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wrote:
Most of the monohull sailors that I know who have sailed cats, complain
that the combined bow waves meet under the bridge deck creating a very
uncomfortable pounding. This effect is said to worsen as wave height
increases. It would seem that the higher off the water the bridge deck
the less this would be of concern but there are obvious limits to this
approach.

My question- Is this an issue with tri's I would also be interested
in input from cat sailors as to how much this is an issue with their
boat and is the only solution increased height for the bridge deck?

thanks sk

I've got a 40' cat with bridgedeck clearance of about 2' (depending on
the load). In sheltered waters around here the biggest waves I've
seen are about 4-5' (heading into them beating). Only ever slapped
the bottom very lightly a few times. Friends with a cat with less
clearance said that big waves jarred their fillings. After some
modifications, the clearance will be about 2'3" when fullly loaded.

The usual rule of thumb is 0.05 LWL is about enough clearance on a cat
for offshore sailing. More is of course better! There will always be
conditions that will cause a particular cat to slap/slam, but you're
trying to minimize that by having enough clearance. Geminis, PDQ 36s,
most South African cats in Caribbean charter service do not have
enough clearance (Moorings/Leopard). Maybe they were sailing these?
The French cats generally do have enough clearance.

I would take the motion of my boat beating to windward in moderate
seas over any comparable size monohull. My daughter can stack
dominoes on their short edge about 4 high before sea motions cause
them to collapse.... We *once* spilled a glass of orange juice in a
bad wave and was cause for great excitement. You get the idea.

Regarding tris, the smaller folding type Farrier tris have issues with
the lower folding struts hitting waves, but this only produces spray,
not slamming. Older Piver/Searunners with solid wings sometimes have
this trouble when heavily loaded, but I have less direct and anecdotal
information about them.

Evan Gatehouse