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Old 25-06-2015, 07:05   #346
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Re: Bestevaer 49ST

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Originally Posted by Dockhead View Post
I have flirted with the idea of cats, even though I am at heart definitely a mono guy. They have a few clear and notable advantages for the kind of sailing I like to do.

And I am definitely over standardized plastic cruising boats with open helm positions, made for weekend sailing and two week Med cruises, not for hard core long distance sailing. That includes "high end" "blue water" boats -- none of them are really made for what I do.

At the end of the day, though, I think something very like the boat discussed in this thread is what I need. Something more workboat-like, heavier duty, and with a pilothouse. This thread has been a real inspiration for me.
THis thread for me has opened the door to Aluminium vessels for consideration.
Aluminium Catamaran..................
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Old 25-06-2015, 07:17   #347
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Re: Bestevaer 49ST

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I think this idea has great merit. I think many sailors overestimate how much load is needed by a diesel engine to keep it healthy. It depends on the RPM. If the alternator is set up to produce most of its rated power at low engine revs, then it wouldn't take that much. You could even install a third, shaft-driven alternator of very large size, which you would only engage at certain RPMs when using the main engine as a generator. Main drawback is you lose the redundant diesel engine, but it's probably a tradeoff worth making in very many cases.

If I had a catamoron, that's exactly what I would do. I would never want a third diesel engine on a vessel which by design is so sensitive to weight. I would use one of the mains to drive a really big alternator, and use that as the genset. Set up right I don't see any problem for the health of the engine.

You can buy alternators up to 10kW, consuming up to 20 horsepower from the main engine:

http://www.americanpowerinc.com/imag...20Cutsheet.pdf

How to arrange the drive for such a brute is a different question, but in a new build project I'm sure it's not unsolveable. With lithium batteries and their huge charge acceptance rates, you can use this power, too.
Instead of adding a 2nd/3rd alternator, what about a hybrid setup:

Seagoing Hybrids - Hybrid Electric Marine Propulsion


You could probably size the diesel slightly smaller given the electric motor can give you an additional 10 KW or so of power for at least a short time in emergencies.

In generator mode it should be more than enough to keep the engine under load.

Redundancy wise, again you only have a single diesel, but you do gain a (somewhat limited) backup propulsion option

Admittedly it is straying very far from the OP's KISS approach
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Old 25-06-2015, 08:39   #348
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Re: Bestevaer 49ST

BTW, regarding water ballast . . . . internal ballast tanks have significant trade-offs . . . . but I was talking last night to someone prepping for a pacific run and he was using (several) external water bladders (like fuel bladders but hung from high side toerail) which he pumped up with an electric pump and had a 'pull line' activated dump valve. This would seem to be an interesting solution if you are going to be on the same tack for quite a while (as you often are on passage). 4 x 30 gal bladders = 1000lbs x 7' lever arm = extra 7000ft-lb righting moment
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Old 25-06-2015, 09:08   #349
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Re: Bestevaer 49ST

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BTW, regarding water ballast . . . . internal ballast tanks have significant trade-offs . . . . but I was talking last night to someone prepping for a pacific run and he was using (several) external water bladders (like fuel bladders but hung from high side toerail) which he pumped up with an electric pump and had a 'pull line' activated dump valve. This would seem to be an interesting solution if you are going to be on the same tack for quite a while (as you often are on passage). 4 x 30 gal bladders = 1000lbs x 7' lever arm = extra 7000ft-lb righting moment

We just got "heeled" to fit our 52' mast under a 48' bridge two weeks ago in Florida. It took 5 fifty-five gallon drums to tip us around 20 degrees with them sitting on the side deck.

Seems like a good idea. Unfortunately, on our Atlantic crossing, we had to have gerry cans on deck for added fuel. We moved them from side to side to adjust ballast as needed..... finally a good excuse for the bad seamanship of cans on deck

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Old 25-06-2015, 11:18   #350
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Re: Bestevaer 49ST

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^^ did you actually read the laminate details? They used only one ply of Kevlar, just on the outside, for abrasion resistance, and the rest was carbon - pretty much exactly as I suggested.
Yes of course, that is why it is called a carbon/Kevlar hull and kevlar is used only on the outside part of the core for impact resistance but you are wrong in assuming that the main composition of outside core was not kevlar. In fact they used only for cosmetic reasons a thin first layer of fiberglass veil and then a full ply of kevlar and finally some carbon reinforcements where needed.

"Prior to layup of the hull's outer skin, Corecell foam core was cut and prefit into the mold. When all the core pieces were in place, they were labeled and removed for reinsertion later. For the outer skin layup, a thin (1.5 oz) fiberglass veil was applied first to enhance cosmetics, followed by one ply of woven Kevlar and then the carbon reinforcements. Next, the prefit, precut Corecell foam core and carbon inner skin materials were applied."

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It's actually a pretty low tech structure. And the design objective (to reduce panel modulus to reduce high speed slamming acceleration) is not very relevant to cruising boat design... You will not find a modern AC or vendee or g class boat built that way. Kevlar is used in those boats in part of the decks in order to make it transparent to sat com signals, but nowhere structurally important..
First of all reduce slamming were only one of the objectives among the others that had to do with maintaining or improving the properties that the old aluminum hulls had including impact resistance. Is for that Kevlar is there on the outer core otherwise a full cored carbon boat would be more than enough. As they say :"It is actually 50 percent stronger and slightly lighter than its aluminum predecessor..."

I fail to understand what the Open 60's that make the Vendee or the AC racing boats have to do with this story regarding aluminium versus kevlar/carbon in what regards weight, solidity and impact resistance.

Obviously those boats are not done the same way not being impact resistance a priority goal even if carbon is tough. More than impact resistance they are designed to be as light and strong as possible (not to impact primarily) and are made basically of carbon with a carbon honeycomb core.


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And hinckley building and materials are certainly not "the best", even in boat building (which is a long way behind aerospace).
In what regards building quality I score Hinckley high and certainly they don't save money on the quality of the materials they use. We are talking about cruising boats not racing boats and in cruising boats impact resistance is certainly one important asset. A kevlar outer core and carbon on the inside core on an epoxy/vinylester boat is certainly one of the best ways to get a very light and very strong boat, including impact resistance and that's why Hinckley uses kevlar on the outer core.
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Old 25-06-2015, 11:47   #351
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Re: Bestevaer 49ST

^^

"one ply of woven Kevlar and then the carbon reinforcements"

It was exactly what is written there, one single ply of kevlar (for abrasion resistance - if i remember 150 g/sqm ply from the spec) and them multiple heavy plys of carbon (for structural properties). I happen to know rather more about this structure than just from that article. I have a good friend who runs one of the top Maine yards who quoted on it, and the composite materials company I used to be CEO of quoted on the carbon/kevlar package for it.

Vendees, volvos and g-class boats have to have significant impact resistance to finish their round the world races. And they do - in carbon. Helo attack blades have to have significant impact resistance and they do in carbon pre-preg.

I am not going to debate Hinckley's "quality" with you, but their structure is just simply 'mid-range' in terms of composites. It is by no means at all high end or sophisticated.

none of this really matters for this thread, so that's it for me here. Pls start a laminate thread if you want to continue.
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Old 25-06-2015, 12:49   #352
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Re: Bestevaer 49ST

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^^

...

none of this really matters for this thread, so that's it for me here. Pls start a laminate thread if you want to continue.
No and I am not interested in discussing laminates. Regarding this thread it is not only about a particular boat but also about the qualities of aluminium as a yacht building material and its advantages that are mainly lightness and impact resistance. I only made a side point saying that some composite boats that use kevlar on the hull can better the lightness and equal the impact resistance of aluminium as a hull building material.

Not only fast extraction seal patrol boats have changed aluminium by Kevlar/carbon as the Euro jet fighters are made of kevlar to improve their capacity of absorption of enemy fire as there are many top boats that use kevlar on the outer layer. There are is even a voyage/exploration boat built by a major brand with the hull made of kevlar or uses Kevlar as one of the main materials.

Regarding aluminium it is still a material used on many middle sized yachts, specially voyage boats, but if you have a look at the hull material used on superyachts you are going to see that on the last decade most of them had changed aluminium for different types of carbon composites (including kevlar). I believe that in the future we will see this happen more and more in smaller boats.

There was some disagreement about this (and that is why i keep on replying) but know that it seems that the point is solidly made I have nothing to add.
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Old 25-06-2015, 13:50   #353
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Re: Bestevaer 49ST

^^ the reason I went aluminum was not at all "lightness and impact resistance". The primary reason was how easy it is to build an entirely watertight can in metal, with everything welded in and no bolt holes. That's possible in composite but much more difficult. And the secondary reason was the zero stress top sides in bare aluminum. I can bounce off piling or have other boats dragging anchor down on me and have zero concern about paint/gel coat. Finally aluminum costs $2.15/kg while 'advanced laminate' costs about $10/kg (perhaps a $25k saving on the sort of boat we are talking about here - small by itself in the big picture, but $25k here and $25k there will add up).

As to impact resistance . . . . If you hit the corner of a container at 8kts it's going to punch thru essentially any material and your solution is integral tanks and watertight bulkheads.

As to lightness . . . . Core panel interior construction is the big opportunity. When we were building hawk I had a friend building a composite boat ( Kevlar, not carbon, entirely because IMS race rule forbid carbon) and our two hull shells weighted exactly the same. He had a much lighter keel, mast, and rudder than I did. I had a lighter weight interior.

Aluminum's big drawback is corrosion, which can be entirely managed but you do have to pay attention. Laminates (properly made) have zero concern there, but core shear is a significant concern (which again can be entirely managed, but is rarely done so, because glass boat owners tend to be less well educated about it).
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Old 25-06-2015, 14:03   #354
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Re: Bestevaer 49ST

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There was some disagreement about this (and that is why i keep on replying) but know that it seems that the point is solidly made I have nothing to add.
Open an lead a new thread Polux. Its an interesting subject. People will be interested in this topic I am sure. Its just that your views will be drowned in this thread because its quite specific to the Bestevaer.
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Old 03-07-2015, 09:46   #355
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Re: Bestevaer 49ST

Update:

Things are progressive slowly, but surely. We had a four hour conference call today with the builder and architect . We hope all our requirements and requests have been understood and the next draft of plans come back with little modifiction needed. Lots has been discussed. We are probably going with a deck stepped mast.

SWL
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Old 03-07-2015, 11:22   #356
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Re: Bestevaer 49ST

Price of Aluminium Cats only become viable over 50 feet.

Oh well
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Old 03-07-2015, 11:57   #357
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Re: Bestevaer 49ST

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Price of Aluminium Cats only become viable over 50 feet.
We do see quite a few French Aluminium crusing cats.

Aluminium under about 4mm becomes impossible to weld and keep fair. Aluminium hull construction costs are also higher which will make smaller cats uneconomic. With these factors I suspect aluminium only becomes viable on larger models as you note.

Here is a 43 foot aluminium cat, but I have done zero reasearch on this boat so this is just for information rather than a recommendation.

http://www.garcia-yachting.com/pdf/M..._Banana_43.pdf
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Old 03-07-2015, 12:00   #358
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Re: Bestevaer 49ST

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We do see quite a few French Aluminium crusing cats.

Aluminium under about 4mm becomes impossible to weld and keep fair. Aluminium hull construction costs are also higher which will make smaller cats uneconomic. With these factors I suspect aluminium only becomes viable on larger models as you note.

Here is a 43 foot aluminium cat, but I have done zero reasearch on this boat so this is just for information rather than a recommendation.

http://www.garcia-yachting.com/pdf/M..._Banana_43.pdf
STARTING at New price from:286000 (approx: 211688 Sterling / $419940 US / $477451 AUS)*
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Old 20-07-2015, 07:25   #359
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Re: Bestevaer 49ST

Plans are progressing well. This may be the first boat Dykstra Naval Architects and K&M are designing via email and Skype, but they are coping with the challenge very well.

DNA have now designed an arch for the solar panel and dinghy. We think they have done an excellent job, making it look as integrated and non obtrusive as possible.

We have been thinking about the fuel system and my task for today was to draw it out in the least confusing way possible. It was a tangle of lines our initial sketches. I have attached the diagram below, as it may be of interest. Note that this is image #61 from us to the architect/builder. Pictures tell a thousand words .

SWL

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Old 20-07-2015, 08:29   #360
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Re: Bestevaer 49ST

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No and I am not interested in discussing laminates. Regarding this thread it is not only about a particular boat but also about the qualities of aluminium as a yacht building material and its advantages that are mainly lightness and impact resistance. I only made a side point saying that some composite boats that use kevlar on the hull can better the lightness and equal the impact resistance of aluminium as a hull building material.

Not only fast extraction seal patrol boats have changed aluminium by Kevlar/carbon as the Euro jet fighters are made of kevlar to improve their capacity of absorption of enemy fire as there are many top boats that use kevlar on the outer layer. There are is even a voyage/exploration boat built by a major brand with the hull made of kevlar or uses Kevlar as one of the main materials.

Regarding aluminium it is still a material used on many middle sized yachts, specially voyage boats, but if you have a look at the hull material used on superyachts you are going to see that on the last decade most of them had changed aluminium for different types of carbon composites (including kevlar). I believe that in the future we will see this happen more and more in smaller boats.

There was some disagreement about this (and that is why i keep on replying) but know that it seems that the point is solidly made I have nothing to add.
The defense applications you quote have more stringent build and repair procedures.

The design of rotor blades and hulls are validated in terms of degraded condition use cases. The overall system is also designed for survivability. Recreational and race boats are not.

I'd be hesitant to apply a milspec laminate schedule to a sailboat hull for two reasons. Firstly you're dealing with different skillsets and secondly sailboat hull repairs tend to be one offs.

Aluminium has better abrasion and impact survivability (not necessarily resistance) than composites. Assuming a typical fibreglass, carbon or kevlar build.

Aluminium is readily formable, field repairable and mechanical properties when welded with pre or post heat treatment are effected by most repairs.

The trend toward carbon hulled super yachts is probably more about bragging rights than any deficiencies in Aluminium. Cost is not an issue.

With composite computerised cut schedules and prepreg the need for skilled fabricators is greatly reduced in the yard. This results in reduced yard labor costs.


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