New bi-rig performance cruiser

Hi
I have been working on a new design for a 47 ft performance cruiser, that ticked as many of my specified boxes as possible. Beam is 8,20 m/27 ft. Beam centreline is 6.3 m/20'8". Max hull beam is 98 cm/3'2". This gives around 1:13.5 beam/length ratio
I have chosen to use 2 unstayed cantilevered masts that can rotate 360 degrees. Masts are 19 meters (62 ft) off the waterline and will be teardrop shaped profiles with a chord of 10% of the mast/sail length. Sail area on each mast around 62 m2 and each mast around 5 m2. Gennaker on the lee side for light winds. No forward beam. Mainsail sheets can be released/adjusted from either cockpit.

Displacement for lightship is around 7 tons, with a 3 ton load. Fully loaded bridgedeck clearance is 100 cm (39") lightship is 15cm/6" higher.
Draught is 52cm/20½" lightship. 2 asymmetric daggerboards.
Forward cockpit with steering, also steering from the aft cockpit and maybe steering from the saloon, otherwise via autopilot.
Construction will be corecell/epoxy vacuum bagged, with kevlar on the inside to about 1m/3' above the waterline.
Aft bimini folds into the targa, fwd bimini and a dodger fold into a recess in the fwd cockpit/deck area.
Despite all the hype for diesel electric propulsion, I have chosen 2 40hp Yanmars with the new 3/6 kVA generators on the flywheel. 700 Watts of solar panels on the coachroof.
The "eyebrow" over the saloon windows is to cut down on heat, and is a separate mould that is attached to the actual roof, with a 50 mm gap, so airflow can cool the windows. The recess on the eyebrow also functions as a handhold.
All winches are recessed to minimise windage, and ensure straight line runs.
Layout is 2 aft doubles with acess to the bunks from 2 sides. I double fwd in port hull, as well as separate shower and toilet. Stbd is the owner side,so a large bathroom fwd, and a workshop area midships.
Nav station is forward facing in the saloon, stbd side. All tanks are midships under the soles. Each hull has 3 waterproof bulkheads, as well as 8 contained spaces under the midships sections. 2 watertanks each side, so water can be pumped aft/fwd or side to side for trimming. Engine rooms fully separated from the accomodation.
The forward 4metre/13' section of each hull is foam filled to about 60cm/2' above the waterline. The area above is for stowing fenders and sails only.

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.

Regards

Alan

 

Hi Alan,

Very surprised that there are no reply yet, so I will get it going.

First of all: Congratulation! Great boat, I can see that you really did your homework, I can see the influence of many designers out there and you picked the best features. I have been doing the same for a few years now to the point that I built a 12.5m Schionning to learn about big cats before I went and built my new home (cat).

I will make my comments on all your point one by one, it will be good to hear the opinions of others as well so that when we do build our last?? boat it will be a really good one.

- just the size I have been considering for a long time, lately I am thinking of longer hulls on the same accommodation and rig of a standard 47 footer for added comfort and speed, perhaps 50~55".

- I would not entertain anything less.

- sorry, here is the only thing I disagree, I need to be able to lower my mast(s) to go under bridges. I do appreciate that rotating masts like those allow you to reduce sail downwind, a very important safety feature, but they need enormous strengthening of the hull and would be rather expensive. I will open another thread on this subject soon as I have a semy-novel concept I would like to discuss, I am sure Yipster and Brian Eiland will love it...

- achievable with modern materials ad a good builder.

- One of the most important comfort --> safety features. Great, I will aim at a little more, perhaps 120cm.

- mmmh, this is where I am still scratching my head: this is a cruising boat, do I want the additional lines, blocks, winches? Do I want to sit on the hulls and get debris in the trunks when in high tidal areas? Do I want the additional pointing ability so that I can happily beat windward across the oceans or just go with the wind? Do I want to get snagged in the middle of the night on a fishing float? I have done-happened to me all the above.
Do I want a combination mini-mini keels and off centerline dagger/center boards??

- I really like that. I would put a small wheel inside as well, sometime it is just too cold and rainy to want to be outside. What about engine controls?
What is the cubic capacity of the forward cockpit? How quickly will it evacuate when it WILL be filled by a large wave?

- Corecell is the best, but I prefer Vinylester.

- excellent for impact resistance. Did you know that you can hardly grind Kevlar? It has an incredible abrasion resistance, some of it on the bottom of the hulls could save a lot of damage if one happens to run aground in mild conditions and had to wait for the tide to rise.

- the same I am considering.

- I have 6 amorphous, stick-on, flexible panels on my roof, they pump out 35+A at midday and still trickle some during sunset.

are you sure you want the workshop in the middle of your suite? I will put my office there, while the workshop aft port and I will have only one dedicated guest cabin and lots of cupboards and storage.

I intend to carry little water, just make it as needed.

That is several cubic meters of foam that will add weight and cost. Also consider that, in time, some moisture might get in there creating more problems. I would just have watertight compartments with inspection ports and all connected to a bilge pumping manifold system such as the one you must have on passenger vessels (like mine was).
Collision bulkheads should be all foam filled and only need be the first 300~500mm of the bows (stems).

Lets hope we get a good thread going here I would like to here all opinions and criticisms, it all helps.

 

late but have to say i like your design Nordic Cat and i'm really curious what rig Spiv has in mind and agree on just bout all he mentioned

 

Will that twin rig spin 360 degrees without collision on booms?

Or does 360 require crew action?

Where are you locating the masts?

Consider using twin - omerwingsail.com?

Or just battened wingmasts?

Look forward to sharing notes with you.

 

Hello Spiv,

Is this a regular exercise? By how much do you need to reduce your mast height for the bridges? There might be another solution.

Roger

 

Hi Spiv,

Thanks for the constructive feedback.

Actually i drew a 43 footer nad lengthened her to 47 feet, adding the forward cockpit.

The hull reinforcements for the masts are much less than having the mast in the traditional position! There i no downward load apart from the mast/boom weight.


The inside steering might well be with a wheel as well, I am discussing the viability with a supplier at present (JEFA). Engine controls will be CAN-Bus based from Mathers, or maybe Yanmar (rumour has it that they will release this year)


I expect the forward cockpit to drain within less than 5 seconds. More than 5% of the surface area will be drains. In fact we will film an actual test to ensure that this is the case on the first boat.
Of course there will be some layers of Kevlar on the bottom of the hulls.


The workshopcan be wherever one wants, on the first boat I will have it midships stbd. Maybe a sette outboard of it. If you look at the top view without the saloon, you can see 2 forward facing desks in the bridgedeck saloon, one for navigation, one for general purposes and electrics management.

There will be a 70 l/h watermaker, with 100 litres backup at all times. Diesel, grey and black, water tanks makes 4 tanks each side!

Good idea with the forward area, thanks, will adopt it!

Regards

Alan

 

Hi mdatrpz,

Each rig, can rotate inboard without touching the other one. Beam centreline is 630 cm. Mast and boom will be less than 6meters.
To turn 360 degrees, will be possible but not smart, as 180 should be enough, otherwise the sheet will have to disconnected, and "walked" around the forward part of the boat, in front of the mast.

Mast will be fully battened, maybe using air battens. I have looked at the omerwing - so many seperate parts worries me - but a 630 mm x 220 mm wing profile isn't far off what the omerwing has!

I expect to finalise rig design in the next couple of months.

Regards

Alan

 

Thanks Yipster,

I expected that you would like the idea of a bi-rig boat, seeing your ideas out here....

I am not entirely happy with the area around the forward cockpit, so will be fiddling with this. At the momemt the weight study is taking alot of time, I gues we have around 800 different items identified with a weight and 3 dimensional position in the boat, and still some to go!

Regards

Alan

 

Hi Roger,
if you were to come to Perth, you would need 7m clearance to get under the Fremantle bridge. Most sailing boats here are rigged with an A frame made using spinnaker poles and attached under the forestay (see pic). Our mast would come down in a couple of minutes.
If you cannot lower the mast you would not be able to enjoy sailing in the Swan River all the way to Perth city.
I want to be able to lower the mast completely, my only restriction will be the beam....

 

Last year, we had contributions from Ilan Gonen about his Soft Wing Sail.

http://www.omerwingsail.com/

He might be persuaded to bring us up to date with any developments he has made to his very promising design.. It's worth an email.

Pericles

 

Hi Perry,
I see that you are in continous contact with lot of people. Great.
I think that the best timing to tell everybody about the new rig will be when I finish testing it. Another month or two..
I want to see first that all is working well.
Ilan


OMER wing sail Ltd
23 Hohit St. Ramat hasharon
ISRAEL 47226
Tel: +972 3 5401675
Mobile: +972 54 4277617
Email: ilan@omerwingsail.com
Web site: www.omerwingsail.com

 

Hi Pericles,

the Omerwingsail is an interesting design, especially as Ilan can compare to his original standard rig, to give an idea about the performance.
I think this rig would be great for all those boats that don't venture far offshore. When i saw the picture inside the sail, i started thinking about how many spare pieces I might need to carry.

In principle it has the same functionality as a fully rotating wingmast with a single sail. It might offer some slight performance advantage over a wingmast, but unless he re-rigs the boat again with a fully rotating wing, we are not likely to know.

The great feature is its reefability..

Regards

Alan

 

He has a new version coming out in a short time. Apparently, much less complicated.

 

Alan,

You will still have to pay attention when gybing - we managed to perform a "not very coordinated gybe" in about 12kts of wind, the result of course being that one boom rested on the other! Could solve the problem easily but in a stronger wind that would have required more muscle power (arm power, not brain power!).

Roger

 

Sometimes it is an advantage not having extra crew on board:!: Can't make everything foolproof. Maybe need to design the booms with "bumper pads" on the ends?? Or else controls on each side of the boat, so you can only do one thing at a time..

Alan