Anyone know of plans for a CNC boat kit that is riveted NOT welded together?

[gonzo]

That is completely incorrect. Fiberglass boatbuilders do not have an angle carbon fiber piece added to transom, etc. The hull is laminated as a single unit; often with the reinforcements included. You are also wrong in that boat builders don't want to sell you data or don't understand what you want to do. It is simply that your idea is very flawed.

 

[valery gaulin]

Wannarivet, just buy a plywood epoxy boat plan and go ahead with your built. There is so many good design for wood epoxy construction up to pretty much any size! In my opinion wood epoxy (cold molded construction) is the best method for the DIY one off boat. Next method would be welded steel construction after in 3rd place welded aluminum construction.

There is other method but usually not good for one off construction for the DIY in my opinion.

 

[wannarivet]

Sigh... Arggg... OK, I'm not articulating myself nor using the proper marine terms and I think that that's where the disconnect is. So, let me try again.
Start by imagining these 3 ways to build a boat: fiberglass hand lay up, flat sheet cut on a CNC machine and welded (metal boat kits) and riveted from either flat or prebent material. Why can't a builder take the advantages of each method and combine them?

Remember, that I used to work in aerospace so I'm a big believer in composite materials.

Let's start with the easy stuff. I called them crossmembers and transom. Mistake, I meant stringers and the bulkheads. For me, the bulkhead is the thing at the back of the fuselage that separates the pressurized cabin from the non pressurized parts of the plane. AFAIK boats made in the 70s and 80s used plywood stringers and bulkheads in a fiberglass hull. Correct me if I'm wrong, but I don't believe that any boat builder screwed the bulkheads and stringers through the hull into the wood. No, they were glassed in. So, if a boat can be built using glassed in plywood stringers and bulkheads, then why can't a boat be made with glassed in stringers and bulkheads made from composite sandwich materials? Furthermore, instead of using fiberglass to glass in the bulkheads, I'd use carbon fiber which would make for a stronger joint. No? This is what I meant by the term carbon fiber angles.

I don't see this idea as flawed, sorry.

Now for the hull. Think metal boat kits. Instead of using aluminum sheets cut out to make the stringers, bulkheads and hull all cut out from aluminum or steel flat sheet on a CNC machine, why can't you put a composite sandwich panel in the CNC machine instead? You get exactly the same parts but with material that is 1/3 the weight and maybe double the cost. Less if you use fiberglass twill instead of carbon fiber twill. The problem is how to join them all? That's why I posted to the forum... Welding won't work but riveting would (the titanic was riveted), which was my original idea. Now imagine all those the parts joined together by what boat builders call glassed in. I already know that boats where glassed in with plywood and they worked fine. Correct me if I'm wrong, but I've never heard of a glassed in bulkhead or stringer breaking free of the glassed in part. Instead, the wood tends to rot.

So, I hope that I've distilled my boat building idea into something that makes more sense.

Rob

 

[gonzo]

Firstly, the Titanic sunk; not a good example. Secondly, if you were in aerospace, would you mix the building methods of a hot air balloon and a 757?

 

[chinaseapirate]

All right, you have distilled a completely new design. From riveted aluminum to composite aircraft cabins "glassed" together. Correct? What is the problem that your asking then? How to find plans? Use Valery's suggestion. Look at plywood plans, and go ahead with YOUR build. Just make sure they are built over a frame and don't call for stressing the hull panels into shape and then fitting the bulkheads to the hull. Your panels won't conform. The aluminum kit plans should work also, probably better because the designs are engineered with the skin carrying a larger % of the hull strength similar to what your composite panels would certainly be capable of. Absolutely do not rivet aircraft cabin interior together...
You are also going to have to route/chisel/saw/poke/whatever out the core in all edges of the panel (where you can't glass both sides of the joint) to a depth greater than the thickness of your your panel and fill all of them back in with a high density filler such as epoxy+chopped fiberglass. And if your core is just novalac coated paper don't dent or crack the hull (lol). You won't find many you tube videos on your construction method either.

 

[Angélique]

Sigh... Arggg... OK, I'm not articulating myself nor using the proper marine terms and I think that that's where the disconnect is.

There's some English boat terminology on the thread:

Beginners Guide To Boating Stuff ! ---> Page 13 ---> post #185 - to - #189 - & - post #192 - + - post #193​

Note: the easiest way to go to all the linked English boating terms there would be just to scroll down the page #13 link.

Good luck !

 

[Rumars]

I guess it's really hard to describe flat panel composite construction.
What kind of boat do you want? Sail, power, oar? Mono or multihull? Plywood, balsa cored (Duflex, DuraKore), foam cored? Do you want to make the panels yourself or buy them?

 

[Angélique]

Forum member [U]Richard Woods[/U] offers the option of GRP flat panel hull construction on some of his Cat designs, like eg Surfsong, a 8.3m deep V hull sail cruiser.

Surfsong ‘‘ 8.3 m Deep V Cruiser - sheet ply or grp flat panel hulls, ply decks ’’

See also Richard's article: Flat Panel Construction

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P.S. - Saw also the option of GRP flat panel hull construction on the Woods sailing Cats:

Windsong ‘‘ 9 m deep V hull ocean cruiser - sheet ply or grp flat panel deep V shaped hulls, ply decks ’’

Mira ‘‘ 10.65 m deep V hull open deck ocean cruiser - sheet ply or grp flat panel deep V hulls, or strip plank round bilge hulls ’’

 

[wannarivet]

Special thanks to Valerie and Angelique, who really nailed what I was looking for. As a bonus, someone actually sent me the study plans for a 27 foot boat for free. He didn't say specifically, but he's very interested in my project because he gets a lot of people who can't weld. The appeal of hand layup is enormous.

Thanks again for everyone's comments.

 

[M&M Ovenden]

Rob,
What sort of boat and size are you looking for ? If you want to work in sheet material aluminum or steel has some favorable properties over composite panels for boat building. Most panel friendly boat shapes use developable surfaces to get some very fair lines. I feel the composite sheets will be far to rigid in this application and don't offer any advantage. You can learn to weld easily.

Cheers,
Mark

 

[Zulu40]

I think that riveting is probably harder and requires more skill than welding. A poorly fitted plate can be fixed with a fat bead of weld. With rivets, that would mean discarding one or more plates and redoing them.

thats the case. When shipbuilding shifted from riveted to weldment structures as in liberty ships, the skill requirements where found to be less, and speed of construction faster

 

[Zulu40]

The boat hull. The density of water is about 750 times that of air. Birds can cause major damage on an airplane. Also, the leading edge of a wing or fuselage is reinforced and not the gauge you are discussing. I can cut my way into an airplane with my pocket knife.

Good analysis of both existing and previous designs concludes that aircraft designed to be on the water such as flying boats are 1.25x heavier than conventional aircraft they replace. Boat amphibians are even heavier at 1.3x
(The Design of the Aeroplane, Stinton D., pp522)

 

[Zulu40]

Good Morning,

I searched google and this forum but could not find any link to a website where could build my own 27 foot (8.2m) aluminum boat CNC kit that is riveted together. There are lots of plans for a welded aluminum boat but none for a riveted boat.

Why rivets?

Well, 1) aircraft are riveted because welding distorts the metal and removes the heat treat, causing fatigue cracking behind the welded area. 2) I can't weld. 3) I want substitute carbon fiber honeycomb for aluminum sheet.

I know that using carbon fiber will cost 5x as much as aluminum but it is half the weight and 5x stronger. The cost of making a really good mold, laying up the carbon fiber and vacuum bagging it all is just too way high for one boat. A good CNC machine can cut carbon fiber just like aluminum and steel.

I found some boat plans for a riveted boat on *************** but no way to see what kind of boat. I'm looking to build a trailerable hardtop cruiser and light weight is very important to me.

I'm guessing that making the keel rib and lots of brackets would be challenging.

Any tips and links would be greatly appreciated.

Thanks.


P.S. I'd love a step hull but that might be out of the question.

Im not totally distressed at the idea, because on occasion we move forward a little in reviewing older methods.
But I have some things for you to consider

I dont think the aircraft / boat analogy holds up, they are quite different structures for different mediums
Places of discovery to go to are flying boats, amphibious aircraft, seaplanes, ground effect machines.
I hope your Russian is good, but Im assuming nyet

Supposing that doesnt deter you, if you havent noticed aircraft have been moving to adhesives for some time
and boats too have been using adhesives in the aluminium sphere
Since a riveted aluminium hull will need sealants anyway, why not shift the idea to adhesives?

Удачи и наилучшие пожелания

 

[Angélique]

Hi Zulu,

Do these adhesives call for a controlled environment during application and curing ?

If so, what are the requirements ?

 

[Zulu40]

PC 11, but its an old adhesive by now
or West Systems G-Flex, but quite expensive

I would think the surface prep would need to be meticulous clean and properly mating surfaces
it possibly involves acid etching, but check with West Systems, they can inform you

but you would want similar surface prep (sans the clean) for riveting anyway
and it is all done by hand