Hadron H1 Sailboat

I’m working around the clock to finish my second sailboat before thanksgiving.

The Lowrider has been indispensable again.

This is the intended design: The Hadron H1 singlehander dinghy by Keith Callaghan

albeit mine should have an asymmetric spinnaker in front.

  1. Cutting out the plywood - 6mm okoume for planks…the rest varies from 4mm to 12mm.

note the puzzle joints. i am hoping the overlay of planks will be mitigate any risk of structural imperfections. plus i reinforced the most vulnerable joins with fiberglass.

  1. I flow-coated (three layers of wet on wet epoxy) everything as much as i could before beginning the build. A lot easier to do this ahead of time flat and off the jig.

For this build I went with US Composites “Thin Epoxy” and their Aerosil-Cabosil and Fairing fillers. They are cheaper than West System without all the marketing. Their pump system is far superior. I will say West System is a mine of information on techniques and best procedures.

  1. Bending the planks over the mdf jig. centerboard box already fitted into jig. it might have been easier had i not flow-coated the first two planks…anyway it got done with a lot of clamps and the occasional temp screw.

  1. Cedar core centerboard and rudder: used lowrider to cut contour pieces to assist when planing.

Here applying three layers of carbon - unidirectional, twill X 2 and a final thin blanket of fiberglass.

Wood boat building regrettably comes with a lot of bad waste.

  1. Filled any gaps with adhesive filler, applied blanket of fiberglass across bottom planks and tape over all seams.

  1. Faired in tape seams and applied another three coats of epoxy that absorbs into filler and any unfilled bubbles in tape.

  1. Primed 2 coats. Waiting on a proprietary filler that pairs with Interlux for final ‘final’ fairing which I will do at the end. Boat color will be red.

  1. Off jig!

  1. Taping interior seams and fairing this week…then interior buildout.



I had to go look at the website. I was a bit surprised by the low transom with the holes in it.

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I’ve seen several competitive sailing dingy designs with that feature. My impression is that it cuts down drag (both wind and water), removes weight, and makes the whole boat “self bailing” if water does get in.


And on bigger boats than dingies…

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Yeah. I had to do some reading. It looks pretty common on race boats. I’ve just never seen it.

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That is beautiful.

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interior almost done. figuring out a heating situation for garage right now.


Where will you fit the garage on the sailboat? Though I can see why you’d want it heated… :slight_smile:


right, i suppose there is still time to turn this into a james bond villain style yacht with portals for dogs, drones and submarines.


James -
Thank you so much for sharing this build. I bought the low rider specifically to up our boat building game.

My son and I have built a handful of boats (CLC skerry, Opti and Frosty) and are getting ready to build some work boats next.

Do you think you share your files that used for this?

This boat just bumped our 2 person lake runabout down in the queue!


Beautiful job! I love the puzzle joints. How are they holding up? Any tips on making them? I may try them to make longer signs.

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The boat is still stationary in my garage. So are the joints.

Purists seem to not like puzzle joints in the boat building community. Aesthetically I love the look of them. They are weird. I feel there are a lot experiments to be done fitting different style joints, woods and materials.

I did puzzle joints with some gnarly old growth pine on a bed headboard and Titebond II, the joints were very close but a little off - the little line of yellow really glue irritates me.

I would do it again with clear epoxy. The glue line would be invisible and it would be structurally more sound and forgiving of any errors.

For a sign where you probably want the wood unpainted I would recommend West System 207 (which doesn’t yellow), wet the joint first (with epoxy) then 5 - 10 mins later apply a mixture of epoxy and filler (wood or colodial) into joints and clamp. Really make sure the joint is clamped down flat across it’s whole width (harder than it sounds). Use packing tape to prevent epoxy sticking to anything.

While it is a pain in the ass to use – epoxy is a lot better in situations where there is a bit of wiggle. The ideal epoxy joint is held together more loosely than a wood joint. The joint cannot be starved of epoxy.

If this will be outside, put a UV topcoat on the epoxy. I like exterior OSMO and Epifanes spar varnish. They are pleasant to work with by comparison.

That might be too much info…

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Perfect amount of info. Thanks. I’m planning on doing a sign that is much longer than my table, 3x+ish. Think doing it in several large pieces joining them. Love the boat.

Is that a modification for an asymmetrical? Have you had it out yet this year?

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yes, for an asym. i’ve just re-started. aiming to be done mid-june. will post more pics then.


Geez, still going on it…? Lol looks great and can’t wait to see the final product! I did a test on the finger joints and it worked well.

A little update on this. Got side tracked prepping for a wedding party.

Adding the deck and carlin here. Using the charcoal to prevent the boat rocking back! Protecting the inside paint with poly.

fitting the front deck.


Looking great!!! Love the cutout in the deck for the bag of charcoal… :rofl::joy:

This is what I’m talking about.