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Catamaran vs mono-hull

Something I noticed on this leg of my cruise is the radical diff tween
the wakes of mono and catamaran hulls for power boats. The monos have
huge wakes while the cats have very small wakes. This should give
better fuel economy. Does it?

Catamaran vs mono-hull

On Fri, 2 Apr 2010 14:28:48 -0700 (PDT), Frogwatch
wrote:

Something I noticed on this leg of my cruise is the radical diff tween
the wakes of mono and catamaran hulls for power boats. The monos have
huge wakes while the cats have very small wakes. This should give
better fuel economy. Does it?

It absolutely does. The less water you push aside the better from
the standpoint of efficiency. One of the big cruising trends we are
seeing this year is the increase in multi-hull sailboats. There are
hundreds of them just here in Martinique and it looks like they will
be in the majority sooner or later.

Catamaran vs mono-hull

On Apr 2, 4:13*pm, Wayne.B wrote:
On Fri, 2 Apr 2010 14:28:48 -0700 (PDT), Frogwatch

wrote:
Something I noticed on this leg of my cruise is the radical diff tween
the wakes of mono and catamaran hulls for power boats. *The monos have
huge wakes while the cats have very small wakes. *This should give
better fuel economy. *Does it?

It absolutely does. * The less water you push aside the better from
the standpoint of efficiency. * One of the big cruising trends we are
seeing this year is the increase in multi-hull sailboats. *There are
hundreds of them just here in Martinique and it looks like they will
be in the majority sooner or later.

Waht about harsh side winds? Can you flip one?

Catamaran vs mono-hull

On 4/2/10 6:13 PM, Wayne.B wrote:
On Fri, 2 Apr 2010 14:28:48 -0700 (PDT), Frogwatch
wrote:

Something I noticed on this leg of my cruise is the radical diff tween
the wakes of mono and catamaran hulls for power boats. The monos have
huge wakes while the cats have very small wakes. This should give
better fuel economy. Does it?

It absolutely does. The less water you push aside the better from
the standpoint of efficiency. One of the big cruising trends we are
seeing this year is the increase in multi-hull sailboats. There are
hundreds of them just here in Martinique and it looks like they will
be in the majority sooner or later.

Sorta depends upon the boats, their designs, their weights, and how they
are used. For example, a 32' WorldCat, with two F250 Yamahas, weighs
about 8000 pounds and at 4000 rpm produces 26.4 mph and burns 26.4 gph.
A Scout with the same engines that weighs nearly a ton more burns about
the same gph and produces a few more mph for the same fuel burn.

Of course, the question was about mono and cat hulls for power boats,
not "multi-hull sailboats," eh?

--
http://tinyurl.com/ykxp2ym

Catamaran vs mono-hull

On 4/2/10 6:30 PM, hk wrote:
On 4/2/10 6:13 PM, Wayne.B wrote:
On Fri, 2 Apr 2010 14:28:48 -0700 (PDT), Frogwatch
wrote:

Something I noticed on this leg of my cruise is the radical diff tween
the wakes of mono and catamaran hulls for power boats. The monos have
huge wakes while the cats have very small wakes. This should give
better fuel economy. Does it?

It absolutely does. The less water you push aside the better from
the standpoint of efficiency. One of the big cruising trends we are
seeing this year is the increase in multi-hull sailboats. There are
hundreds of them just here in Martinique and it looks like they will
be in the majority sooner or later.

Sorta depends upon the boats, their designs, their weights, and how they
are used. For example, a 32' WorldCat, with two F250 Yamahas, weighs
about 8000 pounds and at 4000 rpm produces 26.4 mph and burns 26.4 gph.
A Scout with the same engines that weighs nearly a ton more burns about
the same gph and produces a few more mph for the same fuel burn.

Of course, the question was about mono and cat hulls for power boats,
not "multi-hull sailboats," eh?

Err, make that about 16.1 gph for the fuel burn on both boats...

--
http://tinyurl.com/ykxp2ym

Catamaran vs mono-hull

On 4/2/10 6:15 PM, Tim wrote:
On Apr 2, 4:13 pm, wrote:
On Fri, 2 Apr 2010 14:28:48 -0700 (PDT), Frogwatch

wrote:
Something I noticed on this leg of my cruise is the radical diff tween
the wakes of mono and catamaran hulls for power boats. The monos have
huge wakes while the cats have very small wakes. This should give
better fuel economy. Does it?

It absolutely does. The less water you push aside the better from
the standpoint of efficiency. One of the big cruising trends we are
seeing this year is the increase in multi-hull sailboats. There are
hundreds of them just here in Martinique and it looks like they will
be in the majority sooner or later.

Waht about harsh side winds? Can you flip one?

Of course not:

Foncia capsizes off Lorient – Alinghi crew safe

[Source: Alinghi] AT 11:30 this morning, in 20 plus knots and a lumpy
Atlantic swell, the 60ft trimaran Foncia capsized off Lorient with
Alinghi sailors onboard. Of the 10 crew onboard, Piet van Niekerk and
Francesco Rapetti were airlifted to hospital, both are safe and with no
serious injuries. The rest of the crew along with consultant Alain
Gautier were involved in securing the boat and towing it ashore, the
sailors are shaken but unhurt.

Ed Baird, who was onboard, provides some insight into what happened: “As
we were bearing away, always the highest risk situation on a multi-hull,
both the leeward and the central hull dug into the water and the rudders
came out. From then it was out of our hands and we capsized forwards. As
the mast hit the water, it broke, followed by the rear beam.” He
continues: “The crew reacted very quickly in getting everyone back on
board, doing a head count and checking injuries before calling for help
and beginning to secure the boat.”

Foncia is currently being towed into the harbour upside down to be
craned out and assessed for damage. “We have all been through crashes
and capsizes before, this is all part of the sport,” says Ed Baird,
adding “however this is a temporary situation with Foncia and is not our
equipment, so it is even more disappointing to us that we are involved
in damaging someone else’s gear. We have learned a valuable lesson here
and now must get to work to fix things up for Alain [Gautier].”

Of course, this was a trimaran...but...

--
Conservatives - just pretend Obama's health care legislation is another
unnecessary war and you'll feel better about it.

Catamaran vs mono-hull

Tim wrote:
On Apr 2, 4:13 pm, Wayne.B wrote:
On Fri, 2 Apr 2010 14:28:48 -0700 (PDT), Frogwatch

wrote:
Something I noticed on this leg of my cruise is the radical diff tween
the wakes of mono and catamaran hulls for power boats. The monos have
huge wakes while the cats have very small wakes. This should give
better fuel economy. Does it?
It absolutely does. The less water you push aside the better from
the standpoint of efficiency. One of the big cruising trends we are
seeing this year is the increase in multi-hull sailboats. There are
hundreds of them just here in Martinique and it looks like they will
be in the majority sooner or later.

Waht about harsh side winds? Can you flip one?

Doubtful where you'll be boating. If winds get 30-50 knots while you're
out on the river, the bimini will probably rip before it can lift a
toon. If it's too windy for the bimini, take it down.
Wind will push you much more than a keeled boat, but one of the fuel
advantages of the pontoons is not pushing water aside.
Wind can work for you, or against you more in a pontoon boat than a
deeper keeled boat.

Jim - Likes to talk about boats when not hammering libs.

Catamaran vs mono-hull

On Fri, 2 Apr 2010 19:35:35 -0700, "CalifBill"
wrote:

On a planing hull, maybe not much difference in fuel burn, but still have to
move water. On a displacement hull, thedifference will be dramatic. Yoou
have pretty much effectively double the hull length, giving a higher hull
speed. This should add both performance and fuel economy.

The secret to catamaran efficiecy is light weight combined with a high
length to width (beam) ratio. A typical ratio for either a
displacement powerboat or sailboat is about 3:1. The hull of a
catamaran however might be twice that or even greater. At high
ratios the formula for hull speed goes out the window because wave
making/hull drag is greatly reduced similar to what you'd experience
with a canoe hull or a rowing shell. Basically you can think of it as
being more streamlined. Naval architects refer to it as a lower
prismatic coefficient.

With regard to capsize issues, most cruising sail cats are under
rigged with short masts and small sails. That greatly decreases the
liklihood of becoming overpowered in a wind gust.

I've never heard of a power cat capsizing but it certainly could
happen with the right wave conditions, as it can with any other
powerboat.