My Nacra 5.0 touched water for the first time last weekend (after reencarnation actually...). Unfortunately the wind was too strong so I just tested it with the jib, not really a navigation but I could check most of the stuff. It was on the beach, with short waves coming from the side, and as I wasn't using the main sail, it moved quite a lot. I didn't like how the mast rotated with each wave, I'm planning to leave it on a buoy for a week or two, when i'm there, but the mast will be constantly rotating like this. Is it normal, would it be advisable to block the rotation somehow? It is not the original mast, I got the extrusion and made all the rest myself, so there could be something wrong.

No, do not do that. These boats are made to be dry sailed, not left in the water.

Take it out, put it somewhere safe and if possible shelterd and tie it down.

It is normal for the mast to rotate - in fact it's designed to do so because it offers higher performance if you properly rotate the mast while underway. You should have some sort of rotation limiter that consists of a stainless steel "U" shaped bar coming off the mast just above the boom. A line should go from the boom, through this limiter, and back to a v-jam cleat on the boom. You can limit the amount of rotation while underway by controling the length of this line - but you can't eliminate rotation entirely. Beach cats are really meant to be left on the beach and I wouldn't recommend leaving it on a buoy for more than a day or so.

It is boomless, can't limit the rotation as suggested. I know it's ment to rotate when sailing, but I didn't realise it would also rotate when not sailiing. It will be much easier to leave it on a buoy instead of taking it out and disassemble the mast everyday to cross to street (leaving it on the beach would be the third option, don't wan't any night sailor sleeping on it..). Just while I'm there anyway, and if weather conditions are ok and sailing it everyday, draining water from the hulls, etc. But you got me worried, what are the main concerns of leaving it on a buoy? Possibilty of capsizing, the action of salty water and sun? other?
Thanks

Ohhh...boomless is a little different. My 6.0 had a rotation inducer bar (similar to the limiter) and the bar was at the base of the mast and could be cleated off to induce more rotation since it lacked the boom to push the mast to the side.

I guess there is really no problem for a small amount of time - but it does cause additional wear on the mast step ball and the rigging will be constantly flexed (where-as on a monohull the rigging is very tight and stationary and sees very little flex/twist while sitting still). Securing the boat to the buoy so that it weathervanes without sailing back and forth can be tricky (I thought I saw a thread on that recently).

I'm not sure if I understood, this rotation bar is supposed to be cleated on one side or the other everytime? I'm not thinking in that degree of finesse yet, but I would take the idea to lock it in the central position when not sailing.
About the mast step ball, what material should it be? mine doesn't seem to be the original one, though it appears to be solid. Would it be wrong to use a brass one? Getting the original might be unnecessarily expensive, since I would have to import it.

The mast balls are made of Delrin plastic and are intended to be sacrificial...that is that the ball wears away before wearing the base of the mast. A brass ball would tend to wear away the bottom of the mast which would be extremely expensive to repair compared to an occasional $15 plastic mast ball. You might have to wait a little while for shipping but it shouldn't be THAT expensive to get them shipped to wherever you are.

Another thing to consider is that the base of the mast casting is typically very rough and tends to wear the balls quickly. We use marinetex epoxy to make a small putty disk to put in the mast base, wet it with water, and press a mast ball in place to give it shape. Remove the mast ball before it cures completely. This gives a very smooth perfect fit that will give you years of life on the plastic mast ball.

I finally sailed my Nacra 5.0, I will put a sort of report, with my impressions and some questions here, thanks for listening..
From the original owner I bought the hulls, correctly assembled witht the crossbars, the trailer, the jib, the front stay, the rudders castings (home made by himself, but fairly good), the mainsheet traveler and the ball of the mast.
I repaired the trampoline, and navigated for a while on the web, where I could buy the mainsail, the rudders and the blocks. Then I got a package with rigging cables, traps, harness and other stuff, mainly from a hobbie 16 (everything used and cheap, of course). I had to extend some of the cables. The hardest was to get the mast, I finally got an extrusion and made all the parts on local workshops. The base of the mast is basically a plate with the shape of the mast, with soldered pieces above, to fit on the inside part of the mast. Below, a cilindrical piece soldered to the base, with a semi sheric perforation to fit the ball of the mast. No pins. It works pretty good, I can´t start raising the mast horizontally but about 30° or so, it´s not a problem, and it´s not necessary to raised it rotated 90°, which is an advantage. I put this cilinder in the front part of the base, so the ball is in a very advanced position, I think more than in the original design, I wasn´t very sure of that... To my surprise, it worked excelent. It alwats takes the same angle than the sail. Much better than a Nacra 5.8 that I sailed once, where the mast was always rotated 90°, no matter what. I might have displaced the sail area a bit aft though..
The only thing that bothers me is that I look at the jib and it seems quite small, it might be from a smaller cat, this and what I mentioned about the mast made a surface area not very balanced, the tiller requires some force to keep the direction.
The wind was quite strong, but I never got to raise a hull completely, I prefered to do some trapeze work instead, I feared that the tip would sink and I would capsize. I will go step by step.. I´m interested on opinions about this, perhaps this cat is not very good on raising a hull.
Thanks

The cat is just fine on raising a hull, but you need to do some work on sealing that mast to prevent it from sinking. There are a couple ways to do this:

1) Make a tight-fitting top that rivets on and bed it extremely well. This is what the factory does and it holds up very well

2) Put a plastic bag inside the top of the mast and pour expanding closed-cell foam into it. When the foam has cured, cut it level with the top of the mast and seal it with some epoxy

3) Put a Hobie Bob on top of your mast

After you're sure that the mast won't sink, go out sailing and get a hull up. You can do it even in somewhat light airs by positioning yourself away from the windward hull. Some people go so far as to hike out off the leeward hull, though it feels very odd. Personally, I like to put my feet against the leeward hiking straps and lie across the trampoline with my head on the windward hull. When the hull comes up I'm sort of half-standing, a comfortable position.

Hi Jake, This amounts to a semi-permanent Hobie chip in an upside down configuration. I like that! I leave my I-17 on a pair of jet ski floats (Sport Ports). Keeps the hulls dry but wears out a mast ball a month due to the roughness of the ever-rotating mast base (from the powerboat chop as well as the wind action.) I will try your epoxy trick next season. Thanks for the tip of the year!

Wally

Re unwanted mast rotation at anchor:
Wrap a HEAVY rubber bungee around the mast from something hard (attached cheek block or luff track), then rotate the mast hard to one side or the other and hook it to the trampoline or a line on the trampline.
Your shrouds and parts will last MUCH longer if held under a little strain than banging back and forth all night.

Many years ago, I failed to do this with my first A-class cat, and the shrouds wore through the anodized finish on the mast in one night.

Don't cats have a tendency to "sail" at anchor? Would this tendency be minimized more by having the mast rotated and secured sideways or centered and secured with bungies going both ways?

This cat is not very good turning. Cats in general are harder to turn than sailboats, but this one in particular is worst, some times I have to jibe. The rudders angle is limited because of how the castings were made, I would say they achieve no more than 60° (being 0° the neutral position), but I'm not sure if it is necessary to steer more than that. I guess practice might be the issue here, but any advice would be appreciated.

Practice is definately needed to tack a cat well. You should not need more than 60degrees rudder angle. 45degrees usually does the trick, but there is a lot of technique and tricks to tack well.

PS: Liked your picture, free heel skiing (Telemark style?

Sure man! from your land!
That was at Volcán Chillán in Chile

And with my older daugter snow camping also at Volcan Chillán

I think I will put a cat picture at www.telemarktips.com forum...
Cheers!

What about some tricks to tach well??

Ahhh....Santiago...one of my favorite trips of all time. Good times.

This is one of the common questions on these forums, and you will find all the information you need by doing a search here.

The recent thread was "High wind tacking", I suggest you start there: High wind tacking

It's fun to see the sport of free heel skiing spread, since just 20 years has gone since it's new conception here in Norway. It was almost forgotten, but in the '80s it caught on again..
I spent 10 winters on telemark skis, but my knees could not take it any longer. So I switched to a snowboard from Voile for backcountry use. Split Decision
This cured my knee problems, and I have found it to be a more versatile tool than free-heel skiing (hard to admit, for a norwegian), superb when you break trough the upper crust with skis
I only do off-piste skiing, so it was either this, randonne skis or a lot of pain on telemark skis.

Rolf

Thanks Rolf
Never done snowboard but it always called my attention how much easier it seems on deep snow, are the split decision good for walking? I imagine they are a bit wide for steeps on hard snow, but maybe easier to carry on the pack anyway
Jake, thank you too, it´s not the fist time I get your advise

Walking with a split-board on hard snow (glaciated and steep) is worse than skis, but I dont like to use skis either then.. Otherwise the split-boards are excellent! I only have a few issues with them:
1: They are to wide to follow in the tracks made by regular skis.
2: They are very expensive.
3: They are an uncommons sight, so everybody wonders what you are walking on, before you assemble it on the top.
4: Snowboarding un an glaciated slope is harder with a board than on skis. (might be my lack of skill )
5: You better be able to go downhill all the way to the car, or you have to de-assemble the board again (no problem where I live)

But all the positives outweight all this..