Why Do Catamarans Motor Nearly 100%

[Barra]

Originally Posted by 44'cruisingcat

Not sure how that relates to the comparative honesty of the monohull crews?

But it does show if you're prepared to fudge figures you can make your performance look better than it really is.

Is there prize money up for grabs? I'd imagine there must be given the exorbitant entry fees.

If there's money up for grabs, there's always the chance someone will cheat to get their hands on it.

Dont think there is money directly involved in teh multi fleet anyway. Obviously for catana there was marketing $'s in their eyes but in the lagoon case was just owner ego i guess. He can take those bragging rights to his grave - luxurious AND faster than a catana with race crew!

[admiralslater]

Originally Posted by colemj

I don't think you understood my point. Most of the boats met their design criteria perfectly and floated just fine on their designed waterlines, but changed later due to either "new" models or extra gear. They did not, as you proposed, fail to meet their original designs.

Submerged transoms WERE a purposeful design for many, many boats. I'm talking about transoms that sit in the water, not ones where the bottom step is submerged because of overloading. I don't think any Catana has ever been designed with transoms clear of the water, for example.

So I believe Mr. Slater when he said the extra length was to meet marketing demand for stern steps and not to lift the stern. I don't believe the extra length added much buoyancy, and I have never seen a single PDQ36 that did not have the transom touching the water.

I don't see what a Georgetown race has to do with your argument. Are you just seeking validation that your specific boat design is faster than others? That you keep yours lighter than others? Is this all about racing, or would you like to pit your boat against others when it comes to comforts and space?

Or would you like to keep your wife away from a boat that has a large capacity watermaker, a washing machine and a 10cf freezer?

Or should people who own these boats be shamed for their choices?

Mark

Colemj thanks you got my point exactly . 34 and 36 had almost exactly the same waterline when equipped in the way they were originally intended. I t was only as people insisted on diesels and ac and other high weight items that the line had to move up .I have seen a 36 with moss on the bottom step it was so heavy.

[Mirage Gecko]

Have been considering buying some new or newer sails as mine are 10 years old and have done the equivalent of close to half a circumnavigation.
Now this thread just popped up again and have caught up on some of the posts and I have gleaned from some of the more leaned and prolific posters that clearly know far more than me Cats must infact motor 100% of the time or close to it
So maybe I am wasting money,time and effort replacing my sails and should consider actually taking them down or even further remove them totally from the boat and all the lines etc and save some weight.
Actually as I write I just realised that because the boat is lighter without the sails etc and considering how little I actually sail anyway I could be in for a fairly large reduction in my fuel bill for the year.
Now before I make that decision could someone tell me how much weight will be reduced and more importantly what formula should I use to calculate how much less fuel I will use with the lighter boat.

[downunder]

Originally Posted by colemj

I don't think you understood my point. Most of the boats met their design criteria perfectly and floated just fine on their designed waterlines, but changed later due to either "new" models or extra gear. They did not, as you proposed, fail to meet their original designs.

Submerged transoms WERE a purposeful design for many, many boats. I'm talking about transoms that sit in the water, not ones where the bottom step is submerged because of overloading. I don't think any Catana has ever been designed with transoms clear of the water, for example.

So I believe Mr. Slater when he said the extra length was to meet marketing demand for stern steps and not to lift the stern. I don't believe the extra length added much buoyancy, and I have never seen a single PDQ36 that did not have the transom touching the water.

I don't see what a Georgetown race has to do with your argument. Are you just seeking validation that your specific boat design is faster than others? That you keep yours lighter than others? Is this all about racing, or would you like to pit your boat against others when it comes to comforts and space?

Or would you like to keep your wife away from a boat that has a large capacity watermaker, a washing machine and a 10cf freezer?

Or should people who own these boats be shamed for their choices?

Mark

Excellent comments on catamaran transom design.

[Factor]

Originally Posted by Mirage Gecko

Have been considering buying some new or newer sails as mine are 10 years old and have done the equivalent of close to half a circumnavigation.
Now this thread just popped up again and have caught up on some of the posts and I have gleaned from some of the more leaned and prolific posters that clearly know far more than me Cats must infact motor 100% of the time or close to it
So maybe I am wasting money,time and effort replacing my sails and should consider actually taking them down or even further remove them totally from the boat and all the lines etc and save some weight.
Actually as I write I just realised that because the boat is lighter without the sails etc and considering how little I actually sail anyway I could be in for a fairly large reduction in my fuel bill for the year.
Now before I make that decision could someone tell me how much weight will be reduced and more importantly what formula should I use to calculate how much less fuel I will use with the lighter boat.

If you sell your mast you could probably buy a bit of diesel. I'll give you 250 litres for it, cause I am a good bloke.

[Polux]

Originally Posted by smj

More armchair internet experience.

Yes provided by someone that knows more about cats and multihulls than anybody on this forum, I mean Nigel Irens.
Nigel Irens Design - High Performance Yacht Design. Catamarans, Trimarans, Sail, Power & Racing Boats

https://www.youtube.com/watch?v=eQv1k3CE6hI

[malbert73]

Originally Posted by colemj

I don't think you understood my point. Most of the boats met their design criteria perfectly and floated just fine on their designed waterlines, but changed later due to either "new" models or extra gear. They did not, as you proposed, fail to meet their original designs.



Submerged transoms WERE a purposeful design for many, many boats. I'm talking about transoms that sit in the water, not ones where the bottom step is submerged because of overloading. I don't think any Catana has ever been designed with transoms clear of the water, for example.

So I believe Mr. Slater when he said the extra length was to meet marketing demand for stern steps and not to lift the stern. I don't believe the extra length added much buoyancy, and I have never seen a single PDQ36 that did not have the transom touching the water.



I
Mark

A question I have with no agenda: can anyone explain why any boat that is not designed to plane full time (like powerboat) would be designed with submerged transom? Dragging ass isn't fast, right? My boat loaded with cruising gear just starts to submerge a 1 inch tip of transom at 7+ knots which I assume was intentional by S&S when they designed it. Besides being quieter and more peaceful, must be faster for cats and monos alike not to submerge transoms except at high speeds?


Sent from my iPad using Cruisers Sailing Forum

[2Hulls]

Originally Posted by Boatguy30

But with all things, the proof is in the pudding. Would love to have you all multihullers come to the Georgetown regatta and put the various "theories" to test. Inshore and offshore.

Georgetown? Seriously?

Dave
1st Place Corrected and Elapsed time, all 92 boats on the B courses
2012 SXM Heineken Regatta

[colemj]

Originally Posted by malbert73

A question I have with no agenda: can anyone explain why any boat that is not designed to plane full time (like powerboat) would be designed with submerged transom? Dragging ass isn't fast, right? My boat loaded with cruising gear just starts to submerge a 1 inch tip of transom at 7+ knots which I assume was intentional by S&S when they designed it. Besides being quieter and more peaceful, must be faster for cats and monos alike not to submerge transoms except at high speeds?

The distinction needs to be made between "immersed" transoms and "submerged" transoms. The latter drags ass, while the former has almost no measurable difference.

On very fast boats, immersed transoms are faster. There is physics and engineering behind that, but it is mostly over my head.

I think most designers of cruising boats with immersed transoms make that decision for reasons of hull shape. Free transoms typically have more rocker in the hull shape, while immersed are flatter. Look at Outremer and Catana hulls and you can see they have less rocker than many others. I don't think anyone views Outremers and Catanas as real dogs. Less rocker keeps more buoyancy into play, determines the prismatic shape and decreases the bow-stern rocking in motion. However, it can add more drag - it is all a tradeoff a designer makes.

Once this decision on hull shape is made, then it follows that one either keeps the transom immersed, or goes to unusual, and nautically unnatural, lengths to pull out the stern above the water.

Then there is the "liveaboard" design decisions. Immersed transoms are quieter, easier to board and painter lines don't go under them and wipe off all your bottom paint (or get caught in the prop).

So submerged transoms are on over-loaded boats and are always bad. Immersed transoms to a designed waterline are an intentional design decision after contemplating tradeoffs in what one wants to accomplish with the design.

Mark

[Boatguy30]

It would be great to do some of the Caribbean racing but the cost of having a one/off measured and weighed seemed to run into several thousand dollars. We did have a Catana 58, Custom Crowther 42 and Newick tri as well as a Maine Cat 41 and a few well sailed Leopards plus some other mantas a custom Kurt Hughes 46. So it was quite good and having one of the fastest but smallest boats I built myself perhaps made it more special.

No reason we can't get 30-40 boats in the future.

[goat]

Originally Posted by monte

Apologies for the file pic. Heres one from the sail snapped by Jenijane

Well that certainly ends a lot of arguments. That's some of the best uphill sailing I've ever seen.



goat

[44'cruisingcat]

Originally Posted by Polux

Yes provided by someone that knows more about cats and multihulls than anybody on this forum, I mean Nigel Irens.
Nigel Irens Design - High Performance Yacht Design. Catamarans, Trimarans, Sail, Power & Racing Boats

Hmm... They have full main, and part furled jib, and are complaining about weather helm...

Anyway, we all know mono's are absolutely the best to windward.

So, given the AC 72 catamarans were managing 18+ knots VMG to windward in around 20 kts wind. (And the foils had nothing to do with that, they didn't foil to windward.)

There must be plenty of mono's around that are much faster, right?

Got some polars for us Polux?

[colemj]

Originally Posted by 44'cruisingcat

(And the foils had nothing to do with that, they didn't foil to windward.)

Actually, they were foiling to windward by the last couple of races. They were doing it a month earlier in practice sessions.

Mark

[44'cruisingcat]

Ok, so MOST of the time they didn't foil upwind. (They said the gain in speed didn't make up for the loss to leeway.)


I saw the VMG graphic on one of the earlier races, they weren't foiling. IIRC it was around 18.4 knots.

[colemj]

Originally Posted by 44'cruisingcat

I saw the VMG graphic on one of the earlier races, they weren't foiling. IIRC it was around 18.4 knots.

You must be mistaken - that isn't possible.

I wish people would read these threads more closely…

Mark