Would this appeal to you....?

[Lewisboats]

Scenario: You pull in with your pickup and travel trailer in to this great camping site by a rather large lake (say 3 mi by 7 mi). It is early evening so you do up supper and take in the sun set then hit the rack because you are tired and you want to get up early. The next morning's crack of dawn sees you heading out to get some kind of swimming thing for breakfast. The best place is at the mouth of a creek about 5 miles away but you are buzzing along at about 20 kts in your 12 footer an get there pretty quick. (OK so where did the boat come from :confused: :confused: ???...I'll get to that later). After an hour or so of fishing you have a nice stringer of edibles and you head back. After breakfast comes a well earned siesta, then some hard core lounging and lunch is served. An hour or so after lunch a case of restless hits and you say to your self..."Self...it is time for a bit of a sail". So...with about 20 minutes of rigging up the boat (where the heck are these boats coming from!!!) its off for a couple of hours peaceful sailing (with a few liquid appetite enhancers along for the ride). Well...seeing as you forgot your hat and your balding pate is this guy's color :mad: ...time for a little aloe and supper. Well now...after soothing the troubled brow and appeasing the belly beast you feel a bit guilty and vow to work off a couple hundred of those nasty calories before calling it a night. It is still early evening, so with hat firmly on throbbing scalp you set off for a theraputic row along the shoreline for a couple of miles...(what...another vessel...HOW???)


Let me tell you about Sybil...(not the movie...but the multiple personalities is right). Sybil is a Two piece boat that comes in three pieces. NO NO NO...please don't shake your head and close this post just yet. Sybil is the result of taking the idea: What if you were to design the forward half of a boat so that it would do pretty good as a sailboat and as a planning motorboat (after all, you aren't gonna use it in big waves and once on plane it is pretty much out of the way). What you are left with is two different forms needed for the after part...a planning form for...um...Planning and a decent displacement form for rowing and sailing. {See where I'm headed here???}

WHAT if you cut the boat in half (not quite but close...within 3 inches or so) and had a different after end for your chosen mode of propulsion and mood at the time. HOW about if the whole thing pretty much nested together and fit into a shortbed pickup? And WHAT if the whole kit and kaboodle came in at 180lbs or less (probably less)....


What would you opine?

Steve

PS pictures to follow (freeship hull of course) if anyone bites

[Dan St. Gean]

Interesting idea. Lots of take apart dingys out there. Shouldn't hurt to have a planing transom and a sailing transom for variety if the design is right. Nesting makes the design doable. 2 cents.

Dan

[Lewisboats]

Ahhh the money starts rolling in....:D

Steve

[mcdenny]

Sounds pretty clever. Could the front stay attached to the back pounding over waves at 20 mph?

[Spokaloo]

McD you beat me to it. It may preclude the joint being effective unless you can make it strong enough to be abused. 99% of the people I know with small boats bearing motors take them out and beat the holy hell out of them. As long as you can effectively sustain that level of stress, the idea behind a convertible boat is pretty cool.

E

[outofthenorm]

Clever way around the compromises. We'll assume that the mast breaks down into little chunks and there's a way to shut off the CB slot from underneath - unless the slot is somehow in the back half? I think the above posts are correct - strength in the powerboat mode is going to be the biggest challenge. Cool idea. - Norm

[Cuyahoga Chuck]

When you start talking about a boat that planes you are in a different world. The bottom loading is much greater. Want to smack some waves (even small ones) at speed in a boat that has two bolt-together joints in it? Not me.
Take-apart boats have been around along time and have never been seen as a hot set-up. Even ones that are single purpose.

[Nicholas Scheuer]

Then add a smaller stern section for rowing and sailing?

If all one peice, the hull would not have a "joint" to worry about under power, if that is really a concern. Remember, Phil Bolger has been offering his Folding Schooner plans for a number of years, and he would have withdrawn them from the market if the joint had proven weak.

All in all, this soiunds like a worthwhile proposal. "Multiple use" is certainly a good thing in the camping environment.

Moby Nick

[Spokaloo]

Or, take some different ideas and roll with them.

What if you build one bow section with two longitudinal channels. The sailing stern would bolt up and use one of the channels as bracing for the dagger. In the planing stern, you would have the aft portion, plus two long prongs (if you will) which are longitudinal stiffeners. Ideally this would create the strength needed to hold the two halves. When transporting, have the sailing stern nest in the power stern, and transport with the power stern on so there are no length issues.

Its merely an idea, a springboard from which to extrapolate ideas. Oh, and if you use it, free plans are always nice....

E

[Thorne]

Not to be a downer here, but for the effort involved, surely it would be easier to bring two boats -- one for motoring and sailing, the other a much lighter (ultralight?) boat for rowing.

You could combine the boats the other way -- rowing and sailing -- but it would need to be much heavier with sailing rig, center/daggerboard case, etc.

You don't mention how this guy gets the boat parts down to the water, including the outboard and other parts. And how does he assemble it -- on the beach, on the boatramp, or ? A pretty amazing boat if it can be disassembled, reassembled, and rigged for sail in 20 minutes!

I'm afraid that the whole concept would be way too much trouble and far too complex to build and operate. Most folks that row won't bother with outboards, and vice versa, so why not just build a take-apart boat that either rows and sails, or sails and motors?

[Woxbox]

Or you could drop a sail rig into a Grumman sportboat or similar. A fat canoe with a square transom is a mighty versatile boat, and it comes all in one piece.
Multi-tools in general have a poor history.
Like this:
http://www.photos.org.au/userimages/user756_1149564364.jpg
Or the wrench that doubles as a hammer, or the radio that's also a flashlight and can jump start your car, too! You only have to try these things once or twice to quickly go back to the single purpose-built items, whether vehice, tool or boat.
It's not that you can't make such a boat-idea work, I'm sure you can. It's more a question of whether or not it can ever really satisfy at any of the jobs it's put to.
Anybody ever reverse a reversible jacket?

[Spokaloo]

I think one thing is being lost in all your posts. This forum has a tendency to quell conceptual design ideas such as Steve's. While it may not be ideal, and it may already exist under the sun, its the flow of ideas and the manipulation of norms that create new and interesting designs.

This concept starts with combining two different mediums (much like a Pumper/Ladder or Quint in my world, which can either be a great rig or a complete abortion). If it doesn't work, but a small glimmer of an idea comes out of the design process, say a way to attach sectioned boats more stably than before, then it was well worth the design exercise.

We so frequently rest on the "contemporary" designs such as the dory, which is ages old, but immediately stomp on ideas like this, regardless of the merit. It woluld be far more interesting to throw different concepts out there and make Steve work his butt off adding this, deleting that, and just having fun with it to see what happens.

Is that so wrong?

E

[Thorne]

Yes.


;0 )

[Woxbox]

Absolutely nothing wrong at all. I've spent countless hours thinking, sketching out ideas, making a model once or twice, looking for better boat ideas. I can't say I've come up with any. What I have done as a result, however, is come to appreciate why boats are built the way they are, and why they look and work as they do.
I've wondered about a trimaran that not only contracts athwartships, but also has bows that fold up and back to reduce the size for trailering. Or a folding schooner type expanded to a boat with a livable cabin over which the end or ends fold. Or all kinds of proas, there must be a cruising proa design possible that's got real living space in it.
I think anyone who posts their ideas here is ready for some good-natured ribbing. What I was trying to get at is the difference between what one CAN do in design and construction, and one will really use day-to-day. Ever seen this amphibious motorhome? Lots of engineering and thought in it, but, huh?
http://www.hydraspyder.com/Pictures1%20137web.jpg
Now building a ply boat in sections is no waste of money. The pleasure is as much in the making, as we all know. So I say charge ahead to anyone who wants to give such a plan a shot, and to hell with the naysayers. Myself included.

[Thorne]

Yeah, the heck with me too!


(Hey...wait a minute...)

Seriously, I think that the "all boats to all men" concept is just too complex and demands too much effort for a relatively small gain.

Consider the example posted at the start of this thread. Would someone enjoying a relaxed fishing trip really spend what I'll estimate to be at least a half hour reassembling a boat for a trip of 5 miles -- when the reassembly might only gain him 20 minutes of time over motoring with the less-efficient sailboat hull shape?? Is this same person gonna spend another half hour and drag hulls and outboards up and down the beach so he can have a quiet row in a more efficient hull shape??

Don't think so....

Now if you had a "nano-boat" of high-tech material that could change shape on command, that would be the correct medium for this particular message. (apologies to Marshall McLuhan)

[Lewisboats]

OK...Quick pic to show what the hull(s) would resemble. Still playing with flare and forefoot a bit. Draft is .600 ft or 7.2", disp is 585 lbs for the Row/Sail at shown level draft and disp is 815 lbs for the planning version at shown level draft. Quite a bit I know, especially as the boats shouldn't weigh over 120 lbs per configuration. Raising the draft to 4.5" gives 360 lbs disp for the motor version but only 220 lbs for the Row/sail version. Picking a disp of 400 lbs with motor and fuel for the motor version gives a level draft of 4 3/4" A disp of 310 lbs for the rowing version (without leeboard, rudder, mast, sail and running rigging but with oars) gives a draft of 5 1/4" so figure 5 1/2" for version in sailing trim of about 330-340 lbs. Motor to sail configuration would take 20 min to 1/2 hour but sail to row should only be a 5 minute deal. Presumably the sail is already down, so fold up the boom and spar (balanced Lug), pull the mast, unclamp the leeboard and lift the rudder out. Drop the oarlocks in, grab the oars and launch. Of course...if you can't get a campsite beside the water it will take more time to get things stowed than the Ideal. Besides...you wouldn't necessarily be alone...who's doin' all the cookin'? (No prejudice involved...I'm a better cook than my wife ever was!)

Edited to add...mast and spars should run under 10 ft each so each could break down into halves if necessary. Looking at between 50 and 60 sq ft for the sail area, with the mast fairly well forward ala Cat rig.

Steve

http://angelfire.com/ego/lewisboatworks/Stuff/Sybil.JPG

[Lewisboats]

To continue. Looking at connectivity issues I think that 3/4" ply bulkheads (one on each half) with 2x2 cleats glued and screwed then filleted to the inside hulls, with a layer of glass on the mating faces would be pretty strong...but to be sure, the seat slides down full width and depth over the bulkheads to mate with the 2x material at both sides and bottom then the whole shebang is thru bolted with (5) 3/4" dia. bolts, clamping the seats and the bulkheads together. See diagram. Glued to the mating face of each bulkhead, around each of the bolt holes is a rubber gasket to seal the hole...even though it is at 9"above the chine and well above the waterline. The seat top is at 12" above the chine.
As far as bottom rigidity is concerned, two 1x2s filleted edge on to the bottom on each side of the middle seam (which is rigid enough by itself) comes to an on center distance of 7", surely enough to keep the bottom from flexing. This is for the Motor version of the Aft section only...the front gets one stringer on the bottom per side as does the Row/Sail after section. If you go with 3/4" for each BH and 1/2" for the Cheeks you are looking at a total thickness of 2 1/2" for the joint area, held together with 5 huge bolts AND the seat top...Gotta be strong enough!

Steve
Note on the diagram: Red is the seat with the cheeks that slide over the bulkheads, Black is the bulkheads and 2x2 cleats and blue is of course...one of the bolts.

http://angelfire.com/ego/lewisboatworks/Stuff/BoteBolt.JPG
http://angelfire.com/ego/lewisboatworks/Stuff/BSCB.JPG
Edited to add: Oops...made a mistake drawing the bolt...it should be from red cheek to red cheek (plus metal plates for load distribution). I drew it to the width of the cleats instead.

[Woxbox]

OK, I'll continue to be the naysayer. I had a 25-foot trimaran that I could singlehandedly put together and get in the water in 90 minutes. That included raising and securing the amas, (six connectives on each side) setting up the rig, bending on the sails, getting the outboard ready to start, getting the docking lines and fenders in place, and actually putting the boat in the water and then parking the car and trailer. And probably other stuff I've forgotten.
Nuts and bolts in a job like this are to be avoided. They won't line up right, you'll have to fuss with them endlessly, and you need a tool. The trick with the tri was to use heavy pins secured by hitch pins wherever possible, and when nuts and bolts were required, to have the nuts welded to plates that were mounted to slide around a bit, so that slight dimensional changes in the wood with the seasons weren't a problem. I did need tools - actually one plastic mallet and one socket wrench did the entire job - but most steps were accomplished bare handed.

I think what you want is an adjustible locking mechanism that doesn't require holes in the boat, and that can be attached both high and low on the sides of the hull. I can see that you've put a lot of thought into the design, but connecting the hulls with bolts along a straight line is a bit like adding the perforations between two pieces of paper towel. The stress loads along that line will be huge, and sooner or later it will start to flex, the wood fibers will weaken, and it's all downhill from there.

Think of the latch that holds a typical toolbox closed. How about fabricating four big beefy ones with an adjustment screw to set the tension? You could pull the two boat halves together - pins would line up the halves - then flip over the latches. You'd need a locking mechanism on them, of course, and the job could be done in minutes. With one at each chine and one at each gunnel you'd be spreading out the stress as much as possible.