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Tiny, folding dinghy?


Frank Hagan

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I now have a "big boat", a 19' Potter, that is really not much longer than my Weekender. But the Potter will take me to the off-shore islands, and get me in close to shore. But not close enough to wade in always. So I need a dinghy.

We have a "not-quite-a-toy" inflatable, and it will do. I also plan on building a 10' B&B Yachts Spindrift, although I think its too big for a Potter 19 or Weekender to tow around!

It seems to me we should have a folding boat. I've seen the Portaboat, with 4 long panels and a drop in transom, made entirely of polyethylene. But the 10' boat is still 10' long ... just flat. But I'm wondering about a boat that will fold up to a 5' long bundle, home-made, and very light. Set up should be easy, and it should row well.

Skin on frame? Rigid panels that interlock? Any other ideas?

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I actually have the plans for a B&B Spindrift 10' (although its not the nesting plans ... I'll bet Graham would tell me how to cut it in half!)

But I'm thinking of the folding boats that were popular in the 40's and 50's. They used ply panels and waterproof canvas "hinges", and folded flat into about 1 1/2" of space. Better materials today, although its hard to beat waterproof canvas for the ability to glue it in place and its durability.

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There's a pretty good design called "Handy Andy" at http://www.svensons.com/boat/, and then someone directed me to plans at http://www.microcruising.com/ding1.htm for a folding dinghy. I ordered the CD from Svenson's, and its on its way. But the MicroCruising dinghy looks pretty promising too.

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I had looked at that first link a few days ago, then again when you provided it. Many of those boats I have the books for, but a good site nevertheless. I cannot seem to get the pictures to enlarge enough to read without getting very blurry. If you had not told me it was the Handy Andy I would not have figured out which one.

The Micro Folding Dinghy does not look very stable to me. If you build one, Frank, please let me know?

Have you checked out any of the Potter sites yet? Here are a few.

http://groups.yahoo.com/group/WWPotter

http://www.trailersailor.com/forums/potter/

http://potter-yachters.org./

http://ourworld-top.cs.com/skipperbill/index.htm

http://www.foad.org/%7Eelp

http://www.westwightpotter.com/links.htm

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The Micro Folding Dinghy is too small ... it needs a few inches in beam and length to be more stable. I like the tabs on the sides and bottom that lock the sides in place, though. I may incorporate something like that into a boat that combines the features of the Handy Andy and the Micro Folding Dinghy.

I've been looking at the folding kayaks, which use a collapsable frame inside a PVC "tube"; you collapse the frame and the kayak can be packed in bag. The Finnish military also had very sturdy folding boats they used to row onto Soviet shores, fold up and hide in the brush. The pictures I've seen look like they use a rubber or PVC membrane with wood sides riveted inside and outside for rigidity.

I'm thinking of borrowing on that concept to make a nesting, folding boat. By cutting the boat in half, and then folding it, I can make it small enough to fit under a quarter berth in my new boat. To assemble, pull out the two folded sections, unfold them, attach them at the seat, and launch.

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Frank, I built the 8' Catspaw as a tender for the Bluejacket but find that I am getting too feeble to muscle it up on top of the pilothouse and don't care for any complicated lifting system. I looked at the Portaboat and had the dealer set one up for me. It was not a simple task and he was working on a concrete driveway. On the boat it would be impossibly awkward. Besides, the thing is heavy.

I made up a few trial models of a folding plywood dinghy similar to the Micro but with solid ply transom inserts and a seat made to act as a central crossbrace. I just don't trust what looks like a pretty flimsy affair in the Micro. Also the size is just too small to be practical. One problem is getting it large enough for two adults and small and light enough to be easily assembled in the cockpit and lifted around. Placing the folded boat on top of the pilothouse would be no problem. I'm thinking about assembling on top of the pilothouse but refolding in the cockpit on the return trip.

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The nesting Catspaw would still be too big to store anywhere outside of the cabin of my 19' Potter. I have plans for it here somewhere but I can't seem to find them! I may have to see what Graham would charge for a "reprint" of the plans I had.

I'm thinking of combining one aspect of the nesting boats, two halves that bolt together, with folding panels. I would want one half of the boat to fit folded under each quarterberth. I could have a 10' dinghy that way, but as you noted, it would be tough to assemble in the cockpit! On a Potter 19, the cockpit is really the only workable room for something like that, and it has fairly high freeboard so launching could be a chore as well.

I'll do some models over the next few weeks, and maybe try to build a prototype using inexpensive materials.

I'd love to be able to get more info on the Finnish folding boats ... I saw a picture of one, and it looked pretty sturdy. the transom had pie-shaped pieces that looked like they opened up like a fan. It did look heavy, though, as you can imagine military equipment would be.

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  • 2 weeks later...

I'm working on a 10' long, 44" wide dinghy that will separate into two parts like a nesting dinghy, then fold up into two flat pieces about 26" wide by 5' long. The pieces would then be stored under the quarter bunks.

I figure the size is large enough to be more stable than a smaller folding dinghy. I have the design already for a folding dinghy that doesn't "nest", so I'll be adapting that.

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I now have a "big boat"' date=' a 19' Potter, . . . Any other ideas?[/quote']

Frank,

I also have a WWP-19 and have the same need for a tender. Over the next few months, I'm going to be building a nesting dinghy. I've ordered the plans for the Two-Paw 8. If I did my measuring correctly, this will fit into the cockpit of my Potter while trailing. I've got a couple of long-distance trips planned for next year and hope to take the dink with me, safely stowed in the cockpit.

Now, there will be no practical way to store the Two-Paw on board while sailing, so I'll always be towing it while under way. Storing it during towing was my biggest need.

John

WWP-19, "Beowulf", Edmond, OK

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Frank, I built the 8' Catspaw as a tender for the Bluejacket but find that I am getting too feeble to muscle it up on top of the pilothouse and don't care for any complicated lifting system.

How about some sort of Davit system (is that the right term?). A small 'L' shaped boom, of sorts, mounted on each transom corner. Attached to the gunales furthest away (on the tender) from the transom, then hoisted up and towards the transom. Two stand-offs at the bottom of the tender.

I have two stand-offs that were given to me. The Davits serve as crab pot hoisting points around here also! :)

I am also thinking ahead (dreaming ahead is more like it) about a tender for the BJ24 as well. :)

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For the Potter 19, you would need to put some weight up forward to have a davit system! The boat tends to be stern heavy anyway, especially when I am at the helm!

Seriously, I think a small boat like the Potter would have stability issues with a dinghy mounted on davits. The usual method is to tow the dinghy.

Capt Jake, I think the BJ24 could have a dinghy mounted on top of the cabin house; that's a "traditional" spot for a pilot house cruiser to have a dinghy stored.

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Frank, I have a small zodiac style inflatable that I no longer need. I think it is a 10' model. solid transom and solid floor panels.

Long haul just for a dinky boat though. :)

Capt Jake, I think the BJ24 could have a dinghy mounted on top of the cabin house; that's a "traditional" spot for a pilot house cruiser to have a dinghy stored.
Yup, just have to start modifying to get a small mast and boom in there, to raise it up there..........then a big screen TV, fridge.. ;) ;) :) LOL I need the shop addition in a bad way. :)
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We actually have a two person inflatable that is one step above a toy, and it will do until I figure something else out.

I did find the Two Paw (nesting Catspaw) plans I bought from Graham a while back ... before his forum was here on the board, in fact. John mentioned that he had already measured it for fitting in the cockpit as you trailer the boat, and then you tow it while sailing. So if my crazy nesting/folder doesn't work out, I can build the TwoPaw.

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Capt Jake' date=' I think the BJ24 could have a dinghy mounted on top of the cabin house; that's a "traditional" spot for a pilot house cruiser to have a dinghy stored.[/quote']

Frank,

That is what I intended to do when I built a Catspaw 8. I built it very light from 4mm ply and it came in at about 52lbs finished. Now, the problem is that even though the weight is light enough, it is much too large and awkward for an old fart like me to actually get the thing up there. The mast and boom arrangement would work but seemed too much bother on a boat that can readily take the beach anyway.

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Frank mentioned a finnish military folding boat - I've heard of a similar thing.

About 5 years ago I started work at a company that had employed several imported Russian engineers. One day I saw a co-worker, Aleksey, in the parking lot. He got very excited when he saw my fabric-on-frame kayak in the back of my truck. For the next half-hour I got a description in broken english with diagrams on the white board of the kayak he built for his trips in Russia and points North.

It was a VERY ingenious mix of military surplus aluminum tubing, a canvas skin, and flotation bags. To set the boat up you inserted the folded aluminum skeleton into the cockpit opening of the folded over skin. Then unfold the skeleton and insert the frames. Once the frames and stringers are locked into place you are left with a skin-on-frame kayak that has a loose skin. All that's left is to insert the flotation bags between the frame and the skin of the deck and inflate. The bags pull everything tight and you're ready for serious whitewater.

The boats are built one-off based on body measurements (make this piece twice the length of your forearm, etc) so every one is different and it fits the builder. Aleksey told me that he HAD to make a folding kayak because first, he couldn't buy a kayak at any price (they just weren't for sale) and secondly because the boat had to fit in the luggage rack on the train. From what I remember the boat fit into a bag that was something like 5 feet long.

If you're interested I'll try to find more information on the design (you don't necessarily have to shape it like a kayak). The essentials were really the locking mechanism that secured the boat in its unfolded shape and the use of the inflatable bags to tension the skin.

I did like the folding boat at microcruising.com with the tabbed edges. The shape could be changed if necessary.

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Show your Russian friend the website at http://yostwerks.com/ and see if that's similar to what he does. There's a few sites dedicated to the folding kayaks, including http://foldingkayaks.org/ and http://www.rtpnet.org/robroy/baidarka/slideshow/

I was thinking along the lines of a hull made out of the plastic material they use, with light ply inserts on the inside that make it ridgid. The trick will be finding the PVC material in a wide enough width to use.

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Frank,

The boat that aleksey described seemed a lot simpler to set up.

The skin was sewn up as all one piece with no lacing or other adjustment (picture a boneless kayak). The frame was folded, not disassembled for transport.

To set the boat up he would first fold the skin back on itself so the bow and stern were touching and the cockpit opening was on the outside of the fold. The stringer assembly was inserted in to the cockpit opening and the bow and stern were pushed into their respective ends in the folded over skin. The whole assembly was then unfolded and locked into place using a mechanical linkage reminiscent of a shoe stretcher. I can't remember for sure if there were frames to insert at this point or if the frames folded along with the stringers.

The locking of the stringer assembly pulled tension into the skin fore-and-aft and the inflatable bags between the deck stringers and the skin pulled the skin tight radially.

It was really quite ingenious.

Unfortunately I changed jobs not long ago and I'm no longer in contact with Aleksey.

I'll surf around a bit more and see if I can come up with something like it on the web. In the meantime here are some other folding boats... http://foldingkayaks.org/

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