22m cruising cat design concept

[Becaris]

OK, to start with, I am not a yacht designer. I do make a living creating concepts (though until now, not yachts). What this means is that NOTHING about this design is necessarily correct, and I know it. However, there are a few things I'd like to say about what I'm trying to achieve.

I set out to create the concept for a forward flybridge / semi-pilothouse sailing yacht over 20 meters long with a biplane rig. I do not want to turn this design discussion into a discussion about single or biplane rigs. I would rather we discussed what it would take to make a biplane rig work best on a cruising cat this big and other issues with this design.

Beyond the biplane rig, there are other areas of the design that I would be interested in 'why not'. Like the forward flybridge, the nacelle center, various ratios, hull shapes, mast positions, pretty much anything that comes to mind.

I know this does not look like a standard cat, but that's the point of a concept. Let's take a look at something different, and figure out if it could work, and what it would take to make it work.

If suggestions are made that seem good, I will adjust the model and repost pictures. So, here goes... take a look... discuss away... have some fun.

(These screenshots are now old, if you look deeper in the post there are new pictures with changes suggested by other readers).

[rwatson]

I think the design has some interesting aspects.

I wondered if the 'downstairs' forward windows would be better off with an inward slope from the 'flydeck'.

The 'step' caused by the jump from the downstairs windows spoils a nice aerodynamic shape.

[sandy daugherty]

There seems to be a common theme that sailing vessels are controlled from a 'driver's seat' like a car or an airplane. In reality, watch standers don't spend hours on end sitting in one place, even if all or most of the control lines are led to a single location. Since things don't happen at 55MPH or mach .82, and since there isn't a double white stripe down the middle of every sea lane, Its much more important for a watch stander to be able to get in and out of the helm seat easily to check all the things a watch stander should watch than to make it some kind of throne. That means standing headroom . And standing headroom means one very big lump right up front in your design. Since it is also important that the helmsperson be able to see 360 degrees, and it would be very nice for him to see the corners of the boat for docking, it begins to look a little unwieldy.

Consider dual helm stations, connected through the forward upper deck. Place them forward of the masts, with a clear view fore and aft, blended airodynamically around the mast base, with windshields that roll around to provide open air and egress to the bows, or closed and heated with the main cabin. If the boat is large enough, some horseshoe shaped seating around the helm would keep the Captain the center of attention.

[Becaris]

I agree with you Sandy about not needing to stand at the helm during a watch. However notice that the interior station is part of the salon (and includes a horseshoe shaped seating area behind the helm as does the flybridge). With the windows arranged in a half circle the interior station has good visibility (accept directly astern). And from the flybridge (which is set ahead of the masts, due to the rotating unstayed masts and no jibs) you also get very good visibility, even astern.

Incidentally, both the flybridge and pilothouse stations on this concept are both designed for more social aspects and gawking together while there is something to see (not racing at 55). The design idea is simply taken from other flybridge/pilothouse designs used in passage maker motoryachts that only go about 8 knots. With the design of the two unstayed masts, there aren't lines and winches to run, which allows for some similar design. The idea with this cruiser was to allow a couple to sail a larger yacht with less physical need and more comfort.

I feel that placing dual stations around each mast would put the main cabin in the way of good visibility. However, your point about docking has some merit, I will consider additional controls aft (port and starboard) for docking.

There is a question for you captains, at slow docking speed, using dual engines to get into postion at the dock, do you need access to your rudders or are can you just leave the rudders centered and use the two engines to maneuver?

However, besides docking visibility issues, what other issues do any of you see with this layout? I can give you some interior pictures of the inside helm/pilothouse area if you want.

[Becaris]

rwatson,

I'll try some designs with the front windows angled forward from the bottom of the flybridge.

[RHough]

Originally Posted by Becaris

I feel that placing dual stations around each mast would put the main cabin in the way of good visibility. However, your point about docking has some merit, I will consider additional controls aft (port and starboard) for docking.

There is a question for you captains, at slow docking speed, using dual engines to get into postion at the dock, do you need access to your rudders or are can you just leave the rudders centered and use the two engines to maneuver?

Docking is about the only time the skipper has to be at the controls and able to see well. Once you are away from the dock, the autopilot can drive.

No need to give up rudder control for P&S docking stations. Go with a 'fly by wire system' based on the Volvo IPS or Cummins Zeus. Steering, throttle, and gearshift are all electronic. A wired or wireless remote could be used on the fly bridge and carried to where the skipper needs to be. The state of the art is good enough that they use it to get crane operators out of the cab and allow them to stand where they can better see what they are doing, it is a natural for controlling a boat for docking.

Just a thought.

[Becaris]

Excellent, then I can leave my two steering stations where they are (which are more about looking at electronics than steering the boat most of the time anyway) and use a remote when docking. In a pinch, there is hull side visibility from the extreme sides of the flybridge anyway, I did a ray trace from the proper height to make sure.

[Becaris]

Here is a look at the concept model with forward slanted salon windows at the front, as suggested by rwatson above.

[Nordic Cat]

May I suggest that you lower the height of the coachroof if possible, maybe open up the sides of the flybridge deck a bit to give an "lighter" look. The boat looks top heavy.

I am about to commence on the build of a 15m bi-rig cat, with rotating wingmasts. It's interesting to see that there are more bi-rigs being built and designed nowdays. Maybe shorten the boom vangs a bit also, take a look at the elegant solutions by Eric Sponberg, maybe get him to design the masts for you. He is one of the few designers who has done it several times

Regards

alan

[Becaris]

Thanks for the suggestions. I agree with the height, I was already working toward lowering it. I left the leading edge of the flybridge as I needed that height, but lowered the rest by more than a foot. I may be able to lower it more as well.

As for the masts, I'll take a look.

[Becaris]

Here is a shot with the coach lowered (I lowered the boom down to the new coach height). The flybridge is lowered, but not as much, though the majority of the coach roof is much lower now.

[rwatson]

Yeah - thats getting there nicely.

The only thing that caught my eye was the bulgy bit over the prop. To my eye i would probably think about making the stern run a bit concave so you could have the prop shaft a bit more horizonamontal.

[Nordic Cat]

Try angling the aft end of the saloon to get a less chunky look. Play around with side window shapes to "lighten" the look as well.

The curve of the transoms don't fit in with the rest of the boat - no balance.

What are you going to use the roof on the saloon for? probably need some clearance under the booms.

It's getting there...

Alan

[Becaris]

Right now I'm using the flat roof for solar panels... lots of solar panels. I want this to be a hybrid electric powered sailboat. I've read up on the issues with this, but I think the time is ripe as new battery technologies are coming available that will allow more power storage at lesser weight and faster recharge times. So I'm planning electric motors, solar panels, two wind generators (one on the top of each mast) and of course, a diesel generator for emergencies (no wind, no sun, out of battery power). Is there a reason I need some clearance between the boom and roof (solar panels)? If so, how much?

As for the prop and hull shape, anyone have a picture/diagram of what the hull shape should be in profile to accommodate the props correctly?

When it comes to the aesthetic shape of the coach, windows, and even the curve of the transoms, I'll modify that some once I have some of the more functional aspects adjusted. Any suggestions on that end? Hull shape, width, mast height, mast position, boom length, etc.?

I can supply better measurements of any area if needed.

[rwatson]

For a bit of fun, I touched up the prop area.
I 'felt' that you would need a skeg based on the centre of effort of the sails

:-)