epoxying the two halves together.

[martno1fan]

The easiest join would be a shoebox join that way you can just glue the deck on using pu adhesive,so just make the deck wider and longer by 1/4" and it will fit over the hull with 1/8 clearance each side and end to end vioala.
However might be more work than you want to do so asuming you can get inside to glass the seam id make sure when you mould top and bottom both mould halves match up perfectly so you need to make aparting dam then when you come to making the parts you can clamp both moulds together with the trimmed parts in and what you do is mix up some bog and put that along the join and clamp together,once set glass the seam inside if possible?.As for buffing your plug dont worry too much seems like your over doing it,get some wax on and buff that, to me it looks plenty good m8.
Mart
ps a parting dam is easy to do,place boat on a board and stand and mark where you want the join to be,take some plywood and cut it to fit arround the boat, suports neeed to be placed under to keep it in place once done seal any gaps between dam and hull with modeling clay then wax as normal.Both top of boat and dam need waxing.Make your top mould let set then remove whole thing from dam, flip it over leaving plug in place and wax bottom and the lip created by the dam and mould bottom,you then have two moulds made,remove moulds from plug after a day or so and job done two perfectly matched up moulds.Thats a quick how to theres lots of work involved but it has to be done to get a seamless join.

[martno1fan]

Heres a few pics of one a friend made some years ago and the build thread you should read it you will learn a lot.
Mart

http://www.rcuniverse.com/forum/m_8761328/mpage_1/key_/tm.htm

[minigazz]

Thanks! Great advice as ever! I don't fancy a shoebox, I'm like the idea of a completely smooth seam.
At what point do you trim the excess off of your mouldings? Surely some of your layers will have dried even if all haven't and so it would be very difficult to get two flat edges to bond together?
Also, what is bog mix?
Is the fibreglassing of the seam on the inside vital?
I could get bits of it done, but due to the small size of the boat, I'd struggle to get much further forward than the hatch.
I have read that blog several times, you linked me it in the past, it is fantastic! Its just a little brief in the joining section!
Thanks for the words of encouragement, its always appreciated! I think I'll go and give the hull some attention...