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Old 03-03-2015, 07:59   #16
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pirate Re: Catamaran sailing issues..

This is a big problem with the production cats designed for the charter markets in the main.. accomodation takes priority..
There's no way to store everything central.. all the storage is fwd.. aft is taken up with engines and battery banks so everything topside has to be balanced and measured.
Personally I think once they get over a certain size they should have an inboard with a shaft tunnel running along the keel.. the engine under a platform with steps fore and aft to the cabins/heads.. the battery banks could also be divided and put central just in front of the engines under the step down from the engine cover.
That would free up tons of space for the domestic and cruising gear.
Just my thoughts..

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Old 03-03-2015, 13:24   #17
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Re: Catamaran sailing issues..

Hey everyone thanks for your replies, much appreciated. I suppose the main thing really is wanting to know how much is normal. Ideally we'd go on another catamaran in similar conditions to do a comparison! But they're not big here in New Zealand unfortunately.

Regarding loading, we are very minimalist, we have hardly anything on board and what we do have is stored midships and a little in the bow. The only things at the back are the engines, dinghy and two relatively heavy life rafts. When we bought the boat the first thing we noticed was that it wasn't sitting flat in the water, but were assured many times over that it was...it is improved when the dinghy isn't on the back, probably by about 50%, though we've never really sailed without it as we're generally on the move. So, at the stern it sits at the paint line, at the bow about 10cm higher. It's not a huge amount, but wondering what the effect would be. Possibly the bridge deck is just a bit too low for its size too, and the pounding is aft, and it does make the whole boat shudder and slows progress a lot. It's resulted in many hairline cracks where it pounds the worst too.

The catamaran is advertised as one of the fastest, so we expected better speeds reaching, although the sail plan is quite limited. (ignore the downwind comment from earlier, I meant everything other than heading into the wind..)
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Old 03-03-2015, 13:36   #18
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Re: Catamaran sailing issues..

Quote:
Originally Posted by LydiaS View Post
Hey I don't have a good picture sorry, I'll have a trawl through my husbands pics, but it's about 8-10cm higher at the bow compared to the stern, do you think that amount would make much of a difference? It does have a heavy dinghy so it's better without it, and we're considering trading it in for a much lighter one.
You mean comparing the waterline stripe? or are you just talking the bow is higher?
Not unusual for cats to pound some depending on sea state, Bridgedeck clearance helps. Don't know how much your cat has. It also helps a lot to adjust your direction vs the waves.. tack or gybe more....
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Old 03-03-2015, 13:37   #19
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Re: Catamaran sailing issues..

I would worry about the hairline cracks as this suggests that the bridgedeck structure is flexing..... Am I correct in assuming that this is new boat?
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Old 03-03-2015, 13:40   #20
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Re: Catamaran sailing issues..

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The catamaran is advertised as one of the fastest...
Yep, they're all faster than average cats. Especially according to the listing brokers....

Dave
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Old 03-03-2015, 14:47   #21
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Re: Catamaran sailing issues..

Do your transoms sit out of the water like these, or are the partially submerged?




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Old 03-03-2015, 17:12   #22
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Re: Catamaran sailing issues..

Here's a photo I found online without the dinghy on the back, it was taken just before we collected her, so unloaded too. So the transom isn't in the water, it's just the bow is up, and it's about twice that with the dinghy on..
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Old 03-03-2015, 17:13   #23
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Re: Catamaran sailing issues..

True!
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Old 03-03-2015, 18:29   #24
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Re: Catamaran sailing issues..

Lydia

That pic looks like you have a definite problem with weight distribution for starters. Since you say its lightly loaded and the situation is even worse with the tender then that seems to leave it being a design issue. (BTW its also odd that a tender alone can make such a big difference on a boat this large) What has the manufacturer said to your concerns?

If the slamming is so bad to have cracked the gelcoat then the forces on the BD are so great that it is flexing significantly and will likely lead to further more substantial stress issues down the track so cannot be ignored.
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Old 03-03-2015, 18:35   #25
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Re: Catamaran sailing issues..

PS looking at the second "mock up" photo of the stern this does indeed look like a poorly designed aft BD to me at least. ie the BD ends very well aft and the stems are very short, add in the lowish clearance and it looks like it will suffer from slamming more than normal. Than put a tender mounted even further aft and you have your answer sadly I think.
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Old 03-03-2015, 19:25   #26
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Re: Catamaran sailing issues..

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Originally Posted by Barra View Post
PS looking at the second "mock up" photo of the stern this does indeed look like a poorly designed aft BD to me at least. ie the BD ends very well aft and the stems are very short, add in the lowish clearance and it looks like it will suffer from slamming more than normal. Than put a tender mounted even further aft and you have your answer sadly I think.
Bugger. I wonder if extending the transoms would be possible to counteract it?? Add boyancy to the back somehow? Nautitech have been denying there's a problem, so it's been a bit of a nightmare. I think they've finally come around, (now that Bavaria have bought them out) but want us to take her all the way back to France for them to look at it, and when we only have a month or two a year to be able to sail and have finally managed go get all the way to Greece it's a big pain. Esp if we get there and they still say there's no problem! Thanks so much for your input, it's been really helpful.
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Old 03-03-2015, 19:46   #27
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Re: Catamaran sailing issues..

Yes its at least partly solvable with a transom extension. My boat is based on the catana 401 mould that was extended in the mould as the original design struggled with payload once you had hard cockpits and tenders etc at the stern. Works fine - heres a pic - and compared to the stern pic of the 482 you can see the problem around the aft BD it has pretty clearly i think
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Old 03-03-2015, 20:16   #28
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Re: Catamaran sailing issues..

Quote:
Originally Posted by LydiaS View Post
Here's a photo I found online without the dinghy on the back, it was taken just before we collected her, so unloaded too. So the transom isn't in the water, it's just the bow is up, and it's about twice that with the dinghy on..
That doesn't look so bad to me. Rather have that than the stern up personally.
However, I would be concerned about cracks and what is causing them.
There seem to be two questions here:
1)is the boat is sitting on her lines well enough
2)and slamming.
From what I see in that picture the slamming has nothing to do with how the boat is sitting.
Slamming does occur on cats. Steer off the wind/wave pattern some for speed!
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Old 04-03-2015, 12:24   #29
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Re: Catamaran sailing issues..

Quote:
Originally Posted by Barra View Post
Yes its at least partly solvable with a transom extension. My boat is based on the catana 401 mould that was extended in the mould as the original design struggled with payload once you had hard cockpits and tenders etc at the stern. Works fine - heres a pic - and compared to the stern pic of the 482 you can see the problem around the aft BD it has pretty clearly i think
That's interesting, looks like you have quite a bit more bridgedeck clearance than us...
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Old 04-03-2015, 12:31   #30
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Re: Catamaran sailing issues..

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That doesn't look so bad to me. Rather have that than the stern up personally.
However, I would be concerned about cracks and what is causing them.
There seem to be two questions here:
1)is the boat is sitting on her lines well enough
2)and slamming.
From what I see in that picture the slamming has nothing to do with how the boat is sitting.
Slamming does occur on cats. Steer off the wind/wave pattern some for speed!
The cracks are caused by the slamming, it can be really intense. Agree that we wouldn't want the stern down, but the tendency for the stern to wallow after a wave and subsequently get whacked by it makes life super uncomfortable. Not sure how normal it is, but we suspect that it's worse than some other cats, and just wondering how much the balance would have to do with it, or if it's just the bridge deck clearance that's too low. Ideally we'd try out a few different cats to see how they compare, but not really possible unfortunately!
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