Rotating Rigs on Cruising boats?

[drewke07]

I understand the theory behind the engineering and anodizing. Our aluminum masts were built by professionals. In any event we operate in the real world. We are experienced operators and we were unable to prevent the deterioration of our aluminum columns. Fourteen years ago we went with composite columns. Never had a problem. My experience tells me that the alloy columns were not up to the duty cycle we put them under.

[Fard12]

The reason that you carbon rig worked well was that it was engineered and built correctly. A lot of so-called composite masts tumble down due to all sort of reasons as do alloy masts. That been poor engineering, poor build quality and sailing accidences.
You stated that your alloy mast supplier supplied upgrades to your spreaders (The angle of them) this was done to either support the mast Fore/Aft or athwart ships depending on the new angle supplied less angle for athwart ships and more angle fore and aft.
If the rig was a double diamond with no forward jumpers on the mast (a single spreader facing forward at both top and bottom diamonds with wires running over both) and the mast was going out of column then the moment was never an enough in the mast for this configuration.
Reef heights have to be taken into calculation as well. When deep reefed the load on the mast at the headboard is very high and this is tring to invert the mast as the loads are transferred down the leech of the sail to the main sheet
There are several rig configurations available to multihull owners when purchasing a mast.
If people wish I will go through them and advise the pros and cons for each design, the safest and most fail-safe.

The best form of protection against corrosion is an anodized mast or if you have the money a professionally built carbon mast.

[Mike Banks]

Simplest solution is to let the sail luff rotate around a static circular tubular smooth surfaced mast. The Wharram wingsail is a good, simple and effective example.

[Fard12]

Originally Posted by Mike Banks

Simplest solution is to let the sail luff rotate around a static circular tubular smooth surfaced mast. The Wharram wingsail is a good, simple and effective example.

Maybe good on a Wharram but it wouldn't sail out of site in a dark night.

[Red Horse]

At the moment there is a Kantola here in Hawaii, with a rotating rig. The rig came down a couple of hundred miles south of Oahu and was motored back. According to the owner it just fell down. It was a wood composite foil if memory serves me correctly.There is a large cat here that has been reworked as a power cat since they lost the rig on 3 different occasions. My tri had a rotating rig with synthetic cap shrouds. The person who bought the boat from me dropped the rig around Ft. Bragg. By his own admission to the designer he was pushing the boat in heavy weather with a full main and a 100 percent deck sweeper jib designed for around 20 knots of weather. Wind was around 30 knots with choppy conditions as far as I can find out.
Are there different techniques to sailing with a rotating rig? Do they need more care? Are they just unsuited to cruising boats.
I like them because you have fewer components and you can have a roachy main for more drive.
There was no vang on my boat as I was told it couldn't be engineered to work. I sold the boat before I could try designing something. there must be away around that problem.

Red Horse

[David M]

Originally Posted by Tom Spohn

Another problem some folks had was mounting heading sensors on the mast for use by the auto pilot. Heading changes when the mast rotates.

Thats an easy fix. I have a fluxgate compass mounted on the mast. I have an anemometer/windvane that gives Magnetic wind speed or True wind speed and corrects for deviation. It's made by RM Young. It has a NMEA 0183 serial port out so it can connect to most anything.

[Fard12]

Masts of all type either rotating or not should be able to withstand the rigors of sailing.
A wood composite mast is a waste of time. I have seen many topple over the side of cats over the last 7 or 8 years.
They are generally home made and no insurance company will touch them, nor would I.
The mast and rigging should be designed with the correct safety margins within them so that they don’t fall down.
Rotating rigs do require more attention, as most these days are not rotated off the hound but off rotation tangs with SK75 lashings.

The amount of roach is not affected by having a rotating mast or not but by the amount of money spent on sailcloth. (Dacron, cruise - lam, spectra, carbon. and the requirement for a diagonal batten to hold the roach up.

[DHHong Kong]

I have a new build Schionning Wilderness 1620 on the water in Hong Kong (Gold Coast marina) which is awaiting completion of the 20 mtr Schionning-designed carbon fibre rotating rig.
Currently in a dilemma of what to do re the wind instrument and I would be very grateful for further info, per David M's post, of the supplier of flux gate compass etc to correct/compensate for the rotation and provide the tru signal to the Raymarine ST290 instrument. I understand that Silva/Nexus make such a devioce but have been unable to obtain supplier info.
Our plan was to install two of the Raymarine wind instruments, one each on a pole at each transom, something I have seen on other cats but the compensation device sounds a better way to go.

[Nordic cat]

Originally Posted by DHHong Kong

I have a new build Schionning Wilderness 1620 on the water in Hong Kong (Gold Coast marina) which is awaiting completion of the 20 mtr Schionning-designed carbon fibre rotating rig.
Currently in a dilemma of what to do re the wind instrument and I would be very grateful for further info, per David M's post, of the supplier of flux gate compass etc to correct/compensate for the rotation and provide the tru signal to the Raymarine ST290 instrument. I understand that Silva/Nexus make such a devioce but have been unable to obtain supplier info.
Our plan was to install two of the Raymarine wind instruments, one each on a pole at each transom, something I have seen on other cats but the compensation device sounds a better way to go.

Nexus, B&G and NKE in France all offer a solution for this. B&G use a sensor like a rudder sensor for feedback on the mast rotation.
NKE is used by a large number of the french racing community, apparently their autopilot is also very good. Anyone here with experience?

Maybe Tacktik - but I haven't bothered to check them, apparently there are a large number of quality issues with their kit.

Alan

[DHHong Kong]

Thanks Alan, the problem is getting the senders etc from these suppliers to communicate with the Raymarine ST290 instrument and autopilot. They simply say it cannot be done which is a bit staggering in these days of NMEA signal "standardisation" etc.
Thanks also David M for your response - I sent you a separate email but seems you mailbox is full.

[Nordic cat]

Originally Posted by DHHong Kong

Thanks Alan, the problem is getting the senders etc from these suppliers to communicate with the Raymarine ST290 instrument and autopilot. They simply say it cannot be done which is a bit staggering in these days of NMEA signal "standardisation" etc.
Thanks also David M for your response - I sent you a separate email but seems you mailbox is full.

You can get NMEA to Seatalk converters - maybe ask a few questions on the "electronics forum" here :
http://www.cruisersforum.com/forums/...2-a-12967.html

I'm sure somebody knows how to do it -or else ask your supplier of choice.

I know you can get one waypoint at a time into a raymarine unit from a 3rd party device, but getting a whole route in can be difficult.

Good Luck

regards


Alan

[GordMay]

SeaTalk is a proprietary solution of Autohelm and not compatible with NMEA or CAN. Unfortunately Raymarine keeps the technical details of SeaTalk secret. To assist users who want to develop hard- or software to connect their devices to the SeaTalk bus these pages uncover some of the mysteries. Part 3 adds hints how to interface SeaTalk with a PC. The information is unsupported by Raymarine and was found by watching the bits traveling on the bus.

SeaTalk Technical Reference ~ by Thomas Knauf
Thomas Knauf ****SeaTalk Technical Reference

Including Part 3: Processing SeaTalk Data with a PC:
Thomas Knauf ****SeaTalk Technical Reference

[waikikin]

Fard12, how many of these masts have you seen fail? I got a busted one laying in my yard that had the side kinda blow out after a poorly executed composite diamond tang cracked & let go of the wire leaving a long length of the stick to get outa shape & fall down. I'm gunna scab some track & other fittings off it but reckon it aint worth repairing. I'd like to here how these other masts have been failing, cos it seems as you've represented that poor construction & backyard noideaengineering are the main cause rather than the material choice. All the best from Jeff.

[Fard12]

The masts that I have seen come down have been all composite/wood.
All home made and poorly finished.
They all weigh a ton as well. A well-made alloy mast is lighter. (Apart from the true carbon professionally built mast)
However you just can’t tell some people that all that extra weight they just have put in the mast you may as well put in a non-rotating alloy rig. And that would perform better that what they have built anyway.
The plans that are out there for carbon home made masts are great not. They all say how easy it is to build (a load of BS) how light it will be etc. They lull the homebuilder into a false sense security.
If you can’t afford to purchase a mast from a professional mast maker and are considering building one out of composites then you may as well take all that money a flush it down the can.
Instead look at purchasing a kit mast that you put together yourself. That way all your rigging will be sized correctly not to mention the fact you will have the correct moments in your mast to start with. PS it will also be cheaper this way that a composite mast. Yes even a home built one.

[waikikin]

Fard12, thanks for the reply, I reckon your spot on on the alu kit being the go for goodness & cost, I put a couple together years ago from Alspar & from Sparcraft & they where pretty good & I'll go that way again although I dont think the're around anymore, do you know of some good kit suppliers, I met a Kiwi shipwright a few years back that was bringing 3-4 mast kits from "home" to east coast Aus' for good prices but don't know him anymore or his source.I got some prices a while back from a couple of the SE Queensland mastbuilders/riggers which looked OK but just after some more angles on rigging.The rig I got laying around I just kinda came by for the trouble of picking it up but I think its "heavy" & has obviously represented its structural defiscience to great effect, but I still got some good stuff off it(that was bought from the "shop"). Hey any one want a free cedar - carbon stick, you'll save me the "tipping" fees. All the best from Jeff.