SA Yacht Blog: Proteus 106

First Proteus 106 off the beach in Thailand

I don't often write about boats I haven't seen in the flesh, or actually sailed. But this is one where the design strikes me as quite unique, has strong local connections, and really deserves to be known. It's attractive as a cruiser, a racer or a dayboat....and unique in the value it offers.

Certainly Angelo needs no introduction - he has drawn more good boats than one can count, and I keep discovering new boats from his pen. They are all well thought out and very interesting.

Plan and side elevation.

Functional simplicity at its best...
(click to expand)

When I look at this design, it really strikes me as a modern "Wharram Cat" - in that its very functional, simple and seaworthy. Although that doesn't do it justice - its really quite a high-tech design using simple materials if you see what I mean. And very good looking. Besides the low-profile cabin top, here are two very sound seaworthy hulls with not much windage. It boasts an efficient modern rig with a full roach main and a manageable genoa, with standard back-swept shrouds. Dagger boards are a nice option on the "racing" version. This is a boat that really can sail - it's light and is setup for real sailing. 8 kts round the course, and 15+ off the wind if you have the nerve! The daggerboards don't really impinge on space below.

Note the simple layout below. The cabin top is fully allocated to the saloon - this is the main reason for having a cat if you ask me - a nice saloon and living space from which you can see out - a feature not common on monohulls. One hull hosts the (large) galley, the other the (large) heads. This is a sensible arrangement as it allows decent facilities for these functions, while not crowding the bridge deck. So you get 85% of what big cats offer in a far smaller package.

The rudders are transom-hung - making for easy maintenance and repair if necessary. By the drawing - these are controlled with tillers rather than a wheel - you could have both or either I suppose. I quite like the tiller option as it means you could attach a simple tiller pilot rather than an elaborate auto-helm thing, plus there's nothing wrong with steering by tiller and its quite a bit cheaper.

Daggerboards will give her good sailing, but for cruising the fixed "keels" may be attractive - for beaching, and simplicity, and to protect the saildrives, which may be the preferred option for cruisers. Along with kickup rudders, this is a boat you could take right up to the beach on occasion, and clean the hulls without lifting out.

"Before the Mast!"

Note the clean decks and flat tops to walk on.

Nice motorcat too....

Engine comes in two options - a 20Hp 4-stroke - e.g. Honda - mounted midships on a nacelle, or two small inboards. I think this offers the best of both worlds - cruising or racing. For cruising purposes I think inboards would be the way to go - long distance motoring with diesel, manouverabilty in marinas, fuel-economy and no petrol onboard. For racing, and sailing from a home port, the outboard would be ideal - very light, no prop to drag, very quiet and out of the boat, while still reliable and effective... your dinghy engine could be a backup I suppose. And very good value...

Construction is from a plywood kit. Not very complicated, but it is a fair bit of work. The hull is sheathed in GRP - makes it scratch-resistant and strong. There are no expensive items here - everything is simple and can be achieved with low-tech kit and options. I would indulge in two nice self-tailers for the primaries, a stack pack for the main and a roller-furler for the headsail. Plus a traveller for the main. That's not a lot of money.

The boat is designed to be light. Keeping it light will keep it safe, buoyant, responsive and fast. However, you could load it if you need to, as long as you don't press too hard. Another rather nice thing about cats - most of 'em - is that they don't sink - certainly this one won't...

I think its an ideal design for local and offshore racing - Cape-Rio, Governors Cup and Mykonos, or a cruiser for a small family. It won't break the bank, but it offers very safe and comfortable sailing with impressive performance. And a nice live-aboard option. Did I mention parties and day sails?

Also a damn nice motor-cat if you look at it like that.....

See Angelo's notes below:
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10.6 METER MULTICHINE PLYWOOD/GRP SAILING CATAMARAN

This project has been “gestating” on a personal level for the last 10 years. My aim is the smallest family ocean cruising cat, that is to say with sufficient load carrying capacity to do an ocean crossing with a family, of minimum cost, and capable of amateur construction with the minimum of labour and skill. She is also aimed at being a fast, practical & enjoyable boat for local use. She is small enough for easy shorthanded use. The hull structure is “pre cut” by a CNC cutter as a kitset, or can be cut to plotted templates as a cheaper option if preferred. The Kitset is available from CKD Boats in Cape Town. Their quality is A1 and different ply type options are available. Since wastage is minimised (much less than hand cutting), and CKD buy much more cheaply than private buyers, one generally finds that the kit costs hardly more than buying the raw material, and then you save hundreds of hours in labour. The boat is set up on ply bulkheads and stringers and the skin is glass taped with epoxy resin along the chines, inside and out, there are no chine logs. The hull & deck is mostly 9mm ply with 12mm in the forward wingdeck and hull bottom forward. The outside is GRP/epoxy sheathed. She is simple, strong, fast, comfortable, cheap and “unsinkable”.

The interior consists of four berths (two doubles + 2 singles), a saloon settee, a practical galley with icebox, and a toilet compartment, all with standing headroom (1820 under deckstringers) . She is totally functional, and all that is needed for comfort at sea. She is configured with two machinery and keel variations: A 4 stroke 20HP outboard on a hinging nacelle is fitted for economy, as is tiller steering, with “kick up” rudders. If the motor starts to make trouble it is easily replaced. I haven’t worked out how many times you can relace it to equal the cost of diesels. Other “choices” in the “gilded lily” approach stretch to installed water tank versus fitted 20 lit container storage. However with the outboard and daggerboard combination, and simplest accommodation gear, we have the fastest boat AND the shallowest draught for the smallest outlay. People lose sight of the fact that comfort at sea revolves round some very simple “basics”, a dry bunk with good ventilation, a place to prepare hot food, a place to sit out of the sun & elements, a private toilet, standing headroom. The rest is “bells & whistles” which all come at a price of increased cost, maintanance, and degrading performance.

The rig is the simplest possible, with a pair of cap shrouds and headstay triangulated, single diamond. The sail inventory is essentially a mainsail, a roller furler jib, and a storm jib. Optional: Genneker.

A first class builder estimates 1600 hours, professional hours in a set up boatshop, to unfaired and unpainted hull, deck, joinery stage. CNC cut kits from CKD Boats in Cape Town, a very experienced company, is available at a really competitive price. Email Roy Mc Bride (roy@comlumber.com ) . Most likely you will find the cost of the CNC kit ( including shipping) is less than a private person is likely to buy the raw materials, so that the huge labour saving is more or less “free”!

Wing deck clearance to DWL (@ displ 3800 kg) is 680mm amidships and 1100mm under the cockpit. The windeck does not extend forward which is most important. Top speed broad reaching in flat water and high wind can be around 18 knots (depending more on one's nerve than anything.) and can average 8 knots on an olympic triangle, powered up in 16-18 knots breeze. Payload of crew, fuel, water, provisions in addition to the vessel complete (with sailing and safety gear, normal loose outfit and sails) is nominally about 900 kg. This figure could be increased by another 400 or so kg at the beginning of a long voyage if the boat is

consciously not "overpressed" when so loaded. The length/beam ratio at datum flotation is 9.07. This offers a good compromise between reasonably slim hulls and good load carrying ability. This is augmented by the additional "flare" developed in the topsides, whereby beam (and waterplane area) increases considerably with increasing immersion.

The daggerboard version is more efficient in terms of L/D on the foils. In addition the drag of the daggerboards retracted is zero, whereas the mini keels (both!) continue to offer resistance. The prod and spars are intended to be aluminium extrusions, whose inertias are specified.

The design license costs $4500 New Zealand Dollars per boat to build. Drawings are supplied in PDF format. The templates consist of all frames with shell deduction, stringer cutouts, access cutouts etc shown for hull, deck and superstructure, bow and stern profile, daggerboard, (or alternative keel), kick up rudder. The design consists of: 18 drawings: Lines, hydrostatics, full scale templates (+ 12 x A0 sheets), general construction drawing, CNC parts assembly drawings, CNC parts nesting drawings, arrangement plan and sections, deck arrangement, sail & rigging plan, dagger board & case construction, rudder construction, chain plate details, sundry joint details, doghouse & hatch details, outboard motor hinging nacelle detail, alternative keel detail. Study plans consist of arrangement drawing, deck arrangement, sail & rigging plan. Note: study plans have all section information omitted (other than one "typical" section.) The design has been developed to minimise labour hours and high skill requirements and high costs. The only "exotics" involve the external skins of the ply rudders and daggerboards, which are carbon, since the excessive amounts of GRP needed would make control of the shape and avoiding excess weight problematical.

LENGTH OVERALL 10.600 Meters

BEAM 6.360 Meters

DRAUGHT 0.370/1.75 Meters (dagger up/down)

DISPLACEMENT 2600/3200 Kilogr (light conditon, lght/hvy inst)

MAINSAIL 48 Sq Meters

ROLLER FURL JIB 24 Sq Meters

GENNEKER 58 Sq Meters

FRESH WATER 140 litres (installed or 20 lit containers)

CONTACT:

Lavranos Marine Design, Ph: 09 4802232, Email: Lavranos@ihug.co.nz

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At time of writing, the second one is nearing completion in Cape Town.

See also www.ckboats.com for details of the kit.

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UPDATE: We have received some pics of "Sarita" under construction, and now recently floated at Port Alfred in South Africa. This was a home build on a farm - a good example of a D.I.Y. home-build. The interior is not fully fitted yet but gives a good idea of the accommodations and spaciousness this design offers. I understand the kit was a great success and fitted perfectly. This particular one is slightly unusual in that it has two outboards instead of one - two beautiful Honda 20 four-strokes at that. The rig is yet to be fitted, but the platform clearly offers a lot, in a very good-looking package.

Progress photos follow (click to expand each pic):

Helm station with wheel and engine instruments.
Note this is a deviation from the design (which shows tiller-steering),
but is an example of a wheel mod.