Cruising World Article

[Cheechako]

A couple quick inputs:
We went from a 47 foot Perry designed mono to a 42 ft cat which had keels.
The cat and mono were on each side of a finger pier when we moved onto the cat.
We transferred all gear from the Mono, across the dock to the cat.
The Mono was down 5.5 " on the waterline when loaded. The cat went down less than 2" on the water line.
We cruised with friends who had a custom Perry designed aluminum double ender. In general they were usually slightly better CMG going to weather. One day sailing the south coast of Puerto Rico comes to mind as a good test. We sailed several hours that day from a close reach to beating. Anything less than a close hauled beat I could keep up with them. On the nose we lost a bit to them, but by cracking off made excellent speed going faster and nearing their CMG.
Bottom line, At the end of the day they were slightly ahead of us. By a matter of minutes.

[44'cruisingcat]

Originally Posted by yeloya

I agree..
On the other hand,it wouldn't be fair to put cruising monos and daggerboard cats on the same category anyway.. Remember, I said, "apple to apple"..

Cheers

Yeloya

Plenty of people cruise on daggerboard boats. Many are designed primarily as cruising, or "performance cruising" boats.

The distinction I added for "crusing mono's" was to exclude the big racing canting keelers, which also have canted daggerboards, canards etc, and probably have very little leeway.

[44'cruisingcat]

Originally Posted by Caribbeachbum

Overall this is one of the best comparisons I've read, probably due to your having cruised in both types of yachts. My wife and are are shopping for our last boat (III) and we are considering catamarans for the first time, so I thank you for it.

.

You're welcome, but I feel I should point out that while I posted this article, I didn't write it. It's an article from Cruising World.

However I have owned, raced, cruised and lived aboard both cat' and mono, and do agree with most of what the article says. Which is why I posted it.

[Caribbeachbum]

Originally Posted by SV DestinyAscen

One engine motor sailing isn't a hearsay friend of a friend claim. Since forces required to overcome drag isn't linear but closer to exponential, and fuel consumption is also a product of engine compression losses/rotational mass, one engine motor sailing saves fuel vs two engines.

Not trying to be argumentative, I sincerely do not see how your conclusion is derived from your arguments.

In the context of drag, using only one engine on a catamaran mostly likely makes for increased drag versus using both engines. The off-axis thrust creates moment that must be countered by a few degrees of rudder, and that is additional drag that wouldn't be present when operating both engines.

[Caribbeachbum]

Originally Posted by Andrew Grace

The one engine compares vs 2 is only relevant when comparing the Cat to Cat performance.

i.e: on one engine only our cat will do 5 knots at 3 Litres per hour consumption but when 2 engines are run at the same time the top speed only increases to 7.3 knots which means you only get 2.3 knots of extra speed for burning the additional 3 Litres , so for long haul trips its far better to just run the single engine but have the 2nd available for the extra punch and manoeuvrability for when docking or adverse currents.

Well yes, but as soon as your comparison went from 5kts to 7.3kts, the discussion ceased being about fuel efficiency and started being about operator efficiency. That is probably the more important discussion, it's just not the one we started with.

[smj]

The way I see it is you want to know if running 2 motors at reduced rpm would burn less fuel than running 1 motor at cruising rpm making the same speed? That's a good question and something I've never tried. I can't think of any positives to doing that unless there was a significant fuel savings. The negatives as someone else pointed out is that you are now doubling your maintenance, and in my opinion putting undue wear on both motors as they aren't being worked hard enough which in the long run would be bad for both motors.


Sent from my iPhone using Cruisers Sailing Forum

[SV DestinyAscen]

Originally Posted by Caribbeachbum

Not trying to be argumentative, I sincerely do not see how your conclusion is derived from your arguments.

In the context of drag, using only one engine on a catamaran mostly likely makes for increased drag versus using both engines. The off-axis thrust creates moment that must be countered by a few degrees of rudder, and that is additional drag that wouldn't be present when operating both engines.

Shrug - if you think the drag by a few degrees of rudder will be less efficient you can test it out yourself.

My experience is I'd rather run one engine at higher rpm within its efficient range than have two engines at lower rpm at the same boat speed. Your fuel consumption increases just to keep an engine going (say 0.8liters per hour idle) - which is being used to power pumps/move water/overcome rotational mass and keep things spinning.

[donradcliffe]

I don't think the article is unbiased.

I think that a better comparison of the speed and living space is based on cost, not boat length. The Dolphin 460 was nearly $1 million new, and a ten year old boat is $500k. You can get a lot longer monohull for that kind of money.

The part on capsize is BS. The flat water wind speed limit for full sail on that boat is more like 33 knots than 50+. Sizing the rigging to fail before capsize is another alternative fact that has been debunked.

I would never go back to a heavy full-keeled mono either. My choice would be a performance mono.

[Cheechako]

Originally Posted by Caribbeachbum

Not trying to be argumentative, I sincerely do not see how your conclusion is derived from your arguments.

In the context of drag, using only one engine on a catamaran mostly likely makes for increased drag versus using both engines. The off-axis thrust creates moment that must be countered by a few degrees of rudder, and that is additional drag that wouldn't be present when operating both engines.

OTOH...using the lee engine at high idle when going to weather points the cat up maybe 15 degrees....

[44'cruisingcat]

Originally Posted by Caribbeachbum

Not trying to be argumentative, I sincerely do not see how your conclusion is derived from your arguments.

In the context of drag, using only one engine on a catamaran mostly likely makes for increased drag versus using both engines. The off-axis thrust creates moment that must be countered by a few degrees of rudder, and that is additional drag that wouldn't be present when operating both engines.

It's 1-2 degrees of rudder.

[44'cruisingcat]

Originally Posted by donradcliffe

I don't think the article is unbiased.

And of course you are?

[donradcliffe]

Originally Posted by 44'cruisingcat

And of course you are?

Since I currently don't own either a cat or mono that I am trying to promote for its resale value, I am a lot less biased than you.

[44'cruisingcat]

Oh rubbish. Anyway, I don't claim to be unbiased. I've owned both. I know which I prefer.


And if I wanted to get back into a mono it would be so easy. They're so cheap. It's almost as if nobody wants them.

[Factor]

Originally Posted by Caribbeachbum

Not trying to be argumentative, I sincerely do not see how your conclusion is derived from your arguments.

In the context of drag, using only one engine on a catamaran mostly likely makes for increased drag versus using both engines. The off-axis thrust creates moment that must be countered by a few degrees of rudder, and that is additional drag that wouldn't be present when operating both engines.

ah - no. Apart from the fact that the that any reasonable cat will have efficient lateral slip devices in play anyway, use the leeward motor, you counteract leeway that is being generated by the sails, so little or no overall effect. Dont believe me? get on a decent cat and do it. I was motor sailing (on one engine) on Saturday for a few hours on one engine and the rudder position indicator was showing dead centre. Of course once the wind got to 7 knots we were sailing and at 9 knots we were happy at 6.5, cause even that one engine was off.

[Factor]

Originally Posted by donradcliffe

I don't think the article is unbiased.

I think that a better comparison of the speed and living space is based on cost, not boat length. The Dolphin 460 was nearly $1 million new, and a ten year old boat is $500k. You can get a lot longer monohull for that kind of money.

The part on capsize is BS. The flat water wind speed limit for full sail on that boat is more like 33 knots than 50+. Sizing the rigging to fail before capsize is another alternative fact that has been debunked.

I would never go back to a heavy full-keeled mono either. My choice would be a performance mono.

Good for you. So you are passing postulated judgements in the multi section because?