Boxy Fisher Catamaran idea

As for windage....I don't have a clue. Maybe Rick can calculate that?? All I know is less is better....think of your cabin as a sail that provides no lift...and then imagine sailing to windward...hmmmm

 

OK guys, we've been circling the runway for days now. Let's attempt a landing?

Little by little, yelling, screaming, champing at the bit, SA & NZ wouldbe builders have reached some weird kind of consensus on the designs of their catamarans, and guess what? They're exact copies of the Gunboat 62 in everything, but size and price. So, sit back and visualise yourselves tearing up the ocean and humiliating every monohull skipper with whom you cross paths. There can be only one!

http://uncutvideo.aol.com/videos/cabce7fe77982ed5cbb7fcdf0dd91825

What can I tell you? Well, I could say I told you so, but you'd never believe me.

http://sailingmagazine.net/perry_gunboat62.html

Best regards,

Pericles

PS

http://www.gunboat.com/home.swf

http://www.southwindssailing.com/articles/0206/tribe.html See the bridgedeck clearance.

 

OK, humiliated. That´s sailing.

http://www.panbo.com/archives/2006/03/gunboat_62_wicked_fast_too.html

 

Calculating windage

Calculating windage is fairly straight forward, calculate the area for the given wind direction. Find the actual relative windspeed (use metres/second for SI units) Thenyou need to guesstimate the resistance coefficient for the exposed area. Use about 0.5 for the hull(s) maybe 0.6 for the bridgedeck saloon, and 1.0 for the masts. Standing rigging is probably aound 50% of the mast! Maybe more. I can find actual figures for you if you give me rigging specifications,i.e type and diameter.

You then calculate the windage for each piece, and add them together, to give you Newtons.

Windage = ½ x 1.3 x v e2 x Area 1.3 is air density in kg/m3. v e2 is air velocity squared.

This is also a good method for calculating your anchor size/ rode size

Regards

Alan

 

Hi Pericles, seems to me they had to make the cat that big to get all those sails aboard I bet they get issued from out of the hulls too

The bridgedeck clearance on that big boat is a meter easy ! There's quite a few larger cat sailing video's on Youtube that really looks exciting, and fast !


Hi Alan, thanks. Working the windage area out wouldn't be a problem. I was also hoping to get some information of how it will behave when adrift without any anchors or sail under various wind speeds. Will it just drift fideways, slight foreward... ?

We have a standing joke on the boat. Since I went sailing a couple of times... in almost no wind, and the wind seemingly always blows when we try to fish, it has now developed into when the wind blows you away from the spot there is fish. Nice quiet, no fish !

 

Hi Fanie,
You are burning the midnight oil I see!

Drifting behaviour will depend on wind direction, wave direction, current direction your windage and the underwater lines of your hull, so a difficult one to answer. I sometimes bottom fish on my cat in a place with quite a lot of current. Turning the rudders to minimise windage slows you down, also just having a little bit of the jib unfurled, and adjusted to work your way against the current can help if the wind direction isn't directly on the nose. For larger waves and strong wind you should consider a sea anchor of some kind, or else use the engine....

Regards

Alan

PS I'm going to get my boat built in SA, maybe we can hook up for a beer?

 

Ah ! A good weathered boat. Build some sunshine into it Hookup is a good idea if it can be arranged. Who knows, I may have something to show on the Boxy by then. probably depends where you're going to go to in SA. It may look small on the map, but it took me YEARS to find my wife

Between 2 and 3 is quieter so I can actually get something done here.

 

Fanie,

probably Capetown, if not then Knysna.
I will get in touch before my next visit.

Regards

Alan

 

Wow ! No problem... it's only a 1000km drive from here Problem is who makes the drive ?

 

Alan, let me know when you're going to be in SA. I may be down in that area then. Who knows.

I've started collecting some groceries for the cat. I have eight 15" rims for the trailers already and I've placed an order for some SS to be cut that will turn into blocks, the wheels turned on the lathe already and will be used for the daggerboards, some furling rollers, and a host of other things.

The temptation is there to extend the hulls from 10m to 12m. I just hate when I do that. The limitation is the length and it doesn't look like the 12m hull can fit into my available space. The trailering also looks like it could become challenging in firstly designing the trailer and secondly the length also makes a difference.

I've also started working on some of the instrumentation required. Anyone know where one can find a sea map for the Garmin Nivu 200W

 

Thought I'd spend this post here...

I have received today some laser cut SS parts for making some blocks as well as SS for a few furling rollers for the cat. Since I haven't made up my mind exactly about certain things wrt the hulls and the sails, there seems no point in jumping the gun just yet.

Only things I can begin to get together seems to be some items on the endless list of accessories. It looks as if I'm putting up house for the first time

 

Been a while since I've been here, almost looks abandonned, but don't believe it !

Circumstances is not right for me to jump in and wave the resin brush around yet. In the meantime I'm collecting whatever accessories and boating stuff I can lay my hands on. It does go a bit slower than I anticipated. For one I was hoping to start some of the fiberglass works as soon as this winter (summer's too hot) but it sadly looks like it's going to have to stand over until next winter. I'm looking foreward to start the glassing, but I'm not looking foreward to it - if that makes any sense.

The up side is I have a lot to find out still and I may start better prepared for when I do. This is where you sailors come in. I have a series of rather seemingly stupid questions I have to ask, point is, I just don't know the answer to them.

So far I have gotten some very nice responses and help from you guys, stacks of thanks. Be leaning on you all for a spel longer if you don't mind.

 

Boxy Catrimaran

I hate the winter

Been buzy lately. The grey matter got as couple of good stirs here and there and after a couple of drawings (feels more like a couple of thousand) the term
CATRIMARAN got stuck.

You can think what you want but you cannot say what you want

The 12m cat has two hulls (you think). I could let each hull have it's own sail and mast.

If one however add four more smaller hulls and attached beams, you could end up with two 10m trimarans as well. Why not ?

In some ways this would be very nice. If you plan to stay out there, take the cat. If you're a bunch of guys going fishing, take the two tri's. Would still be trailable...

Anyone comment on this ?

 

She is your "baby" and you have demonstrated that your skills and competencies are abundant and good, so do it? - - - Who am I to argue otherwise, and I still owe you some points as pledged, cause it seems Jeff (the moderator one) has blocked my "giving" capacity/capability - temporarily?

 

Still have to build the garage for it The plans was approved already, but I needed to enlarge it or have the hull stick out the door I suspect they are going to crack up about it, I'm already over my limits limit

He he... Seems to me Jeff have some good judgement. No points required thank you, rather spend the effort in pointing some possible problems out with what I'm about to commit...

Attached rough drawings... of course there will be two tri's. Just toying with some ideas.