Scratch building a mono (old school)

[mlbarnett]

The first thing I did was design an outline of what I propose to build. The basic sport V design is something I've done before many years ago (25 yrs). From the overall design I extrapulated the cross sections so I can begin transfering them to my chosen material, wood.

This method of building is for those who love to create something from nothing. It's about the building process as much as the end product. Not for the uninitiated or distracted.

I estimate this boat will take some 6 months. If I didn't have other responsibilities and a job I could do it in 3 weeks. Such is life.

So for you hardcore builders, I hope you look in now and then and get some pleasure from the work.

Thanks, Mike

[Richie the shipwright]

Bring it on dude, I like your style! nothin like glue on your fingers and timber shavings on the floor! Us scatch builders are a dying breed... Good luck!!

[mlbarnett]

Believe it not I found some nice ply at Hobby Lobby with the price being cheaper than I expected. My only issue will be the thin spruce or birch to cover the hull. I already have a lot of the misc pieces from projects of old. Will also use as much balsa as posible and am comfortable with.

[785boats]

I love scratch building. Although I haven't built a fast electric mono, I've done plenty of 'scale boats', so I appreciate the effort you are going to put into it.

Mike.
A couple of places for spruce strips & aircraft ply over there in the States. Many other things useful to building model boats too.

http://www.aircraftspruce.com/menus/wp/spruce.html

http://www.wicksaircraft.com/aircraft-spruce-plywood.html

Cheers.
Paul.

[mlbarnett]

Thanks, Paul. I'll need to find a source for thin ply.
Mike

[mlbarnett]

Gathered all the wood I needed for the frame. Almost all is left overs from previous projects (used to build planes as well). Will be using primarily balsa throughout with the exeption of transom, a few key structural pieces and of course the skin.
Haven't made any decisions on the thickness of the covering ply. Of course looking for that optimal compromise between weight and strength. Any suggestion?

[big g money]

This place has some thin plywood http://www.bd-international.com/

[mlbarnett]

Creating structural pieces

Alright, took a big step this week end. Using a scanner/printer I transfered all my plans onto card stock paper. Then using scissors and an exacto knife with straight edge cut out all pattern pieces. Then I transfered all the shapes I cut onto 3/16" balsa and 1/8" birch ply. Use a ball point pen, because a sharpie or gel pen will bleed into the grain and make for a fuzzy line. And finally I'm in the process of cutting out all my pieces and giving them a final touch up. What I mean by touch up is taking the time to align mirror and duplicate pieces and sanding or shaving them to be indentical. Also pre fit all pieces into each other individually to sand and adjust alignment and fit. If you take your time and don't rush this stage it will make the up and coming assembly a pleasure instead of a curse fest. You feeling me?

[zx11976r]

Looks good. What is the estimate overall length?

[mlbarnett]

Going to be 24" long and 10" wide. A shallow V, typical of your lake runabout.

[mlbarnett]

Assembled frame

After all the sanding and adjusting, I assembled all the peices using CA. You see in the picture I use a "Magic Magnetic Building Board". It's the one I got when I built airplanes. Using this keeps the keel straight and allows the basic stick frame to be true. It still will twist until the outer covering starts going on. I next sanded the finished frame work to prepare it for skinning. This is the time to "eyeball" the alignment of surfaces and make any small adjustments.

The next step was to treat the wood with a slow epoxy (slower the better) thinned out with denatured alcohol. Rubbing alcohol won't work. I coat all areas of the frame I can't reach, or will have a hard time reaching when the skin starts going on. This seals the grain and bonds all the little gaps and crevices to give it some strength. Use wax paper under your work so nothing sticks as it cures.

I found some 1/32" birch ply at Michael's (the craft store). A 12" x 24" sheet cost $8.99. That's much cheaper than the cheapest I could find on the internet. They have in fact all the balsa, bass, spruce sticks and ply I could want. The only thing they didn't have was specialty pieces like triangle or aileron stock. If you guys have a Micheal's nearby check it out.

[mlbarnett]

laying on the skin

I am now in the process of gluing on the skin. Bottom first then sides. After each piece I sand edges down to their finished size and sand the joints that will be glued with a following piece. When the bottom and both sides were done I mixed a batch of diluted epoxy and coated all the inside bottom and sides. I also coated the inside of the two deck pieces, as when these are glued into place I'd be unable to reach all of the surface in the bow area.

The picture is of the treated inside of the hull with the first deck piece in place.

My original time estimate is all off. I predict that this boat will be in the water within two months.

[rodneypierce]

mlbarnett, you can get ply at nationalbalsa.com They ahve 12x48 sheets of 1/32 ply for near the same price that you paid for the 12x24.

Just for future needs.

[mlbarnett]

Hull nearly complete

As you can see the hull is completely decked, sanded and shaped ready for the first coat of thinned epoxy. During the building of the hatch I discovered that because of the shallow draft, the motor (a 3665) sat above the top of the hatch opening. Especially since I'm mounting the motor aft I have to tip the motor down toward the keel. This raised the back up into the air. So I incorporated an engine cowl which I thought was esthetically pleasing. To further break-up the large flat cover I also added back rest for this little lake runabout.

Underneath I added two strakes per side. Not the traditional style where the bottom of the strakes are flat with the surface of the water, but basically triangular strips with an acute angle facing the water. I'm hoping this will eliminate the need of turn fins, perhaps even trim tabs (though I doubt the later). I enjoy a little experimentation, and if it doesn't work, or proves to be a soure of problems I'll just sand them off and install standard strakes, if any at all.

I also removed the second bulkhead after the decking was complete to open up the main compartment and added a low windscreen (both done after images were taken).

I'd like some input. My motor is a 3060kv and I've run it on a 7.4v 4000mah pack in the recent past (the avatar of the yellow tunnel is using this setup). Pretty quick with decent run times. Is using a 3s pack going to far? 34,000 rpm (by the math) seems high....... thoughts? Don't forget, I'm not adverse to taking risks, but don't want to be a fool either.

[mlbarnett]

motor mount

After placing all key components into hull, and knowing the motor was near the back, I was able to determine that I could balance the boat properly with such a configuration. So I have now installed the motor mount and the stuffing tube. I have coated the hull with two thin layers of diluted epoxy (with a sanding between coats) and am doing the final sanding before primering the hull.

I have ordered some misc. hardware from HOR Racing and should have hull ready when it arrives.