Materials.....any suggestions?

[ccboatworks]

I've been making 1/16th scale boat kits for awhile now, but due to high demand I'm looking into making 12 cell sport hydros. I'm wondering about what materials. How much ply, what thickness, will all balsa be too weak?

My plan is to make a boat out of 1/8" balsa and use 1/32" ply for the deck. If I use ply on the sponson sides and bottoms too will it be too heavy?

Let me know


Chris

CCBoatworks

Miss Bardahls are in production!

[AndyKunz]

Chris,

Appropriate wood selection is always essential. Just because you get a particular thickness doesn't mean it's the right piece of wood!

Last year I built a 36" hydro (www.rc-hydros.com/AMSOIL) which I raced on 18 cells. AUW was 6 pounds 8 ounces. After you subtract motor, cells, electronics, hardware, driveline, etc and an 8 oz cowling you can see it was pretty light.

It was built almost exclusively of 1/16" and 3/32" balsa. I used to have construction photos on my sites but not any longer. The hull has no flotation in it, using instead the structure which consists of numerous water-resistant ;) compartments for flotation. I did the math and I would have to lose more than 50% of the boat before it would go down.

Sponson transoms (1/8" ply) and transom (1/8" ply full width, with 1/8" ply doubler for center 4" or so). The deck is all 3/32" balsa, sanded down for smooth contours. The non trip is 1/16" balsa, the riding surfaces are 1/32" ply. Center section bottom was 1/32" ply. There are a few 3/16" or 1/4" stringers under the deck as well, mostly to increase gluing area.

For the 1/12th boats I've built I've used 1/16" balsa for everything except transoms and motor mount areas.

The 24" laser-cut Slo-mo hulls that Rum Runner is selling now are primarily 1/16" balsa with a few ply parts. I have finished these boats with both 1/16" balsa (very light) and 1/32" mahogany (just as light but prettier!).

The 1/16 scale Tide (22") and Slo-mo (20.5") kits he is releasing (which were published back in 92 or 93) were all 1/16" balsa except transoms. The 20.5" Slo-mo is rather unique in that it has built up sides. After numerous complaints from non-"builder" types, I changed to using sheet sides for the 24" design.

Don - I looked for the construction articles on my hard drive but couldn't find them. I need to go back through some old CD's to see if I have them there.

Andy

[Garry Finlay]

The only other thing that I could add to Andy’s recommendations is to build with handling damage in mind. Most of the dings, dents and cracks on my boats are from my hands, the edge of the work bench, and from the boats sliding around in the back of the car. In most cases 1/16 balsa or 1/32 ply will not cover open spans (between bulkheads, stringers, etc) of 2” without being flimsy.

I'm starting to look at 1/32 or 1/64 ply over foam for the 1/12 LSH class of boat now. A little more weight than all balsa, but oh so tough.

Garry

[AndyKunz]

Good points, Garry. I work hard to make sure that handling damage is not a problem. Dennis on the course, though, is hard to protect against ;) As a rule, I expect damage on boats and really don't mind it - that's just me.

We were out flying last week and my buddy hit the top of a 60' tree with my P-51. It tumbled end of end through the branches, bouncing and flipping all the way down. It landed in long grass. You would have expected major damage but there was none. That night I took the plane home and stuck in on the landing as I went in. Naomi reached over it to pull her coat off a clothes hamper (laundry day - a big event with 6 kids around) and pulled the hamper down on top of the plane. The crunch sound is sooooo sickening!

Sooooo, my wood boats get finished with 0.6oz glass cloth applied with either nitrate dope or West Systems resin. For a good write-up on the technique, see http://home.fuse.net/ryan/ (download section).

Andy

PS - the airplane is fixed and ready to go again as soon as it gets above freezing and the wind is below highway speeds around here.

[Garry Finlay]

The weekend before we had a little snow to walk through to get the boats in the water. This last weekend it was too warm for my coat. One thing, with the water temp way down, motors stay cooler too.

I remember knife - edging my old FG Phoenix-7 into the dirt at a low angle and terminal velocity. Nothing would have helped that.
And it is NOT ready to go again.

Garry

[K.R.Joye]

[QUOTE]Originally posted by AndyKunz
[B]Good points, Garry. I work hard to make sure that handling damage is not a problem. Dennis on the course, though, is hard to protect against ;) As a rule, I expect damage on boats and really don't mind it - that's just me.

ANDY speaking of damage I was just talking to DENNIS and he wanted to know what classes you were running at the Mi Cup so he can start sighting his boats in!LOL
By the way can you burn me a copy of your start CD PLEEEEEEEEEEASE.

GARRY I still prefer 3/32-1/8 light ply for my motor,transom bulkheads & stringers.All other framing use hardbalsa.Ive been using .20-.30 sheet styrene for skin.It waterproof,repairable and easy to paint and trim with scissors.

[Avenger]

hey CC, do you have the laser cutter for all this, or do u send it out to somone to get it built? we have a CNC plasma cutter at my highschool, that is the coolest, the school is going to prepose o bond to get a laser cutter, that thing is gona be the coolest!, and hey maybe i could start to make some boat kits! -Jeff

[AndyKunz]

Originally posted by K.R.Joye
ANDY speaking of damage I was just talking to DENNIS and he wanted to know what classes you were running at the Mi Cup so he can start sighting his boats in!LOL


By the way can you burn me a copy of your start CD PLEEEEEEEEEEASE.[/b]

Whatever classes he's NOT in! ;)

E-mail me montana@fast.net your address.

Andy