Possibility of homebuilt plywood modern dinghy

[mvweebles]

25-years I built a Nutshell Pram. Was a winter project and a lot of fun to build. Wooden Boat Magazine sells plans, but I found the original article in WBM and just lofted the pieces from the magazine article. If I were to do it again, I'd probably put some bouyancy chambers in the stem and stern. Was not a great sailer, but fun enough to putter around an anchorage. If I had to guess, I had 100-150 hours into it when complete. No idea on cost.

https://www.woodenboatstore.com/prod...MxOZwMHnhWF9nI

[Franziska]

Might add there is also the constant camber method by John Marples which allows compound curvature in the panels, but it's a bit more complex.



Still, for a simple dinghy stitch and glue works great. See ours above.

[Woody]

OP's original question was if he could replicate some complicated carbon fiber designs in plywood. I tried to point out that it's not really possible, or easy at least, and also that many of the advantages of these designs are in the weight they save. I asked which design features of them he was hoping to have, and it seems he really just wants a RIB. Muaddib, maybe you can sew some float bags to the topsides of your plywood pram?

[Muaddib1116]

Originally Posted by Woody

Muaddib, maybe you can sew some float bags to the topsides of your plywood pram?

Perfect solution. Thanks for your contributions.

[Woody]

Sorry, I was being serious. This has been done with the Walker bay sailing dinghies. There is the added option of flotation attached to the topsides for the additional stability you are looking for.






Since you're looking to DIY it, here's a video of some homemade flotation tubes attached to a hard dinghy:

https://www.youtube.com/watch?v=m9nCwHGRyuA

Just ideas, YMMV.

[TrentePieds]

Plywood-built Enterprise dinghies ('50 era) had seats running fore'n'aft along the sides. Under them were lashed plastic floatation bags. About a foot in diameter and six feet long, so about 10CuFt volume between the two of them. 10 CuFt confers over 600 lbs of floatation. A flooded plywood Enterprise (230 lbs. IIRC) floats. 600 lbs. of floatation will carry 3 "normal" persons.

There is nothing new under the sun :-)!

TP

[rslifkin]

Thinking about flotation, that was one of my reasons for bolting fenders to our hard dinghy just below the gunwale. By my calculations, the 4 fenders on the side should give about 40 lbs of buoyancy, so 80 lbs total. A bit of extra floatation to supplement the foam under the seats and possibly a little extra stability (although you'd be at a pretty good angle before they touch the water, especially lightly loaded).

[hankstein]

Building a plywood /epoxy dingy is simple ... I built one a few years ago but would never use plywood again ... plywood is just too heavy, even 1/8" is too heavy. I sold the dingy with that boat and would never build another ply dingy. If you can find foam board strong enough that could work ... I would opt for a glass dingy and buy one used. currently I use an inflatable.

[Nicholson58]

Originally Posted by Muaddib1116

I have no experience or expertise with building plywood boats, or building an wooden boats, or building any other type of boats, but I've seen some pretty incredible home built plywood boats online.

- , it seems like a very similar boat could be built out of glass sheathed plywood. Obviously there would be a weight penalty, probably as much as twice the weight vs a carbon build, but I imagine that one could be built for less than a quarter the price.

It doesn’t need to be heavy. Go to US Composites

Fiberglass , Epoxy , Composites, Carbon Fiber - U.S. Composites, Inc.

Economical source for high quality marine epoxy. Fillers and reinforcement. I always use their 635 THIN 2:1 epoxy in bulk sets such as 3-gallon with pumps for all build and repair projects. The offer carbon fiber in both woven and highly versatile stitchmat. Build a very thin plywood boat. Fill and fair using epoxy and 3M microballoons as a paste. This is easily sanded and quite strong. Overlay with carbon fiber stitchmat inside and outside. You will have a crazy strong, light wood core boat.

[ausnp84]

Funnily enough, we’ve been thinking similar recently after our ally inflatable developed a leak. I like the OC Tenders but $16k is lunacy…

From a weight perspective, our dink weighs 35kg and the much longer ply/epoxy kayak I built last winter came in at 20kg, so it’s entirely doable. Seahawk Epoxy also works perfectly if you want an alternative to West.

Thanks for the great (and informative) post!

N

[tdunlap]

Your prayers have been answered. See -

https://cernyyachtdesign.com/project/727/

It is a shameful copy of the OC Tender.

The design is available in a few different sizes. You can buy plans, or a kit with CNC cut plywood.

You could build this out of Okoume plywood and it wouldn't be much heavier than built in foam core. A foam core build would still be pretty easy, but would be more expensive. If you wanted to cut the cost a bit you could use S-glass instead of carbon in the build. S-glass is remarkable in it's strength as compared to e-glass. It is also as strong or stronger than carbon, depending on how it's employed, but not as stiff as carbon. S-glass is certainly suitable for a tender. I think the reason you don't see s-glass too much is it's harder to source.

I think this is a very easy build, depending on your experience.

The challenge with designing a yacht tender, isn't making a light strong boat, it's making it tough enough to drag up a rocky beach, hence the aluminum plate OC Tender puts on the bottom of their boat. How you treat your tender can mitigate this problem somewhat.

I hope you build one, and have fun doing so. Grab a copy of West Systems book on epoxy construction, and watch a few YouTube vids covering this type of construction. You'll have no trouble figuring out what you're doing.

Incidentally, I own the very fist carbon version that OC Tender built. Back when I bought it they were way cheaper. Today, I would probably build this guys design. OC is really pricy, but it was an idea that was way overdue. It checks a lot of boxes as an ideal tender. I like how inflatables preform, but my OC is lighter and with a bit of care and maintenance can last forever. If it gets damaged, I can repair it easily. Not so with inflatables. I think the OC will also hold it value better than an inflatable as well.

[Nicholson58]

Originally Posted by ausnp84

Funnily enough, we’ve been thinking similar recently after our ally inflatable developed a leak. I like the OC Tenders but $16k is lunacy…

From a weight perspective, our dink weighs 35kg and the much longer ply/epoxy kayak I built last winter came in at 20kg, so it’s entirely doable. Seahawk Epoxy also works perfectly if you want an alternative to West.

Thanks for the great (and informative) post!

N

I have used all of these epoxies and more. Note my recommended supplies above with US Composites 635 THIN. Lower cost, longer pot life, slower cure, better wet-out and zero blush. Zero blush means you can add successive layers without sanding or scrubbing. Non hazardous means shipping is low cost by regular means and no We$t or other chandler’s high markup. I have used over 30 gallons of this epoxy for many builds.

[ausnp84]

Originally Posted by Nicholson58

I have used all of these epoxies and more. Note my recommended supplies above with US Composites 635 THIN. Lower cost, longer pot life, slower cure, better wet-out and zero blush. Zero blush means you can add successive layers without sanding or scrubbing. Non hazardous means shipping is low cost by regular means and no We$t or other chandler’s high markup. I have used over 30 gallons of this epoxy for many builds.

Sure thing - everyone has their own preferred epoxy. West grabs a lot of the market share but I find Sea Hawk to be an equally solid product, plus it’s been readily available on most islands throughout the Carib. Like you, I’ve used a lot of it refitting a 43ft cold-moulded tri and then building the stitch kayak, and it’s certainly met my criteria for a good epoxy.

N

[ausnp84]

Originally Posted by tdunlap

Your prayers have been answered. See -

https://cernyyachtdesign.com/project/727/

It is a shameful copy of the OC Tender.

The design is available in a few different sizes. You can buy plans, or a kit with CNC cut plywood.

You could build this out of Okoume plywood and it wouldn't be much heavier than built in foam core. A foam core build would still be pretty easy, but would be more expensive. If you wanted to cut the cost a bit you could use S-glass instead of carbon in the build. S-glass is remarkable in it's strength as compared to e-glass. It is also as strong or stronger than carbon, depending on how it's employed, but not as stiff as carbon. S-glass is certainly suitable for a tender. I think the reason you don't see s-glass too much is it's harder to source.

I think this is a very easy build, depending on your experience.

The challenge with designing a yacht tender, isn't making a light strong boat, it's making it tough enough to drag up a rocky beach, hence the aluminum plate OC Tender puts on the bottom of their boat. How you treat your tender can mitigate this problem somewhat.

I hope you build one, and have fun doing so. Grab a copy of West Systems book on epoxy construction, and watch a few YouTube vids covering this type of construction. You'll have no trouble figuring out what you're doing.

Incidentally, I own the very fist carbon version that OC Tender built. Back when I bought it they were way cheaper. Today, I would probably build this guys design. OC is really pricy, but it was an idea that was way overdue. It checks a lot of boxes as an ideal tender. I like how inflatables preform, but my OC is lighter and with a bit of care and maintenance can last forever. If it gets damaged, I can repair it easily. Not so with inflatables. I think the OC will also hold it value better than an inflatable as well.

You’re an absolute legend. If the prices are correct and the plans + kit is $1650, that makes it a very viable alternative to an inflatable. Thanks for sharing.

N

[DavidM]

I built a 10’ fast tender with similar dimensions to a rib. I’ll attach photo