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Old Jan 24, 2013, 02:43 AM
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New to boats, need guidance!

So I'm new to the hobby, well just boats. I've been reading through all these blogs of people building there hulls from scratch and it is something I want to do. I have plans for a 42" Cat, i think, and i will try to get it printed in A0 paper so i can just trace and cut. I'm going to use 1/8" Basswood for the beams and structural parts and then wrap it in 1/32" Basswood. I pretty much am clueless to what I am doing so i'm just going to wing it. Plus i live in china so stuff is pretty cheap here. If I could get some advice on things to do and not do that would be awesome. Everyone on this site seems very helpful and follow people on there builds with help and excitment. Thats pretty much what I'd like to see happen. I'd like the boat to be fast but still handle good as I am a rookie to boats. So what would be a good set-up as far as motor and ESC?
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Old Jan 24, 2013, 05:11 AM
Steps? What steps?
zozer's Avatar
United States, TX, Humble
Joined Jan 2010
218 Posts
Don't use basswood for the frames and planking. Use 3mm and 1.5mm aircraft plywood respectively as a minimum, 6mm and 2mm would be better. Basswood is soft and will split easily, plywood is much stronger. Fiber glassing the hull after it is built would also be a good idea. Extra weight is not a big problem with modern power, a little extra weight in the hull is better than adding lead later.

As for power - how fast do you want to go, how much do you want to spend, and how long do you want to run? With FE boats, the faster you go the shorter your run times. I'd suggest a 10S single motor setup. A Castle 2028/780 Kv motor or equivalent, 200+ amp ESC and 10S2P/5000 mAh cells would be a good top end setup. You could run this boat on 6S at a slower speed and less run time, up to you.

Frankly, this is a pretty ambitious project for a first boat. I strongly suggest you build a boat in the 650-750mm range on 4S power first, you will make expensive mistakes with the big boat.


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Old Jan 24, 2013, 05:30 AM
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Staffs UK
Joined Feb 2010
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Agree ^^^
defo dont use balsa wood its not strong enough especially for a hull that size
I use a combination of 6mm & 3mm birch ply & 6mm x 6mm square for framework then skin in aero grade lite ply
This forms a strong yet lite enough construction
This is the framework of my 48" X cat



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Old Jan 24, 2013, 06:21 AM
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thanks guys!

Zozer, what size would be better? I would like the boat to go fast say 40-50mph but overall I don't want to flip it an or sink it. So it has to handle good.

F1 - Would maple plywood be ok? I'm in china and all I can find is maple ply online. Not quite sure where I could get birch plywood from.
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Old Jan 24, 2013, 07:41 AM
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Suomi, HKI
Joined Oct 2011
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There are plans online for free.. even on this forum in posts.. Usually they are pdf.. (I think i had to swap them to jpeg) after it used posterazor to make the one big pic as multiple smaller parts.. and printed it out as A3s.. then just cutted em and joined parts together..

But what i actually wanted to say is when u start building from plywood pay attention which way u cut the parts.. one direction its pretty flexible and the other one is more rigid.. lmao.. i know from experience -.-
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Old Jan 24, 2013, 07:56 AM
Norman2
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Connestee Falls, Brevard, North Carolina
Joined Mar 2006
389 Posts
First Boat

Hi, Attached pdf plans of the cat I built at 34" which is the ideal size. Also Attached
photos of the finished product and the frame which was laser cut from 1/8" ply.
Also some photos of the building part. Regards
Norman
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Old Jan 24, 2013, 08:29 AM
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Thanks fissio i will definitely keep that in mind.

Norm, thanks for the PDF and pics. Did you bend the wood around the top of the sides or glue them at the corners? i cant really tell from the pics.
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Old Jan 26, 2013, 07:28 AM
Boaters are nice people.
Sneek, Netherlands.
Joined May 2004
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Quote:
Originally Posted by Ratlander View Post
I would like the boat to go fast say 40-50mph but overall I don't want to flip it an or sink it. So it has to handle good.
Hi Ratlander,

Keep in mind a cat, even 'only' 34", once dialed in, is capable of running way over 60 mph, so the occasional flip will be hard to avoid.
Build propely and with the hatch taped shut, sinking will not occur, but you'll need some means to recover the boat...
Quote:
Originally Posted by Ratlander View Post
Did you bend the wood around the top of the sides or glue them at the corners?
The fact that you ask such a question leaves me wondering about your building skils.
Usually the (flat) panels are glued onto the frames and rounded afterwards.
Read up on the matter, use the search function and the links provided in previous answers.

I agree with Zozer on his advice to start (considerably) smaller than your initial 42", building errors tend to get very expensive on boats that size.

Regards, Jan.
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Old Jan 27, 2013, 05:14 AM
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Quote:
Originally Posted by pompebled View Post
Hi Ratlander,

Keep in mind a cat, even 'only' 34", once dialed in, is capable of running way over 60 mph, so the occasional flip will be hard to avoid.
Build propely and with the hatch taped shut, sinking will not occur, but you'll need some means to recover the boat...

The fact that you ask such a question leaves me wondering about your building skils.
Usually the (flat) panels are glued onto the frames and rounded afterwards.
Read up on the matter, use the search function and the links provided in previous answers.

Regards, Jan.

Jan,
I understand the occasional flip will occur and that i need to tape the hatch shut.

I have read just about every build forum on here that i could find. So I have done my research and understand that have everyone has their own way of doing things!

My building skills and enginuity are pretty high. Seems you were a bit confused about what i was trying to say. What i meant was when i'm skinning the sponson's is when i get to to the corner's. Is it better to roll the ply around around them or can i just butt connect two pieces of wood? I know and plan on doing a bit of sanding to shape the hull how i want. I know how to do that.

I have never "rolled" wood before so i have done my research on that but I'm an american living in china. So some of my resources are a pain in the ass to get.

So what is the best way to skin the sponson's? If it's to roll the wood around the corner, what is the best way to soften the wood?
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Old Jan 27, 2013, 06:04 AM
Boaters are nice people.
Sneek, Netherlands.
Joined May 2004
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Hi Ratlander,

My appologies if you feel offended, which was not my intention; on the other hand, filling in your profile completely can shed some more light on your building skills, regarding age etc.

Skinning the sponsons is done as you decribe, with a but joint, sanded round after the glue has set.

As these are compond curves (with a rather small radius too), the only way to plank that would be diagonally with strips of veneer, the way scale sailboats with an S-shaped cross-section and rescue launches can be planked.

Though this way of planking results in a very light and stiff hull, I'd rather go the 'tradidional' way and cover the wooden hull in a layer of glasscloth and epoxy when the planking is done.

Regards, Jan.
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Old Jan 27, 2013, 06:42 AM
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Jan,

It's all right i totally really feel offended. I will update my profile as that does set a valid point. Thanks for the tips and the guidance. Now, I have never really covered anything in FB, glass cloth & epoxy, but I have watched my dad fix some taxidermy mounts with it. I know you have to wear a mask when using epoxy like that. Do i use the regular 2 part epoxies or something different? Is there differences in glass cloth that i should look for? I've tried searching for some onfo but haven't had much luck.
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Old Jan 27, 2013, 07:30 AM
Boaters are nice people.
Sneek, Netherlands.
Joined May 2004
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Hi Ratlander,

Covering a hull with glasscloth and epoxy isn't (very) hazardous for your health, as long as you work in a well ventilated area and don't stick your nose right in the jar with epoxy...
Do wear gloves (not Latex, as epoxy will migrate through it), or get a lot of experience (I magage to do 'small' jobs like this without getting epoxy resin on my hands)...

When in doubt, read up on the subject.

Keep in mind that glasscloth will not follow sharp edges, so the angles on the hull, that need(!) to stay sharp, such as the trailing edges of the sponsons and steps need to be done one flat surface at the time.
The pictures show the bottom of my 43" M.A.S.covered with a single layer of glasscloth, the small overlap is cut off after the resin has cured and is sanded flush with the ajacent surface, so the edges stay sharp:





Don't overdo it on the amount of epoxy used, you don't want the cloth to 'float' on it, as there will be no bonding to the wood.
The weave has to remain visible when applying the cloth.

Once you're happy with the surface, add one or more thin coats of epoxy resin to 'drown' the structure of the glasscloth, the picture shows the hull after two extra coats:



The dull patches were air trapped under the cloth, when sanding these spots became holes in the cloth, so I had to add glasscloth and epoxy in those spots (and had to sand them flush afterwards):



Typically the weave of the cloth also makes a difference; twill woven will follow curves better than other types of weave, read up on the subject.

Also the thinner(lighter) the cloth, the easier it is to work on curved surfaces, In those cases I often rather use two layers of 25 gr/m than a single layer of 65 gr/m.

I only use the 24h epoxy for laminating a hull, the 5 and 10 minute stuff is more for gluing.

See what's available locally and show us the link, with some luck we can say if it's suitable or not.

Regards, Jan.
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Old Jan 27, 2013, 08:16 AM
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thanks Jan, my name is Ben, btw.

you said:
"Once you're happy with the surface, add one or more thin coats of epoxy resin to 'drown' the structure of the glasscloth, the picture shows the hull after two extra coats"

I should wait until it has dried completely before I add the extra coats of epoxy? Also before adding the extra coats, if I have to wait until it dries, should I sand I smooth? What grit sand paper do you start with on sanding the epoxy?
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Old Jan 28, 2013, 05:38 AM
Boaters are nice people.
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Hi Ben,

If the surface is smooth(ish) without too much dust, you can add another layer as soon as the resin has set.
If you want/need to sand between layers, I'd wait a few hours longer, just test if the sandpaper doesn't clogg up with resin, it's still too fresh then.

Depending on the condition of the surface, I use fine grid paper, you want to smooth the surface, dont add scratches...

To avoid runners, I always add epoxy on a horizontal surface, meaning you'll have to work in stages, turning the hull in the best position.
Working this way takes more time, but you can add more epoxy without having to worry that it will run off...

Working in a warm environment makes the epoxy cures rather quick, so it's no problem to add several layers in one day.

Keep track in which order you treat the surfaces; you can add another layer without sanding within 24h, you'll still have sufficient chemical bonding.
If more time passes and the resin has cured fully, you'll have to sand and degrease before adding more epoxy.

Regards, Jan.
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Old Jan 28, 2013, 10:33 AM
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Joined Jan 2013
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gotcha, thanks a lot Jan. Here are some links to a few different kinds of FG I can get. I'm not sure how it usually is measured but they have it in mm. But just tell me what ya think.

http://item.taobao.com/item.htm?spm=...&cm_id=&pm_id=

http://item.taobao.com/item.htm?spm=...id=18556579298

http://item.taobao.com/item.htm?spm=...id=18545851970

http://item.taobao.com/item.htm?spm=...id=20298220209
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