New Build: KD 860 Open

Thanks, sounds like solid advice. Sompl is good

 

Can read and think but cant write. Tri..

4 ideas good!

Get old mast cheep etc Bild boat. Go sailed. Learn boat, get good on that boat, every problem.

Of you want change a new rig bi sail rig or what ever...after..


2c...

 

Thank you. Probably just go with the standard rig,
Main self tacking jib and some head sails

 

Yes, standard rig makes the most sense. Using wires to hold up the rig on a cat makes a lot of sense because of the high mast loads (due to high righting moment) and wide beam. You should also be able to find a used mast and save yourself time and money.

Biplane rig makes the least sense. My understanding is the biplane rig is inefficient, plus you have two masts (more cost and more weight aloft) and they're both free standing (even more cost and weight aloft).

The free standing single mast also doesn't make sense because it must be mounted on a beam, which is problematic structurally.

I've never sailed a wharram but I've sailed hobie cats without the boom and it doesn't work very well because you can't control the shape of the sail properly. The only way it makes sense is if you're a catamaran manufacturer and you want to save money.

The fact that the designer offers all of these options should make you wonder about his other design choices.

 

More realistic, but far duller than the 'near Gunboat' performance you were seeking 2 weeks ago.
Brief comments:
Building unstayed carbon masts is no more difficult than building the rest of the boat, and almost certainly cheaper than buying alloy, wire and fittings.
Second hand stayed rigs are good if you can find them, but still need forebeam/striker, traveller, chainplates, significantly beefed up (and perhaps moved lengthwise) main beam, winches, tracks and extras all of which will need to be bought or built. They also need more maintenance than unstayed rigs. When you are caught with too much sail up in an increasing breeze, you will wish you had an unstayed rig.
A biplane rig has some advantages, but it would be cheaper, lighter, easier and quicker to just build one rig and step it in one hull. Ditto for a dagger/centreboard.
No cat will tack in big seas under main alone without getting in irons. A headsail and/or strong rudders (gudgeons sized to take a large percentage of the weight of the boat) will be required.
The bottom third of an unstayed mast is plenty strong and stiff enough to mount a staysail. Off wind, light air extras are no problem, and will have a far wider wind range on a small, heavy boat which won't generate much apparent wind. You could also look at a ballestron rig.
Vortex generators and mini keels are a good match for Wharram wingsails. Neither goes up wind well.
Non kick up daggerboards and rudders are accidents waiting to happen.
Wishbones at the mast head are wrong for sail twist and are weight in the wrong place, especially on a small cat.
Big roach main sails are easier to handle and sail than square tops.
Wishbone booms are better horizontal then angled. On stayed rigs, they further limit the amount you can ease the rig.
Snotters and/or non rotating unstayed masts prevent the main being eased past 90 degrees, losing a lot of the safety benefits of unstayed rigs.
8m is a little cat. My wife and I lived on and cruised for a year or so on a 9m Iroquois cat (1,000 kgs/2,200 lbs empty). You need to sail little cats cautiously and watch the weight (we had 2 bunks and a one bench galley, the rest was empty) to get decent performance. 9mm ply is a lot for a little boat, 6 might be adequate in most places. Infused foam/glass would be ~half the weight. Flat panels, ~half the effort.

 

And allot more cost for foam.
The the thinner ply no go...my cruising grounds will be Bahamas and Florida
I'm going with a single fat head sail
With a wishbone boom
Self tacking jib
And a set of proper other sails, whatever is suggested to complement the main and jib

Thanks

 

Go for it, I hope it meets your expectations.

A couple more things for other non experienced people contemplating doing something similar to think about:
A conventional style of boat will be cheaper, less work and you will be sailing sooner if you buy second hand. Check out Stephen Marcoe's fleet. It will also give you a chance to sail the boat and see if it matches your expectations and requirements.
Hull construction cannot be upgraded (except when it rots away ;-)). In most places, the cost of foam vs decent ply on a little boat will be less than you spend on other weight savings.
If you are going to be drying out on rocks, or running over coral a couple of mms of plywood thickness will not make much difference and is not as tough as the same weight of fibreglass. A sq m of 9mm gaboon ply is 1.5 kgs heavier than a sq m of 6mm. That is 4 layers of 200 gsm fibreglass. The stiffness of thick ply is required for large unsupported spans, but for strength purposes on a little boat with a little rig, 6mm is plenty.