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CARBON MAST QUESTION


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Hello Chaps,

me again.

I have finally decided it is time for action. Now I want some technical advice.

My plan is simple.

1. throw out my aluminium masts

2. throw out my sails with sprit booms

3. get a kiwi mob to make me some carbon masts.

4. get new sails cut which have vertical leech battens so they can still roll up... a bit like a Hobie resort catamaran

5. finish making new laminated booms

6. harrass stainless steel fabricator to finish my gooseneck fittings which are shamelessly ripped off from the Seapearl design but made bigger.

7. enjoy an easier boat to sail alone.

My questions are...

1.What data do I give the mast man about strengths required in the finished masts seeing as I have wrecked one set of aluminium ones already and.

2. what sail design considerations should I be considering for the new sails? ie length of battens, number of battens etc etc

The reason behind this is the idea that I can reef by ...

1. unclip vang,

2. loosen outhaul,

3. roll up mast and sail to desired size,

4. reclip vang on,

5. tighten outhaul,

6.continue.

Rob

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Hi Rob

I seem to be missing something.

Have you used the tried and true slab reefing method?

I have a Welsford Golden bay dinghy with sprit boom on a standing lug rig with slab reefing permanently set. It takes 10 seconds to reef.

Simply ease halyard to preset mark, pull on second downhaul permanently attached to the tack reef point, pull on reefing line on boom (fed to clew reef point and down around the boom .. a simple bowline... which makes it self regulating with respect to snotter tension).

It couldn't be easier.

Sail shape is maintained- unlike rolling.

I'm currently nearly finished a CS17- hoisted sails for the first time today- and will be using tracks with the same reefing system.

While carbon masts would be very nice, I'd still fit tracks and slab reef.

YMMV

Cheers

Peter HK

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Hi Rob

A couple of things I should have added-

I've owned a lot of boats- small and large- with all sorts of reefing systems...rolled around the boom, inmast roller reefing, roller furlers for genoas, single line slab reefing run to the cockpit, multi line reefing to the mast base. Roller reefing sort of works for a genoa on a stiff hull (better with a multihull) but for slab reefing on a cat rig, a few tugs on lines at the base of the mast and boom without all the paraphernalia to run it to the cockpit is a very good system for a boat not permanently rigged.

Sprit booms are very nice in that they are self vanging. Wishbone sprits are a more elegant solution for sail shape. I'm not sure adding a standard boom and a vang helps simplify the rig for single handing.

You said an aluminium mast had failed - was it to specification in terms of alloy/temper?

Cheers

Peter HK

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Joel from Boatbuilder Central sells carbon fiber mast kits at this link.  It is basically a sleeve that is already formed so you're not trying to lay up the carbon fiber material by wrapping it around a form.  

You can use This Search to find more posts here on carbon fiber masts.  

Graham used carbon fiber on the EC22 ... its a nine page thread, but if you jump to This Link you can start to see the explanations of the carbon fiber over a bird's mouth spar.

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  Hi Rob,

  Don't you have zipper-luff reefing?  I might be mistaking your boat for another.

  After using the roller-reefing method on a Sea Pearl I'll never do it on another boat.  I prefer to re-step the mizzen (on the water).  The problem with reefing by rolling around the mast is - As the sail is rolled up on the mast it becomes fuller, not flatter, and it can be difficult to get to weather.  I'd rather pull up the centerboard, let the main sheet fly and run dead downwind while I wrap up the mizzen and move it to the 3rd step.  If I' don't have room to do that I'll drop an anchor (even if it doesn't reach bottom) to keep the bow into the wind,sheet the mizzen in hard, roll up the mainsail, then roll the mizzen and move it to the 3rd step and re-set.

  I bet there's a story behind you're interest in changing the rig, though.  What happened?  ;) ;)

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Ken,

I don't want to be a killjoy but I guess I am going to do it anyway.

I have had "Lively" out in 25 knots of wind in open water and was able to reef without danger.  I also have moved the mizzen to the third hole in relatively calm behind and island with a few waves.  I do not think is would be possible to do it in high winds.  The mast length leverage would be very high in addition the windage with the sail rolled up would just be too great.

For those who do not know, "Lively" has mast track and sail slides with two reef points.

Dale

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...carbon masts don't bend.  Period,  They just don't bend to depower in the puffs.

Oh, they'll bend alright. The whole fly rod industry relies on that fact. The thing is, for a given diameter and wall thickness, they're a *lot* stiffer than aluminum so you can't just build a carbon stick the same size as the aluminum one it will replace and expect similar performance with less weight aloft. You must design a carbon spar with the characteristics you want and build it accordingly.

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  Hi Dale,

  Thanks for the warning but I reef before the winds are 25 knots.  ;)  I have re-stepped the mizzen in wind on the water and it isn't fun or particularly safe but it is possible.

  I'd like to have another method of reefing as an option but it hasn't been an important enough option for me to recut the sails so far.

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That's not necessarily so, Ray. If properly sized in diameter, taper and stave thickness, birdsmouth will beat aluminum up 'till around 22', where aluminum starts to shine. Is sizes smaller then this, aluminum has progressively less chance of being as light as a well built birdsmouth. This is primarily because, aluminum is had in continuous section extrusions, which place proportionately more weight aloft then a birdsmouth. A welded aluminum spar that includes taper, would make aluminum more competitive in smaller sizes, but this is an expensive option. Bending and flexibility are all engineering issues that can be sorted out on the drawing board, making both materials suitable and similar in physical properties.

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I guess I am looking for a way to get rid of sail area when sailing alone, or in deep choppy water even with a mate with me.

As for cost. I have a quote from a NZ company around the $1200 delivered mark, which is not that expensive compared to a smoking habit or the million dollars a head given by the govt to buy each GM workers job.

What I see as the advantages of this approach is that you get to stay in the boat at all times, ie undo vang, loosen outhaul and wind up mast with rope around the bottom. Then vang on, outhaul on, and you don't have to stand there fiddling with a pile of sail, lazy jacks etc. The mess you end up with under a sprit is not pretty so I can't see any great loss of efficiency being the point here. Besides it is not about a race either. If you look at the sail rolled up on the mast it is not that big really, relative to the outhaul dimension.

The big problem with the cat ketch I reckon is that as soon as you pull on the main in any way, you make the bow drop to leeward. So if you are anchored as suggested, it hunts around on the anchor and on the 'return trip' it tries to get you over the side if you are up on the foredeck fiddling... No amount of mizzen tension prevents this if the wind is up.

So, assuming that it is not class racing you are after I reckon this is worth a go.

I have here a link to some photos I have garnered off the web and magazines. The one labelled Bolger sail design is sort of closest to what I have in mind. The other ones show a boat with a novel boom which I reckon can be avoided by using turned up hoops that go on the boom ie 3, one at the top to stop the movement, one that moves with a boom fitting on it that only moves in the vertical plane, then another stopper one fixed to the mast.

http://homepage.mac.com/blackburns/filechute/SAIL%20IDEAS.zip

Got to take kids to school so shall look in again later.

Rob

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Kel the stainless man has finished my fittings. So here are some shots of the hardware. Old Greg the retired butcher with a lathe has done me up some hardwood 'donuts' to for mast fittings. They are not finished as yet, they need tidying up...

Here are some shots.

http://homepage.mac.com/blackburns/filechute/BOOM%20FITTINGS.zip

The booms I have made are straight until the last 20% so that you don't get that big gap between the bottom of the sail and the boom. Then the boom drops down to the mast. Should work.

But the problem remains, how does one give the mast man the amount of load on the mast so he builds one strong enough?

Rob

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  • 2 weeks later...

I'm with Ken on the reefing.  Sails wrapped around the mast, I can't point past a close reach--nearly useless to weather.  After several attempts to make that system work better, I now take down the mainmast and lash it on the side deck (it adds a lot of windage, else), and move the mizzen.  Perfectly safe with both masts on steppers, but I only do this at anchor, and I try to anticipate.  Because of (unrelated) major problems pointing with the regular rig, I am now experimenting with replacing the  main altogether with the balanced lugsail from my Piccup Pram (Michalak).  That sail is rigged to jiffy-reef--a faster and safer process than either of the above.

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