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Building a Bolger Bobcat (Payson Tiny Cat) catboat from CAD on up


Make it. Just start in on it! I’d love to see your design.

The good folks at Chesapeake Light Craft in Annapolis have a teardrop that has a sort of faceted design which lends itself to this method, as well as stitch and glue: CLC Teardrop

As for errors in the cutting, I am definitely seeing some patterns and hope to somewhat make sense of it…I am also awaiting my pantograph, so that may alleviate a bit of the problems. Basically, however, I am seeing that some of the panels that are over 6 feet in length are suffering from a half inch here or there at the farthest edges of the board. It is hard to articulate, so maybe I’ll work up a drawing and post it of what was intended (from the CAD drawing) and then what I got (from real-world post-cut measurements). It is nothing big, however, since it gives me a chance to be creative. Part of boatbuilding is being a mechanic and adapting to the unexpected. That, and the great Universe’s cure-all: epoxy.


That’s very helpful. Thank you. It’s funny at the age of 15 I started portraying a sailor as an actor at the original Renaissance Faire. I didn’t actually sail until I was 48. That was on a 100 foot tall ship. I fell in love with it. I’m fond of supporting good work too. That is why I’m in this group.

Thank you


I saw that trailer before, absolutely gorgeous. Boat builders are some of the best wood workers out there and you look like you are on par with them. I’m afraid I don’t have that talent yet, hence CNC.

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Wow, what an awesome project!

I have thought about similar potential projects, albeit much simpler boats/designs.

I previously purchased plans by Ken Simpson for his 1Sheet+ and 1 Sheet Pram, which are small simple boats that can be made from a single sheet of plywood.

I started building them before I knew about Maslow, but I have thought many times now about making these or other simple boats using Maslow with such plans.

You can find the links to all Simpson’s boat plans here:

And the same website has boat designs by other designers found here:


Good links, @kenhej! The duckworks site is a good one. Some of those small one sheet (+) plans are great.

Getting plans into CAD is getting easier with programs like Fusion 360 that allow one to take advantage of dimensioning parameters. If the plans include offsets, that is great. If the plans include measurements from a baseline, even better! Many of H. Payson’s plans (found here) have measurements from a baseline, made for the amateur builder to measure from a plywood sheet’s edge. In Fusion 360, I find that this works great, using one of the axis as that baseline.

If you have a hankering to do your own panel “unwrapping/unfolding” from a complex model, I would suggest some pretty good freeware programs out there:,

  • Hulls, which is an old and very simple application for making boat hull chines is actually quite good in that you can unwrap and lay out chine panels onto virtual ply sheets! You can use this to design the chines, unwrap and then export the chines as DXF files to later massage in something like Fusion 360 (or not).
  • Freeship (plus), is also an older program, but has a lot of neat analysis tools and can help you unwrap hulls portions to create panels you can export as DXF. This application can allow for more curvy forms than Hulls. PRO TIP: to unwrap panels, it is best to have each area as Layers and to also enable/check the ‘developable’ option within the Layers management dialog (slightly hidden).
7th grade project

Just, WOW!!! Can you say best of 2018 :astonished:


Thanks for those additional tips, and pointers to other helpful software, @Sonny_Lacey !

Three other interesting aspects of the Simpson plans that I thought worth noting:

  • His plans offer an alternative method of sealing and protecting the wood using a diluted solution of Titebond 3 wood glue, as opposed to more typically noxious approaches (of particular interest since I wanted to build the boat with my young son)
  • Similarly, he suggests an alternative method of using drywall tape to strengthen and seal seams
  • And finally, many of his designs (all?) include building the boats in sections that can be quickly disassembled for transport/storage, and assembled for use. Many even include the ability to nest the sections together for transport/storage, thus making their footprint much smaller.

These alternative sealing/strengthening methods may result in a shorter lifespan for the boats, but his testing and usage thus far show no obvious signs of such.


@Sonny_Lacey Would it be OK if I wrote about your boat building project in the newsletter this week? I think the rest of the community would get as much joy out of it as we did in the forums


I already asked and got his permission 5 days back - you have the all clear to proceed captain!

At least I believe that was the spirit of our conversation as copied below.

I’m going to jump the gun - Sonny do you mind if the pictures are used in one of the Bi-weekly updates newsletter?

Thank you

Sonny_Lacey5d Bee
Sure thing @Bee go on and use any pics you like.


Thank you

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@bar, sure thing! My honor to have this project included. Thank you!

Here is an update on the boat:

Outside ‘seams’ have been taped and provisionally puttied. Fairing and final smoothing will come much later. Now, I am working on the inside seams and frame-hull attachments. Once the inside is done, it will get another flip and then another layer of fiberglass on the outside (and maybe another on the bottom panel for good measure).


What an amazing built. Can’t wait for the pictures on water. Do you have a rough estimate on total building time until it floats?


@Gero I estimate it will take about a total of two months to get from blueprints to sea trials. Some of this may extend out a bit, as I will move the boat outdoors for final work, but will have to await warmer weather (above freezing) for the later epoxy stages. Therefore, I think that by March it may be ready for a water test, but I will not be (water is too cold, then)…!


@Sonny_Lacey Thank you for the estimate! I have a tiny 2 person electrical ocean boat in mind and temporarily stuck at the hull construction. Was hoping for the Maslow to assist in the build and your post gave me great hope.


Any time, @Gero! If you ever want to go over your design or want some input on hull formation or construction techniques, I’ll be glad to lend a word.

Boat Builders Projects

Looking great. I’ve been doing some stitch and glue, mainly with Devlin Designs. I’m interested in how you’ve done your puzzle joints in CAD. I have been taking the lofting data as you have done and putting them in QCAD. I use EstlCAM to generate the G code.

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Great project! This is exactly why I got on the waiting list. I built CLC’s cute little Eastport Pram and am about to start on a Passagemaker. I gave serious thought to building a Bobcat, but it’s not a great camping design. However, once I scratch that itch, it’s a beautiful gentleman’s daysailer.

I’m very interested in how accurate your rig is, especially out at the ends of the 4’x8’ sheet. Also, what kind of sled is your router on? The triangulation kit looks promising. As a mechanical engineer, I love parallel linkages and 4 bar mechanisms.

On a side note, I just finished my boatbuilding shop ( and am looking for commissions in the PNW (will be starting a teardrop trailer for a friend soon). I love making drawings from offsets. I once took drawings of a wooden clock and generated CAD files for it. I may do that for the Passagemaker. I want to do some fancy teak decking patterns on the thwarts. I actually want to get it done before it gets warm again.


I will be following your progress and adding my $0.02 if I feel I can contribute to the conversation. Good luck on your project!



Welcome to our group. I look forwards to seeing your work.

Thank you


@Sonny_Lacey Where did you get your plans?

I found this:

As I said, I already own the plans for the Passagemaker. They’re printed full-size on large format paper. I was thinking of doing the take-off and using the edge of the paper as the baseline to measure the parts.


I’ll be watching this project closely. Only yesterday I discovered Maslow CNC as I was preparing for my own boat building project. The very next day, I discover another boat builder in the January Maslow newsletter. How exciting! I’ve built two stitch and glue kayak kits, but now I’d like to build a sailing/rowing dinghy. CNC cutting the panels myself would be very satisfying.


Thats the same reason I found this, looking at CNC routers for boatbuilding applications and realising I was never going to have one - then Maslow appeared and changed my outlook.