1/4 scale wood boat build, planking and vacuum bagging questions?

smokeater2005 created the topic: 1/4 scale wood boat build, planking and vacuum bagging questions?

Ok so having found a hull design that I like, I have been doing a little wood boat building research which has of course lead to more questions.

1. Are most RC wood boat builds true to real boat building technics or are they more like a "zippkit" or sheeting type build?

My app is a 65"L*18"W*12"H hull build and I was leaning more on the side of real building because of complex curves and so on.

2. If true to scale, I would be doing a 1-3"W*1/16" thick plank layup @ a 45 degree angle and swaping into a 45 degree layup in the other direction for a secound layer correct?

3. Would vacuum bagging work/help for the secound layer, and more importantly should one do small sections or entire boat bottom at a time?

4. Would it be possible to do a layer or 2 of carbon fiber between the 45 degree plank layers and the top layers of vener wood?

reasoning: 1 for strength, 2 weight savings...
obviously vacuum bagging on the carbon fiber layer to make it strong and worth doing...

5. Lastly, having done a dual carbon fiber layup and vener topping, how much clear should be put on the bottom to ensure a long and usable life?
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smokeater2005 replied the topic: Re: 1/4 scale wood boat build, planking and vacuum bagging questions?

I was thinking, Several boat builds I have seen use the cross angle dual layer planking on the bottom and larger single layer planking on the sides.

This with a double carbon layer overlay and a planking veneer with clear coat topping should provide strength, light weight, looks, and should last?
please correct me if im heading in the wrong direction?
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woody replied the topic: Re: 1/4 scale wood boat build, planking and vacuum bagging questions?


Hi Smoke!

I really like the boat, you are planning to build. It's a true classic beauty.
Regarding the building method, you are right on track.

If I should build a boat like this, I would use lots of profiles, and take specially care about the shaping and the angles.
(When the skin is finished, you can cut out many of the spants, before putting on the deck).
In building the skin on sides and bottom, I would start with some cheaper and bendable planks like 2 or 2,5 mm birch. Use epoxy for glueing to the profiles. Keep the planks in place with small (thin) nails, and remove them when the epoxy has dried.
After that, make a good sanding, to even out bumps etc.
Then follow up with two layers of diagonal planking, using the same method with epoxy, nails and sanding. I would recommend diagonal planks to be 0.8 mm.
The outer skind should be made of mahogany in 0.6 or 0.8 mm.
This should be made one plank at a time at vith precision.

A hull like this will be very strong due to the building method, so if you want to save weight, you can remove some of the profiles.

Good luck with this challenge. I really look forward to follow your build.

Cheers! :cheer:

Woody
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Mercury94 replied the topic: Re: 1/4 scale wood boat build, planking and vacuum bagging questions?

I have built two Dumas Chris Craft kits and they are made by framing then sheeting the framework with plywood. After framing,sheeting,and trimming Mahogany planks are glued starting from the bottom then transom,sides, then deck. After alot of sanding to make everything smooth a couple of coats of finishing resin you are good to go. The white calking joints on the deck are duplicated by using white plastic strips a little thicker than the Mahogany strips in those areas and sanded flush for that classic look. I would apply your carbon or glass on the inside to keep it good looking. Weight should be of little concern when building classic designs IMO.
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smokeater2005 replied the topic: Re: 1/4 scale wood boat build, planking and vacuum bagging questions?

Woody/Merc,

IYO, would it be possible to skip the 2.5mm(1/16"-ish) skining and just use 1/32"*1" strips layed in two layers of 45 degree opposing diagonal planking?

Basicaly I would like to get two things done.
1. make it look purdy from the inside
2. make it to hold an air tight seal so I can vacuum bag carbon fiber from here



putting a mahogany plank veneer on top of the (2) carbon fiber layers would thus hide the carbon fiber and clear coat on top of everything would simulate real wooden boat construction. Thus I would save weight and have a strong and long lasting hull.. in theory i guess...

i am still tossing twin electric drives versus gas. Gas does sound a whole lot better IMO...:-)

Let me know what you guys think?
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smokeater2005 replied the topic: Re: 1/4 scale wood boat build, planking and vacuum bagging questions?

If my before mentioned idea is possible I would venture to say that my construction would look something like this

frame/ stringers sealed with epoxy and then epoxy together.

bottom and side layer of 1/32” x 1” wide 45 degree diagonal planking

lightly sand, spray light coat of epoxy to help with sealing air tight

bottom and side layer of 1/32” x 1” wide 45 degree opposing diagonal planking

lightly sand, fill, sand…

Layer of carbon fiber, Vacuum bagged

Layer of carbon fiber, Vacuum bagged

Uber careful Mahogany strip plank outer covering lay-up and vacuum bagged

Light sand, fill, even lighter sand, wipe stain

Several layers of spray clear or finishing type stuff…
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Mercury94 replied the topic: Re: 1/4 scale wood boat build, planking and vacuum bagging questions?

I think your ideas should work well. Your plans on running electric is a good one for this type of application because nitro or gas would just shake all your fine detail stuff to death. That being said don't think it necessary to build it racing gas boat strong but I guess it wouldn't hurt. One more thing to get that deep dark brown color of the Mahogany is it must be stained before the finish coat of resin is applied. The stuff Dumas uses is a powder you mix with water. It is almost a amber Orange color (strange) but it really brings that scale look. Looked in my workshop and still have quart of it from about 15 years ago.
#19230
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woody replied the topic: Re: 1/4 scale wood boat build, planking and vacuum bagging questions?

Just a few comments (my opinion).

- If the diagonal planking is made with precision and sufficient amount of epoxy, and (if needed) epoxy micro-balloon filler, you will get an extremely strong hull.
In my opinion there will be no need for carbon fibres. If you make the engine rails strong, the hull will easily carry a vibrating gas engine just as glassfibre hulls do.

About vacuum bagging: What is that? Any links explaining that method?

Cheers! :cheer:

Woody.
#19234
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Mercury94 replied the topic: Re: 1/4 scale wood boat build, planking and vacuum bagging questions?

Woody, The hull would not be the problem,it's the details like windshields,gauges,chrome scoops,etc that get damaged or fall apart due the vibration. My boats had steering wheels that moved with the rudder for example. Vacuum bagging is a process to remove excess resin and air from composites. In the latsest article section is a good read called "Composites In Model Boat Construction".
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smokeater2005 replied the topic: Re: 1/4 scale wood boat build, planking and vacuum bagging questions?

vacuum bagging in action/ made simple
Here you go woody...
by vacuum bagging carbon fiber "which is layed up similar to fiberglass" one can achieve extreme strenght to weight properties which is good for model boats and other rc stuff IMO...
the above link is a how too and doesnt cover the strength part...

TEST MATERIAL 1/16" Solid Carbon Fiber Sheet
MATERIAL SIZE 6" x 36"
TEST SPAN 24"
MATERIAL WEIGHT 0.43 Lbs./foot2 - 0.65 Lbs. Total
LOAD TEST WEIGHT* ~ 2.5 Lbs.

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