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Old 30-07-2008, 13:22   #1
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Tobago Modifications

I promised to post a few pictures of the mods I've done, so here they are.

A new 1.5 meter taller rotating wingmast and mast spanner setup

All fibre stays

Self tacking jib

Windscreen with cockpit cover, (very useful up here with all the rain) this entailed moving the winches and re rigging all lines.

A bow sprit, shown here in the folded in position.
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Old 30-07-2008, 14:34   #2
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Great pics and some very interesting mods.
The cockpit enclosure looks great without being over obtrusive.
I notice you have the radar dome mounted above and behind the cockpit and am I right in saying that the anenometer is also with the dome, what is the reason for this?
Will you need to sleeve the the fibre stays with any sort of protection to save against chafe (sorry for my ignorance on this) or are the fibre stays very resistant to chafe.
Cheers
Ian
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Old 30-07-2008, 14:35   #3
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Nice, how well do the rotating mast and self tacking jib work?
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Old 30-07-2008, 15:00   #4
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Quote:
Originally Posted by ireaney View Post
Great pics and some very interesting mods.
The cockpit enclosure looks great without being over obtrusive.
I notice you have the radar dome mounted above and behind the cockpit and am I right in saying that the anenometer is also with the dome, what is the reason for this?
Will you need to sleeve the the fibre stays with any sort of protection to save against chafe (sorry for my ignorance on this) or are the fibre stays very resistant to chafe.
Cheers
Ian

Thanks Ian. The radar dome and anemometer had to be moved from the rotating mast as they can not compensate for the mast rotation. The radar works fine, the wind instruments are useless there!

I looked into getting a masthead windsensor that can compensate for the rotation and found 3 possibilities.

B&G, Nexus and NKE. Nexus and NKE use dual compasses to compensate for the rotation, B&G a potentiometer setup. But to get true and relative wind I would need to buy some computing power, and add and extra log, as none of them are compatible with my exsisting Raymarine stuff

I might do it anyway this winter, as I like to be able to use the VMG function.

The fibre stays are chafe protected from about halfway up with a sleeve. The stays are not very chafe resistant. These will handle 11 tons of load before breaking. I didn't get them pre-streched, but it takes 10 minutes to tighten them up, just loosen off the knots, run the lines to the winches through a block, and tighten them, retie the knots... dead easy.

cheers

Alan
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Old 30-07-2008, 15:23   #5
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Originally Posted by ldrhawke View Post
Nice, how well do the rotating mast and self tacking jib work?

I have had the jib setup for a number of years, and it works really well. I decided to have the curve of the track made just a bit bigger than necessary, i.e. a slightly larger diameter than the theoretical one. This means that the jib doesn't go out as far as it was on the other tack, so I need to loosen it a bit, let the car move outboard to where I want, and then I trim the sail. The other option would be to have an extra line to control the length of travel to each side, but these catch on all protrusions. The new jib has 3 flexible battens about 50 cms long, so it keeps a great shape.

The mast works really well. I loosen the rotator lines (when I remember) prior to tacking. The mast selftacks as the rotation point of the mast is correctly chosen. When on the new tack, I need to adjust the rotation further, as the mast is only a short chord, so it needs to be slightly over-rotated for optimal lee side sail/mast shape. In hard wind I rotate it a bit more to help flatten the main a bit.

The optimal mast chord is around 10-12% of the mast + boom length if you want to sail at around 30-35 degrees relative and don't want to overotate the mast, but there wasn't enough room for such a long section, and no readily available profile.

Even hard on the wind and with the jib at about 6-7 degrees off centre, the whole mainsail is working fully.

I am really pleased with the whole setup.

When sailing in strong winds and a big chop, the lee stay flops around a bit, so I mount a "sucker", just a piece of 10 mm bungy cord that goes from the stay and back to a cleat, and tighten it up. This takes out any slack and gives a smoother ride.

I haven't tried anchoring with the wingmast yet, that might be a bit more hassle than before, but luckily we have no tides up here.

I forgot to loosen the mast in a couple of tacks, and left it on the wrong side for a bit, it cost about 2 knots out of 7 and a massive loss in pointing ability.

I had a bit of a race with a H-boat tacking up through a narrow sound in about 15 knots of wind, and I ran away from him, could point just as high but had a bit more leeway. With daggerboards it would have been even better I think.

It's a totally different and more fun boat to sail now.

Cheers

Alan
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Old 30-07-2008, 15:40   #6
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Quote:
Originally Posted by Nordic cat View Post
Thanks Ian. The radar dome and anemometer had to be moved from the rotating mast as they can not compensate for the mast rotation. The radar works fine, the wind instruments are useless there!

I looked into getting a masthead windsensor that can compensate for the rotation and found 3 possibilities.

B&G, Nexus and NKE. Nexus and NKE use dual compasses to compensate for the rotation, B&G a potentiometer setup. But to get true and relative wind I would need to buy some computing power, and add and extra log, as none of them are compatible with my exsisting Raymarine stuff

I might do it anyway this winter, as I like to be able to use the VMG function.

The fibre stays are chafe protected from about halfway up with a sleeve. The stays are not very chafe resistant. These will handle 11 tons of load before breaking. I didn't get them pre-streched, but it takes 10 minutes to tighten them up, just loosen off the knots, run the lines to the winches through a block, and tighten them, retie the knots... dead easy.

cheers

Alan
Hallo Alan I believe that Tack Tick is bringing out a masthead wind sensor ( wireless ) with compensation for the rotating mast and tack tick works well with Raymarine.
Just a thought


Greetings
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Old 30-07-2008, 21:31   #7
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Another option I've seen is to have two masthead units mounted well aft above the cockpit, (the ones I saw were mounted on a targa) and a selector switch so you always use the windward one, which is in clean air.
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Old 31-07-2008, 05:35   #8
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Originally Posted by fastcat435 View Post
Hallo Alan I believe that Tack Tick is bringing out a masthead wind sensor ( wireless ) with compensation for the rotating mast and tack tick works well with Raymarine.
Just a thought


Greetings

Thanks for the info. I have not heard much good about their instruments, maybe they have improved??

Anyone with experience out there?

Alan
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Old 31-07-2008, 05:40   #9
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Quote:
Originally Posted by 44'cruisingcat View Post
Another option I've seen is to have two masthead units mounted well aft above the cockpit, (the ones I saw were mounted on a targa) and a selector switch so you always use the windward one, which is in clean air.

That sounds like a good option if you have a wide targa. I considered a targa instead of the single mast in the centre, but it would end up way too heavy and difficult to make so that it would look nice.

I will be looking into the Nexus unit a bit more closely when I haul the boat for the winter, they also do some wireless stuff. The service here is really good, so that is a major plus.


cheers

Alan
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Old 31-07-2008, 05:56   #10
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Hi Alan
Sorry for my ignorance in this matter but the regarding the fibre stays, what diameter have you used in comparison to the original steel wire or rod?
Is the fibre soft to touch like nylon 3 braid and is it quite harsh?
I assume that the fibre stays are very UV resistant, but where you have them sleeved to safe against chafe, if you get ingress of water, is that something you have to be carefull of or is it totally resilient to water?
Finally is the sleeving a dyneema type of fabric?
Again compliments on some excellent changes, I especially like the aesthetics of the bimini and screens, congratulations.
Ian
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Old 31-07-2008, 17:28   #11
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The improvments all look well thought out and worthwhile, Alan, well done.

I'm a few months away from standing a rig on my boat, and something i've been tossing up is - to rotate or not to rotate?

Hopefully I can pick your brains to help with my decision.

How much of a gain would you estimate there is to be had by rotating the mast? For instance, have you sailed with the mast centred, trimmed the sails to optimum, then rotated the mast, trimmed again, and checked out what gain there was?

Have you come up with a solution for masthead tri lights? My thinking at the moment is that I would probably just mount a normal tri light, and make sure to centre the mast at night, so the lights lined up properly.

Is the mast ever noisy? I've heard, (but have no experience) that at anchor the mast can tend to "hunt" a little, making the control lines creak.

Any issues with running halyards and reefing lines to the cockpit? (Although yours appear to be at the mast, so you might not know.

The masthead wind transducer is another tricky one. Something that might work with your set-up is to put a "crossbar" on the vertical pole you have there, and mount a transducer on each end of it. The transducer only needs to be a little to windward to be in clean air.
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Old 31-07-2008, 21:08   #12
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Originally Posted by 44'cruisingcat View Post
How much of a gain would you estimate there is to be had by rotating the mast? For instance, have you sailed with the mast centred, trimmed the sails to optimum, then rotated the mast, trimmed again, and checked out what gain there was?
Also worth remembering that a rotating rig should help with getting sails down when you arent directly into the wind. Which can help with reefing - ie slightly off the breeze with the headsail still driving you can feather the mast and have the ability to reef

Quote:
Have you come up with a solution for masthead tri lights? My thinking at the moment is that I would probably just mount a normal tri light, and make sure to centre the mast at night, so the lights lined up properly.
I think Chris White discusses this in his Cruising Multihull book.

Quote:
Is the mast ever noisy? I've heard, (but have no experience) that at anchor the mast can tend to "hunt" a little, making the control lines creak.
On the cat I had with a rotating rig, I had a couple of padyeses in the deck and small turnbuckles that enabled me to absoluturly lock the mast for just that reason.
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Old 01-08-2008, 14:07   #13
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[quote=44'cruisingcat;188607]
Quote:
The improvments all look well thought out and worthwhile, Alan, well done.
Thanks

Quote:
I'm a few months away from standing a rig on my boat, and something i've been tossing up is - to rotate or not to rotate?

Hopefully I can pick your brains to help with my decision.

How much of a gain would you estimate there is to be had by rotating the mast? For instance, have you sailed with the mast centred, trimmed the sails to optimum, then rotated the mast, trimmed again, and checked out what gain there was?
I haven't done these tests, but will do so as soon as possible, a good idea! I expect the results would differ a bit depending on whether one uses a 95% jib, or say a 105% jib or a larger genoa. My jib is around the 95% mark. One thing I have noticed is that I can now sheet my jib in alot further without it causing the main to flutter just aft of the mast, I reckon my jib sheet angle is down to around 6-8 degrees, but I need to take a marker and then actually measure the sheet angle.

Quote:
Have you come up with a solution for masthead tri lights? My thinking at the moment is that I would probably just mount a normal tri light, and make sure to centre the mast at night, so the lights lined up properly.
I only have a white on top at present. I have actually decided to do what you suggest, but at present I have mounted Lopolights, see attached picture.


Quote:
Is the mast ever noisy? I've heard, (but have no experience) that at anchor the mast can tend to "hunt" a little, making the control lines creak.
No noise. I haven't tried anchoring in anything over around 6 knots of wind, so can't say. For creaking lines, I normally slack them off a bit and then take up the slack with some bungy cord, works well mostly. My topping lift starts humming if it's too tight, caused by the Karmann votices being shed, and a bungy to the boom sorts that out.

Quote:
Any issues with running halyards and reefing lines to the cockpit? (Although yours appear to be at the mast, so you might not know.
I had made the possibility of running the halyard and reefing lines back, on the old rig, and it can also be done on this one, but I never used it. A strap around the mast and a couple of blocks will do for the reefing lines. The halyard can be turned over the winch on the mast. I had a fixed turning block for the halyard on the old mast, but the friction was too much for raising the mainsail by hand, but for reefing it would be nice.


Quote:
The masthead wind transducer is another tricky one. Something that might work with your set-up is to put a "crossbar" on the vertical pole you have there, and mount a transducer on each end of it. The transducer only needs to be a little to windward to be in clean air.[/
quote]


It is a nice idea, thanks. I will not do this, as the mast is not very stiff, and easily starts shaking. Adding any more weight up there will make the problem worse, and I can't find a neat way to stiffen it up. I will weld a piece of flat iron ( say 3 mm thickness and 20 mm high) to both the fore and aft of the tube this winter, as I need to dismount it anyway, didn't have time to send it to be electro-polished, so only did a manual polish


cheers

Alan
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Old 01-08-2008, 14:38   #14
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Bow sprit for a Tobago

I have been using a bow sprit for a number of years for the gennaker and Code 0.

I made the fitting on the forebeam, and the aft of the sprit, so that the sprit stays roughly horisontal, that is the reason for the odd shape of the sprit end fitting. The sprit is a piece of 80 mm carbon tube, end fittings in 316 ss.

I now have fixed 10 mm stainless steel stays, I have tried other solutions using Dyneema and blocks, but the blocks got damaged, and I didn't want to fork out 250 for 2 good blocks... The length of the sprit is around a meter, so the sprit is stored on the seagull striker with the furler at the bottom.

To handle the forces pushing the forebeam back, it was neccesary to stiffen it. The way I chose was to mount a nearly horisontal "seagull striker" that could be mounted under the tramp netting, as I didn't want to have a fore/aft tube under the tramp in case one falls on it.
The wires are attached to the ends of the crossbeam, and the the wires tightened up. It's worked well, without this I was getting 3-4 cms aft flex in the crossbeam.

The stays are attached to the fittings on the outside of the bows a bit above the waterline as shown.

Cheers

Alan
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Old 02-08-2008, 08:50   #15
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Another option I've seen is to have two masthead units mounted well aft above the cockpit, (the ones I saw were mounted on a targa) and a selector switch so you always use the windward one, which is in clean air.
I have a friend that has this setup on his F41 "Endless Summer" (that's probably the one you saw) and he is not to impressed with its performance. I was going to do that kind of setup on my Lidgard 43 but have decided not to go this route.
My next plan is to use a windsurfer mast glassed to the aft beam and sticking up on a 30 degree angle almost like an over sized flag pole, I think that Ocean Planet has something like that for the radar, that should get the transducer away from the wind shadow of the main. I hope that mounting it up there will work better, it won't be perfect especially DDW but it's worth a try.

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