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Old 04-03-2015, 12:43   #31
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Re: Catamaran sailing issues..

Quote:
Originally Posted by LydiaS View Post
The only things at the back are the engines, dinghy and two relatively heavy life rafts.
Why two and how heavy?

Exactly where are they stored?

Perhaps get rid of one and move the other forward someplace. Or, store both ashore until you plan to cross oceans.

The placement of life rafts obviously needs to be where they can be deployed quickly and easily, so it's easy to suggest that you re-locate one or both without knowing on your boat where these alternative locations might be. Maybe you have no reasonable alternative locations.

Maybe you said this already - how big is the dink and how big is its outboard? Are they more than you need?

Dave
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Old 04-03-2015, 13:11   #32
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Re: Catamaran sailing issues..

"She sails well downwind though the speeds we're reaching are nothing like we hoped either. 8-10knot max. Any help much appreciated!"

Maybe you should trade up if you want more speed -this one's pretty fast downwind, just needs a little TLC:
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Old 04-03-2015, 13:35   #33
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Re: Catamaran sailing issues..

Quote:
Originally Posted by 2Hulls View Post
Why two and how heavy?

Exactly where are they stored?

Perhaps get rid of one and move the other forward someplace. Or, store both ashore until you plan to cross oceans.

The placement of life rafts obviously needs to be where they can be deployed quickly and easily, so it's easy to suggest that you re-locate one or both without knowing on your boat where these alternative locations might be. Maybe you have no reasonable alternative locations.

Maybe you said this already - how big is the dink and how big is its outboard? Are they more than you need?

Dave
The tender is at least 200kgs....and the life rafts around 45-50kgs each. I suppose we don't need two of them, and they are pretty handy in terms of where they're stored right at the back, but yes we could have a look and see if there are any other storage options.
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Old 04-03-2015, 17:25   #34
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Re: Catamaran sailing issues..

We had a Gemini 105Mc. It is known to have low bridge deck clearance and slam easily. It is what it is.
You seem to have a bigger one that is the same way.

The money you spent on that big boat makes me wonder how it was not possible to sail a few others in that class.

All the gelcoat cracks on the Gemini (common) were blamed on gelcoat laid up too thick. They said it is not structural. I guess that is just how they built them.

Boatman could bring it back to France for you. Easily.
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Old 04-03-2015, 18:07   #35
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Re: Catamaran sailing issues..

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Originally Posted by LydiaS View Post
That's interesting, looks like you have quite a bit more bridgedeck clearance than us...
Probably pretty similar BD clearance overall but relative to 48 vs 42 foot length then yes a bit more.

The real issue on this boat is where the clearance is though. ie BD that starts too far forward and/or finishes too far back plays an as equally critical role as overall clearance. On that one photo of the stern of the 482 the BD finishes very aft (and low) relative to the end of the transoms (compare that to my pic - ive got a tender in there and still a foot or two from there to the end of the transom on a smaller cat)

That means the 482 will slam more than it otherwise would in certain conditions.

It also means it will be more weight sensitive at the stern than a more balanced design hence potentially explaining the tilted waterline so shifting stern weight may help even more than usual as others suggest.
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Old 15-03-2015, 03:22   #36
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Re: Catamaran sailing issues..

full water and petrol tanks can add 1 to 2 tons.

Looks pretty nice cat to me. Lower clearance to improve stability and windward performance. What matters is width of the tunnel vs height. And it is low as seen from the pic.

I suspect overreaction of crew on less common sea situation.

regarding sailing performance .... it gets better with time as one learns to use the boat. This one should go real well.
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Old 15-03-2015, 07:11   #37
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Re: Catamaran sailing issues..

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Lower clearance to improve stability and windward performance.
I think most knowledgeable cat sailors would conclude that lower clearance has little to do with stability and is actually detrimental to windward performance.

Dave
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Old 15-03-2015, 13:46   #38
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Re: Catamaran sailing issues..

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I think most knowledgeable cat sailors would conclude that lower clearance has little to do with stability and is actually detrimental to windward performance.

Dave
i remain of opinion that lower bridge deck clearance adds to stability (less swinging port/starboard) in bad weather. Also catana has "step" around 15 cm above water line for that purpose.
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Old 15-03-2015, 15:57   #39
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Re: Catamaran sailing issues..

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i remain of opinion that lower bridge deck clearance adds to stability (less swinging port/starboard) in bad weather. Also catana has "step" around 15 cm above water line for that purpose.
Of course you are entitled to your opinion, but you are not entitled to your own physics.

In my view, the only way that lower bridge deck clearance can add to stability is if the lower clearance contributes to an over all lower center of gravity of the vessel.

Quote:
Also catana has "step" around 15 cm above water line for that purpose.
For what purpose? To add to stability? Baloney. If you're referring to the knuckles on either side extending from the hulls, they are there to increase interior volume and to provide for alternative blocking areas when the vessels are hauled. And they are far higher than 15cm above the water line.

Dave
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Old 15-03-2015, 16:15   #40
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pirate Re: Catamaran sailing issues..

He might be confusing it with Catalac's..
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Old 15-03-2015, 16:22   #41
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Re: Catamaran sailing issues..

naaa, i had a good look at catana.

this are mine conclusions after couple of years of test sailing and research.

I believe that boat will perform differently under 2 different skippers, depending on skipper understanding of boat and physics around it. And may be more than one valid view.
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