Catamaran vs Monohull... advantages, disadvantages?

[mrcarson]

Over the yrs I've been floating around. I've had Timber yachts. One 32ft concrete Hartley. (GREAT heavy weather boat but slooooow). One Fibreglass. Bouncy bloody things. and 2 Serious Steelies made in shipyards for themselves to cruise round. Been out in cats up to 72 ft. and lots plastic racers. They bounce all over the water. A decent steelie goes through the water. much more stable and easy to walk around on. Plus bouce off containers going down waves, I did in 35knots off Tassie from Adelaide.
I single hand 99% of time. NO crew. No responsibility for anything. and my dogs then cat are much better company. I usually only go out in plus 20 knots 32ft 8 1/2 ton then 42ft 17 ton steelies. 32 ft Pugh I often saw 7/7+ knots and 42 Pugh gave me 11 once. Surfing in South Australian winter storms. 100mile south of S.Aust. Inner staysail and triple reef main. I like stability and going through the water. not making like a cork.
Watching those plastic boats and cats bouncing over the water when it's bumpy and me just gliding along. I KNOW which I prefer.
PLUS. I go sailing to enjoy doing it. Same as running. we used to turn round at end of these marathons and halves and run back to the cars. The doing of is much more enjoyable than racing there then stopping. Even after 71 yrs floating on the water. I'd still go out tomorrow. If I could.
If you like bouncing over the water at speed. with oceans of room on board. Go Plastic or cats.
If you like comfort at sea. and safety. Steelies every time. Specially AFTER you hit a container or tree running down a decent wave. It certainly changes your perspective on things.
Anything other Than decent steel, even ally would probably have split. I'd have gone down. It stopped 17 ton DEAD. and the whole boat shuddered. Mast made a figure S, my arse twitched. But. Just a ding in the 8mm pate t/ween 2 ribs I could lose my fist in. That was the fastest I ever got below to look for a hole in any boat. Bone dry. But I cut out and replaced a 2 ft x 1 ft pice of 8mm plate when I hit Strahan.

Have fun choosing. as long as you sail PROPERLY with common sense AND good maint on vessel. You'll love it.
Even the bits when your arse is twitching. your mouth dry and you wish you were somewhere else. Like a Sth AUstralian Winter storm 60ish miles South of the coast. 3 days of 50plus knots from the South/South East. with whole Southern Ocean to build up on coming up from the Antarctic. Masthead waves with holes the same size behind near ever whitecap roller pushing you. Exhilarating for a while but Far-... After the first day. Biggest thing was having a crap.

[Chotu]

^^^^. Momentum imparts energy to the surface of the hull when you hit something. This argument falls short because it doesn't considering momentum.

To illustrate the point:

Which is "stronger?". A steel car or a piece of paper?

A steel car, right?

What would do better in a 30 mph collision with a brick wall? A steel car or a ball of paper?

We all know the car loses structural integrity and the paper does not and bounces right off.

Heavy boats are not better in collisions. They are worse.

Assuming you build the same hull able to withstand the same forces normal use in the sea puts on the hull, building it lighter reduces the forces put onto the hull skin and structural members by reducing the momentum/energy involved in an impact.

This is how my boat survived a serious hurricane where the entire mooring field let go and smashed all the boats against the seawall. Several sank. There was a lot of damage. Mine was cosmetic only because I didn't have the momentum relative to normal seagoing structural integrity to cause structural damage or puncture the hull.

A lighter boat is a WAY more safe boat. Especially if potential sinking is involved.

What's the most seaworthy thing you've ever seen on the water?

It's a piece of styrofoam. That survives any and all things the ocean can throw at it.

[AuChante]

Originally Posted by Chotu

^^^^. Momentum imparts energy to the surface of the hull when you hit something. This argument falls short because it doesn't considering momentum.

To illustrate the point:

Which is "stronger?". A steel car or a piece of paper?

A steel car, right?

What would do better in a 30 mph collision with a brick wall? A steel car or a ball of paper?

We all know the car loses structural integrity and the paper does not and bounces right off.

Heavy boats are not better in collisions. They are worse.

Assuming you build the same hull able to withstand the same forces normal use in the sea puts on the hull, building it lighter reduces the forces put onto the hull skin and structural members by reducing the momentum/energy involved in an impact.

This is how my boat survived a serious hurricane where the entire mooring field let go and smashed all the boats against the seawall. Several sank. There was a lot of damage. Mine was cosmetic only because I didn't have the momentum relative to normal seagoing structural integrity to cause structural damage or puncture the hull.

A lighter boat is a WAY more safe boat. Especially if potential sinking is involved.

What's the most seaworthy thing you've ever seen on the water?

It's a piece of styrofoam. That survives any and all things the ocean can throw at it.

Could be misleading. Things don't scale up linearly. A fiberglass aircraft carrier would probably not be too tough. Mrcarson's examples are well within fiberglass lengths though... weight not so much.
Best way I can think of it is with cars. My pickup weighs 6,000 lbs but my wife's Mazda is 4,000 lbs. That's allot of weight to be a few feet long... with many other considerations in there of course. It's probably a wash in the end. fiberglass is more delicate but lighter, so it could be stronger... this will wind up being a bigger can of worms that the original question.


Genuinely curious: Would you rather be fixing a hole in the middle of the atlantic in a steel or fiberglass boat?

[mrcarson]

Originally Posted by AuChante

Could be misleading. Things don't scale up linearly. A fiberglass aircraft carrier would probably not be too tough. Mrcarson's examples are well within fiberglass lengths though... weight not so much.
Best way I can think of it is with cars. My pickup weighs 6,000 lbs but my wife's Mazda is 4,000 lbs. That's allot of weight to be a few feet long... with many other considerations in there of course. It's probably a wash in the end. fiberglass is more delicate but lighter, so it could be stronger... this will wind up being a bigger can of worms that the original question.


Genuinely curious: Would you rather be fixing a hole in the middle of the atlantic in a steel or fiberglass boat?

Answer... A steel boat. easier to drill holes and adhesive a plate then screw it. Also easy to weld internally if you have small welder/genny with you.
Just get a tarp over the outside first to minimise any water flow. Water pressure will hold it there.
PS. A Steely can carry lots of crap a lightweight plastic can't.

Boats bumping. Steel. EVERY time. MY last 2 were.

[aqfishing]

Originally Posted by mrcarson

Answer... A steel boat. easier to drill holes and adhesive a plate then screw it. Also easy to weld internally if you have small welder/genny with you.
Just get a tarp over the outside first to minimise any water flow. Water pressure will hold it there.
PS. A Steely can carry lots of crap a lightweight plastic can't.

Boats bumping. Steel. EVERY time. MY last 2 were.

Nothing takes the sea like steel boat, no argument there. However steel does also sink VERY fast! Welding a patch with water coming in is a hell of a lot harder than you think. Stopping it is also not easy, unless you in very calm sea and have scuba gear.

[mrcarson]

Quick answer.
8mm in plate From above Waterline down to keel. Keel sides 1/2in. 1 in bottom plate. 2 in solid round bar stempost to keel toe. Plates Fully welded to that. 6 and 5mm plates above that. 32ft built to go round the world. First stop Antarctic waters. Built by 2 x shipwrights in Whyalla Shipyard from ship steel plates.She had a 38ft stick/17ft 6in boom. and actually sailed quite well, lengthened waterline. Broader transom and Stern waterline. I could pass a Duncanson 29 in light airs and they are known to be good at it.
She was built like a racing tank and every ton of ballast dropped her just on 1/2 deeper draught.
PS. Scuba Gear? 70 yrs at sea and I can't even swim yet. I trust my boats for that and used to go Pointer and Tiger shark fishing when younger..
Get IN water that contains them. Yea!!!!!!. In your dreams mate.

[smj]

Originally Posted by mrcarson

Quick answer.
8mm in plate From above Waterline down to keel. Keel sides 1/2in. 1 in bottom plate. 2 in solid round bar stempost to keel toe. Plates Fully welded to that. 6 and 5mm plates above that. 32ft built to go round the world. First stop Antarctic waters. Built by 2 x shipwrights in Whyalla Shipyard from ship steel plates.She had a 38ft stick/17ft 6in boom. and actually sailed quite well, lengthened waterline. Broader transom and Stern waterline. I could pass a Duncanson 29 in light airs and they are known to be good at it.
She was built like a racing tank and every ton of ballast dropped her just on 1/2 deeper draught.
PS. Scuba Gear? 70 yrs at sea and I can't even swim yet. I trust my boats for that and used to go Pointer and Tiger shark fishing when younger..
Get IN water that contains them. Yea!!!!!!. In your dreams mate.

One mans dream is another mans nightmare.

[chrisr]

as someone who spent my working life maintaining steel ships, there is NO way i would have a steel boat for fun

i know they have their good points, but imho the good lord showed his sense of humour when he decided that the only thing that makes sense to build ships out of, rusts like fury in salt water...

cheers,

[Jim Cate]

i know they have their good points, but imho the good lord showed his sense of humour when he decided that the only thing that makes sense to build ships out of, rusts like fury in salt water..

And his sense of fair play when he decreed that timber floats in salt water, and that the salt helps to preserve it.

If only he hadn't thought of varnish...

Jim

[chrisr]

Originally Posted by Jim Cate

And his sense of fair play when he decreed that timber floats in salt water, and that the salt helps to preserve it.

If only he hadn't thought of varnish...

Jim

to be fair, he did give us fiberglass to compensate

cheer,

[mrcarson]

Originally Posted by chrisr

as someone who spent my working life maintaining steel ships, there is NO way i would have a steel boat for fun

i know they have their good points, but imho the good lord showed his sense of humour when he decided that the only thing that makes sense to build ships out of, rusts like fury in salt water...

cheers,

Jim.
NEVER Varnish Inside or out. OIL your timbers every 6 months with a hand cloth. Works a treat.
Christ.
Ship steel. ALL Plates hot dipped with Galv, b4 welding up. Vinyl Tar right through interior of hull/keel. Then insulation, cladding, fittings etc.
Keel internal. Lead Ballast block to suit. Suspended off bottom of keel ribbing with S/S long bolts. They whole cavity filled with 44+ gallons of old OIL Based paint. to harden, seal from moilsture and movement. marine primer ext over Galv outside. then top coat and A/F. (eplaced every 12/15 months in Australia).
Then I slipped. Grit Blasted to "grey" to just above W.L. then reprimed, A/F over every 8/9 yrs.
Built in '85. Bought in ;88. Used near eyery day of ownership. Retired in '94 and mainly lived on her from there.
Rerigged standing every 8/9 yrs. sails changed every 5 to 7 yrs. as needed. She worked hard. Safely and gave me a LOT of enjoyment. All Heavy weather.
She was built in Whyalla Shipyard by 2 x Boilermaker/shipwrights, for themselves.
You could see different styles of welding on each side of hull. ALL Full. NO Stitching.
If they were ALL built like that, there would be a lot more around, Believe me.

[double u]

"...What would do better in a 30 mph collision with a brick wall? A steel car or a ball of paper?..."

...& I had thought this type of "argumentation" & "evidence" was reserved for other types of fora...

[Drunkonwatch]

Originally Posted by chrisr

as someone who spent my working life maintaining steel ships, there is NO way i would have a steel boat for fun

i know they have their good points, but imho the good lord showed his sense of humour when he decided that the only thing that makes sense to build ships out of, rusts like fury in salt water...

cheers,

100% not my idea of cruising as well the Maintenance regiment is lame having spent a fair amount of time with steel boats. Aluminum though………