Lighter Weight JAE 21

[Timbo Whalen]

Just ordered a boat from Mini craft rc Roman Sergeevich Agafonov from Siberia. All carbon fiber! Even carbon fiber turn fin.

Butch, please check your messages here and/or Facebook... I've one coming, too.

Thanks-

tim

 

[Mark Anderson]

Nothing wrong with a 3.4 pound 20 boat.
A JAE style tub mold is very easy to build out of 1/2 inch plexiglass. I built one years ago. It all bolted together. We laid up the decks flat and bonded them to the tub as the last step after all of the bulkheads etc. were in. Eric probably still has the mold in a box somewhere.
That said, currently I am building tubs with ply/foam sides and getting very light and rigid assemblies. My current boat is 1/16 ply outside and 1/32 ply inside of a 1/8 Klegacell core. I am building a new one with 1/32 in and out.

 

[rctinman]

Hi Bob.. I liked how you lightened up the tub sides. Did you use a router, and not go all the way through the side, or did you go all the way through, and then add ply to the insides? Any idea how much weight you saved doing this? Do you think it was worth the effort? An all around great build!

Thanks,
Steve Ball

 

[BobBonahoom]

Hi Bob.. I liked how you lightened up the tub sides. Did you use a router, and not go all the way through the side, or did you go all the way through, and then add ply to the insides? Any idea how much weight you saved doing this? Do you think it was worth the effort? An all around great build!

Thanks,
Steve Ball

Hi Steve, I thought about the router route, but decided it was too hard to hold it all in my mill. So I just cut it out with my little table jig saw and then super glued pieces of 1/64" veneer on the inside. I cut the bait box off, got rid of the transom doubler (since there is no strut to support). It was a lot of work. We will find out how much it helps next spring! Here is a small section from a spreadsheet I made to keep track of each weight reduction idea. These first three things gave me about 1/2 pound.

The inside of the tub was sealed with 2 coats of PPG Concept, single stage clear, thinned and brushed on. Forgot to put that in the spreadsheet.

 

[Lay26]

did you look at cutting material from the flywheel? and using delrin motor mounts?

 

[rctinman]

Thanks for the info Bob! I'll be looking to see the results also! Again, nice work and a lot of great ideas!

Steve

 

[dr gary turner]

Somethings we have done to save weight
Sides made with dvynicil foam.030 carbon fiber and 1/64 on the inside

Delrin motor mounts. Just grommets in the sides with just 2 1/4 nylon scews. Boil the nylon and they can be colored with Roy dye. It makes the nylon much stronger and rigid

Very little paint on the tube. Metallic paint is heavy. PPG cleat is lighter than paint

Sealing: Jamestown 2 part sealing epoxy is like water and less weight than MASS OR WEST SYSTEM. Don’t use it for gluing.

Where do you get the wire drive? Did you build it

BTW I think the dyvinicil and 1/32 on the out side and 1/64 on the inside would be lighter than the .030 CF

Good ideas on this thread
Looking forward to more ideas


BTW: I was at the Bullard boat building shop today and he was installing new ProModeler servos in his twin. They looked great. No humming. Extremely quite

 

[BobBonahoom]

did you look at cutting material from the flywheel? and using delrin motor mounts?

I am using Delrin motor mounts. I thought about trimming the flywheel, but wasn't sure what that would do to engine performance.

 

[BobBonahoom]

Somethings we have done to save weight
Sides made with dvynicil foam.030 carbon fiber and 1/64 on the inside

Delrin motor mounts. Just grommets in the sides with just 2 1/4 nylon scews. Boil the nylon and they can be colored with Roy dye. It makes the nylon much stronger and rigid

Very little paint on the tube. Metallic paint is heavy. PPG cleat is lighter than paint

Sealing: Jamestown 2 part sealing epoxy is like water and less weight than MASS OR WEST SYSTEM. Don’t use it for gluing.

Where do you get the wire drive? Did you build it

BTW I think the dyvinicil and 1/32 on the out side and 1/64 on the inside would be lighter than the .030 CF

Good ideas on this thread
Looking forward to more ideas


BTW: I was at the Bullard boat building shop today and he was installing new ProModeler servos in his twin. They looked great. No humming. Extremely quite

Hi Doc,
The wire drive came from Jeff Wohltz. He will make them to your specs. I am trying 0.078" wire with a single home made oilite bushing fixed in the center of the stuff tube. The collet came directly from Octura. They don't have them in their catalog, but they do sell a 1/4-28 x 0.078" wire. Where do you get the 0.030 carbon on dyvinicil foam?

Yes the PPG clear is very light. I just can't bear to give up the paint yet..maybe next time. Thanks for sharing the info on Jamestown epoxy!

 

[Lay26]

So dr turner if i make a 2 part mould of the boat and use 2 layers of carbon fiber vac bagged are you saying that the foam core laminated boat framed up the traditional way would be lighter?

 

[Greg Bonahoom]

Yes the PPG clear is very light. I just can't bear to give up the paint yet..maybe next time. Thanks for sharing the info on Jamestown epoxy!

We are building a second one without paint. Will post the results once it is finished.

 

[dr gary turner]

Sorry, but who is building the CF turn fin

 

[dr gary turner]

Greg we make the sandwich
CA the Cf and 1/64 on the dyvinicil

Many sources for the dyvinicil

 

[dr gary turner]

We are building a second one without paint. Will post the results once it is finished.

“Lay” I don’t know.

 

[Butch Londrigan]

Roman Sergeevich Agafonov

 

[BobBonahoom]

Greg we make the sandwich
CA the Cf and 1/64 on the dyvinicil

Many sources for the dyvinicil

Doc, so you guys know how to handle CA glue on a large area sheet? I have never done anything like that. Sounds a little scary. How to you apply the glue and work with it before it starts to set?

 

[Lay26]

i would think you use the slow cure ca glue....would give some time to set the piece in place

 

[Terry Keeley]

You could calculate which would be lighter if you wanted.

For a 20 size hull 2 layers of 3.8 oz/sq ft. cloth per side over 1/8" Rhoacell 71 (4.7 lb/cu ft.) would make nice sides. Two or 3 layers of the same cloth laminated together would work for the top & bottom. You could figure the same weight of resin as cloth for a good vacuum layup.

For wood I'd think you'd need 1/32" ply inside and out over the foam and 1/32" top & bottom.

Might end up close to the same weight but the CF boat would prolly be stronger and a heck of a lot stiffer.

 

[dr gary turner]

Yep, slow cure and have the pieces ready to go

We build the sandwich first over sized
Put template made out of 1/4 plexiglass on the sandwich with 2 sided stick tape and route the shape out and drill all of the holes through the template

 

[Gabriel Tavares]

Guys, I know that it could be a dumb question but have you ever tried an carbon fiber rudder?
The major problem I guess is to sharpen properly, bu in an extremely low weight project...
Just an insight...