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Old 31-01-2015, 14:51   #16
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Re: Nautitech Open 40

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Originally Posted by brainmaker View Post

(...)

Some responses: Barnakiel - why no boards - the designer wrote an interesting and convincing article on that, let me summarize it here. To have boards - would mean an extra 400 kgs of weight; would add danger of tripping over; would add noise inside and design problems inside; you need to operate them; plus first and foremost they don't improve performance much, or even pointing. The N55 Marc Lombard design (his first, before the N Open 40) outperformed others...

Others remarking on the absence of wind instrument info - it worked at the beginning, but then stopped working. The boat had just returned from the London boatshow and the rigging looked a bit slack to me and Paul Heys agreed with that. Looking up during the sailing, there was quite a bit of sinusoid shaking at the top there, I think it must have disconnected a wire. The one time you really want wind info ... it ain't there. In UK it's called Sods law :-)
I am not sure why two boards would weigh 400 kg. I have replaced a broken board on a Catana (47 series) and we did not have any problem removing, shipping nor reinstalling the replacement one. Two small guys hence the board could not have been 200 kg. Maybe 100 kg max, and in a bigger cat too.

Going 20 knots is one thing and going X knots to windward or downwind is another story, esp. in a cat. Not seeing the wind angle info is in this case like skiing downhill in a country without ski lifts.

Still, I respect 20 knots as I do know how hard it is to make a boat go that fast. Too bad boats like this cannot be sailed in full cruising mod (meaning watch me mamma: western lifestyle).

b.
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Old 31-01-2015, 16:36   #17
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Re: Nautitech Open 40

Welcome to the performance club brainmaker. gonna be hard to go back to a lagoon now eh?

I also dont like those particular aft helms as they are a particularly bad version. Other versions like catanas work much better with 100% forward vision over the coach roof. To go to a flybridge helm would throw up quite a few performance compromises which this design is obviously not in the game of doing.

Im gonna query the 9 knots motoring to 30 knots wind through a 3 foot chop though. Unloaded or not thats simply too good to be true by quite a margin with 2 x 30hps at 2500rpm so something seems amiss here calibration wise and now im wondering if that affected the sailing speeds too?

Likewise the daggerboards (which imho this boat should have) explanation doesnt stack up. My boards weigh 80 kg each for a 40 foot cat. yes theres the strengthened sheath weight as well but no way is that net difference vs mini keels going to come anywhere near 200 kg let alone 400kg. Sounds more like an internal design livability compromise than anything else.
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Old 31-01-2015, 17:26   #18
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Re: Nautitech Open 40

Dear Barra and Barnakiel - first on the speed under engine and speed in general - I checked tides beforehand and SOG from GPS and the log was calibrated properly. I was most surprised by the performance under engine as we were going straight into a very short lumpy steep sea in the Solent - such that she jumped a lot as can be seen at the end of the video - and such that the whole structure reverberated when she crashed down - you could feel it was very light indeed. On that subject - my L380 premium never felt like that, as my Lagoon expert Javier Rodrigo once told me, his words came to mind in that situation, the L380 is the stiffest of all Lagoons, he used the words "it is like a rock" - and he's right, I never felt shaking or relative movement or strain when one hull is out of the water and the other in. I did feel that in the Open 40 which is noticeably lighter and more flexible, but it did not give me the feeling it would give problems. I slept half my youth going up and down the North Sea in the forepeak of a 28 foot mono of which the hull next to me crashing into waves lying on one ear, each slap you could feel the gelcoat moving and flexing, GRP is amazing stuff. L380 - never heard a squeak; L400 - constant squeaking, L450 - lots of squeaking. Bit less over time as you own it, could be a settling/gelcoat issue but this is getting far too unscientific.

Now on the point of the daggerboards - I mentioned 400kgs - that is not for just the daggerboards but for the structures that hold them, the crash boxes, the lifting equipment, and so on. I am not a racer type of person, but a cruiser. I vividly recall Henk de Velde a Dutch multihull racer capsizing a racer with boards and someone dying in that incident. I don't want boards. Plus more moving parts, noise, things to go wrong, keep it simple. I can't attach pdf's hereto so I can't give you the whole article by Bruno Voisard on daggerboards versus stub keels.

He does make one point which I find very interesting and which I agree with as a good feature: its stub keels/low aspect ratio keels are fixed such that they are sacrificial in the event for instance of a reef crash or other violent grounding - they can come off, and leave the main hull intact and not holed. I like that kind of built in, fit and forget redundancy and passive safety. If only they would have a comfortable, useful flybridge ... I cannot get over how irritating it is to have 2/3rds of your vision blocked when you are used to a flybridge and scanning the horizon 360 degrees from "up top" in a nicely angled back sofa... having to get up every five minutes to walk to the other side to see if you're not hitting something, massively annoying. Think I would get my jigsaw out and cut a hole in the bimini and install a very comfortable chair !!
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Old 31-01-2015, 17:31   #19
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Re: Nautitech Open 40

Oh Barra & Barnakiel ! On the motoring into chop 2500 rpm 9 knots - I just realized - we had the main up with 2 reefs - that would have indeed given some more power most probably.
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Old 31-01-2015, 17:49   #20
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Re: Nautitech Open 40

yeah that makes much more sense. main would have added 3 plus knots im guessing ie motoring into that kind of wind and chop and you would be lucky to do 6 knots i reckon, more likely 5 SOG

Each to their own on the boards but for the record boards are generally regarded as safer re capsize as they allow the boat to slip sideways and not trip in side seas. Just because a racing cat that had boards flipped does not mean it flipped because of the boards.
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Old 31-01-2015, 18:59   #21
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Re: Nautitech Open 40

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Now on the point of the daggerboards - I mentioned 400kgs - that is not for just the daggerboards but for the structures that hold them, the crash boxes, the lifting equipment, and so on. I am not a racer type of person, but a cruiser. I vividly recall Henk de Velde a Dutch multihull racer capsizing a racer with boards and someone dying in that incident. I don't want boards. Plus more moving parts, noise, things to go wrong, keep it simple. I can't attach pdf's hereto so I can't give you the whole article by Bruno Voisard on daggerboards versus stub keels.
I recommend you sail a board cat before spending money on any cat. The lifting equipment on my boards is a about 30 feet of 1/2 inch double braid. No noise. Nothing has ever gone wrong with them. You're a victim of marketing.

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If only they would have a comfortable, useful flybridge ... I cannot get over how irritating it is to have 2/3rds of your vision blocked when you are used to a flybridge and scanning the horizon 360 degrees from "up top" in a nicely angled back sofa... having to get up every five minutes to walk to the other side to see if you're not hitting something, massively annoying.
Your vision is blocked by the continuous roof extending over the cockpit. With a "normal" gap between the saloon roof and cockpit cover you could see forward without moving. If you like flybridges, get a Lagoon. Simple. Do you want a sailing machine or a lounge chair? Just keep in mind that that flybridge pushes the rig up and you end up with lesser sail area, a mast too tall for the hull and the resultant higher COG.

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Old 31-01-2015, 19:08   #22
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Re: Nautitech Open 40

Then what about the weight of that fly-bridge you want???

So you will add weight and windage of the fly-bridge, forego the boards, and what happens then to that performance factor?

It all does not add up, mate.

I say minus fly bridge plus boards and she will sail better yet.

Sure there are many ways to build a boat and I am happy to see someone tried to think laterally if a bit. Just must admit in a similar vane I would just get myself a:



No fly bridge? No problem!

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Old 31-01-2015, 19:21   #23
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Re: Nautitech Open 40

I wonder what difference to load carrying capacity keels v boards makes. Surely the added displacement of keels would add directly to load capacity, being that they displace around 300kg of water at 1m depth....maybe not...
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Old 31-01-2015, 19:25   #24
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Re: Nautitech Open 40

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I wonder what difference to load carrying capacity keels v boards makes. Surely the added displacement of keels would add directly to load capacity, being that they displace around 300kg of water at 1m depth....maybe not...
Hi Monte - depends on whether the keels are solid, as in sacrificial keels, or hollow and also serving as bilges, as in some cats. Right?

Mr. brainmaker, I should have added in my previous post that certainly you can decide whether you like boards or not. My recommendation is to make such a decision on legit reasons.

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Old 31-01-2015, 19:29   #25
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Re: Nautitech Open 40

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L380 - never heard a squeak; L400 - constant squeaking, L450 - lots of squeaking. Bit less over time as you own it, could be a settling/gelcoat issue but this is getting far too unscientific.
I found our 380 squeaked more than the 400 until I took a circular saw to where some of the timber panels were fitted a bit close to the surrounding glass areas. That stopped most of the squeaks. The 400 has virtually no squeaks, just one inside the sink cupboard I cant locate, I open the door and it stops, kind of like trying to open the fridge door quickly to catch out the guy that turns on the light..
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Old 31-01-2015, 20:19   #26
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Re: Nautitech Open 40

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depends on whether the keels are solid, as in sacrificial keels, or hollow and also serving as bilges, as in some cats. Right?
I've never seen solid sacrificial keels - they are always foam-filled and positively buoyant.

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Old 31-01-2015, 22:11   #27
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Re: Nautitech Open 40

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I wonder what difference to load carrying capacity keels v boards makes. Surely the added displacement of keels would add directly to load capacity, being that they displace around 300kg of water at 1m depth....maybe not...
Yes. Tony Grainger recommends them in many of his cruising designs because of that.

Simply comes back to increased bouyancy from the displacement of the mini keels minus their constructed weight. Without converting for salt water 1 cubic meter of fresh water weighs 1000kg. Grainger suggests between 400 to 500kg advantage in load carrying.

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Old 01-02-2015, 03:56   #28
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Re: Nautitech Open 40

Dagger boards vs. fixed keel is an ongoing debate between cat designers. I've sailed, serviced both and read all the articles I could find. Both have cons and pros; there is no absolute winner..

All in all; if you are racing, if you plan to make high lattitudes, if you sail frequently upwind, go for the boards. Otherwise, I believe sacrificial fixed keels are a better option.

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Old 01-02-2015, 08:10   #29
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Re: Nautitech Open 40

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I've never seen solid sacrificial keels - they are always foam-filled and positively buoyant.
Roger that. So there is a net load carrying benefit for sure. And no question that the supporting structure and the boards themselves (when up) add weight to a board boat.

But of course, it's a lot more than just upwind. Skin friction, anyone? Those who have never surfed long period open ocean rollers on a board boat may not appreciate the benefit here. Cats in general are resistant to broaching, but take away the permanent keels and it becomes just about impossible.

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Old 01-02-2015, 08:24   #30
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Re: Nautitech Open 40

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Hi Monte - depends on whether the keels are solid, as in sacrificial keels, or hollow and also serving as bilges, as in some cats. Right?
Yep. OR / OR

Will however displacement adding keels not be too fat and drag the performance down? Then we would have sorta chain of steps that each removes a fine fractional of performance and when we add up the fractions the boat is suddenly full X knots slower?

Having read what the Dashews wrote on 'side sliding hulls' I must admit I became pretty sure this may work in a huge safety factor for many types of boats, including cats.

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