New Bi-Rig Performance Cruiser

[multihullsailor6]

Originally Posted by BigCat

That's frightening. I'd e-mail the designer immediately and ask for his comments. If you do, please post any reply he makes. I'd probably build bigger rudders. I can see how a very light boat might be unable to tack, but being unable to gybe is puzzling, to say the least. I would think the only effect the biplane rig would have on this is that you don't have a foresail to back to help you around, so it is like a cat or una rig in that regard. If your sail area is too far forward, you have problems tacking, and if it's too far aft, you have problems gybing. A problem doing both doesn't sound like a rig balance problem.

Hi BigCat!

It wasn't too frightening, as we had a nice beach downwind to beach the cat on, but the waves and surf would have done material damage! So we ended up anchoring on a lee shore 100m away! Chinese saying says "When in deep ****, first trust the anchor, thereafter call the Coastguard!"

Yes, it was puzzling that the boat refused to turn more than directly downwind to enable us to gybe, by then we were fully reefed and soon running out of usable water.

Roger

[fastcat435]

Originally Posted by David M

Gideon,
Is that correct...9 tons for the 58 foot hull alone or 9 tons in a ready to sail condition with all the amenities you mentioned? Do you mean short tons at 2000 pounds or do you mean long tons at 2240 pounds (1000kg)? In my business we use both.

Perhaps keep it simple, at least for me please, and use kilograms? I know us Yanks are still in the dark ages using pounds, feet and short tons. Don't worry, there are plenty of conversion websites for us.

One of your competitors in South Africa has a 48 foot boat with a light displacement at 8000kg and a 66 footer with a light displacement at 15,400kg. What will be the light displacement of your 58 footer in ready to cruise condition in kilograms?

I think your boat is going to hit a sweet spot in between those two lengths.

David

Hello David Yes I am sorry I missed this one
The target weight is 9000 kilo,s ready to sail but with empty diesel and water tanks
Our standard equipment is on board so with RIB outboard a full set of sails kitchen inventory etc etc.
Our 52.5 ft cat came out at 7600 kilo and since then we have changed the interior from resin infused foam to nomex honeycomb with 1.4 kilo per squire met weight or about half of the resin infused foam.
When I told our Architect Angelo Lavranos that we where aiming for 4800 kilo for the 435 presently lenghtened to 46 ft 9 inches he told us that he did not think it was possible but we made it with a carbon fiber bimini on top as extra. that is for the diesel version , the Green Motion version is heavier but uses less fuel so it might even out, we will know in 2 or 3 months , we build our cats on load cells to make sure they get the best balance and to check the weights.
All part weigths are noted on a spread sheet so we know where we save weight.
We build our cats like others build an aircraft, very weight concious but always keep quality and strenght in mind.
In our new factory we will put up 16 Web cams so customers that have ordered boats can see the progress and can even zoom in to see special parts.
You made a remark before about our pricing.
One of the reasons for our reasonable prices is that we work without agents and for that same reason you will never hear an agent of another make talk complimentary about our yachts. thiis saves 12 to 18 % in cost and that is a lot of money on a yacht of 1.200.000,00 euro

Greetings

Gideon

[Nordic cat]

Originally Posted by multihullsailor6

Hi BigCat!

It wasn't too frightening, as we had a nice beach downwind to beach the cat on, but the waves and surf would have done material damage! So we ended up anchoring on a lee shore 100m away! Chinese saying says "When in deep ****, first trust the anchor, thereafter call the Coastguard!"

Yes, it was puzzling that the boat refused to turn more than directly downwind to enable us to gybe, by then we were fully reefed and soon running out of usable water.

Roger

Any newsfrom Schionning on this issue?

[multihullsailor6]

Originally Posted by Nordic cat

Any newsfrom Schionning on this issue?

Hi Alan,

The owner hasn't contacted Jeff Schionning (yet). However, we've been discussing the rudder situation a lot and the current thinking is to enlarge the rather small looking rudders by approx. 20% coming SA winter. Most probably by extending them aftwards.

FYI on the sail aspects of a bi-rig: The boat in currently in Langebaan, yesterday's sailing was a wipe-out with a true South Easter blowing with 40kts, today we had a gentle 10-15ktsso we played around on Langebaan lagoon, sailing with only one sail up, in our case the starboard one. Tacking with this sail configuration: when the starboard hull was the lee hull she would tack nicely. When the starboard hull was the windward hull, she would not tack, just round up and stall. With sailing backwards we got to beam on and that was it, she would just drift sideways. It didn't matter what the situation with the boards was.
In the afternoon we sailed with both sails up, tacking on the leeward sail only (releasing the windward one when starting to go about) not a problem.

Regards
Roger

[Nordic cat]

Originally Posted by multihullsailor6

Hi Alan,

The owner hasn't contacted Jeff Schionning (yet). However, we've been discussing the rudder situation a lot and the current thinking is to enlarge the rather small looking rudders by approx. 20% coming SA winter. Most probably by extending them aftwards.

FYI on the sail aspects of a bi-rig: The boat in currently in Langebaan, yesterday's sailing was a wipe-out with a true South Easter blowing with 40kts, today we had a gentle 10-15ktsso we played around on Langebaan lagoon, sailing with only one sail up, in our case the starboard one. Tacking with this sail configuration: when the starboard hull was the lee hull she would tack nicely. When the starboard hull was the windward hull, she would not tack, just round up and stall. With sailing backwards we got to beam on and that was it, she would just drift sideways. It didn't matter what the situation with the boards was.
In the afternoon we sailed with both sails up, tacking on the leeward sail only (releasing the windward one when starting to go about) not a problem.

Regards
Roger

I would suggest that you guys contact Jeff Schionning, he lives up around Baviaanskloof most of the year. You can get his phone number from James at Custom Marine in Knysna.
another way could be to join the Schionning forum, and ask the questions there.

I would not reccomend just increasing rudder area backwards, better is to make them deeper, this won't affect the rudder balance much, (if it is OK at present)

Keep us posted on developments please

Regards

Alan

[BigCat]

When I read the first post about the Radical Bay's steering problems, I sent an e-mail to his company, suggesting that they read it and respond to this forum. They didn't respond. The usual responses to steering problems like this are bigger rudders and moving the rig aft, or raking the masts aft. Moving the daggerboard forward would be another solution. I don't think the biplane rig is responsible here, as this problem hasn't been reported with other biplane rigged boats, but it has been encountered with boats having rigs on the centerline. The issue is almost certainly either one of too much lead-the CE being too far forward of the CLR, or the rudders just aren't big enough. I have links to other sites about biplane boats at the bottom of my web page, under a heading that gathers them together as a category.

[multihullsailor6]

Regarding the Radical Bay's tacking / steering problems mentioned earlier have just heard that Jeff Schionning also advises to increase the rudder size by 50%. Discussions are still on-going as how best to do it.

Roger

[fastcat435]

Hallo Alan

coming back to your quote

"Like your statement that you can save further weight by using basalt fibres (I think it was). It is true that you can save weight by using lighter and stronger fibres. BUT, you also know that when building to CE/RCD standards, the requirements for the outside of the hulls is 1200 g/m2, with no possibility to work around this. So the weight saving will be ZERO!"

There is nothing in the CE/RCD standard that says that 1200 g/m2 needs to be used
I have gone through all 63 CE directives and have not been able to find that, I have checked with CE bureau in the Netherlands and again no directive like that in place.
That means that you can save considerable in weight by going to R glass or carbon Fiber or as we are doing to basalt fiber and are saving well over 23 % for our hull deck and bulkhead in fiber and resin saving over 400 kilo for the total FastCat 455
or around 8 % of the total sail away weight ..

If you want I can get you specific info on the basalt fiber, It compares mostly with R glass but lower in price.

Greetings

Gideon

[Maren]

Originally Posted by Nordic cat

I would much appreciate comments and ideas from the great pool of knowledge here, as I am reaching the final design stages, and expect to start building within a few months.

I think it’s a good looking boat; it looks like you were heavily inspired by a number of designers:

• John Shuttleworth designed an extremely similar hullform a number of years ago – there is a production model by tek-composites

• Chris White / Morrelli & Melvin for the centercockpit / pilothouse.

• Any of a number of designers for the bi-rig

I don’t think this is bad either as this is the way the state of the art gets pushed forward and I don't know of any one combined all these features. Morrelli & Melvin didn't come up with the center cockpit. They got it from Chris White who certainly didn't come up with the idea of a pilot house.

If this is the case, you're going to want to review any weight sensitivity issues as the Shuttleworth hull is very much performance oriented.

It seems like Schionning Marine would be your competition in some aspects. Their Wilderness line has some close features, including the bi-rig. Mahna Mahna is a wilderness 1230 that looks quite similar, minus the center cockpit.

Here is a photo:

[Nordic cat]

Originally Posted by Maren;153399[QUOTE

]I think it’s a good looking boat; it looks like you were heavily inspired by a number of designers:

That is absolutely the case - I think it would difficult to come up with something that has not been done before. Thanks for the positive comment

• John Shuttleworth designed an extremely similar hullform a number of years ago – there is a production model by tek-composites

I very much like the looks and the thinking behind his designs, but there were several designers using the flared and rounded hull before him. Tris have used this for many years. The main difference is that my hull is flatter on the sides for easier fendering etc.
Tek-composites folded many years ago - the boats were a mix of Shuttleworth and John Tekatch ideas - lovely looking boats!

• Chris White / Morrelli & Melvin for the centercockpit / pilothouse

  .

[/quote]Chris Whites' Atlantic series were a major step forward in my view, also better suited to the colder climates.

• Any of a number of designers for the bi-rig

I beg to differ here, there aren't many boats over 40 ft with a bi-rig, not even 30 ft in fact. For this size of catamaran I haven't found a designer who designed the rig and the boat, but there may be one out there.

I don’t think this is bad either as this is the way the state of the art gets pushed forward and I don't know of any one combined all these features. Morrelli & Melvin didn't come up with the center cockpit. They got it from Chris White who certainly didn't come up with the idea of a pilot house

.

If this is the case, you're going to want to review any weight sensitivity issues as the Shuttleworth hull is very much performance oriented

My underwater lines will be different from his, as well as the bow areas. My prismatic coefficient is higher. This is a performance cruiser, so weight is an issue, I have around 1000 individual parts defined in my weight sheet, everything down to 200 grams is identified. Using infusion and stringent design and material choices will keep this boat at around 6.8 tons lightship, which is lighter than a 48 ft Atlantic or Gunboat, but still building to CE!

It seems like Schionning Marine would be your competition in some aspects. Their Wilderness line has some close features, including the bi-rig. Mahna Mahna is a wilderness 1230 that looks quite similar, minus the center cockpit

I am designing and building this boat for myself, so no moulds etc. If it works out as well as I hope, I might consider offering the design up for sale.

There are at least 3 Schionning designs being built for bi-rigs as far as I know, but I haven't seen a single drawing of their rigs. The Mahna-Mahna picture looks like a Radical Bay rig photoshopped onto a Wilderness. I doubt that the final rig will be so low Aspect Ratio.
I expect to be in the water in about a year.

Regards

Alan

[fastcat435]

Alan
If she sails as good as she looks you have got a winner

Good Luck

Gideon

[Nordic cat]

Originally Posted by fastcat435

Alan
If she sails as good as she looks you have got a winner

Good Luck

Gideon

Thanks.

We have been working hard, and are now in the process of finalising the design, so am enclosing a few drawings and renders for comment from the great knowledge and experience here.

Looking forward to your comments

Regards

Alan

[fastcat435]

Absolutely Stunning

Good work Alan

Gideon

[Maren]

Originally Posted by Nordic cat

We have been working hard, and are now in the process of finalising the design, so am enclosing a few drawings and renders for comment from the great knowledge and experience here.

Ok, here goes:

Could you put up an enlarged section, please? I would like you put up from 4 to 9 on the bridge deck plan view and hull plan. This is my reasoning:

It looks like after you pass from the center cockpit through the door, you have immediately on your right or left the nav station and … something with a chair on other side. The set up is similar to the Atlantic 50 if I recall. I am trying to get a distance between the back of the chair on the port side and the counter with the range on it. Offhand, I think you would do better to change the galley layout so a person coming from the port hull could slip behind the port chair in the same way you can with the starboard.

Also I think you might wish with move the aft wall of the saloon/galley back a bit. Even a few inches will increase that space so it isn’t quite so tight.

A few other questions:

I see the aft and fore steering stations, was one of the interior chairs a steering station too (as with the Atlantic) or was it just to make it symmetric with respect to the nav station?

Does this have a rub rail?

On the side elevation plan -- is that a wind screen in front of the fore cockpit?


Thanks and I will more comments afterward

[Nordic cat]

Originally Posted by Maren

Thanks for taking the time and using the effort to look at the drawings a bit more in detail. I appreciate all feedback. Boat design is after all the art of compromise, and sometimes one needs to re evaluate earlier decisions
I will post the detailed drawings that tomorrow, as I don't have the necessary software on my laptop- just the viewer.

The starboard side is the nav station, where all the nav instruments are, and a demountable wheel. The port side is the same, but this is where all the electrical panels and switches are, it other use is as a day desk for ad-hoc use.

There is 80 cms between the desk and the fwd end of the galley, so there is enough room to slip by.
There are skylights aft of where the chairs are to let you see the sails.

The spaces just outboard of the door to the fwd cockpit has 2 sets of batteries mounted on a small trolley. Above these is storage space for tools, odds and ends and a grab bag with personal stuff.

I have decided to split the electrics into port and starboard with a cross connector if one side fails/is damaged. All the 12VDC is a bus based distribution system so there will be on large size cable through each hull. This will save alot of weight.

Outboard of the nav stations there are storage hatches for files etc.

.
Yes, the stbd one.

Yes, and it also is used as a panel stiffener.

There is a bimini for the forward cockpit that folds down below deck level. a dodger or a windscreen of some sort will be designed to give a bit of protection. With 3 steering positions, I doubt that this will be much used apart from anchoring/going alongside in bad weather.
The lines from the masts to the fwd. winches are run under deck, so no lines to trip on and no windage from winches.

The rest of the line runs and rig details aren't finally sorted yet.

The saloon table folds so for normal use it is only ½ size which should be good for around 4 people.

Regards

Alan