[MHml] Catamarans

[Dave Culp]

So, riddle me this, o learned one. Why is a seagul striker typically
aligned vertically, and not in line with the force it is resisting,
which is parallel with the forestay? A simple answer might be that the
typical crossbeam is elliptical, with sufficient bending resistance in
a fore-aft direction, but really, wouldn't it make more sense to align
the striker with the force itself?

Just wondering...

Dave

On 9/7/06, Roy Mills <rsirfj at shaw.ca> wrote:
> At 12:33 PM 9/7/06, you wrote:
> >And here, I was going on the rather pedestrian viewpoint that a striker of
> >either family was actually an extension of one of the horizontal beams and
> >not the sprit at all.
> >
> >Apparently, it is also referencing any vertically aligned structural element
> >that gives triangulated strength to any given beam component. Note to self:
> >fix terminology filings.
>
>          Well said Chris. I was going to have chipped in to say that
> a dolphin striker in my experience is a downward pointing pole, with
> a mast step on top and a wire or other metal bracing element
> underneath, the pole taking the pressure from the mast and
> transfering it down to the metal brace underneath, which in turn
> transfers the strain back up to a strongpoint on each hull.  Dolphin
> strikers originally were found on old time ships which had a pole
> pointing downwards underneath the bowsprit or jib boom to give a
> better angle of resisting pull to a line leading from the end of the
> sprit or boom back to the bow. The bowspit or jib boom was being
> pulled upwards by tension from stays or halyards from foresails
> fastened to it, so the dolphin striker helped resist that upward
> pull. Since dolphins played around the bows of ships and the downward
> pointing pole often plunged into the sea as the boat  pitched, it
> became called the dolphin striker, in joke.
>
>           Catamarans need a similar triangulated structure to brace
> the front crossbeam against the pull of the foresail and jib halyard
> . In this case the pole points upwards and presses against the centre
> of a wire bridle leading from one end of the front crossbeam to the
> other, so it is called a seagull striker.
>
>          And no, I don't think we automatically call a cruising
> catamaran ugly, it is just that to get all that accomodation and
> standing headroom into the available dimensions they tend to look
> somewhat clumsy in comparison with one which is not built for charter
> but for greater speed and can look more graceful.
>
>           You will soon get the hang of the names of the sails and
> rigging, most of them go back hundreds of years to rather different
> boats, but tradition being what it is, the old names still get used,
> like dolphin striker.  Seagull striker is a newly coined name based
> on that old one to suit something sticking up into the air rather
> than down towards the sea.
>
>          I can't comment on Rolly Tasker sails these days. Some years
> ago their reputation was for quite good sails at a low price,
> therefore good value for money on that basis, but not the best sails
> for a more demanding sailor.
>
>          Roy Mills
>
>
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