I usually build one-off all fiberglass. I make a wooden plug with cheap plywood, cover it with visqueen, attach 3/4" or 1" Plascore to the plug and then fiberglass it. Pop it off the male mold, straighten things up and then fiberglass the inside. To build that way I start with boat ribs like everyone else. But in the one-off fiberglass case they are temporary ribs. With cheap plywood fastened to the ribs to make a form or plug.
But I might revert to former ways. I've been working on an all-wood idea I don't think anybody else has tried yet. Perhaps they have but I certainly haven't heard about it yet. This came to me in the middle of the night when I had a fever and the flu. Eyes wide open at 3am and I haven't been able to sink this idea since. Not yet anyway. Perhaps someone here can shoot holes in it.
Woody Hindman could have built this way but he didn't. I'd start with temporary ribs, as I do for a male fiberglass plug. There would be an angled chine strip at the bottom edge of the side panels, to provide a fastening place for the bottom panel. 1/4" plywood sides. 1/2" plywood bottom, fastened to the chine strip. No nails. This wood all be done with Torx screws, so it could all be taken apart and re-assembled at any time.
Turn it over. Add another angled strip at the top edge of the side panel similar to the chine strip. Now fasten a "ledge top gunwale" similar to the following. The photo below is a wood/fiberglass boat with a ledge top gunwale. I'm thinking much the same thing but the ledge would be wider and there would be no fiberglass. Mike Edmondson in Boise made this boat (a Montana Riverboats Honky Dory).
Along the inside surface of the 1/4" side panels at each regularly spaced layout spot, where a rib would have been placed in a traditional framed boat you would place a 3/8" inch by 2" plywood stiffener stretching from chine to ledge top gunwale, just to stiffen things up a bit and to provide fastening for storage lockers and rower's and passenger's seat rails.
No glue. No epoxy. Everything is screwed together with Torx screws and Butyl Roofer's caulk which seals well but has no bonding strength. That way any part of the boat can easily be removed and replaced, without hassle. No fiberglass paint or varnish. The whole boat, inside and out, would be oiled with AJ's world famous concoction.
Now you have an all plywood boat that can be taken apart like an erector set. That has no ribs. That boat could have been made 100 years ago. Well. They didn't have the Butyl caulk then. But everything else they did.
I'm working on a 17' extra extra wide decked white water boat now. All fiberglass. I told myself that would be my last boat. I'm closing in on 70 and I don't want any new projects. Just a little maintenance here and there but no new boats anymore. But I might have to give up on that. And build one last woody. We'll see.
....now that I think about it you could build an all wood fully decked white water boat that way too, where the deck bolts down onto a gasket. I built one decked white water boat that way with fiberglass--with a removable bolt-down deck. And it was a big success. Most wooden white water boats (Briggs etc) have permanently attached decks with way too many compartments underneath (for me anyway). A bolt down deck can be almost free floating, with only one or two partition walls to keep it from pooching down as you walk around on top. That could be made to work with an all wooden bolt down deck. I'm sure of it.
Anyway it's an all woody idea so I thought it made sense to share it here. And see what holes others can bore into this idea.
Hey Sandy, I think that is totally doable. There was a guy at one of the first boat shows that had a similar concept. It was more traditional in that it was permanently built but the side ribs were not attached to the bottom ribs (there actually might not have been any bottom ribs). It was a pretty flexible boat with the traditional gunnels but I think your "ledge" would fix that. I would think you would only need the side ribs where you would mount seats or the fly deck. I have seen traditional boats with some of the ribs left out with no problems.
Can you ever really be done building boats?
So what would be the advantages of this boat? Why build it?
All the parts are easily removed. Wear out a bottom panel? Unscrew it and replace it.
The only good rib is a barbequed one. Ribs make boats fragile. If you smack a rock mid-way between two ribs all is usually well because the plywood can bend there. But if you smack a rock right next to a rib there is no give. So the plywood breaks.
The ideal boat is stiff enough not to flex during normal use. But still a boat that will flex a lot when severely impacted. Rigid areas break. Bendable areas bend. Ribs in a boat, moreover, are always in the way. You trip over them. Water doesn't drain properly. Leaves bugs sand and detritus collect at rib joints.
I am going to Chicago in May. To see my daughter's belated graduation. I'll go to a good rib joint there. But in a boat there is no such thing.
Mike: You're right. Boat building is never done!
In 1968, my Dad and his Dad, built two drift boats in Seattle. Each were about 16x48 on a jig. I am not sure where they got the plans or ideas, if any. They were hardcore fisherman at that time and just needed a boat to go chase steelhead. My Dad guided in one of those boats for a full 20 years and I personally learned to row in it as well as a kid on the Solduc, Calawah, Bogechiel, Hoh river systems on the Olympic Peninsula.
These boats only had 4 small side ribs for mounting the oarsman and passenger seat framing (Note the unique removable passenger seats in the below photo) and had no floor ribs. It had an inner chine and no outer batten (until later), only a fiberglass bottom that wrapped up the side about 5 inches. A 2 foot wide longitudinal 1/2 inch piece of plywood was added to the 3/8 inch floor to reduce flex on the inside of the boat. This boat lived through its Northwest river experience (not to mention my learning curve) and then got two water tight compartments added to it, front and back to go out in the ocean so we could fish for rockfish (and so my Dad could go on his La Push to Vancouver Island rowing trek) in about 1983.
The boat now lives under a tarp in my Dad's front yard, still in river worthy condition 48 years later. My Dad and I always talk about river boats with no ribs and how they do great on rocky rivers. I think you are onto something.
Cheers, Robb Grubb
I like it. That large rear compartment would help keep the hull shape stable too. Nifty boat.
Here's what I like about this idea: it's fast and easy. I've been building one-off all fiberglass boats since the mid-1980s. I'm done with it. I have no regrets but it's a lot of messy sticky work. And I'm over it.
What I want most is a fast way to make prototype hulls, so I can better see what works and what doesn't. I thought about making a male mold, covering that with thin 4mil Visqueen and then Plascore over top of that. Quickly tape the seams with 6" fiberglass tape and then take it to the LineX dealer to have it sprayed inside and out. But they wanted $600 for that. Plus an additional $150 to change from black to a custom LineX color. That's a bit too much dollars for quick prototypes. For me.
The all plywood no glue lots of Torx screws build, with roofer's caulk at the seams, and covered with oil instead of paint, would be a two day build after the parts were cut out. I'd still use a ledge top gunwale rather than wood strip. That really makes a stiff boat.
Keith Steele was rumored to be able to nail out a boat in a single day, when working with a crew and a pile of pre-cut parts. This method wood be faster yet. It would also lose a lot of weight by throwing out the ribs. You could gain some of that weight back by using 3/8" plywood on the sides instead of 1/4" inch. 3/8" plywood sides with a 1/2" ledge top gunwale would be as stiff as it gets. And yet the sides and bottom would still flex some, when and if they smashed a big rock in big water.
I'm going to finish up my last all-fiberglass boat and never look back. I've got a woody now. A woody with no ribs. No glue. No fiberglass. Screws caulk and plywood. Start to finish.
I'm excited about this idea. I'm not so sure how well it wood work for a fully decked white water boat. All-fiberglass might still be best for that. But for a simple open boat for day-trip fishing I think the all plywood ribless boat is a hot idea.
I have also been thinking along these lines. Its a constant debate in my head between needed structure and useless structure. How much can you get rid of and still be left with a strong hull?
I think the critical point in your idea is the chine log. Nailing down its dimensions and species will be critical to the overall durability of the design. The chine log ends up distributing and absorbing wave and impact energy on the hull during use.
My concern a boat built in this manner will require each part to hold the hull in tension. If for example you need to replace the bottom and remove it, the relieved tension will cause the hull to distort. One might be able to over come this tendency by using seats and deck structure as spreaders. This movement gets even weirder when I think about removing and repairing a side panel.
I do love the idea though that (like Egyptian boats) the boat could be disassembled, packed, transported, and then reassembled for use. But I am unsure that a boat built using this method will be more easily repairable than a boat built using traditional (non-epoxy) methods.
I do think that for prototyping this would be a quick way to inexpensively (in time and cash) whip out a hull. I can't wait to see more posts about it!
RE> "If for example you need to replace the bottom and remove it, the relieved tension will cause the hull to distort"
Yes and no. I think the ledge top gunwale is critical to this design. To remove the bottom you could also clamp some 2x4s side to side, ledge top gunwale to ledge top gunwale in 2 or 3 places. Maybe throw in one or two side to side braces close to the chine. Then flip the boat over and then remove the bottom. Now the shape of the boat cannot change.
I made several molded boats back in the 80s with 1/2" inch end grain balsa wood as a fiberglass core. That didn't turn out well. The fiberglass cracked here and there along the chine and then the balsa soaked up moisture like a sponge. So I braced my boat up as above and then cut the bottom off with a water feed concrete saw. And replaced it with plywood/fiberglass. Today I would have replaced it with Plascore.
3/8" plywood for the sides... what about the bottom?
What size Torx screws?
1/4" or perhaps 3/8" for the sides. I'm thinking 3/8"
1/2" plywood for the bottom and for the ledge top gunwale.
Torx screws would be driving through plywood into an angled chine strip, which is typically/traditionally made from 3/4" stock. So for 3/8" plywood on top of 3/4" strip stock you'd want a screw 1/8" less. Or 1" inch long.
But keep in mind this is a theoretical discussion. I have designed and built many boats. I've had many great successes and some spectacular failures. Actually doing it takes time moxey and most of all obsessive compulsive determination. I will build one of these--I'm sure of that. But I have a big all fiberglass project to finish up first.
This boat would rely on the strength of the mechanical screw bonding, of plywood to chine strip. So it might be worth while to use something like 1" white oak or ash instead of 3/4" fir. But to bend that would get ugly. You'd have to heat it up. Or even steam it.
The best thing would be to make a chine strip in place laminated and glued together from two thinner strips. Then you wouldn't need steaming. That takes some moxey away from the "fast and easy" goal. But it's not that hard. I've made gunwales laminated in place, on a form, gluing and clamping 1/4" thick strips. Two 1/2" strips of white oak would make a stour 1" inch thick chine strip. And also a similar strip at the top of the side panel, to help join the side panel to the ledge top gunwale.
I agree that the hull can be stabilized through bracing and then worked on without any concern for movement.
Regardless the idea of a hull held together with mechanical fasteners for ease of repair is a critical design concept that if used properly can lend itself to easier hull upkeep. Sometimes we just need to put modern chemistry aside, grab the Dolphinite, screws, and have at it. If you start to build things with the thought that you or someone else will need to take it apart someday the way it is built might just change for the better.
What about using a nice looking plywood like Meranti? Is it tough enough?
Meranti is what I assumed. Cheap enough and good enough. I started out building with AA Marine Grade Fir way back when. Right after Lake Missoula let go at the end of the last ice age.
But as we all know they changed the specifications for marine fir and it isn't much good anymore. I buy "Marine Grade Fir" at my local lumber yard (I have to order it in for $48 bucks a sheet). But it isn't much good for anything but forms and temporary plugs. It isn't good enough to actually build a boat with.
I'm not current on plywood technology. I stopped using it years ago. And now I'm getting interested in using it again. I'll be interested to hear what others have to say.