Aftmast rigs???

[DennisRB]

Nice thread! I was in Perth recently and I saw that cat. I didnt know it had a mast that could be lowered, but it makes sense as Perth has a some great waterways all blocked by low bridges. What design was the yellow cat?

 

[Spiv]

Nice thread! I was in Perth recently and I saw that cat. I didnt know it had a mast that could be lowered, but it makes sense as Perth has a some great waterways all blocked by low bridges. What design was the yellow cat?

The current owner broke the original rotating, lowering, carbon mast and replaced it with a much cheaper, fixed alloy mast. So now he cannot do river charters.

The design is a Schionning Cosmos 12.5, but I changed the roof to give me more space inside. The boat has a day charter complement of 40 pax.

 

[DennisRB]

Cool. I had it pegged as a Schionning. Something like that would be ideal.

 

[brian eiland]

Back in Perth I had a conventional cat with a lowerable mast.
My main problem was to keep it in column once the shrouds got loose as it wanted to go either to port or starboard, I solved the problem then, but it took me 15min to get set up and only 1m to lower or raise it by electric winch.
An "A" frame would be much easier.

I now have been living on a production cat for 5y, but I am still keen to build a new one with an "A" frame and the idea of having foils as in Chris White (that you just mentioned) is very attractive.
Very well worth studying and developing it.

You are exactly correct Stefano, and as you try to raise and lower an even taller mast the problems gets worst,...it really tries to go sideways (either side). I was working one one solution on our Firefly trimaran that involved splitting each shroud into two 'arms' (upside-down 'Y')to be attached to outboard ends of the crossbeams on both the front and rear. The aft 'arm' was actually rigged as a running line inboard to a small winch that could be adjusted as necessary to keep the mast (36 feet) going up straight.

It also simplified adjusting the rigging's tension, and tied the structural components of the vessel together nicely, rather than just thru fiberglass hull components.

Newick's Somersault as used a similar shroud attachment.

 

[Spiv]

The key is to have the two side stabilizing lines anchored 'in line' with the mast pivoting pin.

I solved the problem by attaching two lines to the middle of the spreaders and tying the other end to the top of the raised daggerboards using 2 block and tackle for tensioning.
it was a little 'springy' as the daggerboard flexed a little, but even on a 19m mast, the load was not large.

I had two 5m poles going from the bottom of the forestay to both side of the coachroof, they provided the fulcrum needed to lower/raise the mast over a certain angle.

I then had to swing the boom out of the way and used an electric winch (the type you use on the front bumper of 4wd vehicle) to raise and lower the mast.
I'd also changed the galvanised wire with spectra.

The mast rested on 'crutches' until it was raised again.

Once we got good at it, it took us 15~20min to get from sailing to be ready to lower the mast, then just 1min to lower or raise it.

 

[brian eiland]

The key is to have the two side stabilizing lines anchored 'in line' with the mast pivoting pin.

That of course was a good solution, but it was not to practical on that trimaran with most all of its 'attachment points' well below the level of the mast pivot point.

 

[brian eiland]

Carbon Fiber Furling Gear

Just doing a little research this morning into some of the more recent tech in carbon fiber forestays, particularly furling ones, and wanted to just record some of the links so I would remember to return for review.

http://www.carbo-link.com/furling-cables

http://www.maxspar.com/alu_carbon_genoa_profile.htm

http://www.facnor.com/uk/products/custom_products/carbon_headsail_furlers/default.asp

Perhaps I could make use of 3 carbon fiber stays in combination with a carbon fiber mast to eliminate some of the differences in expansion between dymeen and alum, and carbon that can result in the need to 'retune' the rigging in different climate conditions.
http://www.briontoss.com/spartalk/showthread.php?t=2156

 

[Kojii]

Latest location Relentless -bought by a fisher

Relentless, a North Pacific 47' experimental delta rig with aft bipod mast, designed and built by Fred Greenway, now in Newport, Oregon, one of the busiest fishing ports on west coast. Also gets kinda windy along that stretch. Yet the furcula remains intact (if shortened from original).
Let the wild speculation begin...

 

[brian eiland]

.....
Recently I moved to a new residence, and had occasion to unpack a box that contained a small model of this design that I had taken to the 2005 Miami Boat Show. It has 'renewed' my interest to 're-explore' the possibilities with this rig. I'll post a few pics of that model soon.

A few more pics of that model I unpacked not long ago...

 

[brian eiland]

...and a few more

 

[brian eiland]

A newly constructed model yacht with same is discussed at:

http://www.rcsailing.net/forum1/showthread.php?5471-Delta-rig

The boat is an RG65; class rules are (basically) 65cm LOA, 110 cm mast height, 2250 sq cm area. Typically run 1 kg with 500 gr bulb.
Cheers,
Earl

Oh, it's just a "try it and see what happens" kind of playing around -- easy to do with toy boats I doubt that Claudio would argue that it was anything more than that.
Cheers,
Earl

I went trying to locate this fellow Claudio, only to find my 'subscription' to that RC Sailing forum had expired,...so I am reapplying as I see this fellow Claudio is still quite active on that model boat forum.

Does anyone know if he ever participated in this or another forum??

 

[markstrimaran]

Thanks for the rc link. I might have my boat sailing soon. Mounting amas or akas today.

 

[brian eiland]

more Bolger's Staysail (mast aft) Rig

Lets see, I may have to reorganize this material, and/or add to it, but here are a few reference documents for Bolger's Staysail Cat.
...and a letter he writes to a client about its potential

Just looking around the internet a few days ago I ran across another photo of Bolger's experiments with an aft-mast arrangement,...this one with a full wishbone boom that reminds me somewhat of Dave Beirig's single-sided wishbone, 'CamberSpar'.

The Camber Spar™ is a device developed over 20 years ago by a sail maker to answer the need to have a way to control sail shape of self-tacking jibs. Think of it as one half of a wishbone boom seen on windsurfers, but inside the sail. When combined with full battens the Camber Spar™ provides a sail that is quiet, holds its shape in all wind angles and ranges, and self-tacks. It can even allow you to sail wing on wing without a whisker pole

I have given thought to attaching my mizzen's wishbone boom directly to its 'forestay' rather than to the mast. :?:

 

[Kojii]

Delta sails in commercial application

http://seagatesail.com/application-studies/commercial-applications/tanker/

I doubt these guys invest in this kind of effort without a thorough analysis of the ROI, but I guess it is possible they are three sheets to the wind...

 

[brian eiland]

.... but I guess it is possible they are three sheets to the wind...

FUNNY

...lets add an image to that posting of yours Kojii