tried to build a light weight tub... and failed :(

[Marty Davis]

Tom, if I may suggest...

Use 1/8 balsa with either 1/64 or 1/32 skins for the sides (I use the 1/64!). the 1/32 bottom and 1/64 top are good. Make the front radio box bulkhead out of the same. I use either 1/8 or 3/32 ply for the transom (in-between the sides) and a 1/32 or 1/16 transom doubler all the way across. The front of the engine compartment probably needs something beside foam...I would use 1/8 balsa with 1/64 ply on the inside (the side towards the engine). Yes CA is the way to go for all of the joints (with a THIN coat of epoxy over the joints on the insides). Radio box lid rails should be 1/32 ply, the radio box lid should be 1/64 if the pipe is not going to mount to it or 1/32 if the pipe mount is going on it. You may want to add SMALL pieces of either balsa or 1/32 ply where the mount goes. The cowling (if used) should be 1/32 and 1/64.

The big thing is to stay away from the epoxy! Think about where the forces/stresses are and add strength only in those places...EVERYTHING ELSE IS JUST ALONG FOR THE RIDE!

And then there are all of the other parts....

Glenn

Tom:

I agree 100% with Glenn. This is the way that I also build my boats.

Glenn and Marty,

What would your hull weigh before sealing or installing hardware?

Ron

Ron:

I am not sure of the weight of just the center section. It was very light.

I did things a little different this time. I used Klegicel 1/8" instead of balsa. Seemed as strong as the balsa. Will have to see how it holds up. I also used .007" carbon as a skin over the kelgicel. Won't use it again as it is very crack prone and takes a LOT of surface prep before painting.

I will probably try some carbon honeycomb 1/8" the next 21 boat.

The finished boat came in at 3 1/4 lbs which is a record for me.

 

[Charles Perdue]

I've been trying to talk a buddy of mine in to making me a CF balsa panel without success. He keeps saying I need to make the whole thing out of carbon. I just don't have the tools. He might help me out yet!

How should the ply be attached to the balsa? Medium ca?

Have you tried the okume plywood Glenn?

How about the wire drive for .21's got that figured out?

Tom, I have found that carbon/balsa is WAY overkill for a .21 boat...carbon/foam or carbon/kevlar honeycomb is what I normally use.

Yes thick CA will work to put the ply on the balsa. No I have never tried the okume.

Yes my new .21 hydro has a wire drive setup that Charles Perdue built. If we can find someone to build a few of the pieces, I may start selling the entire wire drive setup that Charles has developed.

Glenn

Tom, since finally figuring out why the wire in the wire drive was breaking and making design changes to address this problem, myself and others have been running this setup for over 2 years without a single failure. The wire drive has already been used in the setting 2 records.

It is also being run in a 45 rigger with excellent results.

It is a very low drag system and is virtually bullet proof.

No details are being released at this time as we are trying to get going in producing this system for the boating market

Charles

 

[Ted buckley]

I've been trying to talk a buddy of mine in to making me a CF balsa panel without success. He keeps saying I need to make the whole thing out of carbon. I just don't have the tools. He might help me out yet!

How should the ply be attached to the balsa? Medium ca?

Have you tried the okume plywood Glenn?

How about the wire drive for .21's got that figured out?

Tom, I have found that carbon/balsa is WAY overkill for a .21 boat...carbon/foam or carbon/kevlar honeycomb is what I normally use.

Yes thick CA will work to put the ply on the balsa. No I have never tried the okume.

Yes my new .21 hydro has a wire drive setup that Charles Perdue built. If we can find someone to build a few of the pieces, I may start selling the entire wire drive setup that Charles has developed.

Glenn

Tom, since finally figuring out why the wire in the wire drive was breaking and making design changes to address this problem, myself and others have been running this setup for over 2 years without a single failure. The wire drive has already been used in the setting 2 records.

It is also being run in a 45 rigger with excellent results.

It is a very low drag system and is virtually bullet proof.

No details are being released at this time as we are trying to get going in producing this system for the boating market

Charles

"No details are being released at this time as we are trying to get going in producing this system for the boating market"

Mmmmmmmmmm..... Very interesting.. h34r:

 

[Chris Wood]

yep

1/8 balsa with 1/32 ply

that is what all my productions boats are.. here is a plus of LAMINATION.. you can drill out the balsa in areas and sheet over it. you still have the strength and loose a little weight. all my bulkheads except for the transom are balsa laminate.

i use corner stock in most of the corners as reinforcement.

it takes more time then just making the tub out of plywood but the grains of the 1/32 ply are much better than plywood not near as poras and SHOULD be lighter.. all depends on how you do it.

I havn't messed much with 1/64. i am relucktant to for the fact it is like paper and very easy to see thru and one little mistake and the stuff is DUST lol

chris

 

[misshydro]

I tried to build a light weight jae tub and failed. Here is what I did:

tub sides are 1/4" light ply with big holes cut in them to make them lighter. Then I skinned it with 1/64" plywood

radio box front bulkhead is 1/8" 3 ply

Transom is 1/16" plywood (was going to double this but have not yet)

front is just foam, no bulkhead.

tub top is 1/64" plywood

tub bottom is 1/32 plywood

No tub nose has been attached yet. It was going to be just balsa.

weight is 225 grams

How can this be improved?

Tom, we built my light weight JAE .12 with 1/16ply tub with 1/8 ply added to the rear trasom. Skins and sponsons are made from 1/32.. now my new jae is alittle over 1/2 apound lighter then my first jae .12 zippkits

 

[Tim_Duggan]

This thread should be pinned!

 

[TomMoorehouse]

I think this calls for a wood weight experiment!

i'm thinking cut 4" x 4" squares of various woods and get the weights. anybody willing to help?

 

[dwilfong]

I think this calls for a wood weight experiment!

i'm thinking cut 4" x 4" squares of various woods and get the weights. anybody willing to help?

I got the Okoume lets give it a shot.

4X4x1/4" 34g

David

 

[TomMoorehouse]

David, what is the actual thickness? I read the okumes are usually 3,4,5,6mm

thanks for the help! ill have time on friday i hope to test some weights.

 

[dwilfong]

David, what is the actual thickness? I read the okumes are usually 3,4,5,6mm

thanks for the help! ill have time on friday i hope to test some weights.

.246

 

[Terry Keeley]

What about 1/8" Rhoacell foam with a layer of 6oz CF on each side? Weight the epoxy and lay it up with a bunch of weight and I guarantee it'll be lighter and stronger than any "natually occuring fibrous celluloid" product! :lol:

 

[Brad Christy]

Tom,

Try laminating 1/32" ply over both sides of 3/32" balsa. Apply epoxy (very lightly) to ply only and press over a flat surface. Use this same lay-up for your bulkheads. I also add plywood disks into the balsa (between the 1/32" laminate) where the boom tubes will be. I've never weighed them, but with two layers of 1/8" ply for a transom and a hard maple noseblock, I'm fairly certain my BlasckJack tubs are less than 225g.

Thans. Brad.

Titan Racing Components.

BlackJack Hydros

 

[TomMoorehouse]

What about 1/8" Rhoacell foam with a layer of 6oz CF on each side? Weight the epoxy and lay it up with a bunch of weight and I guarantee it'll be lighter and stronger than any "natually occuring fibrous celluloid" product! :lol:

I do have some 2oz carbon fiber... are you vacuum bagging it or using peel ply? can you explain the process better?

 

[Terry Keeley]

What would be perfect is 2 layers of 2oz over balsa or foam but I'd prefer foam as it doesn't warp. Also if you get a crack somewhere it won't suck up water and oil like a sponge. :unsure:

Check out the 1st page here: (click the + beside Title)

https://www.intlwaters.com/gallery/thumbnails.php?album=707

You could do the same without the vacuum but use lots of weight, many have done it. The trick is to weight the epoxy and use only what is needed, otherwise it's not only heavier but also weaker than it should be. High fibre to resin is the best.

 

[Charles Perdue]

One thing that I do is I use basswood blocks instead of maple. It is not only lighter, it also glues better.

Another way of increasing stiffness AND decreasing weight is to get away from flat sides (VERY Old School). A slight rounded shape or a triangle shape of the outside skin (think like the shape of the sides of a Wing Ding) will accomplish both of these at the same time.

Charles

 

[moparbarn]

.246 should be the 6mm, or close to it. works out to be 6.24 mm

 

[misshydro]

What about 1/8" Rhoacell foam with a layer of 6oz CF on each side? Weight the epoxy and lay it up with a bunch of weight and I guarantee it'll be lighter and stronger than any "natually occuring fibrous celluloid" product! :lol:

I do have some 2oz carbon fiber... are you vacuum bagging it or using peel ply? can you explain the process better?

joe is going to do an exparment.. his friend Dan Kramer sudjusted this to joe.. Get 1/64 ply,then coat one side with epoxy. Then put a layer of tissue thin fiblerglass cloth over the epoxy coated 1/64 ply side. then put that in between two pieces of glass add weight to it to help squeeze out any access epoxy. then out your pieces out for your rigger. was told it would be lighter and stronger then other rigger out there... ok I want to put this out here.. how light is to light??? we dont want to be blow over king like chip handover..At these races I see to many blow overs. We dont want to make them to light to the point where there no good to race them neighter.. then all that time and money was wasted for nothing :angry: another question you you guys? Do you think the 1/4"solid carbonfiber tube is to big and heavy for the.12?? Had acouple of guys told joe he should try 3/16 for the.12..

 

[Marty Davis]

What about 1/8" Rhoacell foam with a layer of 6oz CF on each side? Weight the epoxy and lay it up with a bunch of weight and I guarantee it'll be lighter and stronger than any "natually occuring fibrous celluloid" product! :lol:

I do have some 2oz carbon fiber... are you vacuum bagging it or using peel ply? can you explain the process better?

joe is going to do an exparment.. his friend Dan Kramer sudjusted this to joe.. Get 1/64 ply,then coat one side with epoxy. Then put a layer of tissue thin fiblerglass cloth over the epoxy coated 1/64 ply side. then put that in between two pieces of glass add weight to it to help squeeze out any access epoxy. then out your pieces out for your rigger. was told it would be lighter and stronger then other rigger out there... ok I want to put this out here.. how light is to light??? we dont want to be blow over king like chip handover..At these races I see to many blow overs. We dont want to make them to light to the point where there no good to race them neighter.. then all that time and money was wasted for nothing :angry: another question you you guys? Do you think the 1/4"solid carbonfiber tube is to big and heavy for the.12?? Had acouple of guys told joe he should try 3/16 for the.12..

Don't worry about blow over. If you boat is setup correctly, you can't get it too light.

 

[misshydro]

What about 1/8" Rhoacell foam with a layer of 6oz CF on each side? Weight the epoxy and lay it up with a bunch of weight and I guarantee it'll be lighter and stronger than any "natually occuring fibrous celluloid" product! :lol:

I do have some 2oz carbon fiber... are you vacuum bagging it or using peel ply? can you explain the process better?

joe is going to do an exparment.. his friend Dan Kramer sudjusted this to joe.. Get 1/64 ply,then coat one side with epoxy. Then put a layer of tissue thin fiblerglass cloth over the epoxy coated 1/64 ply side. then put that in between two pieces of glass add weight to it to help squeeze out any access epoxy. then out your pieces out for your rigger. was told it would be lighter and stronger then other rigger out there... ok I want to put this out here.. how light is to light??? we dont want to be blow over king like chip handover..At these races I see to many blow overs. We dont want to make them to light to the point where there no good to race them neighter.. then all that time and money was wasted for nothing :angry: another question you you guys? Do you think the 1/4"solid carbonfiber tube is to big and heavy for the.12?? Had acouple of guys told joe he should try 3/16 for the.12..

Don't worry about blow over. If you boat is setup correctly, you can't get it too light.

even if the boat is setup wright,,it will still blow over if its to light .. saw that in hobart and other races last year.

 

[gooycheese]

I will say i don't ever blow off due to being to light ( My Boats aren't light for sure). I blow off most of the time i would guess from driving to aggressive.... get to close drive up a rooster.... or push a little too much in too the wind with a prop i shouldn't be using in those air and water conditions

Racing does that to people some times push a little too much