Mouse Boats and Flats Rats

By Jon Rieley-Goddard
(Excerpted from Messing Around In Boats)
(click here for more information about MAIB)

The smallest boat I've ever owned was a yellow backpacker's inflatable raft about 2' wide and 3' long. You blew it up and got in butt first, legs sticking out over the front. Being full of air, it had total flotation and none at all, all at the same time. Which way it went depended on its ability to stay inflated. In the shallow water of mountain lakes this wasn't a big deal, but one time in deep water at the base of a granite cliff I came to the realization that my little raft didn't have much of a safety factor in snow-melt water 100' deep.

Me and my Flats Rat, Herk, on Hundred Acre Pond at
Mendon Ponds Park near Rochester, New York, on
a perfect fall day 2003. It was Herk's launch day.

Fast forward about 30 years. "The second smallest boat that I've ever owned, the Flats Rat, is also one of the most fun boats that I've had the pleasure of building and using. It's 8' long and about 34" wide with a foot of depth where I sit. Cost was about $70, time about 40 hours. Fun factor is almost without limits.

To understand the Flats Rat you need to understand the Mouse, a boat that was born on the Internet. The Mouse was originally designed, then released, for free to boatbuilders on the Internet. The release of the Mouse design was modeled after Open Source software development. Mouse is the child of an English guy named Gavin Atkin. His website is a treasure trove of free stuff having to do with building boats, including computer programs, free, for designing boats. The designer also started a Yahoo club concerning the Mouse, where builders stay in touch and share photos of their Mice.

My wife, who I affectionately call the
"Reverend," paddles her Flats Rat Perk on
Hundred Acre Pond.

The Mouse appeared in three photos that ran in the July 15, 2001 issue of MAIB in an article titled "John Gardner Small Craft Workshop 2001." A caption that ran with the photos says that no one knew what the little mystery boat was. A few issues later a reader wrote to clear up the confusion and supply the name and some details.

The Flats Rat is a bulked-up version of the Mouse, perfect for chubbier boaters. The designer says that the Flats Rat has 8" of freeboard with 300 lbs. of load. In contrast, the Mouse will hold a kid or two, or one adult not overfond of ice cream and such delights. Freeboard is minimal, about 5". The original reason behind the first Mouse design was to give beginners a taste of stitch-and-glue construction methods. Payloads totaling much above 200 Ibs. are problematic. In the two years or so since the first Mouse roared into virtual reality, more than 100 numbers have been issued to builders and many variations on the original design have been posted.

This is where the Flats Rat comes in. A messing-about-type guy in Texas by the name of David Routh designed the Flats Rat as a variation on the Mouse. And he prefers nail-and-glue construction (somebody say amen to that). Where the Mouse has a vee bottom, the Flats Rat has a flat bottom. Propulsion is by double paddle and I found that 8-1/2' paddles work just fine.

The Mouse parameters specify plumb sides, pram ends, vee bottom, hard chines, and plywood sheathing, with stitch-and-glue or nail-and-glue construction. Strip planking or traditional lapstrake planking is not inside the parameters. The Flats Rat goes together with nails and glue, which I greatly prefer over the glop-intensive stitch-and-glue approach. It's a personal thing, but my aversion is strong. My dad and I built a 10-footer called the Graefin-10 when I was in middle school, and I still remember the trouble that we had with Bondo in the heat of summer. No stitch-
and-glue for me, thank you. Been there, done that.

Part of the fun of building a little boat like the Flats Rat or the Mouse is building in the basement, which here in Buffalo, New York, is a good thing in the winter. Mouse boats and cognates have minimal plans, so another fun thing is adding your own touches. The prototype Flats Rat had sealed bulkheads at the ends with small, round, plastic hatch covers. I chose to use the approach that Jim Michalak uses on many of his boats such as the Piccup. I made watertight bulkheads but my hatch covers are large and made of plywood and are held down by shock cord criss-crossed and held in place by snapping the cord under screw eyes on the sides of the opening.

Another modification that I introduced in the second Flats Rat that I made was to use two narrow keel strips instead of a skeg, which I used on my first one. And in both boats that I built, I backed the bulkheads and transom ends with 3/4" pine to give me something to nail into with ringed bronze boat nails.

I'm getting ahead of myself some. I've actually built two of these little beauties, Herk and Perk. The first one went together in secret in the basement last August just before a family vacation on Lake Ontario. My wife (subsequently referred to as the Reverend) noticed a lot of banging going on, but I was able to scam her on the noise for the two or three days it took to complete the hull. Just finishing up some stuff for the sailboat, I told her. Was she surprised? Does Buffalo get a lot of snow in the winter?

Launch day for Herk and I

On the family vacation I launched for the first time a Piccup Squared sailboat that I had been building all spring and summer from plans by Jim Michalak, but it was the Flats
Rat that captured the hearts and minds of the men and women and children in my wife's extended family. Girls as young as 5 and as old as I won't say, and guys of large and larger sizes all found this little paddle boat to be an absolute delight. To get a turn in the Flats Rat you had to get in line. Seven of us tried it out and we had so much fun that we spent a second precious day of our week at Selkirk Shores State Park driving back up to the protected waters of Salmon River Reservoir, a half-hour inland from Lake Ontario, to enjoy the little boat some more.

Oh sure, I enjoyed the sailboat and it is a beauty in its own right, but it was the little paddle boat that had me. As soon as we got back to Buffalo I went back down in the basement, and 50 hours and $120 later, mostly for two sheets of lauan underlayment, a gallon of epoxy, and a few pounds of boat nails, I had one of my own, a little green jewel to match the Reverend's little yellow one. These boats can go together with wood and plywood leftovers from other projects and paint and epoxy left in the bottom of dented containers.

I heartily recommend that you build a Mouse or Flats Rat. Here's the deal. If you have a computer and online connection, you can download the plans from the Internet, print them out, and be on your way. For free. If you don't have that capability, someone in your family, in all likelihood, does. And they don't have your aversion to computers and such, either. I list the necessary Internet addresses at the end of this article. They will know what to do with them. They might even teach you how to say URL.

We launched my Flats Rat, Herk, in September on a faultless fall day of lively wind and clear sky. A high pressure zone had been giving us day after day of blue sky and fall-tinged warmth with 60s and 70s. It was T-shirt and shorts weather on the cool side. We went to Mendon Ponds Park south of Rochester, New York, near Pittsford and Locks 33 and 34 on the Erie Canal. Mendon Park is out in open country. There are three kettle ponds, glacial lakes, and we paddled on the largest of them. Hundred Acre Pond. There was a strong wind just short of white caps. That gave me a lot of information to ponder concerning the skeg vs. keel strips question that I had posed for myself in building the two little boats.

We launched at a simple dock (no power boats allowed) and were on our way in minutes. I put a small round ice cooler between my extended legs and the Reverend (my wife...remember) had a six-pack size cooler in her little boat. The lake is approximately 1/2-mile wide and 1-1/2 miles long by my estimate. Because it was formed by glacial action and the kettle pond effect, its margins are regular. The depth is sufficient for paddle boats, aquatic grasses grow almost to the water's surface all over the lake and lily pads were present, too, but only in patches. A few beautiful aquatic white flowers persisted among the lily pads.

We had the lake to ourselves except for an old guy in a plastic mini-kayak of the sort that the Flats Rat gives some competition to. The old guy paddled across the lake, then flipped onto his back and drifted with the wind. Our paths crossed once. As we paddled up the shore against the wind we came near a gaggle of geese. After the gaggle split into two groups moving in two directions, one group of four or five geese exploded into flight, honking, flapping, and generally complaining and accusing.

When we made the turn to go downwind, I discovered that my boat with the keel strips had what at first seemed like a counter-intuitive habit of trying to round up into the wind if I paddled normally, dipping one blade, then the other, etc., etc. At first I was puzzled, and I noticed that if I paddled on one side only I could maintain my heading or would need to switch to paddling for a while on the other side only. I decided that the stern, which has a bit more volume than the bow, with my upright torso adding to the weathervane effect and my weight establishing a pivot point aft of center, was accounting for the boat's desire to round up. The other option was to drag the paddle rather than paddle mostly on one side. That had the effect of controlling the boat's drift downwind, too.

The Reverend's little boat, which has a skeg instead of keel strips, did not act all that differently, except for slightly better tracking downwind. I'll have to try her boat to see for myself. I noticed that both boats wiggled some when we were paddling normally, but it wasn't any more pronounced in mine than in hers. These boats are built more for fun than for speed. The designer reports 3.2mph on the GPS as the top speed.

I like the keel strips and will continue to use them because the lauan plywood that I used in both boats oilcans in the Reverend's boat when you step in. I also noticed flexing when I tossed her boat from the truck onto the water while we were using it on our vacation. This oilcanning is not a big problem, but the two single strips do give a lot of added structural improvement for the effort expended and adds almost no weight. I copied the twin keel strips, which are aligned directly below the coaming strips, from the Piccup Squared project.

One alteration in the Reverend's little boat will be a few strips across the inside of the cockpit forward so she can have something to brace her feet against. When I built my little boat I shortened the cockpit about an inch at each end after seeing that the best sitting position, leaning against the aft bulkhead, still made the boat trim a bit by the stern. The Reverend could move her cutdown lawn chair seat 4"-5" forward, but that would call for a more complex arrangement than just throwing in the chair and paddling away.

My wife's 10-year-old niece paddles Perk at
Salmon River Reservoir near Lake Ontario
in the Thousand Islands region. The Flats Rat
accepts up to 300 Ibs. of payload, more or
less, with no complaints or vices.

Since I am taller, I find it comfortable to brace against the forward bulkhead and use a boat cushion to sit on, keeping out of the pint or two of bilge water I deposit in the boat when I get in (have to remember a big sponge to get rid of that water next time). I have noticed that sitting on one boat cushion feels right and sitting on two boat cushions feels like I'm in danger of bringing my weight too high for safe buoyancy. I'm planning on playing around with a simple built-in seat. I have several styles to pick among in my library of boatbuilding books.

After drifting down the lake, we had lunch at a picnic area across from the dock. We retraced our route around the lake back to the dock. We had one of the most pleasurable times on the water that we've ever had together. The next day, I was still grinning.

Websites and Other Internet Information

My own website,, has text and photo building logs for several boats that I've built, including a Weekend Skiff that I described in an article that ran in the August 15. 2002, edition of MAIB, and several Michalak designs, including a Harmonica canalboat, Moby Dink, Quark, and the Piccup Squared. And building logs of the two Flats Rats. The site has wads of pictures, including an extensive log of our trips on the Erie Canal in our Harmonica.

And my other website,, offers reviews of books about boating, from choosing to building to enjoying. There is a portal on the site through which you can purchase the books that I review. I wouldn't think of building boats without building my boat library, too.

Mouse creator Gavin Atkin offers plans for many Mouse boats at his website, His collection of links to free things such computer software for designing boats is extensive and helpful.

The website of Flats Rat creator, David Routh, is His website also has a lot of pix and text about the various Lake Conroe (Texas) Messabouts that have taken place in recent years.

Another website with free downloads of Mouse plans is Duckworks magazine, an online resource known to some MAIB readers, at This site has a good community feel.

There are also Yahoo Groups concerning Mouse boats and boats designed by Jim Michalak. Go to and do a word search. Joining a Yahoo Group is easy, directions are on the first page that you will encounter.

Listen, if you have made it this far and you don't like computers or the Internet, here's what you do. Take your copy of MAIB with this article inside and go to your local public library. Walk up to the reference desk and stab your finger at those Internet addresses in the paragraphs above. Grunt or make some other appropriate noise. You won't even have to break into speech. The librarian will know what to do. If he/she tries to get you to sit down at a computer, simply say, "No thanks..-all I need is for you to go here and download and print out some boat plans for me." Better yet, ask your 12-year-old nephew to do it for you.

Fear and/or loathing of things digital is no excuse. You can do this. And you will be glad that you did. Those of you who have Internet access can email me ( with any questions that you have about these fine little boats.