For aficianados

A Wharram Pahi under sail

There’s a saying that wind will capsize a cat but waves will capsize a tri.   Anything will capsize a mono but it will come back up again or else sink to the bottom of the ocean.   The other two will sit upside down and rest.

Ye takes yer choices.     In making a final choice of design – that is before getting into the fine detail to the nearest sixteenth of an inch – I was going back and forth between the cat and the tri, not wishing to clamp lead to the bottom and wanting to be able to near-beach the boat in the shallows.

Constant thoughts in mind were steep, seven metre seas and gale force squalls out of nowhere, e.g. coming down off a mountain.   Keep coming back to the Pahi type above but with the pitching taking out, i.e. less rocker [the curve at the bottom].

Undersides not unlike this but chined

Anyway, all things considered, from price to seaworthiness, I’ll go for the cat and here are some of the required elements:

1.   31 ft LOA plus LWL, 20ft beam [15ft centre-to-centre], each hull 5ft beam at the gunwhales and 4ft at the WL.   Double-chine for strength [see pic below] and ease of building, using epoxied 3/8th ply, maybe Douglas fir.  Double-ended a la Archer.

2.  Only slight rocker but suggestion of sheer through scalloped bows and sterns [see Pahis and the pic below], slightest of tumblehome [for the leeboards, see top maroon strip in the pic below], cabin roofs fall away to the centre of the boat.

3.  Four beams, each 6ft 2in apart, strapped down. This creates three large compartments in each hull, each discrete and separated by walls, with inward facing hatches for access.

Undersides also not unlike this

4.  Thought long and hard about rudders and finally went for kick-ups, as with the leeboards.  Reason was that when a gust is abeam, the hulls need to slide sideways.   Underslung rudders require skegs and fairing into a shallow keel.   Can’t have it both ways with cats.

5.  Port hull [bow to stern]: Front cone, bulkhead with crumple struts, compartment for folding bike, 1st beam [for mast], head [with stand up shower] and vanity unit, 2nd beam, cabin 1, 3rd beam [for mast], cockpit [standing room], 4th beam, water storage, sealed bulkhead, aft buffer cone.

6.  Stbd hull [bow to stern]: Front cone, bulkhead with crumple struts, compartment for folding bike, 1st beam [for mast], galley, 2nd beam, cabin 2, 3rd beam [for mast], cockpit [standing room], 4th beam, water storage, sealed bulkhead, aft buffer cone.

Dipping lug for’ard and standing lug aft

7.  Deck area: Aft of 1st beam – three boxes across for storm sail, anchor, sea anchor [all neatly away], behind that the ship’s dinghy crossways, suspended half above and below deck on seatbelt webbing for lowering, then decking.

8.  Aft of 2nd beam – living deck [planking] but traveller hawse across near rear for Main 1. Aft of 3rd beam – deck [planking], then two boxes port and stbd, clear of tiller, for drogue and tools.

9. Two masts, each 23ft and 21ft, bowsprit and bumpkin, four sails – yankee, jib, main, mizzen.

Two balance lugsails

10. Estimated speed: upwind maybe 8 knots with leeboard, beam reach maybe 14 knots, downwind not a lot less, cruising 10-12 knots [who needs more?].

11. This craft is not meant to go about easily – it was designed to track, not to be able to pivot. To go about, it would have to be sailed about and foremain kept backwinded until around. Small price to pay.

Gaffrigged – the route I’m going

7 comments for “For aficianados

  1. October 8, 2012 at 19:38

    Had an inkling no one would comment on this. LOL.

  2. ivan
    October 8, 2012 at 20:52

    Had an inkling no one would comment on this. LOL.

    The only question I have is, where are you going to build it? After all it is not the sort of thing you can build in your living room is it?

    That being said, I did help a friend build a 35m steel cat on the old docks on Sydney harbour in the 70s. It took almost two years, he had money to burn and I had the time.

  3. October 8, 2012 at 21:25

    Have the place to build it – that came first. 35m’s not small.

  4. ivan
    October 8, 2012 at 23:32

    I think it had to be that length to fit the two 900HP diesel engines, two 10kW diesel generators and all the other mechanical parts.

    If memory serves me correctly it was a design he got from an American designer based on the design in Boating sometime in 69. I think the displacement was in the region of 80 tons and had a range of about 1500 miles before refuelling. Again from memory headroom was over 6ft 6in everywhere. Beyond that memory becomes a little vague although I do remember the fun we had fitting the rather large variable pitch props and the two bow thrusters.

  5. JD
    October 8, 2012 at 23:39

    it’s aficionados James – and you an English teacher tsk tsk 🙂

    (aficionado = Spanish word meaning a lover of la corrida de toros)

  6. October 9, 2012 at 07:42

    and you an English teacher

    Yes but not a Spanish teacher. Also, the meaning for the English speaker is:

    I agree though that foreign imports should be in their transliterated or original form, e.g. München for Munich, Moskva for Moscow.

  7. October 9, 2012 at 08:05

    Again from memory headroom was over 6ft 6in everywhere.

    Well Ivan, as an engineer, you’d know that headroom should start being over 6 feet around 40 feet long and 6’6″ would make the craft around 70 feet long if all is in proportion, motor or sail. Yours was 35 metres.

    This is the issue with 31ft – one really can’t give standing headroom [6’2″ in most craft] without it becoming tubby and slabsided. Cats have that tendency unfortunately and it militates against primary stability, as well as being ugly. The vanishing stability of a cat anyway is unacceptable.

    I was looking at some designs in youtubes yesterday and was struck by how appallingly tubby they were. One was a promo for a luxury cat and the thing was hobbyhorsing [lightly] in two foot waves and about 7 knots of breeze. It was rolling around like a drunk man.

    When I saw the hull profile, I wondered that such people called themselves designers and engineers. Mustn’t name names but few designers stand out.

    Wharram, on the other hand, whose cats are known as “hippy” cats because they are low tech, has designed them from the stance of the man who originated cats as an acceptable form in the west for everyday transportation. He designs in his experience.

    That hobbyhorsing is not really his fault. When you go deep in the midsection, unless you do similar at bow and stern [or at least at bow], plus you design fine lines which bob up and down rather than smash and slap on the water, you pay with rocker, which causes hobbyhorsing and pitching.

    It’s a pain in the butt, design. Don’t know if I love it or hate it.

    On the 31ft [necessarily the limit for design reasons in the rig], there is only 6’2″ in the cockpit and in one companionway in one place]. The rest are 5’2″ and even then it’s at its limit for height.

    Don’t know if you’re interested but I got away [I hope] with that by making it double-chined and then colouring the vertical panel light and the others dark, with the gunwhale and cabin roof light again. Wharram colours his undersides black.

    That goes against all recommendations [upended boat safety etc]. Presumably he doesn’t expect his designs to go over. Truth is – there’ve been thousands of them, even through cyclones and they don’t go over. One gains that with a certain ugliness. Sigh.

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