Aftmast rigs???

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.

 

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

 

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.

 

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.

 

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.

 

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

 

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...

 

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

 

...and a few more

 

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??

 

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

 

more Bolger's Staysail (mast aft) Rig

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'.

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

 

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...

 

FUNNY

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