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Getting a GBE to Cat 3


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#11 NZTiger

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Posted 12 April 2019 - 10:41 AM

Thanks for the help. 

 

I have a fairly good understanding of the safety gear (flares, EPIRB, grab bag, rig cutting tools etc) requirements. We're at Cat 5 at the moment (except for the depth sounder) and purchased a lot of the Cat 3 safety equipment when we sailed the boat to Auckland from the far north.

 

In a nutshell my issues are:

- Design/build the electrical system from scratch which covers: Nav lights, tiller pilot, bilge pumps, VHF radio, depth sounder etc  (looks to me like electric bilge pumps are not required for cat 3)

- Where do you put the nav lights on an 8.5m catamaran?

- What's the ideal layout and construction of a good jackstay system?

- What is the solution for guardrail and lifeline requirements for an 8.5 multihull?  I would feel safer not having them at all on a multihull in the event of a capsize instead relying on the jackstays.


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#12 Adrianp

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Posted 12 April 2019 - 11:28 AM

Electrics on an 8.5 are a bit of a pain in the arse as they they are constantly getting wet.

 

Manual bilge pumps only required and on Freedom these were portable being mounted on Plywood. Good buckets are what you actually use to bail water out of a GBE. 

 

On Freedom, we mounted the switchboard and connections inside Systema Boxs to keep them dry and give them the best chance of surviving a capsize. Another tricky bit is to get the wires from one hull to the other. Voom just had the separate electrical system in each hull using one of those little 7ah 12v sealed batterys. Freedom had it all from one hull and wires going through the beam - which let water into the hulls at times.

 

Voom had a handheld depthsounder, Freedom had a fishfinder with stern mounter transducer on a removable slider.

 

Nav lights on the outside of the hull, just in front of the main beam, stern light on one of the transoms. Perhaps look at the Railblazer battery LED lights as they might be acceptable.

 

Jackstays - just one each side from the rear beam to the front beam by the hulls. On Freedom we rigged these that they were lashed to the back beam and could be cut free to then become a righting bridal off the front beam. 

 

No Lifelines needed for a CAT 3 multi, just the Jacklines. 


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Formally Freeeeeeeeeedom but we've got our new boat - Lady Nada - https://sailingladyn...wordpress.com/ 


#13 Freedom GBE

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Posted 12 April 2019 - 09:31 PM

Easy. Not allowed to use the motor, no need for a steaming light right, duct tape and torch will do.

 

Tricky bit. The second reef will invert the mast, need inner forestay. Drill 5mm hole in center, front of spreaders, tie 5 mm Dyneema, attach pulley system on front beam and hook to 5mm Dyneema. The inner forestay needs to come of during tacks and taken through the dork to the other side. 

 

More trickery.  Drop and running over kite at speed happens to everyone, something has to give. Need a piece of string, strong enough to hold up prod during normal drops but will snap under load and save the whole front beam from breaking. Erice calls it the frangible fuse. 


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#14 NZTiger

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Posted 15 April 2019 - 10:00 AM

Easy. Not allowed to use the motor, no need for a steaming light right, duct tape and torch will do.

 

Tricky bit. The second reef will invert the mast, need inner forestay. Drill 5mm hole in center, front of spreaders, tie 5 mm Dyneema, attach pulley system on front beam and hook to 5mm Dyneema. The inner forestay needs to come of during tacks and taken through the dork to the other side. 

 

More trickery.  Drop and running over kite at speed happens to everyone, something has to give. Need a piece of string, strong enough to hold up prod during normal drops but will snap under load and save the whole front beam from breaking. Erice calls it the frangible fuse. 

Just for clarification on the inner forestay issue. 

 

When the main is deep reefed, the tension on the mainsail pulls the bottom of the mast towards the stern which gives the main an inefficient shape? Is there a safety/gear breakage issue as well?

 

Given my decidedly average sailing skills and that the cat 3 racing we'll be doing will be more about completion than performance, I wouldn't be too concerned about sailing performance in a race that's blowing hard unless we're talking about turning the boat into a dangerously uncontrollable pig in a crazy sea state.


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#15 TimB

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Posted 15 April 2019 - 10:40 AM

NZtiger, its a breakage issue..... when the main is reefed to or past the second reef the rig becomes a "masthead with no lowers". So the middle of the mast is unsupported (backwards) and can easily invert, pop backwards and in the extreme break. the temporary inner forestay stops this. it also  stops the  mast from bowing back which increases the mainsail draft, which you don't want when reefed this far. flat as possible is best.

 

cheers tb


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#16 Freedom GBE

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Posted 15 April 2019 - 10:29 PM

Inner forestay is unwritten item that is checked by good inspectors, some inspectors will get justifiably slightly angry if you dont have one fitted properly.

 

I think you got the picture and TB explains it well. A deep reef puts the top of the mainsail well below the forestay. The forestay is pulling the top of the mast forward and the main is pulling it backwards, bending and easily breaks the mast. Even more when it is rotated a lot.

 

Had to use inner forestay when it was suddenly gusting over 40 knots, not racing anymore just in survival mode. Trying to sail upwind, hobbie horsing into 2m chop, a lot more fun when the rig stays up. Getting home in one piece on those ocasions is celebrated more than winning. 


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#17 NZTiger

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Posted 16 April 2019 - 09:02 AM

Great, thank you. 

 

So far my to do list consists of:

- 12 additions/modifications to the boat, rigging or sails

- 35 items of safety equipment/tools/navigation aids/medical gear

 

I'm guessing the sail/rigging modifications and electrics will be the two biggies.  The rest should be fairly straight forward. I think I'll go for two independent electrical systems, one in each hull to avoid running cables between the hulls.  Given the way we use the boat, I would like most of the cat 3 modifications to be removed when not in use and then easily re-installed when required.

 

Is there a straight forward 'alternative steering method' used by 8.5 catamarans? I assume you still need one for a multihull despite being able to make the two rudders completely independent with a crescent if one failed completely.


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#18 Clipper

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Posted 16 April 2019 - 10:03 AM

I also counted the other rudder as alternative steering. And l lost one in the coastal, we just disconnected the bar and carried on.

 

As for the rigging being a big one, not really, I drilled some holes and fitted a backing plate for a t fitting up the rig while on mooring. A dynex loop to double around the front beam and a few blocks to allow adjustment (make it tight) is all that is required.  Just use a dynex inner forestay.


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#19 GregW

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Posted 16 April 2019 - 07:05 PM

Ken, I recall you had a small jib (storm jib?) the you used to hang from the temp stay. Can you please describe the setup for that and pics if poss?


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#20 Clipper

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Posted 16 April 2019 - 07:42 PM

Dont think i have pics, but will have a go at explaining it.

Inner forestay connected mid way between hounds and spreaders. Forestay was dynex with a poly cover so metal hanks wouldnt chafe too much. Lower end had a low friction ring in it. Looped a piece of dynex around beam on one side of forestay, up through ring and then had a 4:1 pulley setup for tension.

Mast rotation locked in centre to avoid issues with dork when tacking, also depowered the rig massively.

Pull on tensioner until main forestay slack.

Hoist storm jib on normal jib halyard (was way higher than top of inner forestay - didnt seem to be an issue)

Put both reefs in.

Hang on.

Was used in anger a number of times, most memorably a singlehanded blast back from kawau while as hung over as f&ck. Think it was 1 hour 15 mins from bee hive to north head? Actually, i must have a photo, a crew.org guy took some as i went past. I’ll try and find.
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