catamaran project

[bangka]

this is my first rc boat. a scratchbuild catamaran. made up my own design, and no previous boat experience so the dimensions are not really that good. i think it's a bit big or look heavy for a .21 engine. anyway i enjoyed building so far :D

pics here are before i assembled the main frame and the sponsons.

main frame

[bangka]

sponsons

[bangka]

sponsons and frame

[Watercadet]

Good for you! That is cool that you are getting out and just doing it. Have fun and don't epoxy your fingers!!

[Doubledog]

No building experience he says.

[bangka]

yup, this is the first time i'm building a boat, not counting my tamiya 1:72 pt-15 display model, which is aborted. i did have glues on my fingers, because it is only now that i've read something that i realized i need gloves.

[Hydro Junkie]

Who needs gloves? That's what soap and water are for. It looks good, so far. I might have put a shallower angle on the bow, but that's just me. Keep us posted on how it's going

[bangka]

hi! that's what i thought at first, that would increase speed right? but i was afraid that it might fly or flip. :D anyway, i can always build a second one once i get some exprerience.
here's a pic of the completed frames. i might glass it this weekend if i will be able to complete the refinement of the frame.

i have a question though, what is the best fiberglass weight to laminate the boat? i was thinking of putting a 2oz and 3/4oz. will this be ok or is it too weak?
thanks!

[TXTRCR]

thats a sweet looking Cat, but its not scratch built, the peices are numbered. thats a kit, but you still did a really good job putting it together. You should have seen my Dumas Atlas Van Lines 36 inch Hydroplane that i built, man did that turn out bad, the boat was built with a permenent turn left. the left sponson was about 1/2 inch higher than the right sponson tip. the cowling didnt fit without qlueing on some extra peices of wood to fill the gaps. Your boat turn out nice, and if that is a scatch built kit and you just used some scraps from another kit :eek: YOU RULE :D

[bangka]

txtrcr, it's completely made from scratch. i used 2mm ordinary plywood. i did draw the plans on cadd and printed it full size, that's why you see those numbers. i do research a lot before undergoing this project. i did have trouble putting the bottom sheeting. i'm still thinking of a better way. thanks for the nice words.
ernest

[bangka]

hi! how will i prepare my wooden hull for fiberglassing? there are some imperfections, like woods don't meet perfectly, etc. will i use wood filler to properly shape the hull? and also apply filler all over the plywood sheeting to smoothen this out? thanks a lot!
ernest

[Hydro Junkie]

Epoxy and microballoons works well. It's sandable, shapable, can be mixed to any thickness you need, it's liteweight, and best of all, it's waterproof. As for fiberglassing, it's not normally needed. To seal the hull, just coat the hull with a slow setting epoxy thinned with alcohol and sand it smooth. If you sand through the coating you will need to apply more to cover the gaps. When you get the hull sealed, spray a coat of primer on and let it dry. When dry, spray on a different color and let it dry. When the second color is dry, sand the hull with a sanding block. Any low spots will show up as not sanded top color. Fill these with the epoxy/balloon mix and let dry. Repete the paint process till the hull sands uniformly, then paint with your chosen basecoat. Whether you put on fiberglass or not, you will still need to do the paint and sand technique. The glass just replaces the thinned epoxy as the seal coat. Have fun and "Happy Sanding"

[bangka]

here's what i've got so far. hull is almost finish, maybe 1 more week.

[bangka]

another one

[scottericsonon]

that is friggin awesome

im thinking REALLY hard about building an all wood hydro over the winter

scott

[Hydro Junkie]

I agree with Scott, it does look good. You should be very proud of the craftsmanship you've put into it. Speaking of Scott, have you decided which hydro you want to build yet, and are you looking at scratchbuilding or a kit?

[TXTRCR]

you guys and gals that have the patients to sit down and design and then build a boat from scratch are amazing. i have started many a scratch built boat, they start off looking rather good but as i get towards the finish line i lose patients and start taking short cuts and the finished boat shows it. i would like to build a boat its much cheaper than buying a hull, and you have total creative control over how the boat comes out, but i just cant do it. i like driving the boats more than i do working on them. great job on the boat. thats the design of cat i like, deep tunnel.

[Recko]

Congratulations!!!!!
You have done outstanding job. Keep it up.

Recko

[Hydro Junkie]

One thing I would recommend would be to add glue blocks to the inside between the center bottom and the center sidewalls where you can still get to. It will give more strength to the bottom and make it harder for the hull to break apart. When I figure out how to get pics on this site, I'll show you what i mean.

[bangka]

thanks! i think i consider it a very low cost hull. total cost so far is maybe 20-30$. more than 1/3 of that goes to glues and CA.
what do you mean by that hydro? please post some pics. i think i'll gonna try and put fiberglass in the middle portion only, where the engine is located.
it will be very nice to here some suggestions on building, i still have a lot to learn.

[Hydro Junkie]

I've got to get some film developed and scanned before I can do that, so it might take a while. What I was referring to is to cut some either 1/8th or 1/4 inch square stock into pieces that will fit lengthwise between the cross frames for your center section. These will be epoxied between the sidewalls you glued to the sponsons and the bottom of the boat. They give the boat more strength making it harder to knock out the boat's bottom. In a hydroplane, they also make the hull more rigid.

[bangka]

ok i got it. but i'm still interested in your pics. i actually made a bit of that in the bottom of the boat. but not in the inside. i'll do that, thanks!!

[TXTRCR]

i see that you cut a bunch of strips to cover the top and top corner of the sponsons, did you do that for the sides as well. or did you cut one solid peice to fit and then bend it in shape. thats a neat way to go about making curves and a hull i never would have thought about cutting strips like thats. very good work. how much are you up to in weight now. is this nitro, electric or gas powered.

[bangka]

the side and the bottom sheetings are in one piece. i trace the side and the bottom on a cardboard and this serves as the template for the plywood. i don't know the weight right now cause i don't have a scale, but i'm actually concern because its a bit heavy. i only use ordinary 2mm plywood which is heavier i think compared to light ply or other plywoods used commonly by modelers.
this will be powered by a .21 engine. it's about 33" which i think make it a bit underpowered.

[TXTRCR]

it should move quite nicely with the right prop i believe. it may not be a speed demon but it should go pretty well. looks great, i wish i had the time and patients to build one.

[Hydro Junkie]

You skinned it with 2mm ply? That could be why it's so heavy. On your next boat, skin it with 1.5mm. It bends easier than the 2mm, with half the weight. You also won't want to put any glass on this one. With the 2mm ply, the additional weight will make it a power hungry slug. If you have the funds, you might consider putting a .40 in this one.

[bangka]

first of all, i couldnt find any ply that's thinner that 2mm. i ask all the hobby shops here and none. second, i don't have the money to buy from abroad.
what do you think is the ideal hull weight for a .21 engine? please give one so i will have an idea. the hull size i think is definitely a .45 class i think. anyway i'll go ahead with it. this is an expriment anyway. makes me wiser, hehehe!
one question you guys, does the bearing or bushing in the strut needs to rotate? or is it ok if the bushing is fixed? because i have something in mind for my homemade strut.
thanks!

[Hydro Junkie]

I know you can't afford to order from abroad this time. It just surprises me 1.5 isn't available. As for bushings and bearings, go bearings. The outer race shouldn't move after it's installed If you have to use bushings, they shouldn't move either. Bushings have to be lubicated very heavily to prevent the shaft from binding, and yes, been there done that(ripped the bottom right out of my first boat)

[bangka]

hi! i've weight my boat yesterday, it top about 1.8kg, approx. 4pounds. is it too heavy for a .21 size boat?

[Hydro Junkie]

In all probability, yes. I built a Dumas 30" 1973 Pay N' Pak years ago that was SUPPOSED to use a .20. When I was done building it, it weighed between 3 and 4kg. The poor little HB .20 I had bought(not a good boat engine) couldn't even get it up on plane due to the weight. If the funds are available, get a hot .45, so you can get some speed out of it.

[Chris LaPanse]

Nice cat!
A .21 should be fine, unless it is extremely heavy or you like having too much power (like me :D)

[bh696]

your craftsmanship really impressed me. that is a nice boat period, not just nice for a first boat.

[Chris LaPanse]

I just noticed the weight- the .21 will plane it, but if you want real speed, go .32-.45

[bangka]

well i'd be delighted if i'll be able to make it run in the range of 25-35mph. :-)
but i guess the hull is really for a .45 engine. haven't done much this past weeks, busy with work.

[BoatDoc]

just curious...how's the project coming???? i'd sure like to see what kind of progress you've made.