Many modern catamarans incorporate these features already.

Paul Oman wrote:

Seems to me that watertight bulkheads forward of the mast,
aft of the forward cockpit, and watertight floorboards
(lots of stories of water rising up thru the floorboards)
would be life/boat saving design elements.

Most cats have collision bulkheads forward. Mine has 4 watertight
compartments forward, and two aft. Also, with no keel and foam
construction, its virtually unsinkable.


Also, engine
and batteries in water tight compartments vented to the
deck (always - rising water kills the engine and or
electric pumps/radio).

Many cats have this - and with two engines the odds are further improved.



Maybe even a watertight companionway hatch so that the
entire main cabin could become a giant air chamber....


A bit problematical ... a singlehander might want to seal himself in for
the southern ocean, but most folks want easy access to deck.



If not watertight bulkheads, how about inflatable airbags
in the cabin to keep the hull afloat?

This can be done for some boats, but ocean cruisers often chose very
heavy boats, making this difficult to implement. A 6000 pound keel
requires about 100 cubic feet of flotation - that's a 5 foot cube for a
fairly modest boat!



On more unconventional design considerations - bilge keels
would have keep many of the boats I read about from
pounding their topsides to death on reefs or beaches. I
know bilge keels have there faults (I've read about
everything I could find on bilge keel cruisers) but a boat
that reduces draft when not heeled over and sits upright
could be a real life saver.

Again, cats incorporate bilge keels. Many cats have "sacrificial keels"
and will "reduce their draft" from 3 feet to 2 automatically when
passing over a reef!



Even more radical might be a A frame type mast (ie. sold
shrouds, no center mast) would keep the rigging in place
after a roll-over/broach much better then a stick with
wire rigging.

I'm curious - is there any evidence for this?



Anyway, I'm surprised more offshore boats aren't resigned
or retro-fitted for max survival. As I read this book it
made me realize these aren't just boats, often they are a
couple's home for decades (and lost in minutes). Surely a
few watertight bulkheads and watertight/airtight hatches,
while probably a pain to deal with on a day to day basis,
could keep you alive and your home/boat afloat.

Some of the modern cruisers have some of these features. And the long
distance racers have many of them. But, a large number of world
cruisers are using boats built 30 years ago. Most new boats never leave
protected waters, and even the ambitious cruisers usually are actually
island hopping. Statistically, there's a rather small market for this.

"Jeff Morris" wrote in message
...
Many modern catamarans incorporate these features already.

Paul Oman wrote:

Seems to me that watertight bulkheads forward of the mast,
aft of the forward cockpit, and watertight floorboards
(lots of stories of water rising up thru the floorboards)
would be life/boat saving design elements.

Most cats have collision bulkheads forward. Mine has 4 watertight
compartments forward, and two aft. Also, with no keel and foam
construction, its virtually unsinkable.


Also, engine
and batteries in water tight compartments vented to the
deck (always - rising water kills the engine and or
electric pumps/radio).

Many cats have this - and with two engines the odds are further improved.



Maybe even a watertight companionway hatch so that the
entire main cabin could become a giant air chamber....


A bit problematical ... a singlehander might want to seal himself in for
the southern ocean, but most folks want easy access to deck.



If not watertight bulkheads, how about inflatable airbags
in the cabin to keep the hull afloat?

This can be done for some boats, but ocean cruisers often chose very heavy
boats, making this difficult to implement. A 6000 pound keel requires
about 100 cubic feet of flotation - that's a 5 foot cube for a fairly
modest boat!



On more unconventional design considerations - bilge keels
would have keep many of the boats I read about from
pounding their topsides to death on reefs or beaches. I
know bilge keels have there faults (I've read about
everything I could find on bilge keel cruisers) but a boat
that reduces draft when not heeled over and sits upright
could be a real life saver.

Again, cats incorporate bilge keels. Many cats have "sacrificial keels"
and will "reduce their draft" from 3 feet to 2 automatically when passing
over a reef!



Even more radical might be a A frame type mast (ie. sold
shrouds, no center mast) would keep the rigging in place
after a roll-over/broach much better then a stick with
wire rigging.

I'm curious - is there any evidence for this?



Anyway, I'm surprised more offshore boats aren't resigned
or retro-fitted for max survival. As I read this book it
made me realize these aren't just boats, often they are a
couple's home for decades (and lost in minutes). Surely a
few watertight bulkheads and watertight/airtight hatches,
while probably a pain to deal with on a day to day basis,
could keep you alive and your home/boat afloat.

Some of the modern cruisers have some of these features. And the long
distance racers have many of them. But, a large number of world cruisers
are using boats built 30 years ago. Most new boats never leave protected
waters, and even the ambitious cruisers usually are actually island
hopping. Statistically, there's a rather small market for this.

First off the sea can and will, on occasion, destroy anything made by man.
So you always need to understand that you can only increase the probability
of survival...you cannot guarantee it. So this all is a game of
statistics...how may dollars are you willing to pay to double the
probability of surviving the next storm you hit? Remember that your
survival is a pretty good bet to start...Maybe 99.5% or more for a
reasonably equipped fibreglass boat conseratively operated. So how many
dollars would you pay to go from 99.5% to 99.75%?

In a bad sea people abandon boats that survive. Many of the existing boats
can easily survive a knockdown or even a roll...though with some damage.
But if caught in a really bad storm that lasts for any significant time
survival becomes difficult whether the boat sinks or not. Life inside a
washing machine is difficult.

Hitting a bad reef is not likely to be survived by bilge keels. Once hung
you best get off quickly or the boat is gone. A reef simply grinds the
bilge keel off. On the other hand a bilge keel is not going to be nearly as
good keeping the top side up as a conventional keel. Bilge keels certainly
have their place in drying harbors and thin water but don't really have
much charm when in the deep blue sea.

Practically you need not be water tight to survive a roll. Normal boat
structures will take some water but not enough to sink them in a roll. You
can set them up so engine and batteries survive most anything. Water tight
is probably overkill.

Water killing the engine generally indicates a bad hole. Sometimes you can
get a huge amout of water into a boat by a simple plumbing failure. In any
case a rip in the hull can still get the engine compartment or some other
required system. You are in big trouble if your fuel tank vents are under
water or your main electrical panel goes.

Jim Donohue