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Old 27-10-2015, 11:25   #46
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Re: Pros & cons of buying a multihull over a mono hull

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Originally Posted by 2hullvenus View Post
Small point...

"green water" doesn't happen as much on lighter catamarans.

As a little illustration, picture a beer bottle capped and floating in some choppy conditions. When the wave action is right, it goes under and pops back up.

Now picture a rectangular chunk of Styrofoam in the same conditions right next to the beer bottle.

What happens to the Styrofoam? It never goes under.

The behavior of a lighter catamaran in rough conditions is similar.

I've been soaked half my life on monohulls because the bow crashes through waves.

Since switching to catamarans, I have never been so much as hit with spray. Green water over the bows really doesn't happen unless your catamaran is more of the Lagoon (heavy) type.

Disclaimer: a glale in the North Atlantic is the roughest weather I've been dumb enough to go out into. Ymmv in named storms or other situations one should never go in.
I must agree. Having spent most of my life pushing all sorts of catamarans and tris as hard as I could I have never take a full greenie(if that's a thing). Before you ask most of it on Lake Ontario(biggest recorded wave 26 feet) and lots in the Grenadines. Those boats including a heavy Brown Searunner 41 always managed to keep the bow up .The wettest boat was a 36 Newick ,it just felt like you were underwater even if you weren't . Sorry for the drift
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Old 27-10-2015, 12:29   #47
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Re: Pros & cons of buying a multihull over a mono hull

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Originally Posted by admiralslater View Post
I must agree. Having spent most of my life pushing all sorts of catamarans and tris as hard as I could I have never take a full greenie(if that's a thing). Before you ask most of it on Lake Ontario(biggest recorded wave 26 feet) and lots in the Grenadines. Those boats including a heavy Brown Searunner 41 always managed to keep the bow up .The wettest boat was a 36 Newick ,it just felt like you were underwater even if you weren't . Sorry for the drift
This brings up a question. First I confess that my cat experience is limited to a playing with Hobie Cats, a coupled of day sails and one charter in the BVI on larger, cruising cats.

I would think that a boat mono or cat, encountering a steep or breaking wave would either:
1. punch through it
2. go over it
3. somewhere in between

Unless the bow has a shape that completely throws the water out and down then I would think 1 or 3 would have to allow some solid water over the bow that would head aft. Option 2 I would think the boat if it carried any speed at all would launch over the top of the wave and into the air. Not sure if I would prefer green water or going airborne.

Maybe I'm missing something but what does happen in a cat when you run head on into a large, very steep or breaking wave?
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Old 27-10-2015, 12:52   #48
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Re: Pros & cons of buying a multihull over a mono hull

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Originally Posted by skipmac View Post
This brings up a question. First I confess that my cat experience is limited to a playing with Hobie Cats, a coupled of day sails and one charter in the BVI on larger, cruising cats.

I would think that a boat mono or cat, encountering a steep or breaking wave would either:
1. punch through it
2. go over it
3. somewhere in between

Unless the bow has a shape that completely throws the water out and down then I would think 1 or 3 would have to allow some solid water over the bow that would head aft. Option 2 I would think the boat if it carried any speed at all would launch over the top of the wave and into the air. Not sure if I would prefer green water or going airborne.

Maybe I'm missing something but what does happen in a cat when you run head on into a large, very steep or breaking wave?
It's a matter of inertia and buoyancy. Those are my guesses as to why anyway.

It simply pops up over steep wave, sending you on a jarring upward elevator ride. Very much #2.

The momentum from the mono's mass tends to cause it to punch through the waves.

The observation comes from many years on both. Cats behave like cork or Styrofoam in steep waves, monos, like a beer bottle.

To satisfy the anti cat contingent, I'll concede that once you do take green water over the deck, you're probably pretty close to flipping. ha ha ha

Seamanship comes into play here as well. It's not advisable to really hammer any boat directly into dangerous seas. You go at an angle. I like 35 to 45 degrees or so.
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Old 27-10-2015, 14:35   #49
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Re: Pros & cons of buying a multihull over a mono hull

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Originally Posted by 2hullvenus View Post
It's a matter of inertia and buoyancy. Those are my guesses as to why anyway.
Yes, that does seem to be the basic physics and the reason for my question.



Quote:
Originally Posted by 2hullvenus View Post
It simply pops up over steep wave, sending you on a jarring upward elevator ride. Very much #2.

The momentum from the mono's mass tends to cause it to punch through the waves.

The observation comes from many years on both. Cats behave like cork or Styrofoam in steep waves, monos, like a beer bottle.
I think this could be said as a general rule of thumb but I had a racer cruiser monohull that was fairly light displacement and under certain conditions would launch over the top of a steep wave like an Olympic ski jumper.


Quote:
Originally Posted by 2hullvenus View Post
Seamanship comes into play here as well. It's not advisable to really hammer any boat directly into dangerous seas. You go at an angle. I like 35 to 45 degrees or so.
Yep.
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Old 27-10-2015, 14:56   #50
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Re: Pros & cons of buying a multihull over a mono hull

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Originally Posted by Skip JayR View Post
Related to the following aspect I like to mention, that I started with monohull/dinghi sailing steadily climbing up to sipper 80 ft. monohulls. During my skipper job (professionally in the 90th) I got the chance to overtake a 15 meter Cruising Catamaran (single built, Aluminium) for a private owner and experienced the speed >20 knots.

Here a clear pro for multihulls... poking you to follow the 24hx7d live tracker of the TJV (Transat Jaques Vabre 2015) which started on Sunday (yesterday) with 42 boats in 4 divisions... more details here:

12th edition of Transat Jacques Vabre: 8 Tris (Multi50 & Maxis) started on Sunday

The princips are same for cruising boats. What counts is the size and the boat type which are clustered for the TJV as following.
  • Class 40... ~12 meters LOA... average speed 11 knots
  • IMOCA (open 60)... ~18 meters LOA... average speed 14-15 knots
  • Multi50 (one design Trimarans).... ~15 meters LOA... average speed 15-16 knots
  • Maxi Trimarans (open design 90-110 ft.)... ~24-31 meters LOA... average speed 18-19 knots
After sailing the first 27 hours we clearly can see the heavily lack of monohulls... The newly designed IMOCAs of bigger size (60 ft.) cant compete against the smaller Multihulls of "only" 50 feet.

Here we remember, that the average age of the "old Multi50s" is 6 years, being built is 2009.... while the leader of the IMOCA fleet is still behind. It is Alex Thomson with his brand new and with foils highly tuned BOSS boat (couple of weeks ago launched). It is the black boat in the screenshot of the "live tracker".

TJF2015 - Live Ticker at 04:00 pm UTC 26th Oct 2015... (you can follow on your own live here using your browser)


The result as I see it is drastically... and speaks for multihulls. The Class 40 (the bulk of boats on top) falls into the trap of a very low depression which was announced within the meteo consulting/briefing on Saturday...

The slower 40 footers (just 3 knots slower than the IMOCAs and 4-5 knots slower than the Multi50s) have to sail W-WNW course directly into the centre of the low depression- Instead: the target is Brazilian coast so they should head down to South to find back to the ideal course (the white-grey line in the tracker picture).



The fastest Maxi Tris Sodebo and Macif (you can see on the bottom of the tracker screenshot) - by their speed potentials - get the chance to hunt easily way.

The benefit is easily to be understood: More leight weighted = bigger speed, more safely the journey... same rule for a "cruising multihull" in comparison to "bigger monohulls". No difference as the physical principles are the same.

So don't think, that it doesn't count to have 2-3 knots higher speed during long distance sailing. Its worth to keep a cruising catamaran/trimaran leight weighted for getting the essential benefit to keep the boat + crew on the safe side of "bad weather"...

Happy & Safely Sailing !
Oooops--one of the tri's has already capsized and will have to be rescued.

The leading IMOCA monos have now passed over the low and are going 3k faster than the leading 50 ft multis. Would you like a little wager on who gets to the finish first??
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Old 27-10-2015, 15:13   #51
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Re: Pros & cons of buying a multihull over a mono hull

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I prefer the space of a mono and the stability at anchor.
Is that really what you meant to say?
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Old 27-10-2015, 15:15   #52
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Re: Pros & cons of buying a multihull over a mono hull

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Is that really what you meant to say?
NO! I Freudianed the Mono for Multi!!

I had a warped upbringing...........

I actually just noticed the mistype just 5 mins before you commented.
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Old 27-10-2015, 16:12   #53
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Re: Pros & cons of buying a multihull over a mono hull

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Originally Posted by admiralslater View Post
The original post talked about living and working aboard, with out much discussion of sailing.....
No one wasted much time responding to that, did they!?

So, a few catamaran live aboard considerations I haven't seen posted:

His and Her Hulls. Sometimes available LOD is just not far enough apart! With a cat you can have his & her hulls. This is handy, not just when you've had a squabble, but for normal living/working aboard too, like when you need some quiet space to work for example....or when your SWMBO needs a quiet place to consult with her divorce attorney.

Air Con. Living and working aboard in warmer climates will likely mean you will want AC. Cooling a typical cruising cat, with that big greenhouse like deckhouse, is more thermodynamically challenging, and thus more expensive, than a similar class of mono. More expensive initially because there is more work involved, and potentially multiple units, in getting cool air to all those spread out spaces and likely more expensive to operate too. Sun awnings and window/hatch covers on a cat make a BIG difference.

Foredeck Hangout Space. The saftey nets make a great place to hang out. Lay down and watch the stars for example.

Guests aboard. Traffic flow is more spread out on a cat...not all down the center of the hull as in a typical mono. Cabins, typically at the extreme corners, offer more privacy than is typical on a mono. Ditto for heads...which is important sometimes...like for guest who haven't quite adjusted to the mix of "bugs" in Mexico yet.

Cockpit/Main Salon/Galley Up combo very good for entertaining.

People May Hate You (this could be a pro or a con). Once, in a popular cruising anchorage we had sundowners aboard our cat. Lots of cruisers showed up, but there was plenty of room. One couple who attended had a very nice smaller traditional mono...beautiful boat, but not very roomy. The next day another get together was schedulded ashore. As I walked up, the male of that couple told me he hated me...I laughed...he didn't...he was serious as a heart attack. Seems that a rather heated discussion had ensured between this couple after leaving our party on the very subject of this thread.
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Old 27-10-2015, 16:29   #54
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Re: Pros & cons of buying a multihull over a mono hull

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Air Con. Living and working aboard in warmer climates will likely mean you will want AC.
I've spent many, many winter months (dry season) living and working aboard my boat in the tropics without AC and I'm convinced I don't need it. That said, I haven't spent much time in the tropics in the wet season so maybe a case could be made that AC can be a relief infrequently in those parts of the year. This also assumes little or no time in marinas where natural airflow can't do its job. The best part about no AC - no generator needed. Less cost, less maintenance, and less weight. Your mileage may vary......

Dave
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Old 27-10-2015, 16:57   #55
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Re: Pros & cons of buying a multihull over a mono hull

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I've spent many, many winter months (dry season) living and working aboard my boat in the tropics without AC and I'm convinced I don't need it. That said, I haven't spent much time in the tropics in the wet season so maybe a case could be made that AC can be a relief infrequently in those parts of the year. This also assumes little or no time in marinas where natural airflow can't do its job. The best part about no AC - no generator needed. Less cost, less maintenance, and less weight. Your mileage may vary......
We are liveaboard in a marina in the tropics. We haven't used aircon for the last 4-5 months (winter/dry season), but the weather has just started to change. We ran it for a few hours last weekend and between now and around Easter next year, it will be getting a regular workout. It really is necessary for comfort in a tropical marina in the summer/wet season (and it keeps the mould at bay at the same time!).

BTW, the ac is only available when on shore power. I don't have a problem with that - anchored out it's not so necessary.
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Old 27-10-2015, 20:07   #56
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Re: Pros & cons of buying a multihull over a mono hull

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I've spent many, many winter months (dry season) living and working aboard my boat in the tropics without AC and I'm convinced I don't need it. That said, I haven't spent much time in the tropics in the wet season so maybe a case could be made that AC can be a relief infrequently in those parts of the year. This also assumes little or no time in marinas where natural airflow can't do its job. The best part about no AC - no generator needed. Less cost, less maintenance, and less weight. Your mileage may vary......

Dave
I rarely use my ACs here in the tropics unless in a marina with poor airflow (or bugs, or heavy rain...) on a hot night. In fact, this lack of use is becoming a maintenance issue. Aboard right now with no AC and comfy with just fans. But was dripping sweat working on the boat this afternoon.

The tropics is one thing, but I used to liveaboard in Texas...AC is not a luxury there...it is life support.
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Old 28-10-2015, 00:49   #57
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Re: Pros & cons of buying a multihull over a mono hull

Florida boy for years.
A/C a requirement.

2013- required A/C in the MED. If it can be run cheaply and quietly then I say go for it.
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Old 28-10-2015, 07:04   #58
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Re: Pros & cons of buying a multihull over a mono hull

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Originally Posted by 2hullvenus View Post
Small point...

"green water" doesn't happen as much on lighter catamarans.

As a little illustration, picture a beer bottle capped and floating in some choppy conditions. When the wave action is right, it goes under and pops back up.

Now picture a rectangular chunk of Styrofoam in the same conditions right next to the beer bottle.

What happens to the Styrofoam? It never goes under.

(...)
Yes. I imagined styrofoam too before I started sailing. Then I found things are not that scalable.

Read into the accident last year off the Azores (I think that was a Lagoon). Also into a recent Gunboat loss.

Destructive green water is a major consideration no matter what size or style the boat. Unless we are talking submarines, life boats and similar craft.

I respect your opinion but I will stick with mine.

Cheers,
b.
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Old 28-10-2015, 09:40   #59
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Re: Pros & cons of buying a multihull over a mono hull

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Yes. I imagined styrofoam too before I started sailing. Then I found things are not that scalable.

Read into the accident last year off the Azores (I think that was a Lagoon). Also into a recent Gunboat loss.

Destructive green water is a major consideration no matter what size or style the boat. Unless we are talking submarines, life boats and similar craft.

I respect your opinion but I will stick with mine.

Cheers,
b.

I wouldn't consider the Lagoon to be a light catamaran which 2hullvenus was referring to. And the Gunboat didn't suffer damage from green water, they lost their rig from a 70 kt. wind gust which then apparently did some damage to the boat.


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Old 28-10-2015, 09:43   #60
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Re: Pros & cons of buying a multihull over a mono hull

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Yes. I imagined styrofoam too before I started sailing. Then I found things are not that scalable.

Read into the accident last year off the Azores (I think that was a Lagoon). Also into a recent Gunboat loss.

Destructive green water is a major consideration no matter what size or style the boat. Unless we are talking submarines, life boats and similar craft.

I respect your opinion but I will stick with mine.

Cheers,
b.
It's a metaphor.

We are comparing 2 things, not suggesting a catamaran behaves exactly like a piece of Styrofoam, nor that a mono behaves exactly like a beer bottle.

It is a metaphor used for illustrative porposes and for those that don't have years of seatime on both platforms.

In my 25 years of sailing very avidly on my own boats, a bit over half the time on monohulls, the rest on catamarans (all of which I've owned and lived on as well as cruised domestically), I've come to view the difference in motion as similar to the metaphor used.

If you are caught in breaking waves in any boat, you made a seamanship error. You should have been more careful about the weather. Or... not attempted an inlet when wind/current were opposed in shallow water.

I stand by my point, which is: catamarans pop up and over the waves to a great extent while monos go through them (on average). This means little to no "green water" (I've never even been sprayed on cats,even in a gale) and less concern for that situation.

Again, as I did say, if you're foolish enough to get caught in breaking seas because you didn't bother to look at the weather, all bets are off no matter mono, multi, tanker or roro.
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