Alley Cat

Design Proposal
by Jeff Gilbert

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(click image to enlarge)

20ft Alleycat Concept

Alleycat is a pocket motorsailing cat, for use in sheltered water. At the moment it’s a concept. This means I’ve drawn some sketches, and done enough calcs to be certain it will perform as expected in the water, be structurally viable, be ergonomically OK, and not be a ridiculous cost. Alley is not developed beyond this point, and needs a full plan set, which takes me 300 to 500 hours. This will be done if interest in the concept seems strong. There is one carrot – if someone with the ability and time to progress it at a steady pace wishes to build the prototype, I will provide them free plans as they go. However this cannot happen till February 2004, as I have accepted a comittment to supply build plans for my 28-foot Gumboots design, with a full time build commencing October. Jim Townsend, builder of Hot Chili prototype, has opted to build the worlds first Gumboots, which will be one of the very few truly ocean capable cats under 28 feet sporting a full (1,90m) headroom Galley. I’ll also be fully occupied in Tasmania fitting out my retirement home in which I wont live till 2008, but which requires both Galley and Head, as well as access to the poop deck (in otherwords a ruddy great staircase). It’s a stone house on 5 acres, in which myself and a buddy named Matt Aylen, having failed to enjoy Urban Growth and Married Life, are escaping from the city. He to mix recorded Music, and me to draw multiple boat designs at a less frustrating rate (I’m in my last 5 years of Wage Slave labour).

In imperial dimensions Concept Alleycat is 20 x 8 x 0.75 x 2240 loaded (6 x 2.5 x 0.2 x 1000 metric). It may trail at half that – but the ton allows for loading with water, fuel and food, books, fishing gear, a guitar, stereo, cameras & clothes, a boogie board, and on and on, and this is why below the foredecks will be all stowage. The draught may be deeper if you are sailing with kick-up external daggerboards/rudders, or are using the motor. You can travel under sail on a quiet day in 2 feet of water, and moor in a foot, so you don’t really need a dinghy, although you can tow one, or carry an 8-footer on the foredeck. (I’d rather have the foredeck for myself!)

Alley Hulls are full slab-sided Dory with a maybe little styling curve. This is for ease of build and interior comfort plus shoal ability. Daggerboards are Hot Chili style (kicking up from behind side rungs not shown in the drawing).

Aims of Alleycat

  • 1/ Allow a couple or small family a sheltered water holiday in comfort regardless of weather.
  • 2/ Provide the pace to economically explore a decent area regardless of weather.
  • 3/ Sail really well when conditions allow.
  • 4/ Require zero launch preparation.
  • 5/ Be attainable - not be a ridiculous cost to build in terms of a combination of effort, toxicity and cash.
  • 6/ Have honest good looks.

How does Alleycat meet these?

1/ Two big essentials- a private head with sealed door and ventilation, and a decent stand-up galley with 6 foot headroom. There are two bench-height food prep areas and a utility box on the back deck. The back deck can easily be tarped over, and has 2 armchairs in a traffic free corner, with an Aussie style gas-rigged ploughshare BBQ plate fixed to the solid deck railing it would be a great spot. I’d tend to use a camp gas cooker for hot areas and paraffin full stove in for cold areas. The back rail will have some rear support and a lift-up for boarding, plus an inboard step. Under the deck is tankage and stowage.
The bridgedeck is for cooking and seating in the day, backrests can be rigged from bed squabs, and an overhead hatch allows getting across if you cant stoop to 4ft 6 inches. At night the bridgedeck is the bed from which you can access the head or the food. The good part is in bed the lady can have the head side and the gent the other-out the verandah with him! The bed can be across the boat if one organises the table that way – normally the table can simply fold down. Forrd access is by side-decks which clip into the external daggerboard rungs (not shown in drawing), if you don’t want to clamber thru a swing-up window.
There can be inside steering wheel to the outboard or you can leave that area open for access to the forrd in-hull stowage. One hull could be a kid’s bed and two can sleep on the net/tramps under the stars.
Also note that this boat can be used as a caravan if you trail her a long way.

2/ I recommend a 15 HP Honda 4 stroke (or similar) because of its ability to charge batteries (Voltage regulated 6 amp alternator), its low noise, and also because even flat out it uses under 6 litres an hour and will push the boat to a calculated 14 knots. Running at around an Aussie gallon an hour (4.5l) it’ll get your fully loaded Alleycat along at 10 knots giving you the range to really see some sights at economy comparable with some 4WD autos. I mention the Honda because it is the lightest 15 at 43kg (95lb) but best of all is available in long (20inch) and extra-long(presumably 25 inch) shafts as well as the standard 15 which is too short for mounting over the tunnel. The extra long would mean a completely clear bridgedeck tunnel and a sweet mount straight from the rear of the deck.

3/ Sailing ability is largely up to what size sail plan you put on, and no matter what I say people will have their own ideas. However the design rig will be a dead simple sloop with an under 20 feet off the water mast in a tabernacle so you can pop it up at will, and it wont protrude too much when trailering. At only 20 feet with only 8 feet of beam, and a bit more than usual windage in the house, I don’t regard this boat as suitable for tackling big winds and heavy seaways despite a bridgedeck clearance of 18inches or 7.5% -standard for offshore cats. You can’t have it both trailerable, with a bit of windage, and safe in a nasty swell. There are plenty of sheltered places to trail to that are safe to sail it in, and with at least 12 knots motoring at your disposal there are places where you can pop across the bar for a spot of sea fishing then home at night. However on smoother water with a breeze there is no reason why this cat cant sail with the best of them, it has plenty of form stability and with water tanks and fuel tanks full and low in the hulls you can set her really flying. You just don’t want the added factor of a seaway and a gust combined setting her on her ear. She is a beast of many talents, but shes not a trailerable offshore sail-racing houseboat! Nor is she meant to wave hulls about, or be raced. She’s a motorboat that will sail darned fast in the right wind and water. She will tack, she will go upwind under sail, no fears there.

4/ The mast is in a tabernacle, and can be raised as you zoom away under power.

5/ Alleycat is to be made of Plywood, 6, 9 and 12mm mostly, and will be designed with a lot of right angles – it wont need a lot of tools. It will need epoxy and quite a lot of ply sheets 30 at a guess. It only needs glass on the outside of the hulls, and its only essential to safely above the waterline, as with Hot Chili plus scale factor 15 square meters of cloth will do. It will need a bit spent on fittings to make it comfy. A decent motor is essential. Second hand rigs are a possibility, but no winches will be needed for the standard rig. Its impossible to estimate total costs for a project like this, but I don’t think it could go over $15,000 US, and a cunning operator can build it for a fraction of that. If you are planning to trip it around you need to spend extra a good trailer, but it will fit many second hand cat trailers. If you intend putting it in one spot why not just truck it there. Remember with its range one spot may do for years. Also remember the money you don’t spend on entertainment while you are building her.

6/ The looks are oddly trad -there is no way to get headroom in the galley of a 20ft cat using the usual sweet organic curves. Besides, you finish up with a plastic box in which you can’t stand up –no way for a week on the water if it rains. And many of us take our holidays when we can, and must set them in advance, so you could get stuck in just such a situation. So the interior needs to be woodsy and cosy. Hence the looks are more in the way of an old workboat - a long hull with a wheelhouse box. But in fact the “box” from the outside is only 3 feet high. Alleycat for sure doesn’t look like your regular sporty cat. Nor does it look like a shanty boat. Alleycat is for the comfort of the lucky people on board, and maybe that’s bad for the onlooker. As a designer I hope not, but if I were on board I wouldn’t give a hoot!

This is a project that won’t be too daunting, and could have some attraction for people who normally wouldn’t consider boating. I know a lot of lowly paid single people are skilled with their hands, and could afford a sheet of ply a week and a tarp to cover their work (for the money they spend relieving their sense of helplessness), or borrow a garage. I know a lot of highly paid people who are broke. They may have just had a nasty divorce and lost the lot, gaining an ugly rented flat and a lifetime bill. They will have minimal possessions such as their fishing rod. Such a person is in despair of escaping the renting cycle, or even owning anything. They may have a car. Alley cat could be a good thing for them. They could build a real viable exciting alternative to a caravan. Two pals on the dole could do it. A couple just out of school could do it to see if marriage would really work!!!. I know you get to wash up in a bucket, chop-up food on a stowable plank left over from the build, you have to assemble your bed (unless you decide on single beds forrd in the hulls) etc etc. Hull stowage is awkward, everything you want is on the bottom etc etc). But you can go where you want. There is a great view, once you have selected it (this may take some travelling). You can sleep on a tramp under the stars, too. And you don’t need a furniture bill to move on board. Also notable is that in Australia, if on a pension, you can reclaim a good chunk Marina Fees as on-the-spot rental rebate.

So there it is. If you want one badly enough to start building the prototype, let me know at