Help with Design Modifications

Cardboardking, consider building a PDRacer as your spring break project. http://www.pdracer.com/ It's possible to build one in a week and you won't find a lower cost boat to build. (I've seen it done in a day and a half.) Then take it sailing on local lakes or other protected water. The quickest way to learn the basics of sailing is in a small boat.

With experience building a boat, even a very simple boat, and some sailing you will be much better prepared to decide on what your next project will be.

 

"Set Of Requirements...?" I know, total newbie question...

I had already looked around the Internet for information about the sailing trip to Catalina. What I found was several different postings of the same article indicating that you shouldn't attempt the trip in anything smaller than a 22-25 ft. boat. Being the congenital non-conformist that I am, I read that as, "Okay, so I need at least an 18-20 ft. boat." Actually, that interpretation was partially spawned by the apparently large number of 18-20 ft. boats in existence. I figured, if 18-20 ft. boats are so common, somebody must be sailing to Catalina in them.

Check. I love the Manhattan/Redondo/Hermosa Beach area, so I'm thinking that Marina Sailing's Redondo Beach facility should be my school of choice. $700 to get basic certification. If I can't get started before then on weekends, I'll definitely enroll as soon as my summer vacation starts.

When I was out to dinner with a friend a while back, my fortune cookie from the Chinese place where we were eating said "You never hesitate to tackle the most difficult problems." She knows me well and made me promise to keep it. To this day, it sits on the shelf in my bedroom where I can see it every morning as I prepare to take on the day's challenges.

I like your suggestion about crewing on somebody else's boat. That idea had already occurred to me after reading in Sail magazine about volunteer crew members tagging along on the Atlantic Rally for Cruisers. I do intend to take the classes at an ASA approved school, but I am looking forward to getting more time on the water, and helping other people get in their time by supplementing their crew.

I love to learn new things, and I am excited about becoming a qualified sailor. I realize that I have a lot to learn, but that's part of the fun.

Okay, cool! I could get this in the water in no time. I already have most of the materials necessary, and it's a lot simpler even than the other one I was starting on. I'll go back and finish the other one when I have more boat-building/sailing experience. I'll cut my teeth on the PD Racer.

Thanks for the suggestion!

 

I'd build another boat besides the PDR. The PDR (sorry Mik) is a concrete mixing tub, with a sail stuck on it. You can learn the basics in one, but will very quickly find it's way too slow and way too short to be useful for much else.

Since you're into the molded hull method (why?) you might consider a little molded sailor, say 14' or less. These aren't as easy to build as a concrete mixing tube, but you'll find all about the construction method, which is a primary goal, as well as learning to sail.

SOR is Statement Of Requirements, which is essentially a list of the goals, the design should address as best as practical, given the prioritization instilled. This wish list will continuously evolve, as you gain experience, but eventually at some point, you'll have sufficient enough of an idea of what you actually need, rather then what you think you need. For fun, make the SOR now, then put in a drawer. Pull it out after consider sailing time and see where you stand on some of it. You'll find some of our attitudes about some of your "requirements" become justified.

As for a quick build, just to get you out there, there's no such thing. You can build a PDR's hull pretty quickly, but you'll have spars, appendages, sails, rigging, etc., to do too, so not as fast as it might appear. I'd recommend something bigger, possibly also flat bottomed to make life easier, but with sufficient sailing ability to continue to challenge you, as your skills build. There are lots of these 12' - m14' sailor plans around. I even have several.

 

CKing, love your enthusiasm. Crewing and building something more boatlike than the PDR are very good advice.
You are gonna have fun.

 

You see CardboardKing, I think you can see now that no one here had any intention to dissuade or discourage you but only to advise and educate a bit. The forum is a great resource.



BTW, your screen-name suggests that you do projects with cardboard. Are you like that gentlemen that developed that bicycle using only cardboard? He was told by several that it would never work.

 

The PD Racer does have a certain resemblance to a mixing tub, and any 8 foot long boat will not be fast. However building a PD Racer doesn't preclude building another boat to get more experience. Everybody has to start somewhere. Cardboardking can build a PD Racer and start sailing it in the time it will take him to decide which "little molded sailor, say 14' or less" to build next.

 

I spent most of the morning looking around the PD Racer web site. I realize that it isn't the end-all-be-all of wind-powered watercraft, but I just needed something to get me out on the water. I started building it after lunch, and already my sides are almost done. Tomorrow, I'll finish cutting out the sides and also the transom and bow. Probably start assembling it too. Then, over the weekend I'll finish assembling it, and then do the epoxy next weekend.

As I've said before, I am a little worried about the sail aspect. Is it possible to just buy a mast and sail off-the-shelf?

I really like this other dinghy that I have the plans for. It's much more what I want in terms of a small, homebuilt sailboat. It's ten-feet long, calls for a 1/4" thick, iron centerboard and has what to me feels like a gigantic sail for such a small boat. I suspect I'll be very happy with it once I get it built.

I am going to finish the PD Racer first, though. I can use what I learn from that to get better results with the other boat.

There's nothing I can't do with cardboard. I actually got that nickname from the school where I teach. The projects I've done with cardboard for our homecoming floats over the years have set a new standard at our school. A few years ago, when the theme was "Under the Sea," my students and I built this shipwreck. It was then, standing in the hull of my almost full-scale shipwreck, that I realized I could probably build a real boat out of cardboard.

My cardboard PD Racer is under construction. For the sides I'm using a double-thick box that I got from school. I've cut three of the side pieces out of it, and I'll be doing a fourth tomorrow. Then, I'm going to laminate two of the pieces together using Elmer's glue to create a four-layer thick sheet of corrugated cardboard. The four pieces I've cut out will form the two sides. They'll each be about 3/4" thick when they're done.

For the bow I'll probably do six layers. For the transom I can probably get away with four. I'll glue it all together, with good strong bracing at all of the joints. Then, I'll coat it with a layer or two of actual papier mache, and then I'll seal that with fiberglass and epoxy.

I'll be posting pictures and updates as I go.

 

Good for you and your students. Fun stuff.

I think you will become one of this forum's future success stories.


Now, you really remind do me of this gentleman:

 

Here is a clip of a guy that built a decent looking cardboard kayak. It inspired me to try it too, and though it worked sort-of, the six layers of latex paint allowed water to slowly soften the cardboard so it eventually became soggy.

I would not advise using cardboard if you intend to keep it, even fiberglass will eventrually allow water to penetrate and fail the structure. It would be a waste of fiberglass, use CDX plywood, it does not cost much and will hold up longer. AC plywood is even better but costs more.

http://www.youtube.com/watch?v=N3ttAHF950E

 

I'm personally not interested in any nautical cardboard project but are you saying that it's not possible to seal the bulk material first and then apply the fiberglass?

 

I do not know, might be possible. But wood and synthetic foam does not lose its strength if there should be seepage through the outer layers. It seems to me that eventually moistture will pentrait what ever means use to seal it, and the cardboard looses its strength and turns to mush.

The cardboard boats I built worked, but they just could not stay in the water for more than about 45 or 50 min at a time. The latex allowed moisture through to the cardboard, I would have thought that it would have sealed it out, but apparently it is not a water proof. The two I built were not glassed, but just a light wood frame with cardboard skin, with six coats of paint on both sides. One was a kayak type hull, the other was an 8' pram type dingy.

 

There was some long discussion many years ago (okay decades) about the use of cardboard in composite panels. The conclusions were it could be employed in honey comb like structures with great success, though you do have to keep after damage. Cardboard (depending on type) can become completely saturated with resin, which will make it immune to saturation, though type and application does play a big role. The major problems, beside moisture degradation is weight and the amount of goo it takes to seal it up. Mixed with other materials it can have some benefit. For example I did test panels with "chip board" style of cardboard (the stuff on the back of note pads). It was applied in an X pattern (3/4" squares), covered with a single sided corrugated cardboard, of course all buttered with epoxy and fabric sheathings. Not as light as foam, but stronger and a whole bunch cheaper.

 

Interesting post. I've been wondering about the various techniques using "goo".

I have not yet found it, but is there already a thread here summarizing the "goo" vs material ratio or percentage of all the different composite techniques? In the examples you referenced, both cardboard and chip-board require quite a bit of "goo", so besides the ratio, it would also be great to know the resulting densities. An example that I know of is that the current achieved composite mix of the latest Gunboats is 65% carbon fiber with the remaining 35% as "goo". I do not know the absolute density.

Thinking about it more, a great reference would be a table of percentage mix, absolute densities, cost and resulting strength of all the composites such as fiberglass, plastic, balsa core, marine plywood, honeycombs, mixtures of two or more, etc. This would allow a comparison evaluation of the cost/benefit with metal and traditional wood construction.

 

Most of the common reinforcement materials (cloth, foam, wood, fillers, etc.) have physical properties listed online with various resin/fiber ratios under different application methods (hand laminate, bagged, infusion, etc.). Generally, you want as high a fiber ratio as you can get with high modulus materials. Cardboard, used like this, would be a core or form, for the laminate, which fall into a different set of guidelines. Cardboard wouldn't be the structural element, the laminate would be, so just well sealed and bonded are the goals of the goo, in regard to the cardboard. From a price point, cardboard has much to promote it, but from a weight and load bearing stand point, it's less desirable, in spite of it's cost.

The interior doors in your home are likely cardboard cored, with plastic or plywood skins bonded to it. There are also many other products that employ this type of construction. This is why you can buy a new real wood, light weight, closet door for your bedroom for under 50 bucks at a big box store. The 1/8" plywood skins cost less than $5 each, the cardboard pennies and the glue, maybe a buck, with some particle board or cheap pine around the edges. They probably make 300% on the product.

 

I've posted a few pictures of my "work in progress" in the member galleries. It's working title is "CBD Racer," but that probably won't be it's actual name, because I don't think I'll ever actually race it. The pictures just need to get approved, and then they'll be up.

My plan is to build all of the structure internally, and then build the air boxes around it, so that all I'll have to seal is mostly flat surfaces and some corners. I also intend to layer the outside of the laminated corrugated sheets with some of the thinner stuff, just as PAR mentioned a post-or-two ago. I have no doubt that the resulting structure will be sufficiently strong and waterproof enough for my first little lake sailer.

I've been building things with cardboard and paper since I was a kid. I even built some working Transformers toys out of construction paper. But, it wasn't until today that I realized how strong paper can actually be.

I was unloading my car of all of the cardboard boat construction materials that I've accumulated over the past few days, and in the mix were these kind of peanut shaped, hollow bars of something that feels like steel but looks like cardboard. Not having any idea what I would do with them, but being impressed with their sturdiness, I threw them in with the rest of the stuff I was picking up. When I was unloading the car today, I took a closer look at them and realized that they are just paper. They are just tightly bound, custom-shaped rolls of paper. And yet they give the impression that they're made of metal. At that point, I figured, "Yeah, I can definitely make a boat out of paper and cardboard."