New Bi-Rig Performance Cruiser

[BigCat]

As always, Alan, your drawings are beautiful. 3 steering stations is quite a lot-better have valves to eliminate not just the stations while the others are working, but also the lines, so as to reduce friction in the system.

This is going to be an expensive boat to build, with its elaborate lines and 3 steering stations.

How are the masts held up? Is this going to be the kind of setup with a strut between the mast heads and shroud / stays to the bow and stern of the opposite hull?

It looks like the booms won't clear the opposite mast if they are let forward on the side where that is an issue. I'd try to make it possible for them to clear each other--it could come up in a sailing emergency.

If the masts are cantilevered, you might want larger base diameters. 10% bury is often said to the minimum feasible in cantilevered masts.

I find myself wondering if there is adequate clearance for persons using the stairs down into the hull-I'd mock it up and try the dimensions out in person, and if you aren't tall, invite a tall person to try out the mock-up.

I'm glad you're going with the bi-plane rig. When pioneers push the margins, it makes it easier for other pioneers.

[mikereed100]

Alan,

Beautifull boat. I think you have a winner. Just for fun I thought I'd mention something that I will be trying on my own boat concerning the settee. One of the great advantages of designing your own boat is that you get to do it your way rather than being stuck with the parameters set in place by the charter industry. With this in mind I have decided to forgoe the settee/table altogether. Meals will be taken at a "bar" that is incorporated into the galley that will seat 4.

Advantages include:

• Increased galley counter space
• Meal service can be done while seated without getting up
• Meal prep and some cooking can be done while seated
• Since this only seats 4, I will have a built-in excuse not to host large get-togethers on my boat (an advantage not to be underestimated to the antisocial)
• If I can't avoid hosting a large group it is easy enough to set up a table in the cockpit where I will be taking most of my meals anyhow.
• Opens up a large area in the saloon which can be used for innovative, comfortable seating/lounging

Disadvantages are:

• Decreased storage in the galley. This will be spread about the saloon in my boat
• May be hard to keep your seat in a seaway due to the "barstools", however these will still be fairly low.

Anyhow, just a thought. Good luck with the project. Who says cats can't be good looking?

Mike

[BigCat]

No table? My wife prefers to work at the dining room table with her laptop to working in the office. It is also where we hang out rather than in the living room. If your chart table isn't very big-and they usually aren't these days, it does double duty as a chart table, kid's study table, etc. In a house, I'd give up a living room before I'd give up a dining room-and nobody has to navigate in a house.

[Nordic cat]

Originally Posted by BigCat

Thanks, I'm working with Jefa here in Denmark to come up with a system that gives good feedback, and is still doable. let's see where we get, otherwise it will probably be a Hydrive system using hydraulics with some feedback to one station at a time.

Precut foam panels, and infusion over frames should help bring the hours down, but yes, it won't be the cheapest boat around, but its my dream!

The masts will be totally unstayed and independent of each other.

Good spot, yes there is a small misunderstanding between me and the guy doing the CAD work. The booms and masts will be able to rotate 360 degrees. Booms will be about 40 cm shorter and mast a bit higher.

The mast chord will be 630 mm at the bottom, the ratio is 1:3, so around 200 mm wide tubes. Bury is just over 2 meters.

I'm glad you're going with the bi-plane rig. When pioneers push the margins, it makes it easier for other pioneers.

Being an engineer, I just get annoyed by the conservative approach most people in sailing have! People actually ask if the masts won't break, yet they happily jump into a 30 year old jet and go on holiday!
This isn't pioneering work, it's just playing catch-up to the real world

Regards

Alan

[Nordic cat]

Originally Posted by mikereed100

Alan,

Thanks for the positive feedback Mike.

I did give this a bit of thought, but I like to be able to sleep in the saloon if I have inexperienced crew, heavy traffic etc. so I have made the sette long enough for that. also I like to snuggle into a corner with a good book sometimes.

May I suggest you look at the picture below from the new Dragonfly 35 tri, a fantastic boat, also from Denmark.

The blue fold down seats are a neat way of having "bar stools" that don't slide around, or take up room when not in use. They lift up and lock for use.

Regards

Alan

[mikereed100]

I did give this a bit of thought, but I like to be able to sleep in the saloon if I have inexperienced crew, heavy traffic etc. so I have made the sette long enough for that. also I like to snuggle into a corner with a good book sometimes

My feelings as well. In the space that would have been home to the settee and table I have drawn a kind of combination day bed and couch with a narrow table so I have a place to nap and play my guitar in the saloon. Also leaves room for a nice comfy reclining chair on the other side of the companionway for reading, something I have never had and always wanted on a boat. Here are a couple preliminary drawings to show what I mean. Definitely not for everyone but it will be fun to try.

Mike

[mikereed100]

No table? My wife prefers to work at the dining room table with her laptop to working in the office. It is also where we hang out rather than in the living room. If your chart table isn't very big-and they usually aren't these days, it does double duty as a chart table, kid's study table, etc. In a house, I'd give up a living room before I'd give up a dining room-and nobody has to navigate in a house.

like I say, definitely not for everyone! On the other hand, my girlfriend lives in a 20' x 15' one room cottage ($950/mo, welcome to California!). I built her a kitchen/bar identical to the one in the drawing above only smaller, seats 3, and it has served us perfectly for 4 years. In fact it was she who suggested doing the same on the cat. This leaves us room for a large, flat area to sprawl on without having to negotiate a table. I have also found that when I have access to a large table I just pile crap all over it until it is unusable. The chart table I have drawn is pretty big so should be fine for laptops and small projects. However I won't be surprised if it too becomes unusable due to accumulation of detritus. There will be a computer station and workshop down below.

Anyhow, it's fun to play around with alternatives to the standard layout. Keeps the mind limber. One member of this forum has a platform with beanbags in the saloon which I think is brilliant!

Best regards,
Mike

[Joli]

Originally Posted by Nordic cat

Being an engineer, I just get annoyed by the conservative approach most people in sailing have! People actually ask if the masts won't break, yet they happily jump into a 30 year old jet and go on holiday!
This isn't pioneering work, it's just playing catch-up to the real world

Regards

Alan

Being an engineer I am happy with my conservative attitude. It is a comfort to step on a yacht who's design and build has been proven.

Yes, I do look at the build plate when getting on a jet and have declined to fly when the build date is beyond my comfort zone.

Pretty design by the way.

Cheers, Joli

[BigCat]

It's not high tech, but Batwing's unstayed masts are going like the Energizer bunny, 35 years and 50,000 miles later. They are fir trees-they were cut down with an axe, roughly trimmed with the same axe, and then given a bit of trimming with a drawknife. 440 sq ft. mainsail on a mast 8" max diameter, 270 sq ft. foresail, same size mast due to pitching stresses right forward. 770 sq. ft. of sail on a 34' boat, and the toerail never went under.

[rob denney]

Originally Posted by BigCat

If the masts are cantilevered, you might want larger base diameters. 10% bury is often said to the minimum feasible in cantilevered masts.

G'day,

It is not about mast height, it is about righting moment. The smallest bury we have used is 750mm/30" on an fairly heavy 11m open bridge deck cat. The mast was 13m/43' long, which is 5.7%. Works well. Pictures at harryproa / masts / Taywun

regards,

Rob

[Nordic cat]

Originally Posted by Maren

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.

Hi Maren,

Here are the sections as well as the GA for the area you requested. Looking forward to your comments and ideas.

Regards

Alan

[Maren]

Originally Posted by Nordic cat

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 have a passion for good design (and this strikes me as quite a good one) so this is no trouble at all, and thanks for putting them up. However, I can pretty much guarantee there'll be at least one idea you won’t like though. Let's hit what I think are the easy ones first, realising some are merely requests for information.

Table -- I would use a 25-50-25 split on it the outer leaves folder centerward (still fore/aft as you have it). While you won’t have quite as much room as the other design, the difference will be minimal and it will be easier to get past the settee to the corner. If you end up sleeping there as you said you might, you have a bit more room to move and still be able to reach the top for cup, clothes, book etc. You could also have the leaves hang straight down which would leave the center section open. To me this is good in the event you have intention of having an inlay in the same manner the Dolphin 60 does.

Batteries – have you calculated the anticipated power loads? Also, do you intend to have an inverter?

Engines -- I don't see access points. I take it isn't through the berths but from the outside.

Rub rail as a panel stiffener – That’s interesting. How does that work?

Companionway stairs -- As I PM'ed you I can't really see much from the cross-sections other than there is standing room as far forward as Station 2. The head height for the stairs seems a touch low. It’s one of the things I disliked about the Lagoon 410. I felt like I needed to be wearing a helmet.

So much for the easy ones.

The aft steering station seems like it will mostly be used when docking which is part of the reason I think you could move the aft wall of the galley/saloon back.

Now for the tough one.

• Port desk – you indicate you’ll have 800 mm. As I see it, the max would only be 700 mm as the storage under the desk gets in the way. 700 mm is fine but if then have someone in the chair; you are looking at 400mm or less, where as the starboard shouldn’t have this problem as you can move diagonally.
• Unless you let ‘Otto’ do some of the driving, you will be standing for the duration of sailing.
• Say I go sailing with a friend of mine in a mono hull. The cockpit is a pleasant intimate experience because we are physically closer and generally able to look at each other. This is less so if we are on a catamaran as the steering station is elevated and set off from the others. I like the cockpit on your boat but you will still be set off for the most part since you are standing at the wheel and others may or may be.

What I’m indirectly addressing is what I call the fetishism of symmetry in sailing … and yet almost no one steers on centerline. Why fight it?

My idea is this: Offset the fore door to the cockpit by about 700 mm, give or take. Move the two winches to within about 300 mm of each other so that one person can easily access both. Steering station is moved to just off the center line but closer to the door. Because you are sitting you can now see under the sails and now have a full 180 degrees of unobstructed view, the remaining portion will be visible through the windows as before. Directly behind is now a combined nav/steering station (possibly with a joystick) and desk which has the same field of view as the fore steering station.

[Nordic cat]

Originally Posted by Maren

I have a passion for good design (and this strikes me as quite a good one) so this is no trouble at all, and thanks for putting them up. However, I can pretty much guarantee there'll be at least one idea you won’t like though. Let's hit what I think are the easy ones first, realising some are merely requests for information.

That is a good idea, that I hadn't thought of, I will do some sketches and play around with it. Thanks.

I will have 2 banks of at least 3 Li-ion batteries of around 120 Ah, one bank on each side of the door to the front. There will be 700 W of solar panels. A 2kW inverter. Each engine has a 3kVA generator between the flywheel and gearbox. (Yanmar) So I should be able to charge the batteries very quickly, but haven't done the exact calculations yet. I expect a 100 A charger for each bank.

Correct, there is a hatch hinged at station 8 that goes aft and incorporates the top 3 transom steps, so when this is open, there is easy access to the engine rooms. The engine and drive can be lifted out in one piece if necessary, and the step down is low.

The same as a "rib" on the inside. The height of the rail creates the stiffness. I like to be able to "rest" a corner of the boat against a pole when manouvering short handed in wind. A rub rail will protect the topsides.

I will post the section where the stairs are, you will see around 2 metres vertical height as a minimum.

I redid the measurements on the drawings and at my desk here. There will be minimum 350 mm to pass behind the chair if I sit there, and I'm a big guy. Anyway, I don't expect alot of traffic there, and this desk will primarily be used for working on the electric systems, and as a general desk, if the saloon table isn't the one being used.
Worst case, one would have to get up, or roll inboard.

There will be a chair in the forward cockpit. Once out at sea the autopilot will do nearly all the work. The height of the seats in both cockpits and saloon is such that you can see through the windows of the saloon without getting up, so watch keeping is easy. This was a key parameter for me to achieve this. Many boats either have the saloon seats raised or else you can't see the area near the boat. So regardless of whether you are standing or seated, you will have a an allround view.

I expect the aft steering position to be used primarily for docking, or for sail trim in bad weather. In good weather steering will be out forward.

• What I’m indirectly addressing is what I call the fetishism of symmetry in sailing … and yet almost no one steers on centerline. Why fight it?

The seat in the forward cockpit, and in the saloon steering position will be at the same level, and enable one to look under the booms/vangs. Skylights in the coachroof will enable viewing of the sails from the inside to a large extent.

I didn't want the winches at the forward steering station too close together, I want plenty of room around them so lines dont get caught in the steering, and space under the winches for line stowage. One step to each side from the wheel is enough for this. A second step, and I can brace myself in the forward inboard corner in rough weather. The area forward of the steering wheel has the instruments, engine controls, and anchor winch controls, so the anchor can be retrieved by one person if necessary.

There will be a demountable steering wheel in the saloon, stbd side (not shown)

I will post the detailed section later.

Regards

Alan

[Nordic cat]

Here is a drawing of the section at the stairs. One of the emergency hatches in each hull is under the stairs. The stair in front of the hatch is designed to be lockable in port, and can be pushed out in the very unlikely case of an inversion.

This shows the 195 to 200 cm headroom also in the stairway.

Regards

Alan

[Maren]

Originally Posted by Nordic cat

Here is a drawing of the section at the stairs. One of the emergency hatches in each hull is under the stairs. The stair in front of the hatch is designed to be lockable in port, and can be pushed out in the very unlikely case of an inversion.

This shows the 195 to 200 cm headroom also in the stairway.

Ah, good. How tall is your manikin or, more importantly, you? As I indicated before, this was one of several features I really did not care for on the Lagoon 410. Every time I went down the stairs it was a half turn while descending because they cut it too close. And it wasn't just me.

On the other hand, what are the options? Increase freeboard or decrease the walkway on deck by chamfering the angle. Neither are really desirable.
You could cut a step in to the hull (which is what was done on the 410) but I absolutely would not do that.

If you can, try this as it's pretty easy. Turn you manikins around so they are going down the steps. If you think they are still good then I will too.