JEM Watercraft

A few weeks back, I saw a post in a boat design forum from Tom McGuinness, owner of http://www.tailboats.com.

He was discussing/researching the best manufacturing method for production boat building. I joined in the discussion and we got to e-mailing back and forth. Next thing you know, we had ourselves a project.

We bounced ideas and design concepts back and forth. Tom had the design in his head and drew some images. I helped translate that into a boat that can be built via Stitch-and-Glue. The goal is to prototype his design in a wooden boat. Then venture into creating a mold, with any design refinements, and produce fiberglass hulls.

Here's a concept picture:



As you can see, it's a Sit-On-Top style kayak design specifically to accommodate the needs of Tom's tailfin propulsion system. I also think it would serve very well as a sailing kayak because of semi-rounded hull bottom, is self bailing with the scuppers, and will have provisions for a retractable dagger board in the cockpit. The stern is also shaped like those seen on high performance sail boats. More image to come soon.

All the materials are on order and should be arriving in a week or 2. Tom has agreed to let me post a building log. The log will be beneficial to me because the building method will be a hybrid of techniques designed for the Zephyrus plans (modeled after the famous Kruger Sea Wind).

I'd like to thank Tom for contracting with me to undertake this project.

So let the building begin!

This design calls for a dagger board trunk. I bought some fiberglass cloth off of e-bay about a year ago. It supposed to be 6-ounce but it turned out to be 9-ounce. Couldn't find a use for until now. Covered the dagger board trunk walls with it.



Plenty of frames to help shape the hull. Most here are permanent since this is a Sit On Top design.



Picture of some of the panels getting butt-blocked (spliced). Notice the "jig saw puzzle" ends that fit together. I did this as an experiment to help identify panels. It helped differentiate panels of similar size. But I didn't think it was any easier than just measuring the ends. Was kind of a pain to sand and make everything fit.



It's a stitch-and-glue monitor lizard!



Ok maybe it's the beginning of the frames.

Glued up the front frames. The cleats (the light colored wood) are made from some leftover poplar plywood I tried on another kayak. Poplar plywood is very lightweight....even lighter than okuome. Trade off is that it's brittle and doesn't bend so good.

But all I'm using it for here is additional surface area so no concerns about the brittle nature of it, although the cleats add a LOT of stiffness to the frames.

The cockpit will be glued on top of the cleats so the more contact glue area I get the better.

Frames will be tabbed together with strips of fiberglass.

Well if you squint yours eye, tilt your head, and use your imagination, it's starting to look like a boat!

Next set of panels added.



You can see the nice rounded bottom shape starting to form. Hey you potential Zeph builders....are you paying attention?

Just wondering: Do the jig-saw ends in the panel splices add any stabiltiy or streighth to the joint?

DaveAllyn wrote:Just wondering: Do the jig-saw ends in the panel splices add any stabiltiy or streighth to the joint?

I suppose you could claim some advantage in strength to keep the boat from "folding" in half....kinda like the "taco" effect of hitting a rock in a white water raft. But the slight increase is unmeasurable as its applies to this boat.

To me, they are more trouble then they are worth.

Main hull stitching complete.







Anyone every see the movie Hell Raiser? Remember the bad guy with all the nails in his head?

JEM wrote:Anyone every see the movie Hell Raiser? Remember the bad guy with all the nails in his head?

Kinda looks like a wild cucumber to me ...

Build on...

All seams filled in, stitches removed, and stitch holes filled.

Started glassing the inside. Doing the inside in strips. Got a real nice deal on some 8" tight-weave cloth from www.raka.com (where JEM customers get 5% off list prices...cheap plug) . Stuff is a little tough to wet out and takes extra effort. Ok for smooth rounded surfaces like this one, but a pain to work in the corners.

In hind sight, I'll probably stick to regular weave cloth in the future.

I'll do the hull exterior in one large piece of regular weave cloth. This will be a sit-on-top so the hull interior will be hidden. No worries about feathering all the tape edges. I'll just knock down the high spots after cure to give any moisture less of a place to build up.