A different breed of cat?

[Nordic cat]

I just received the latest renders of my boat, and would like to share them.
I know this is a boat that will even have cat owners questioning my sanity, but I have spent a couple of years on the design and concept, The NA work has been done by Anton du Toit in Cape Town, and I really impressed with what he has done, as well as the great renders.

Comments and questions are most welcome...

regards

Alan

[Kai Nui]

Only thing I can say is absolutely beautiful. I have been facinated with the Bi-Rigs for years. Couple that with the boat itself, and I think you have a winner.

[knottybuoyz]

That's pretty impressive Alan. What are the basic dimensions etc.?

[Lodesman]

Alan,

It looks stunning. I've always liked your triple-helm concept. I'm ambivalent about the bi-rig; I'm anxious to hear how it works out for you.
Then I'll just be waiting for you to start selling them

Kevin

[solarbri]

Hot looking boat there Alan.
Have you heard of the Sanyo HIT solar panels that are two sided?
Whatever small amount of light that is allowed through the panel is reflected off of the floor below and produce even more power!!
They would seem to be the perfect shading material for you cockpit bimini.

[David M]

Nice looking boat.

Wouldn't one sail blanket the other on a broad reach? If so, wouldn't a jib prevent this problem? Do you plan on hoisting a downwind sail on broad reaches and runs?

[sctpc]

Originally Posted by Nordic cat

I know this is a boat that will even have cat owners questioning my sanity, but I have spent a couple of years on the design and concept,

regards

Alan

Alan why would anyone question your Sanity, Mate it looks very impressive I like the fore deck counter sunk for nice summer cruising.

What type of motors? what length, beam, wingdeck clearance, accommodation, in you attachment you only have the helm on the starboard side, will it have remote steering?

[bill good]

The question of balance comes to mind. I would like to see how it will saill thru all dirrections

Regards Bill Goodward

[Nordic cat]

Originally Posted by knottybuoyz

That's pretty impressive Alan. What are the basic dimensions etc.?

Thanks KBz, as we are now at the stage of ordering the materials, and we have an October 15 deadline for delivering the lines to CNC cut the frames for the moulds, most dimensions are now finalised.

What we haven't finalised yet is the shape of the underwater hull lines in the aft sections. There are 2 points we need to decide on:
1.) I want the maximum waterline beam further aft than normal (around 60-63% rather than the normal 50-55% aft) This for better balance when loading, but also to increase the so called "hull speed"

2.) The height of the transom when sailing. I read a very interesting thesis that claimed that immersed transoms made for lower resisitance when sailing, as they make the boat "look longer" to the water. The thesis did a large number of caculations, for different immersion states, and the evidence for immersed transoms was clear. But he used a number of constraints to limit the number of variables applied. We are going to do some CFD analysis before the final decision is made. If we look at the latest crop of VO70 boats, they all have immersed transoms when sailing...

In my mind, the ideal situation would be: Transoms just "kissing" at ½ load and not sailing (no wave slap at anchor) and immersed a bit when sailing in most conditions. It will be interesting to see what the software predicts.



The dimensions are:


LOA: 14.95 m/ 49 feet
Lwl: not finalised around 13.5 to 14.5 m
Beam max.: 8.76 m/28' 9"
Hull beam waterline: 1.07m
Hull beam: 2.46m/8 ft.
Bridgedeck clearance lightship: 100 cm/3'3"
Sail area mainsails: 148 m2
Sail area mast (each) 8.1 m2
Mast height (I): 17.8 m/58.4ft.
Power: 2 x 40 hp Yanmars with saildrives and 3 KVA AC generators


Target displacement for base boat in lightship condition. i.e. no fuel/water is around 7 tons.
Max. load ~4 tons


Alan

[Nordic cat]

Originally Posted by David M

Nice looking boat.

Wouldn't one sail blanket the other on a broad reach? If so, wouldn't a jib prevent this problem? Do you plan on hoisting a downwind sail on broad reaches and runs?

Thanks David.

There will be a range of about 15 degrees when one sail blankets the other, just like on a traditional bermuda rig, so in reality no difference when the main blankets the genoa. Here you can let the windward sail out a bit and use it to direct air at the leeward sail.

The rigs can rotate 360 degrees, so I can reef in any wind direction.

I will have a jib and a gennaker for very lightwind work, but given the predicted performance of the boat, we should be able to work the wind forward of the beam in all but the very lightest wind conditions.

The different VPP's come up with predictions between 90 and 110% TWS on a reach, load dependant of course.

But, the proof will be out on the water, so this is a bit of a gamble.

Alan

[Talbot]

You have my respect for your intention to push the multihull design barriers.

The render looks really good and I will be really interested in the reality.

I agree with your belief about the transom. However, you also need to consider its behaviour when a large breaking wave catches you up from astern (assuming you have a drogue out or something similar.)

I understand from a reasonably unreliable source that its bound to be heavier than another manufacturers boat

[Abaco]

Alan,

She is beautiful. I really like the forward steering station. One questions. Where will the mainsheets be led to prevent conflict with the coachroof when the windward boom is amidships?

[Nordic cat]

Originally Posted by Abaco

Alan,

She is beautiful. I really like the forward steering station. One questions. Where will the mainsheets be led to prevent conflict with the coachroof when the windward boom is amidships?

Hi Abaco,

The forward steering position is inspired by the lovely Chris White designs, but I have selected to make the cockpit wide rather than long, as the CW designs have too much of a "mono" layout IMO, where you have to edge past the helm station to get to the winches and lines.
My design means that I can't have berths on the bridgedeck, but this is the worst place to sleep in bad weather anyway.
With 1 forward (port side) cabin and 2 aft cabins with no engines, I have what I want. This is a cruiser not a charter boat anyway.

The mainsheets will be fixed on the outer edge of the coachroof, which is about 60 cms inboard of the "centerline". This should be about right for beating, if we need to get the boom more centered to the mast we can use a barber-hauler, but in my experience with cats, they are best sailed a bit loose.

The mainsheet only has to handle the sideways forces from the rig, and not the upward ones that are handled by the fixed vang, so maybe we can manage with only a 1:2 setup. If not we will have a tandem setup with a 1:2 and say a 1:4 or more for fine trim.

The main sheet will be double ended, one end at the aft helm station, and one at the forward cockpit. The sheet will be run inside the boom and into the mast, down and out at the bottom of the mast, and back up to the deck level. The outhaul, reef lines, and aft sail tension will also be led this way, as will the halyards. At the deck level there will be covered line runs to the forward cockpit.

This is the plan, but we haven't finalised the details, we will probably build a mockup of the lower part of the mast, from the boom down, to ensure that we can handle the twist when the mast rotates, both relative to the boom, as well as to the boat.

Any ideas on how to improve this would be most welcome, as there aren't alot of other boats like this out there to talk to.


Alan

[Saildoggie]

Realy cool design!!

The forward deck sections remind me of the Island Spirit designs, I have saled a few of those, in fact racing on an IS 37 next month in Foxy's Cat Fight, JVD, BVI.

Are the masts stayed at all??

Downwind could be awesome in lighter air with a big chute although you would probably need running backstays for that!

[freetime]

Top.1 Design. If i had the money i should buy one asap...